‡‡‡ Chapter 4 was amended by 
Local Law 
77 
of 2023
. This law has an effective
 date of June 10, 2023.
CHAPTER 4
VENTILATION 
SECTION MC 401
GENERAL
401.1 Scope.
This chapter shall govern the ventilation of spaces within a building intended to be occupied. Mechanical exhaust 
systems, including exhaust systems serving clothes dryers and cooking appliances; hazardous exhaust systems; dust, stock and 
refuse conveyor systems; subslab soil exhaust systems; smoke control systems; energy recovery ventilation systems and other 
systems specified in Section 502 shall comply with Chapter 5.
401
.2 Ventilation required.
Habitable and occupiable spaces shall be provided with ventilation in accordance with this section.
1.
Every 
occupiable
space shall be:
1.1.
Naturally ventilated in accordance with Section 402 and mechanically exhausted in 
accordance with Table 403.3.1.1; 
or
1.2.
Mechanically ventilated in accordance with Section 403.
2.
All habitable spaces and occupiable spaces provided with air conditioning shall be mechanically ventilated in accordance 
with Section 403.
3.
Every habitabl
e space
shall be naturally ventilated in accordance with Section 402.
4.
Every habitable space shall be mechanically ventilated if required by Section 403
. 
Ambulatory care facilities (Group B) and Group I
-
2 occupancies shall be ventilated by mechanical means in accordance 
with Section 407.
401.3 When required.
Ventilation shall be provided during the periods that the room or space is occupied or during operation 
of gas appliances.
‡‡‡
401.4 Intake opening location.
Ventilation air intake openings shall compl
y with all of
the following:
1.
Intake 
openings
shall be located
not less than 10 feet (3048 mm) from lot lines or buildings on the same lot. For buildings 
on lots measuring less than 20 feet (6096 mm) in width, intake openings shall be located at the cent
erline between lot 
lines. Where openings front on a street or public way, the distance shall be measured to the centerline of the street or 
public way.
2.
Outdoor air intakes for office occupancies having occupied floors located more than 75 feet (22 860 mm) above the 
lowest level of fire department vehicle access serving spaces above the second story and serving spaces greater than 
10,000 square feet (929 m
2
) of floor area shall be located at least 20 feet (6096 mm) above ground level, at least 30 feet 
(91
44 mm) from exhaust outlets and other exhaust discharges, and at least 20 feet (6096 mm) from areas that may collect 
vehicular exhaust, such as off street loading bays.
3.
Mechanical and gravity outdoor air intake openings shall be located not less than 10
feet (3048 mm) horizontally from 
any hazardous or noxious contaminant source, such as vents, exhausts (including but not limited to exhaust from dry 
cleaning establishments, spray booths, and cooling towers), streets, alleys, parking lots and loading dock
s, except as 
specified in Item 3 
of 
Section 501.3.1. Outdoor air intake openings shall be permitted to be located less than 10 feet (3048 
mm) horizontally from streets, alleys, parking lots and loading docks provided that the openings are located not less 
than 
25 feet (7620 mm) vertically above such locations. Where openings front on a street or public way, the distance shall be 
measured 
to the centerline 
of the street or public way.
4.
Where the requirements of Item 3 above cannot be achieved, 
intake
openings shall be located not less than 3 feet (914.4 
mm) below contaminant sources where such sources are located within 10 feet (3048 mm) of the opening. 
5.
Intake openings in Group I occupancies shall comply with ANSI/ASHRAE/ASHE 170, as require
d.
VENTILATION
6.
Intake openings on structures in flood hazard areas shall comply with the additional requirements of Appendix G of the 
New York City Building Code.
Exception: 
Group R
-
3 occupancies are not required to comply with Section 401.4. 
401.4.1 Required damp
ers in intake openings.
Outdoor air intakes shall be provided with dampers in accordance with 
Chapter 6.
401.5 Intake opening protection.
Air intake openings that terminate outdoors shall be protected with 
corrosion
-
resistant 
screens, louvers or grilles. O
penings in louvers, grilles and screens shall be sized in accordance with Table 401.5, and shall be 
protected against local weather conditions. Outdoor air intake openings located in exterior walls shall meet the provisions f
or 
exterior wall opening protec
tives in accordance with Section 705 of the 
New York City 
Building Code.
TABLE 401.5
OPENING SIZES IN LOUVERS, GRILLES AND SCREENS 
PROTECTING OUTDOOR EXHAUST AND AIR INTAKE 
OPENINGS
OUTDOOR OPENING TYPE
MINIMUM AND MAXIMUM 
OPENING SIZES IN 
LOUVERS, 
GRILLES AND SCREENS 
MEASURED IN ANY 
DIRECTION
Intake openings in
residential oc-
cupancies
Not < 
1
/
4
inch and not > 
1
/
2
inch
Intake openings in other
than resi-
dential occupancies
> 
1
/
4
inch and not > 1 inch
For SI: 1 inch = 25.4 mm.
401.6 
Contaminant sources.
Stationary local sources 
producing
air
-
borne particulates, heat, odors, fumes, spray, vapors, 
smoke or gases in such quantities as to be irritating or injurious to health shall be provided with an exhaust system in 
accordance
with Chap
ter 5 or a means of collection and removal of the contaminants. Such exhaust shall discharge directly to an approved 
location at the exterior of the building.
401.6.1 Wind
-
driven rain.
All exterior louvers for building ventilation systems shall conform to the requirements of Chap-
ter 16 of the 
New York City Building Code
, where applicable, and the following:
1.
Comply with the requirements of AMCA 550. Louvers shall comply with the intru
sion requirements of wind
-
driven 
rain without the use of a damper. Outdoor air intake openings located in exterior walls shall meet the provisions for 
exterior wall opening protectives in accordance with Chapter 16 of the 
New York City Building Code
; 
or
2.
Be installed on a plenum configured to intercept any wind
-
driven rain penetrating the louver and to prevent the rain 
from entering the building ductwork system. Such plenum shall be waterproofed and equipped with a drainage system 
to convey water penetrat
ing the louver directly to the outdoors or in accordance with the 
New York City Plumbing 
Code
.
SECTION MC 402
NATURAL VENTILATION
402.1
General.
Natural ventilation of occupiable and habitable spaces
shall comply with Chapter 12 of the 
New York City 
Build
ing Code.
402.2 Reserved.
402.3 Reserved.
402.4 Reserved.
SECTION 
MC 
403
MECHANICAL VENTILATION
‡‡‡ Chapter 4 was amended by 
Local Law 
77 
of 2023
. This law has an effective
 date of June 10, 2023.
CHAPTER 4
VENTILATION 
SECTION MC 401
GENERAL
401.1 Scope.
This chapter shall govern the ventilation of spaces within a building intended to be occupied. Mechanical exhaust 
systems, including exhaust systems serving clothes dryers and cooking appliances; hazardous exhaust systems; dust, stock and 
refuse conveyor systems; subslab soil exhaust systems; smoke control systems; energy recovery ventilation systems and other 
systems specified in Section 502 shall comply with Chapter 5.
401
.2 Ventilation required.
Habitable and occupiable spaces shall be provided with ventilation in accordance with this section.
1.
Every 
occupiable
space shall be:
1.1.
Naturally ventilated in accordance with Section 402 and mechanically exhausted in 
accordance with Table 403.3.1.1; 
or
1.2.
Mechanically ventilated in accordance with Section 403.
2.
All habitable spaces and occupiable spaces provided with air conditioning shall be mechanically ventilated in accordance 
with Section 403.
3.
Every habitabl
e space
shall be naturally ventilated in accordance with Section 402.
4.
Every habitable space shall be mechanically ventilated if required by Section 403
. 
Ambulatory care facilities (Group B) and Group I
-
2 occupancies shall be ventilated by mechanical means in accordance 
with Section 407.
401.3 When required.
Ventilation shall be provided during the periods that the room or space is occupied or during operation 
of gas appliances.
‡‡‡
401.4 Intake opening location.
Ventilation air intake openings shall compl
y with all of
the following:
1.
Intake 
openings
shall be located
not less than 10 feet (3048 mm) from lot lines or buildings on the same lot. For buildings 
on lots measuring less than 20 feet (6096 mm) in width, intake openings shall be located at the cent
erline between lot 
lines. Where openings front on a street or public way, the distance shall be measured to the centerline of the street or 
public way.
2.
Outdoor air intakes for office occupancies having occupied floors located more than 75 feet (22 860 mm) above the 
lowest level of fire department vehicle access serving spaces above the second story and serving spaces greater than 
10,000 square feet (929 m
2
) of floor area shall be located at least 20 feet (6096 mm) above ground level, at least 30 feet 
(91
44 mm) from exhaust outlets and other exhaust discharges, and at least 20 feet (6096 mm) from areas that may collect 
vehicular exhaust, such as off street loading bays.
3.
Mechanical and gravity outdoor air intake openings shall be located not less than 10
feet (3048 mm) horizontally from 
any hazardous or noxious contaminant source, such as vents, exhausts (including but not limited to exhaust from dry 
cleaning establishments, spray booths, and cooling towers), streets, alleys, parking lots and loading dock
s, except as 
specified in Item 3 
of 
Section 501.3.1. Outdoor air intake openings shall be permitted to be located less than 10 feet (3048 
mm) horizontally from streets, alleys, parking lots and loading docks provided that the openings are located not less 
than 
25 feet (7620 mm) vertically above such locations. Where openings front on a street or public way, the distance shall be 
measured 
to the centerline 
of the street or public way.
4.
Where the requirements of Item 3 above cannot be achieved, 
intake
openings shall be located not less than 3 feet (914.4 
mm) below contaminant sources where such sources are located within 10 feet (3048 mm) of the opening. 
5.
Intake openings in Group I occupancies shall comply with ANSI/ASHRAE/ASHE 170, as require
d.
VENTILATION
6.
Intake openings on structures in flood hazard areas shall comply with the additional requirements of Appendix G of the 
New York City Building Code.
Exception: 
Group R
-
3 occupancies are not required to comply with Section 401.4. 
401.4.1 Required damp
ers in intake openings.
Outdoor air intakes shall be provided with dampers in accordance with 
Chapter 6.
401.5 Intake opening protection.
Air intake openings that terminate outdoors shall be protected with 
corrosion
-
resistant 
screens, louvers or grilles. O
penings in louvers, grilles and screens shall be sized in accordance with Table 401.5, and shall be 
protected against local weather conditions. Outdoor air intake openings located in exterior walls shall meet the provisions f
or 
exterior wall opening protec
tives in accordance with Section 705 of the 
New York City 
Building Code.
TABLE 401.5
OPENING SIZES IN LOUVERS, GRILLES AND SCREENS 
PROTECTING OUTDOOR EXHAUST AND AIR INTAKE 
OPENINGS
OUTDOOR OPENING TYPE
MINIMUM AND MAXIMUM 
OPENING SIZES IN 
LOUVERS, 
GRILLES AND SCREENS 
MEASURED IN ANY 
DIRECTION
Intake openings in
residential oc-
cupancies
Not < 
1
/
4
inch and not > 
1
/
2
inch
Intake openings in other
than resi-
dential occupancies
> 
1
/
4
inch and not > 1 inch
For SI: 1 inch = 25.4 mm.
401.6 
Contaminant sources.
Stationary local sources 
producing
air
-
borne particulates, heat, odors, fumes, spray, vapors, 
smoke or gases in such quantities as to be irritating or injurious to health shall be provided with an exhaust system in 
accordance
with Chap
ter 5 or a means of collection and removal of the contaminants. Such exhaust shall discharge directly to an approved 
location at the exterior of the building.
401.6.1 Wind
-
driven rain.
All exterior louvers for building ventilation systems shall conform to the requirements of Chap-
ter 16 of the 
New York City Building Code
, where applicable, and the following:
1.
Comply with the requirements of AMCA 550. Louvers shall comply with the intru
sion requirements of wind
-
driven 
rain without the use of a damper. Outdoor air intake openings located in exterior walls shall meet the provisions for 
exterior wall opening protectives in accordance with Chapter 16 of the 
New York City Building Code
; 
or
2.
Be installed on a plenum configured to intercept any wind
-
driven rain penetrating the louver and to prevent the rain 
from entering the building ductwork system. Such plenum shall be waterproofed and equipped with a drainage system 
to convey water penetrat
ing the louver directly to the outdoors or in accordance with the 
New York City Plumbing 
Code
.
SECTION MC 402
NATURAL VENTILATION
402.1
General.
Natural ventilation of occupiable and habitable spaces
shall comply with Chapter 12 of the 
New York City 
Build
ing Code.
402.2 Reserved.
402.3 Reserved.
402.4 Reserved.
SECTION 
MC 
403
MECHANICAL VENTILATION
VENTILATION
403.1 Ventilation system.
Mechanical ventilation shall be 
provided
by a method of supply air and return or exhaust air. The 
amount of supply air shall be approximately equal to the amount of return and exhaust air. The system shall not be 
prohibited
from producing negative or positive pressure; such pressures shall not r
esult in door opening forces in excess of those indicated 
in the 
New York City Building Code
and shall not prevent doors from closing as required by the 
New York City Building Code
. 
The 
method
to convey ventilation air shall be designed and installed in ac
cordance with Chapter 6.
403.2 Outdoor air required.
The minimum outdoor airflow rate shall be determined in accordance with Section 403.3.1.1.
Exception:
The minimum required rate of outdoor air may be reduced where the registered design professional demo
nstrates 
that an engineered ventilation system is designed in accordance with ASHRAE 62.1 
Indoor Air Quality Procedure
.
403.2.1 Recirculation of air.
The outdoor air required by Section 403.3.1.1 shall not be recirculated. Air in excess of that 
required by
Section 403.3.1.1 shall not be prohibited from being recirculated as a component of supply air to building spaces, 
except that:
1.
Ventilation air shall not be recirculated from one dwelling 
unit 
to another or to dissimilar occupancies.
2.
Supply air to a
swimming pool and associated deck areas shall not be recirculated unless such air is 
dehumidified
to 
maintain the relative humidity of the area at 60 percent or less. Air from this area shall not be recirculated to other 
uses or occupancies
.
3.
Where mech
anical exhaust is required by Note b in Table 403.3.1.1, recirculation of air from such spaces shall be 
prohibited. Recirculation of air that is contained completely within such spaces shall not be prohibited. Where recir-
culation of air is prohibited, all 
air supplied to such spaces shall be exhausted, including any air in excess of that 
required by Table 403.3.1.1.
4.
Where mechanical exhaust is required by Note g in Table 403.3.1.1, mechanical exhaust is required and recirculation 
is prohibited. Recircula
tion of air that is contained completely within such spaces shall not be prohibited.
403.2.2 Transfer air.
Except where recirculation from such spaces is prohibited by Table 403.3.1.1, air transferred from 
occupiable spaces is not prohibited from serving a
s makeup air for required exhaust systems in such spaces as kitchens, 
baths, toilet rooms, elevators and smoking lounges. The amount of transfer air and exhaust air shall be sufficient to provide
the flow rates as specified in Section 403.3.1.1. The requir
ed outdoor airflow rates specified in Table 403.3.1.1 shall be 
introduced directly into such spaces or into the occupied spaces from which air is transferred or a combination of both.
403.3 Outdoor air and local exhaust airflow rates. 
Buildings that are no
t more than three stories in height above grade plane, 
and that (i) are within Occupancy Group R
-
2 or Occupancy Group R
-
3, (ii) are adult homes or enriched living housing as 
described in Section 308.3.1 of the 
New York City Building Code,
within Occupancy 
Group I
-
1 and have 16 occupants or fewer, 
or (iii) are community residences or intermediate
-
care facilities as described in Section 308.3.2 of the 
New York City Building 
Code,
shall be provided with outdoor air and local exhaust in accordance with Section 
403.3.1.1.2. All other buildings intended 
to be occupied shall be provided with outdoor air and local exhaust in accordance with Sections 403.3.1.1 through 403.3.1.6.
403.3.1 Reserved.
403.3.1.1 Outdoor airflow rate. 
Ventilation systems shall be designed t
o have the capacity to supply the minimum 
outdoor airflow rate determined in accordance with this section. In each occupiable space and, where required, each 
habitable space, the ventilation system shall be designed to deliver the required rate of outdoor 
airflow to the breathing 
zone. The occupant load utilized for design of the ventilation system shall be
not less than the number 
determined
from 
the estimated maximum occupant load rate 
indicated
in Table 403.3.1.1
. 
Ventilation rates for 
occupancies not represented 
in Table 403.3.1.1
shall be those for a listed occupancy classification that is most similar in terms of occupant density, 
activities and building construction; or shall be determined by an approved engineering analysis. The ven
tilation system 
shall be designed to supply the required rate of ventilation air continuously 
during
the period the building is occupied, 
except as otherwise stated in other provisions of the code.
With the exception of non
-
tobacco hookah establishments, t
he ventilation rates in Table 403.3.1.1
are based on the 
absence of smoking in occupiable spaces. Where smoking is anticipated in a space other than a non
-
tobacco hookah 
establishment, the ventilation system serving the space shall be designed to provide v
entilation over and above that re-
quired by Table 403.3.1.1
in accordance with accepted engineering practice.
Exceptions:
1.
The occupant load is not required to be 
determined 
based on the estimated maximum occupant load rate indi-
cated in Table 403.3
.1.1 wh
ere 
approved statistical data 
documents
the accuracy of an alternate anticipated 
occupant load.
‡‡‡ Chapter 4 was amended by 
Local Law 
77 
of 2023
. This law has an effective
 date of June 10, 2023.
CHAPTER 4
VENTILATION 
SECTION MC 401
GENERAL
401.1 Scope.
This chapter shall govern the ventilation of spaces within a building intended to be occupied. Mechanical exhaust 
systems, including exhaust systems serving clothes dryers and cooking appliances; hazardous exhaust systems; dust, stock and 
refuse conveyor systems; subslab soil exhaust systems; smoke control systems; energy recovery ventilation systems and other 
systems specified in Section 502 shall comply with Chapter 5.
401
.2 Ventilation required.
Habitable and occupiable spaces shall be provided with ventilation in accordance with this section.
1.
Every 
occupiable
space shall be:
1.1.
Naturally ventilated in accordance with Section 402 and mechanically exhausted in 
accordance with Table 403.3.1.1; 
or
1.2.
Mechanically ventilated in accordance with Section 403.
2.
All habitable spaces and occupiable spaces provided with air conditioning shall be mechanically ventilated in accordance 
with Section 403.
3.
Every habitabl
e space
shall be naturally ventilated in accordance with Section 402.
4.
Every habitable space shall be mechanically ventilated if required by Section 403
. 
Ambulatory care facilities (Group B) and Group I
-
2 occupancies shall be ventilated by mechanical means in accordance 
with Section 407.
401.3 When required.
Ventilation shall be provided during the periods that the room or space is occupied or during operation 
of gas appliances.
‡‡‡
401.4 Intake opening location.
Ventilation air intake openings shall compl
y with all of
the following:
1.
Intake 
openings
shall be located
not less than 10 feet (3048 mm) from lot lines or buildings on the same lot. For buildings 
on lots measuring less than 20 feet (6096 mm) in width, intake openings shall be located at the cent
erline between lot 
lines. Where openings front on a street or public way, the distance shall be measured to the centerline of the street or 
public way.
2.
Outdoor air intakes for office occupancies having occupied floors located more than 75 feet (22 860 mm) above the 
lowest level of fire department vehicle access serving spaces above the second story and serving spaces greater than 
10,000 square feet (929 m
2
) of floor area shall be located at least 20 feet (6096 mm) above ground level, at least 30 feet 
(91
44 mm) from exhaust outlets and other exhaust discharges, and at least 20 feet (6096 mm) from areas that may collect 
vehicular exhaust, such as off street loading bays.
3.
Mechanical and gravity outdoor air intake openings shall be located not less than 10
feet (3048 mm) horizontally from 
any hazardous or noxious contaminant source, such as vents, exhausts (including but not limited to exhaust from dry 
cleaning establishments, spray booths, and cooling towers), streets, alleys, parking lots and loading dock
s, except as 
specified in Item 3 
of 
Section 501.3.1. Outdoor air intake openings shall be permitted to be located less than 10 feet (3048 
mm) horizontally from streets, alleys, parking lots and loading docks provided that the openings are located not less 
than 
25 feet (7620 mm) vertically above such locations. Where openings front on a street or public way, the distance shall be 
measured 
to the centerline 
of the street or public way.
4.
Where the requirements of Item 3 above cannot be achieved, 
intake
openings shall be located not less than 3 feet (914.4 
mm) below contaminant sources where such sources are located within 10 feet (3048 mm) of the opening. 
5.
Intake openings in Group I occupancies shall comply with ANSI/ASHRAE/ASHE 170, as require
d.
VENTILATION
6.
Intake openings on structures in flood hazard areas shall comply with the additional requirements of Appendix G of the 
New York City Building Code.
Exception: 
Group R
-
3 occupancies are not required to comply with Section 401.4. 
401.4.1 Required damp
ers in intake openings.
Outdoor air intakes shall be provided with dampers in accordance with 
Chapter 6.
401.5 Intake opening protection.
Air intake openings that terminate outdoors shall be protected with 
corrosion
-
resistant 
screens, louvers or grilles. O
penings in louvers, grilles and screens shall be sized in accordance with Table 401.5, and shall be 
protected against local weather conditions. Outdoor air intake openings located in exterior walls shall meet the provisions f
or 
exterior wall opening protec
tives in accordance with Section 705 of the 
New York City 
Building Code.
TABLE 401.5
OPENING SIZES IN LOUVERS, GRILLES AND SCREENS 
PROTECTING OUTDOOR EXHAUST AND AIR INTAKE 
OPENINGS
OUTDOOR OPENING TYPE
MINIMUM AND MAXIMUM 
OPENING SIZES IN 
LOUVERS, 
GRILLES AND SCREENS 
MEASURED IN ANY 
DIRECTION
Intake openings in
residential oc-
cupancies
Not < 
1
/
4
inch and not > 
1
/
2
inch
Intake openings in other
than resi-
dential occupancies
> 
1
/
4
inch and not > 1 inch
For SI: 1 inch = 25.4 mm.
401.6 
Contaminant sources.
Stationary local sources 
producing
air
-
borne particulates, heat, odors, fumes, spray, vapors, 
smoke or gases in such quantities as to be irritating or injurious to health shall be provided with an exhaust system in 
accordance
with Chap
ter 5 or a means of collection and removal of the contaminants. Such exhaust shall discharge directly to an approved 
location at the exterior of the building.
401.6.1 Wind
-
driven rain.
All exterior louvers for building ventilation systems shall conform to the requirements of Chap-
ter 16 of the 
New York City Building Code
, where applicable, and the following:
1.
Comply with the requirements of AMCA 550. Louvers shall comply with the intru
sion requirements of wind
-
driven 
rain without the use of a damper. Outdoor air intake openings located in exterior walls shall meet the provisions for 
exterior wall opening protectives in accordance with Chapter 16 of the 
New York City Building Code
; 
or
2.
Be installed on a plenum configured to intercept any wind
-
driven rain penetrating the louver and to prevent the rain 
from entering the building ductwork system. Such plenum shall be waterproofed and equipped with a drainage system 
to convey water penetrat
ing the louver directly to the outdoors or in accordance with the 
New York City Plumbing 
Code
.
SECTION MC 402
NATURAL VENTILATION
402.1
General.
Natural ventilation of occupiable and habitable spaces
shall comply with Chapter 12 of the 
New York City 
Build
ing Code.
402.2 Reserved.
402.3 Reserved.
402.4 Reserved.
SECTION 
MC 
403
MECHANICAL VENTILATION
VENTILATION
403.1 Ventilation system.
Mechanical ventilation shall be 
provided
by a method of supply air and return or exhaust air. The 
amount of supply air shall be approximately equal to the amount of return and exhaust air. The system shall not be 
prohibited
from producing negative or positive pressure; such pressures shall not r
esult in door opening forces in excess of those indicated 
in the 
New York City Building Code
and shall not prevent doors from closing as required by the 
New York City Building Code
. 
The 
method
to convey ventilation air shall be designed and installed in ac
cordance with Chapter 6.
403.2 Outdoor air required.
The minimum outdoor airflow rate shall be determined in accordance with Section 403.3.1.1.
Exception:
The minimum required rate of outdoor air may be reduced where the registered design professional demo
nstrates 
that an engineered ventilation system is designed in accordance with ASHRAE 62.1 
Indoor Air Quality Procedure
.
403.2.1 Recirculation of air.
The outdoor air required by Section 403.3.1.1 shall not be recirculated. Air in excess of that 
required by
Section 403.3.1.1 shall not be prohibited from being recirculated as a component of supply air to building spaces, 
except that:
1.
Ventilation air shall not be recirculated from one dwelling 
unit 
to another or to dissimilar occupancies.
2.
Supply air to a
swimming pool and associated deck areas shall not be recirculated unless such air is 
dehumidified
to 
maintain the relative humidity of the area at 60 percent or less. Air from this area shall not be recirculated to other 
uses or occupancies
.
3.
Where mech
anical exhaust is required by Note b in Table 403.3.1.1, recirculation of air from such spaces shall be 
prohibited. Recirculation of air that is contained completely within such spaces shall not be prohibited. Where recir-
culation of air is prohibited, all 
air supplied to such spaces shall be exhausted, including any air in excess of that 
required by Table 403.3.1.1.
4.
Where mechanical exhaust is required by Note g in Table 403.3.1.1, mechanical exhaust is required and recirculation 
is prohibited. Recircula
tion of air that is contained completely within such spaces shall not be prohibited.
403.2.2 Transfer air.
Except where recirculation from such spaces is prohibited by Table 403.3.1.1, air transferred from 
occupiable spaces is not prohibited from serving a
s makeup air for required exhaust systems in such spaces as kitchens, 
baths, toilet rooms, elevators and smoking lounges. The amount of transfer air and exhaust air shall be sufficient to provide
the flow rates as specified in Section 403.3.1.1. The requir
ed outdoor airflow rates specified in Table 403.3.1.1 shall be 
introduced directly into such spaces or into the occupied spaces from which air is transferred or a combination of both.
403.3 Outdoor air and local exhaust airflow rates. 
Buildings that are no
t more than three stories in height above grade plane, 
and that (i) are within Occupancy Group R
-
2 or Occupancy Group R
-
3, (ii) are adult homes or enriched living housing as 
described in Section 308.3.1 of the 
New York City Building Code,
within Occupancy 
Group I
-
1 and have 16 occupants or fewer, 
or (iii) are community residences or intermediate
-
care facilities as described in Section 308.3.2 of the 
New York City Building 
Code,
shall be provided with outdoor air and local exhaust in accordance with Section 
403.3.1.1.2. All other buildings intended 
to be occupied shall be provided with outdoor air and local exhaust in accordance with Sections 403.3.1.1 through 403.3.1.6.
403.3.1 Reserved.
403.3.1.1 Outdoor airflow rate. 
Ventilation systems shall be designed t
o have the capacity to supply the minimum 
outdoor airflow rate determined in accordance with this section. In each occupiable space and, where required, each 
habitable space, the ventilation system shall be designed to deliver the required rate of outdoor 
airflow to the breathing 
zone. The occupant load utilized for design of the ventilation system shall be
not less than the number 
determined
from 
the estimated maximum occupant load rate 
indicated
in Table 403.3.1.1
. 
Ventilation rates for 
occupancies not represented 
in Table 403.3.1.1
shall be those for a listed occupancy classification that is most similar in terms of occupant density, 
activities and building construction; or shall be determined by an approved engineering analysis. The ven
tilation system 
shall be designed to supply the required rate of ventilation air continuously 
during
the period the building is occupied, 
except as otherwise stated in other provisions of the code.
With the exception of non
-
tobacco hookah establishments, t
he ventilation rates in Table 403.3.1.1
are based on the 
absence of smoking in occupiable spaces. Where smoking is anticipated in a space other than a non
-
tobacco hookah 
establishment, the ventilation system serving the space shall be designed to provide v
entilation over and above that re-
quired by Table 403.3.1.1
in accordance with accepted engineering practice.
Exceptions:
1.
The occupant load is not required to be 
determined 
based on the estimated maximum occupant load rate indi-
cated in Table 403.3
.1.1 wh
ere 
approved statistical data 
documents
the accuracy of an alternate anticipated 
occupant load.
‡‡‡ Chapter 4 was amended by 
Local Law 
77 
of 2023
. This law has an effective
 date of June 10, 2023.
CHAPTER 4
VENTILATION 
SECTION MC 401
GENERAL
401.1 Scope.
This chapter shall govern the ventilation of spaces within a building intended to be occupied. Mechanical exhaust 
systems, including exhaust systems serving clothes dryers and cooking appliances; hazardous exhaust systems; dust, stock and 
refuse conveyor systems; subslab soil exhaust systems; smoke control systems; energy recovery ventilation systems and other 
systems specified in Section 502 shall comply with Chapter 5.
401
.2 Ventilation required.
Habitable and occupiable spaces shall be provided with ventilation in accordance with this section.
1.
Every 
occupiable
space shall be:
1.1.
Naturally ventilated in accordance with Section 402 and mechanically exhausted in 
accordance with Table 403.3.1.1; 
or
1.2.
Mechanically ventilated in accordance with Section 403.
2.
All habitable spaces and occupiable spaces provided with air conditioning shall be mechanically ventilated in accordance 
with Section 403.
3.
Every habitabl
e space
shall be naturally ventilated in accordance with Section 402.
4.
Every habitable space shall be mechanically ventilated if required by Section 403
. 
Ambulatory care facilities (Group B) and Group I
-
2 occupancies shall be ventilated by mechanical means in accordance 
with Section 407.
401.3 When required.
Ventilation shall be provided during the periods that the room or space is occupied or during operation 
of gas appliances.
‡‡‡
401.4 Intake opening location.
Ventilation air intake openings shall compl
y with all of
the following:
1.
Intake 
openings
shall be located
not less than 10 feet (3048 mm) from lot lines or buildings on the same lot. For buildings 
on lots measuring less than 20 feet (6096 mm) in width, intake openings shall be located at the cent
erline between lot 
lines. Where openings front on a street or public way, the distance shall be measured to the centerline of the street or 
public way.
2.
Outdoor air intakes for office occupancies having occupied floors located more than 75 feet (22 860 mm) above the 
lowest level of fire department vehicle access serving spaces above the second story and serving spaces greater than 
10,000 square feet (929 m
2
) of floor area shall be located at least 20 feet (6096 mm) above ground level, at least 30 feet 
(91
44 mm) from exhaust outlets and other exhaust discharges, and at least 20 feet (6096 mm) from areas that may collect 
vehicular exhaust, such as off street loading bays.
3.
Mechanical and gravity outdoor air intake openings shall be located not less than 10
feet (3048 mm) horizontally from 
any hazardous or noxious contaminant source, such as vents, exhausts (including but not limited to exhaust from dry 
cleaning establishments, spray booths, and cooling towers), streets, alleys, parking lots and loading dock
s, except as 
specified in Item 3 
of 
Section 501.3.1. Outdoor air intake openings shall be permitted to be located less than 10 feet (3048 
mm) horizontally from streets, alleys, parking lots and loading docks provided that the openings are located not less 
than 
25 feet (7620 mm) vertically above such locations. Where openings front on a street or public way, the distance shall be 
measured 
to the centerline 
of the street or public way.
4.
Where the requirements of Item 3 above cannot be achieved, 
intake
openings shall be located not less than 3 feet (914.4 
mm) below contaminant sources where such sources are located within 10 feet (3048 mm) of the opening. 
5.
Intake openings in Group I occupancies shall comply with ANSI/ASHRAE/ASHE 170, as require
d.
VENTILATION
6.
Intake openings on structures in flood hazard areas shall comply with the additional requirements of Appendix G of the 
New York City Building Code.
Exception: 
Group R
-
3 occupancies are not required to comply with Section 401.4. 
401.4.1 Required damp
ers in intake openings.
Outdoor air intakes shall be provided with dampers in accordance with 
Chapter 6.
401.5 Intake opening protection.
Air intake openings that terminate outdoors shall be protected with 
corrosion
-
resistant 
screens, louvers or grilles. O
penings in louvers, grilles and screens shall be sized in accordance with Table 401.5, and shall be 
protected against local weather conditions. Outdoor air intake openings located in exterior walls shall meet the provisions f
or 
exterior wall opening protec
tives in accordance with Section 705 of the 
New York City 
Building Code.
TABLE 401.5
OPENING SIZES IN LOUVERS, GRILLES AND SCREENS 
PROTECTING OUTDOOR EXHAUST AND AIR INTAKE 
OPENINGS
OUTDOOR OPENING TYPE
MINIMUM AND MAXIMUM 
OPENING SIZES IN 
LOUVERS, 
GRILLES AND SCREENS 
MEASURED IN ANY 
DIRECTION
Intake openings in
residential oc-
cupancies
Not < 
1
/
4
inch and not > 
1
/
2
inch
Intake openings in other
than resi-
dential occupancies
> 
1
/
4
inch and not > 1 inch
For SI: 1 inch = 25.4 mm.
401.6 
Contaminant sources.
Stationary local sources 
producing
air
-
borne particulates, heat, odors, fumes, spray, vapors, 
smoke or gases in such quantities as to be irritating or injurious to health shall be provided with an exhaust system in 
accordance
with Chap
ter 5 or a means of collection and removal of the contaminants. Such exhaust shall discharge directly to an approved 
location at the exterior of the building.
401.6.1 Wind
-
driven rain.
All exterior louvers for building ventilation systems shall conform to the requirements of Chap-
ter 16 of the 
New York City Building Code
, where applicable, and the following:
1.
Comply with the requirements of AMCA 550. Louvers shall comply with the intru
sion requirements of wind
-
driven 
rain without the use of a damper. Outdoor air intake openings located in exterior walls shall meet the provisions for 
exterior wall opening protectives in accordance with Chapter 16 of the 
New York City Building Code
; 
or
2.
Be installed on a plenum configured to intercept any wind
-
driven rain penetrating the louver and to prevent the rain 
from entering the building ductwork system. Such plenum shall be waterproofed and equipped with a drainage system 
to convey water penetrat
ing the louver directly to the outdoors or in accordance with the 
New York City Plumbing 
Code
.
SECTION MC 402
NATURAL VENTILATION
402.1
General.
Natural ventilation of occupiable and habitable spaces
shall comply with Chapter 12 of the 
New York City 
Build
ing Code.
402.2 Reserved.
402.3 Reserved.
402.4 Reserved.
SECTION 
MC 
403
MECHANICAL VENTILATION
VENTILATION
403.1 Ventilation system.
Mechanical ventilation shall be 
provided
by a method of supply air and return or exhaust air. The 
amount of supply air shall be approximately equal to the amount of return and exhaust air. The system shall not be 
prohibited
from producing negative or positive pressure; such pressures shall not r
esult in door opening forces in excess of those indicated 
in the 
New York City Building Code
and shall not prevent doors from closing as required by the 
New York City Building Code
. 
The 
method
to convey ventilation air shall be designed and installed in ac
cordance with Chapter 6.
403.2 Outdoor air required.
The minimum outdoor airflow rate shall be determined in accordance with Section 403.3.1.1.
Exception:
The minimum required rate of outdoor air may be reduced where the registered design professional demo
nstrates 
that an engineered ventilation system is designed in accordance with ASHRAE 62.1 
Indoor Air Quality Procedure
.
403.2.1 Recirculation of air.
The outdoor air required by Section 403.3.1.1 shall not be recirculated. Air in excess of that 
required by
Section 403.3.1.1 shall not be prohibited from being recirculated as a component of supply air to building spaces, 
except that:
1.
Ventilation air shall not be recirculated from one dwelling 
unit 
to another or to dissimilar occupancies.
2.
Supply air to a
swimming pool and associated deck areas shall not be recirculated unless such air is 
dehumidified
to 
maintain the relative humidity of the area at 60 percent or less. Air from this area shall not be recirculated to other 
uses or occupancies
.
3.
Where mech
anical exhaust is required by Note b in Table 403.3.1.1, recirculation of air from such spaces shall be 
prohibited. Recirculation of air that is contained completely within such spaces shall not be prohibited. Where recir-
culation of air is prohibited, all 
air supplied to such spaces shall be exhausted, including any air in excess of that 
required by Table 403.3.1.1.
4.
Where mechanical exhaust is required by Note g in Table 403.3.1.1, mechanical exhaust is required and recirculation 
is prohibited. Recircula
tion of air that is contained completely within such spaces shall not be prohibited.
403.2.2 Transfer air.
Except where recirculation from such spaces is prohibited by Table 403.3.1.1, air transferred from 
occupiable spaces is not prohibited from serving a
s makeup air for required exhaust systems in such spaces as kitchens, 
baths, toilet rooms, elevators and smoking lounges. The amount of transfer air and exhaust air shall be sufficient to provide
the flow rates as specified in Section 403.3.1.1. The requir
ed outdoor airflow rates specified in Table 403.3.1.1 shall be 
introduced directly into such spaces or into the occupied spaces from which air is transferred or a combination of both.
403.3 Outdoor air and local exhaust airflow rates. 
Buildings that are no
t more than three stories in height above grade plane, 
and that (i) are within Occupancy Group R
-
2 or Occupancy Group R
-
3, (ii) are adult homes or enriched living housing as 
described in Section 308.3.1 of the 
New York City Building Code,
within Occupancy 
Group I
-
1 and have 16 occupants or fewer, 
or (iii) are community residences or intermediate
-
care facilities as described in Section 308.3.2 of the 
New York City Building 
Code,
shall be provided with outdoor air and local exhaust in accordance with Section 
403.3.1.1.2. All other buildings intended 
to be occupied shall be provided with outdoor air and local exhaust in accordance with Sections 403.3.1.1 through 403.3.1.6.
403.3.1 Reserved.
403.3.1.1 Outdoor airflow rate. 
Ventilation systems shall be designed t
o have the capacity to supply the minimum 
outdoor airflow rate determined in accordance with this section. In each occupiable space and, where required, each 
habitable space, the ventilation system shall be designed to deliver the required rate of outdoor 
airflow to the breathing 
zone. The occupant load utilized for design of the ventilation system shall be
not less than the number 
determined
from 
the estimated maximum occupant load rate 
indicated
in Table 403.3.1.1
. 
Ventilation rates for 
occupancies not represented 
in Table 403.3.1.1
shall be those for a listed occupancy classification that is most similar in terms of occupant density, 
activities and building construction; or shall be determined by an approved engineering analysis. The ven
tilation system 
shall be designed to supply the required rate of ventilation air continuously 
during
the period the building is occupied, 
except as otherwise stated in other provisions of the code.
With the exception of non
-
tobacco hookah establishments, t
he ventilation rates in Table 403.3.1.1
are based on the 
absence of smoking in occupiable spaces. Where smoking is anticipated in a space other than a non
-
tobacco hookah 
establishment, the ventilation system serving the space shall be designed to provide v
entilation over and above that re-
quired by Table 403.3.1.1
in accordance with accepted engineering practice.
Exceptions:
1.
The occupant load is not required to be 
determined 
based on the estimated maximum occupant load rate indi-
cated in Table 403.3
.1.1 wh
ere 
approved statistical data 
documents
the accuracy of an alternate anticipated 
occupant load.
VENTILATION
2.
The occupant load used in computing the required ventilation shall be the maximum number who will occupy 
the room or space simultaneously during any 2
-
hour p
eriod.
3.
Dynamic reset (Demand Controlled Ventilation). The system may be designed to reset the design outdoor air 
intake airflow and/or space or zone airflow as operating conditions change. Dynamic reset shall be designed in 
accordance with ASHRAE 62.1 a
nd comply with footnote k of Table 403.3.1.1.    These conditions include, but 
are not limited to:
3.1.
Variations in occupancy or ventilation airflow in one or more individual zones for which ventilation airflow 
requirements will be reset. Note: Examples of
measures for estimating such variations include: occupancy 
scheduled by time of day, a direct count of occupants, or an estimate of occupancy or ventilation rate per 
person using occupancy sensors such as those based on indoor CO
2
concentrations.
3.2.
Variations in the efficiency with which outdoor air is distributed to the occupants under different ventilation 
system airflows and temperatures.
3.3.
A higher fraction of outdoor air in the air supply due to intake of additional outdoor air for free cooli
ng or 
exhaust air makeup.
TABLE 403.3.1.1
MINIMUM VENTILATION RATES
OCCUPANCY CLASSIFICATION
OCCUPANT DENSITY
#/1000 FT
2a
PEOPLE OUTDOOR
AIRFLOW RATE IN 
BREATHING ZONE, R
p
CFM/PERSON
AREA OUTDOOR
AIRFLOW RATE IN 
BREATHING ZONE R
a 
CFM/FT
2a
EXHAUST 
AIRFLOW
RATE 
CFM/FT
2a
Correctional facilities
Booking/waiting
50
7.5
0.06
—
Cells
without plumbing fixtures
25
5
0.12
—
with plumbing fixtures
g
25
5
0.12
1.0
Day room
30
5
0.06
—
Correctional facilities
Dining halls
(see food and 
beverage service)
—
—
—
—
Guard stations
15
5
0.06
—
Dry cleaners, laundries
Coin
-
operated dry cleaner
20
15
—
—
Coin
-
operated laundries
20
7.5
0.06
—
Commercial dry cleaner
l
30
30
—
—
Commercial laundry
10
25
—
—
Storage, pick up
30
7.5
0.12
—
Education
Art classroom
g
20
10
0.18
0.7
VENTILATION
Auditoriums
150
5
0.06
—
Classrooms (ages 5
-
8)
25
10
0.12
—
Classrooms (age 9 plus)
35
10
0.12
—
Computer lab
25
10
0.12
—
Corridors (see public spaces)
—
—
—
—
Day care (through age 4)
25
10
0.18
—
Lecture classroom
65
7.5
0.06
—
Lecture hall (fixed seats)
150
7.5
0.06
—
Locker/dressing rooms
g
—
—
—
0.25
Media center
25
10
0.12
—
Multiuse assembly
100
7.5
0.06
—
Music/theater/dance
35
10
0.06
—
Science laboratories
g, k
25
10
0.18
1.0
Sports locker rooms
g
—
—
—
0.5
Wood/metal shops
g
20
10
0.18
0.5
Food and beverage service
Bars, cocktail lounges
100
7.5
0.18
—
Cafeteria, fast food
100
7.5
0.18
—
Dining rooms
70
7.5
0.18
—
Kitchens (cooking)
b
—
—
—
0.7
Non
-
tobacco smoking   
establishments
b
70
60
—
—
Hotels, motels, resorts and dormitories 
Bathrooms/toilet
—
private
g
—
—
—
25/50
f
Bedroom/living room
10
5
0.06
—
Conference/meeting
50
5
0.06
—
Dormitory sleeping areas
20
5
0.06
—
Gambling casinos
120
7.5
0.18
—
Lobbies/prefunction
30
7.5
0.06
—
Multipurpose assembly
120
5
0.06
—
Laboratories
j
Biological
—
—
1.0
1.0
VENTILATION
Chemical
—
—
1.0
1.0
Industrial and nonteaching
—
—
1.0
1.0
Nonproduction chemical labs
—
—
1.0
1.0
Offices
Conference rooms
50
5
0.06
—
Main entry lobbies
10
5
0.06
—
Office spaces
5
5
0.06
—
Reception areas
30
5
0.06
—
Telephone/data entry
60
5
0.06
—
Private dwellings, single and multiple
Garages, common for multiple units
b
—
—
—
0.75
Kitchens and Kitchenettes
b
, 
m
—
—
—
25/100
f
Living areas
c, i
Based upon number of 
bedrooms. First bed-
room, 2; each additional 
bedroom, 1
0.35 ACH but not less
than 15 cfm/person
—
—
Toilet rooms and bathrooms
g
—
—
—
20/50
f
Public spaces
Corridors
—
—
0.06
—
Courtrooms
70
5
0.06
—
Elevator car
—
—
—
1.0
Legislative chambers
50
5
0.06
—
Libraries
10
5
0.12
—
Museums (children’s)
40
7.5
0.12
—
Museums/galleries
40
7.5
0.06
—
Places of religious worship
120
5
0.06
—
Public spaces
Shower room (per shower head)
g
—
—
—
50/20
f
Toilet rooms 
–
public
g
—
—
—
50/70
e
VENTILATION
Retail stores, sales floors and 
showroom 
floors
Dressing rooms
—
—
—
0.25
Mall common areas
40
7.5
0.06
—
Sales
15
7.5
0.12
—
Shipping and receiving
—
—
0.12
—
Smoking lounges and non
-
tobacco   
smoking establishments
b
70
60
—
—
Storage rooms
—
—
0.12
—
Warehouses (see storage)
—
—
—
—
Specialty shops
Automotive motor
-
fuel dispensing 
stations
b
—
—
—
1.5
Barber
25
7.5
0.06
0.5
Beauty salons (without nail salon 
services)
b
25
20
0.12
0.6
Nail salons
b, h
25
20
0.12
0.6
Embalming room
b
—
—
—
2.0
Pet shops (animal areas)
b
10
7.5
0.18
0.9
Supermarkets
8
7.5
0.06
—
Sports and amusement
Bowling alleys (seating areas)
40
10
0.12
—
Disco/dance floors
100
20
0.06
—
Game arcades
20
7.5
0.18
—
Gym, stadium, arena (play area)
—
—
0.30
—
Heath club/aerobics room
40
20
0.06
—
Health 
club/weight room
10
20
0.06
—
Ice arenas without combustion engines
—
—
0.30
0.5
Spectator areas
150
7.5
0.06
—
‡‡‡ Chapter 4 was amended by 
Local Law 
77 
of 2023
. This law has an effective
 date of June 10, 2023.
CHAPTER 4
VENTILATION 
SECTION MC 401
GENERAL
401.1 Scope.
This chapter shall govern the ventilation of spaces within a building intended to be occupied. Mechanical exhaust 
systems, including exhaust systems serving clothes dryers and cooking appliances; hazardous exhaust systems; dust, stock and 
refuse conveyor systems; subslab soil exhaust systems; smoke control systems; energy recovery ventilation systems and other 
systems specified in Section 502 shall comply with Chapter 5.
401
.2 Ventilation required.
Habitable and occupiable spaces shall be provided with ventilation in accordance with this section.
1.
Every 
occupiable
space shall be:
1.1.
Naturally ventilated in accordance with Section 402 and mechanically exhausted in 
accordance with Table 403.3.1.1; 
or
1.2.
Mechanically ventilated in accordance with Section 403.
2.
All habitable spaces and occupiable spaces provided with air conditioning shall be mechanically ventilated in accordance 
with Section 403.
3.
Every habitabl
e space
shall be naturally ventilated in accordance with Section 402.
4.
Every habitable space shall be mechanically ventilated if required by Section 403
. 
Ambulatory care facilities (Group B) and Group I
-
2 occupancies shall be ventilated by mechanical means in accordance 
with Section 407.
401.3 When required.
Ventilation shall be provided during the periods that the room or space is occupied or during operation 
of gas appliances.
‡‡‡
401.4 Intake opening location.
Ventilation air intake openings shall compl
y with all of
the following:
1.
Intake 
openings
shall be located
not less than 10 feet (3048 mm) from lot lines or buildings on the same lot. For buildings 
on lots measuring less than 20 feet (6096 mm) in width, intake openings shall be located at the cent
erline between lot 
lines. Where openings front on a street or public way, the distance shall be measured to the centerline of the street or 
public way.
2.
Outdoor air intakes for office occupancies having occupied floors located more than 75 feet (22 860 mm) above the 
lowest level of fire department vehicle access serving spaces above the second story and serving spaces greater than 
10,000 square feet (929 m
2
) of floor area shall be located at least 20 feet (6096 mm) above ground level, at least 30 feet 
(91
44 mm) from exhaust outlets and other exhaust discharges, and at least 20 feet (6096 mm) from areas that may collect 
vehicular exhaust, such as off street loading bays.
3.
Mechanical and gravity outdoor air intake openings shall be located not less than 10
feet (3048 mm) horizontally from 
any hazardous or noxious contaminant source, such as vents, exhausts (including but not limited to exhaust from dry 
cleaning establishments, spray booths, and cooling towers), streets, alleys, parking lots and loading dock
s, except as 
specified in Item 3 
of 
Section 501.3.1. Outdoor air intake openings shall be permitted to be located less than 10 feet (3048 
mm) horizontally from streets, alleys, parking lots and loading docks provided that the openings are located not less 
than 
25 feet (7620 mm) vertically above such locations. Where openings front on a street or public way, the distance shall be 
measured 
to the centerline 
of the street or public way.
4.
Where the requirements of Item 3 above cannot be achieved, 
intake
openings shall be located not less than 3 feet (914.4 
mm) below contaminant sources where such sources are located within 10 feet (3048 mm) of the opening. 
5.
Intake openings in Group I occupancies shall comply with ANSI/ASHRAE/ASHE 170, as require
d.
VENTILATION
6.
Intake openings on structures in flood hazard areas shall comply with the additional requirements of Appendix G of the 
New York City Building Code.
Exception: 
Group R
-
3 occupancies are not required to comply with Section 401.4. 
401.4.1 Required damp
ers in intake openings.
Outdoor air intakes shall be provided with dampers in accordance with 
Chapter 6.
401.5 Intake opening protection.
Air intake openings that terminate outdoors shall be protected with 
corrosion
-
resistant 
screens, louvers or grilles. O
penings in louvers, grilles and screens shall be sized in accordance with Table 401.5, and shall be 
protected against local weather conditions. Outdoor air intake openings located in exterior walls shall meet the provisions f
or 
exterior wall opening protec
tives in accordance with Section 705 of the 
New York City 
Building Code.
TABLE 401.5
OPENING SIZES IN LOUVERS, GRILLES AND SCREENS 
PROTECTING OUTDOOR EXHAUST AND AIR INTAKE 
OPENINGS
OUTDOOR OPENING TYPE
MINIMUM AND MAXIMUM 
OPENING SIZES IN 
LOUVERS, 
GRILLES AND SCREENS 
MEASURED IN ANY 
DIRECTION
Intake openings in
residential oc-
cupancies
Not < 
1
/
4
inch and not > 
1
/
2
inch
Intake openings in other
than resi-
dential occupancies
> 
1
/
4
inch and not > 1 inch
For SI: 1 inch = 25.4 mm.
401.6 
Contaminant sources.
Stationary local sources 
producing
air
-
borne particulates, heat, odors, fumes, spray, vapors, 
smoke or gases in such quantities as to be irritating or injurious to health shall be provided with an exhaust system in 
accordance
with Chap
ter 5 or a means of collection and removal of the contaminants. Such exhaust shall discharge directly to an approved 
location at the exterior of the building.
401.6.1 Wind
-
driven rain.
All exterior louvers for building ventilation systems shall conform to the requirements of Chap-
ter 16 of the 
New York City Building Code
, where applicable, and the following:
1.
Comply with the requirements of AMCA 550. Louvers shall comply with the intru
sion requirements of wind
-
driven 
rain without the use of a damper. Outdoor air intake openings located in exterior walls shall meet the provisions for 
exterior wall opening protectives in accordance with Chapter 16 of the 
New York City Building Code
; 
or
2.
Be installed on a plenum configured to intercept any wind
-
driven rain penetrating the louver and to prevent the rain 
from entering the building ductwork system. Such plenum shall be waterproofed and equipped with a drainage system 
to convey water penetrat
ing the louver directly to the outdoors or in accordance with the 
New York City Plumbing 
Code
.
SECTION MC 402
NATURAL VENTILATION
402.1
General.
Natural ventilation of occupiable and habitable spaces
shall comply with Chapter 12 of the 
New York City 
Build
ing Code.
402.2 Reserved.
402.3 Reserved.
402.4 Reserved.
SECTION 
MC 
403
MECHANICAL VENTILATION
VENTILATION
403.1 Ventilation system.
Mechanical ventilation shall be 
provided
by a method of supply air and return or exhaust air. The 
amount of supply air shall be approximately equal to the amount of return and exhaust air. The system shall not be 
prohibited
from producing negative or positive pressure; such pressures shall not r
esult in door opening forces in excess of those indicated 
in the 
New York City Building Code
and shall not prevent doors from closing as required by the 
New York City Building Code
. 
The 
method
to convey ventilation air shall be designed and installed in ac
cordance with Chapter 6.
403.2 Outdoor air required.
The minimum outdoor airflow rate shall be determined in accordance with Section 403.3.1.1.
Exception:
The minimum required rate of outdoor air may be reduced where the registered design professional demo
nstrates 
that an engineered ventilation system is designed in accordance with ASHRAE 62.1 
Indoor Air Quality Procedure
.
403.2.1 Recirculation of air.
The outdoor air required by Section 403.3.1.1 shall not be recirculated. Air in excess of that 
required by
Section 403.3.1.1 shall not be prohibited from being recirculated as a component of supply air to building spaces, 
except that:
1.
Ventilation air shall not be recirculated from one dwelling 
unit 
to another or to dissimilar occupancies.
2.
Supply air to a
swimming pool and associated deck areas shall not be recirculated unless such air is 
dehumidified
to 
maintain the relative humidity of the area at 60 percent or less. Air from this area shall not be recirculated to other 
uses or occupancies
.
3.
Where mech
anical exhaust is required by Note b in Table 403.3.1.1, recirculation of air from such spaces shall be 
prohibited. Recirculation of air that is contained completely within such spaces shall not be prohibited. Where recir-
culation of air is prohibited, all 
air supplied to such spaces shall be exhausted, including any air in excess of that 
required by Table 403.3.1.1.
4.
Where mechanical exhaust is required by Note g in Table 403.3.1.1, mechanical exhaust is required and recirculation 
is prohibited. Recircula
tion of air that is contained completely within such spaces shall not be prohibited.
403.2.2 Transfer air.
Except where recirculation from such spaces is prohibited by Table 403.3.1.1, air transferred from 
occupiable spaces is not prohibited from serving a
s makeup air for required exhaust systems in such spaces as kitchens, 
baths, toilet rooms, elevators and smoking lounges. The amount of transfer air and exhaust air shall be sufficient to provide
the flow rates as specified in Section 403.3.1.1. The requir
ed outdoor airflow rates specified in Table 403.3.1.1 shall be 
introduced directly into such spaces or into the occupied spaces from which air is transferred or a combination of both.
403.3 Outdoor air and local exhaust airflow rates. 
Buildings that are no
t more than three stories in height above grade plane, 
and that (i) are within Occupancy Group R
-
2 or Occupancy Group R
-
3, (ii) are adult homes or enriched living housing as 
described in Section 308.3.1 of the 
New York City Building Code,
within Occupancy 
Group I
-
1 and have 16 occupants or fewer, 
or (iii) are community residences or intermediate
-
care facilities as described in Section 308.3.2 of the 
New York City Building 
Code,
shall be provided with outdoor air and local exhaust in accordance with Section 
403.3.1.1.2. All other buildings intended 
to be occupied shall be provided with outdoor air and local exhaust in accordance with Sections 403.3.1.1 through 403.3.1.6.
403.3.1 Reserved.
403.3.1.1 Outdoor airflow rate. 
Ventilation systems shall be designed t
o have the capacity to supply the minimum 
outdoor airflow rate determined in accordance with this section. In each occupiable space and, where required, each 
habitable space, the ventilation system shall be designed to deliver the required rate of outdoor 
airflow to the breathing 
zone. The occupant load utilized for design of the ventilation system shall be
not less than the number 
determined
from 
the estimated maximum occupant load rate 
indicated
in Table 403.3.1.1
. 
Ventilation rates for 
occupancies not represented 
in Table 403.3.1.1
shall be those for a listed occupancy classification that is most similar in terms of occupant density, 
activities and building construction; or shall be determined by an approved engineering analysis. The ven
tilation system 
shall be designed to supply the required rate of ventilation air continuously 
during
the period the building is occupied, 
except as otherwise stated in other provisions of the code.
With the exception of non
-
tobacco hookah establishments, t
he ventilation rates in Table 403.3.1.1
are based on the 
absence of smoking in occupiable spaces. Where smoking is anticipated in a space other than a non
-
tobacco hookah 
establishment, the ventilation system serving the space shall be designed to provide v
entilation over and above that re-
quired by Table 403.3.1.1
in accordance with accepted engineering practice.
Exceptions:
1.
The occupant load is not required to be 
determined 
based on the estimated maximum occupant load rate indi-
cated in Table 403.3
.1.1 wh
ere 
approved statistical data 
documents
the accuracy of an alternate anticipated 
occupant load.
VENTILATION
2.
The occupant load used in computing the required ventilation shall be the maximum number who will occupy 
the room or space simultaneously during any 2
-
hour p
eriod.
3.
Dynamic reset (Demand Controlled Ventilation). The system may be designed to reset the design outdoor air 
intake airflow and/or space or zone airflow as operating conditions change. Dynamic reset shall be designed in 
accordance with ASHRAE 62.1 a
nd comply with footnote k of Table 403.3.1.1.    These conditions include, but 
are not limited to:
3.1.
Variations in occupancy or ventilation airflow in one or more individual zones for which ventilation airflow 
requirements will be reset. Note: Examples of
measures for estimating such variations include: occupancy 
scheduled by time of day, a direct count of occupants, or an estimate of occupancy or ventilation rate per 
person using occupancy sensors such as those based on indoor CO
2
concentrations.
3.2.
Variations in the efficiency with which outdoor air is distributed to the occupants under different ventilation 
system airflows and temperatures.
3.3.
A higher fraction of outdoor air in the air supply due to intake of additional outdoor air for free cooli
ng or 
exhaust air makeup.
TABLE 403.3.1.1
MINIMUM VENTILATION RATES
OCCUPANCY CLASSIFICATION
OCCUPANT DENSITY
#/1000 FT
2a
PEOPLE OUTDOOR
AIRFLOW RATE IN 
BREATHING ZONE, R
p
CFM/PERSON
AREA OUTDOOR
AIRFLOW RATE IN 
BREATHING ZONE R
a 
CFM/FT
2a
EXHAUST 
AIRFLOW
RATE 
CFM/FT
2a
Correctional facilities
Booking/waiting
50
7.5
0.06
—
Cells
without plumbing fixtures
25
5
0.12
—
with plumbing fixtures
g
25
5
0.12
1.0
Day room
30
5
0.06
—
Correctional facilities
Dining halls
(see food and 
beverage service)
—
—
—
—
Guard stations
15
5
0.06
—
Dry cleaners, laundries
Coin
-
operated dry cleaner
20
15
—
—
Coin
-
operated laundries
20
7.5
0.06
—
Commercial dry cleaner
l
30
30
—
—
Commercial laundry
10
25
—
—
Storage, pick up
30
7.5
0.12
—
Education
Art classroom
g
20
10
0.18
0.7
VENTILATION
Auditoriums
150
5
0.06
—
Classrooms (ages 5
-
8)
25
10
0.12
—
Classrooms (age 9 plus)
35
10
0.12
—
Computer lab
25
10
0.12
—
Corridors (see public spaces)
—
—
—
—
Day care (through age 4)
25
10
0.18
—
Lecture classroom
65
7.5
0.06
—
Lecture hall (fixed seats)
150
7.5
0.06
—
Locker/dressing rooms
g
—
—
—
0.25
Media center
25
10
0.12
—
Multiuse assembly
100
7.5
0.06
—
Music/theater/dance
35
10
0.06
—
Science laboratories
g, k
25
10
0.18
1.0
Sports locker rooms
g
—
—
—
0.5
Wood/metal shops
g
20
10
0.18
0.5
Food and beverage service
Bars, cocktail lounges
100
7.5
0.18
—
Cafeteria, fast food
100
7.5
0.18
—
Dining rooms
70
7.5
0.18
—
Kitchens (cooking)
b
—
—
—
0.7
Non
-
tobacco smoking   
establishments
b
70
60
—
—
Hotels, motels, resorts and dormitories 
Bathrooms/toilet
—
private
g
—
—
—
25/50
f
Bedroom/living room
10
5
0.06
—
Conference/meeting
50
5
0.06
—
Dormitory sleeping areas
20
5
0.06
—
Gambling casinos
120
7.5
0.18
—
Lobbies/prefunction
30
7.5
0.06
—
Multipurpose assembly
120
5
0.06
—
Laboratories
j
Biological
—
—
1.0
1.0
VENTILATION
Chemical
—
—
1.0
1.0
Industrial and nonteaching
—
—
1.0
1.0
Nonproduction chemical labs
—
—
1.0
1.0
Offices
Conference rooms
50
5
0.06
—
Main entry lobbies
10
5
0.06
—
Office spaces
5
5
0.06
—
Reception areas
30
5
0.06
—
Telephone/data entry
60
5
0.06
—
Private dwellings, single and multiple
Garages, common for multiple units
b
—
—
—
0.75
Kitchens and Kitchenettes
b
, 
m
—
—
—
25/100
f
Living areas
c, i
Based upon number of 
bedrooms. First bed-
room, 2; each additional 
bedroom, 1
0.35 ACH but not less
than 15 cfm/person
—
—
Toilet rooms and bathrooms
g
—
—
—
20/50
f
Public spaces
Corridors
—
—
0.06
—
Courtrooms
70
5
0.06
—
Elevator car
—
—
—
1.0
Legislative chambers
50
5
0.06
—
Libraries
10
5
0.12
—
Museums (children’s)
40
7.5
0.12
—
Museums/galleries
40
7.5
0.06
—
Places of religious worship
120
5
0.06
—
Public spaces
Shower room (per shower head)
g
—
—
—
50/20
f
Toilet rooms 
–
public
g
—
—
—
50/70
e
VENTILATION
Retail stores, sales floors and 
showroom 
floors
Dressing rooms
—
—
—
0.25
Mall common areas
40
7.5
0.06
—
Sales
15
7.5
0.12
—
Shipping and receiving
—
—
0.12
—
Smoking lounges and non
-
tobacco   
smoking establishments
b
70
60
—
—
Storage rooms
—
—
0.12
—
Warehouses (see storage)
—
—
—
—
Specialty shops
Automotive motor
-
fuel dispensing 
stations
b
—
—
—
1.5
Barber
25
7.5
0.06
0.5
Beauty salons (without nail salon 
services)
b
25
20
0.12
0.6
Nail salons
b, h
25
20
0.12
0.6
Embalming room
b
—
—
—
2.0
Pet shops (animal areas)
b
10
7.5
0.18
0.9
Supermarkets
8
7.5
0.06
—
Sports and amusement
Bowling alleys (seating areas)
40
10
0.12
—
Disco/dance floors
100
20
0.06
—
Game arcades
20
7.5
0.18
—
Gym, stadium, arena (play area)
—
—
0.30
—
Heath club/aerobics room
40
20
0.06
—
Health 
club/weight room
10
20
0.06
—
Ice arenas without combustion engines
—
—
0.30
0.5
Spectator areas
150
7.5
0.06
—
‡‡‡ Chapter 4 was amended by 
Local Law 
77 
of 2023
. This law has an effective
 date of June 10, 2023.
CHAPTER 4
VENTILATION 
SECTION MC 401
GENERAL
401.1 Scope.
This chapter shall govern the ventilation of spaces within a building intended to be occupied. Mechanical exhaust 
systems, including exhaust systems serving clothes dryers and cooking appliances; hazardous exhaust systems; dust, stock and 
refuse conveyor systems; subslab soil exhaust systems; smoke control systems; energy recovery ventilation systems and other 
systems specified in Section 502 shall comply with Chapter 5.
401
.2 Ventilation required.
Habitable and occupiable spaces shall be provided with ventilation in accordance with this section.
1.
Every 
occupiable
space shall be:
1.1.
Naturally ventilated in accordance with Section 402 and mechanically exhausted in 
accordance with Table 403.3.1.1; 
or
1.2.
Mechanically ventilated in accordance with Section 403.
2.
All habitable spaces and occupiable spaces provided with air conditioning shall be mechanically ventilated in accordance 
with Section 403.
3.
Every habitabl
e space
shall be naturally ventilated in accordance with Section 402.
4.
Every habitable space shall be mechanically ventilated if required by Section 403
. 
Ambulatory care facilities (Group B) and Group I
-
2 occupancies shall be ventilated by mechanical means in accordance 
with Section 407.
401.3 When required.
Ventilation shall be provided during the periods that the room or space is occupied or during operation 
of gas appliances.
‡‡‡
401.4 Intake opening location.
Ventilation air intake openings shall compl
y with all of
the following:
1.
Intake 
openings
shall be located
not less than 10 feet (3048 mm) from lot lines or buildings on the same lot. For buildings 
on lots measuring less than 20 feet (6096 mm) in width, intake openings shall be located at the cent
erline between lot 
lines. Where openings front on a street or public way, the distance shall be measured to the centerline of the street or 
public way.
2.
Outdoor air intakes for office occupancies having occupied floors located more than 75 feet (22 860 mm) above the 
lowest level of fire department vehicle access serving spaces above the second story and serving spaces greater than 
10,000 square feet (929 m
2
) of floor area shall be located at least 20 feet (6096 mm) above ground level, at least 30 feet 
(91
44 mm) from exhaust outlets and other exhaust discharges, and at least 20 feet (6096 mm) from areas that may collect 
vehicular exhaust, such as off street loading bays.
3.
Mechanical and gravity outdoor air intake openings shall be located not less than 10
feet (3048 mm) horizontally from 
any hazardous or noxious contaminant source, such as vents, exhausts (including but not limited to exhaust from dry 
cleaning establishments, spray booths, and cooling towers), streets, alleys, parking lots and loading dock
s, except as 
specified in Item 3 
of 
Section 501.3.1. Outdoor air intake openings shall be permitted to be located less than 10 feet (3048 
mm) horizontally from streets, alleys, parking lots and loading docks provided that the openings are located not less 
than 
25 feet (7620 mm) vertically above such locations. Where openings front on a street or public way, the distance shall be 
measured 
to the centerline 
of the street or public way.
4.
Where the requirements of Item 3 above cannot be achieved, 
intake
openings shall be located not less than 3 feet (914.4 
mm) below contaminant sources where such sources are located within 10 feet (3048 mm) of the opening. 
5.
Intake openings in Group I occupancies shall comply with ANSI/ASHRAE/ASHE 170, as require
d.
VENTILATION
6.
Intake openings on structures in flood hazard areas shall comply with the additional requirements of Appendix G of the 
New York City Building Code.
Exception: 
Group R
-
3 occupancies are not required to comply with Section 401.4. 
401.4.1 Required damp
ers in intake openings.
Outdoor air intakes shall be provided with dampers in accordance with 
Chapter 6.
401.5 Intake opening protection.
Air intake openings that terminate outdoors shall be protected with 
corrosion
-
resistant 
screens, louvers or grilles. O
penings in louvers, grilles and screens shall be sized in accordance with Table 401.5, and shall be 
protected against local weather conditions. Outdoor air intake openings located in exterior walls shall meet the provisions f
or 
exterior wall opening protec
tives in accordance with Section 705 of the 
New York City 
Building Code.
TABLE 401.5
OPENING SIZES IN LOUVERS, GRILLES AND SCREENS 
PROTECTING OUTDOOR EXHAUST AND AIR INTAKE 
OPENINGS
OUTDOOR OPENING TYPE
MINIMUM AND MAXIMUM 
OPENING SIZES IN 
LOUVERS, 
GRILLES AND SCREENS 
MEASURED IN ANY 
DIRECTION
Intake openings in
residential oc-
cupancies
Not < 
1
/
4
inch and not > 
1
/
2
inch
Intake openings in other
than resi-
dential occupancies
> 
1
/
4
inch and not > 1 inch
For SI: 1 inch = 25.4 mm.
401.6 
Contaminant sources.
Stationary local sources 
producing
air
-
borne particulates, heat, odors, fumes, spray, vapors, 
smoke or gases in such quantities as to be irritating or injurious to health shall be provided with an exhaust system in 
accordance
with Chap
ter 5 or a means of collection and removal of the contaminants. Such exhaust shall discharge directly to an approved 
location at the exterior of the building.
401.6.1 Wind
-
driven rain.
All exterior louvers for building ventilation systems shall conform to the requirements of Chap-
ter 16 of the 
New York City Building Code
, where applicable, and the following:
1.
Comply with the requirements of AMCA 550. Louvers shall comply with the intru
sion requirements of wind
-
driven 
rain without the use of a damper. Outdoor air intake openings located in exterior walls shall meet the provisions for 
exterior wall opening protectives in accordance with Chapter 16 of the 
New York City Building Code
; 
or
2.
Be installed on a plenum configured to intercept any wind
-
driven rain penetrating the louver and to prevent the rain 
from entering the building ductwork system. Such plenum shall be waterproofed and equipped with a drainage system 
to convey water penetrat
ing the louver directly to the outdoors or in accordance with the 
New York City Plumbing 
Code
.
SECTION MC 402
NATURAL VENTILATION
402.1
General.
Natural ventilation of occupiable and habitable spaces
shall comply with Chapter 12 of the 
New York City 
Build
ing Code.
402.2 Reserved.
402.3 Reserved.
402.4 Reserved.
SECTION 
MC 
403
MECHANICAL VENTILATION
VENTILATION
403.1 Ventilation system.
Mechanical ventilation shall be 
provided
by a method of supply air and return or exhaust air. The 
amount of supply air shall be approximately equal to the amount of return and exhaust air. The system shall not be 
prohibited
from producing negative or positive pressure; such pressures shall not r
esult in door opening forces in excess of those indicated 
in the 
New York City Building Code
and shall not prevent doors from closing as required by the 
New York City Building Code
. 
The 
method
to convey ventilation air shall be designed and installed in ac
cordance with Chapter 6.
403.2 Outdoor air required.
The minimum outdoor airflow rate shall be determined in accordance with Section 403.3.1.1.
Exception:
The minimum required rate of outdoor air may be reduced where the registered design professional demo
nstrates 
that an engineered ventilation system is designed in accordance with ASHRAE 62.1 
Indoor Air Quality Procedure
.
403.2.1 Recirculation of air.
The outdoor air required by Section 403.3.1.1 shall not be recirculated. Air in excess of that 
required by
Section 403.3.1.1 shall not be prohibited from being recirculated as a component of supply air to building spaces, 
except that:
1.
Ventilation air shall not be recirculated from one dwelling 
unit 
to another or to dissimilar occupancies.
2.
Supply air to a
swimming pool and associated deck areas shall not be recirculated unless such air is 
dehumidified
to 
maintain the relative humidity of the area at 60 percent or less. Air from this area shall not be recirculated to other 
uses or occupancies
.
3.
Where mech
anical exhaust is required by Note b in Table 403.3.1.1, recirculation of air from such spaces shall be 
prohibited. Recirculation of air that is contained completely within such spaces shall not be prohibited. Where recir-
culation of air is prohibited, all 
air supplied to such spaces shall be exhausted, including any air in excess of that 
required by Table 403.3.1.1.
4.
Where mechanical exhaust is required by Note g in Table 403.3.1.1, mechanical exhaust is required and recirculation 
is prohibited. Recircula
tion of air that is contained completely within such spaces shall not be prohibited.
403.2.2 Transfer air.
Except where recirculation from such spaces is prohibited by Table 403.3.1.1, air transferred from 
occupiable spaces is not prohibited from serving a
s makeup air for required exhaust systems in such spaces as kitchens, 
baths, toilet rooms, elevators and smoking lounges. The amount of transfer air and exhaust air shall be sufficient to provide
the flow rates as specified in Section 403.3.1.1. The requir
ed outdoor airflow rates specified in Table 403.3.1.1 shall be 
introduced directly into such spaces or into the occupied spaces from which air is transferred or a combination of both.
403.3 Outdoor air and local exhaust airflow rates. 
Buildings that are no
t more than three stories in height above grade plane, 
and that (i) are within Occupancy Group R
-
2 or Occupancy Group R
-
3, (ii) are adult homes or enriched living housing as 
described in Section 308.3.1 of the 
New York City Building Code,
within Occupancy 
Group I
-
1 and have 16 occupants or fewer, 
or (iii) are community residences or intermediate
-
care facilities as described in Section 308.3.2 of the 
New York City Building 
Code,
shall be provided with outdoor air and local exhaust in accordance with Section 
403.3.1.1.2. All other buildings intended 
to be occupied shall be provided with outdoor air and local exhaust in accordance with Sections 403.3.1.1 through 403.3.1.6.
403.3.1 Reserved.
403.3.1.1 Outdoor airflow rate. 
Ventilation systems shall be designed t
o have the capacity to supply the minimum 
outdoor airflow rate determined in accordance with this section. In each occupiable space and, where required, each 
habitable space, the ventilation system shall be designed to deliver the required rate of outdoor 
airflow to the breathing 
zone. The occupant load utilized for design of the ventilation system shall be
not less than the number 
determined
from 
the estimated maximum occupant load rate 
indicated
in Table 403.3.1.1
. 
Ventilation rates for 
occupancies not represented 
in Table 403.3.1.1
shall be those for a listed occupancy classification that is most similar in terms of occupant density, 
activities and building construction; or shall be determined by an approved engineering analysis. The ven
tilation system 
shall be designed to supply the required rate of ventilation air continuously 
during
the period the building is occupied, 
except as otherwise stated in other provisions of the code.
With the exception of non
-
tobacco hookah establishments, t
he ventilation rates in Table 403.3.1.1
are based on the 
absence of smoking in occupiable spaces. Where smoking is anticipated in a space other than a non
-
tobacco hookah 
establishment, the ventilation system serving the space shall be designed to provide v
entilation over and above that re-
quired by Table 403.3.1.1
in accordance with accepted engineering practice.
Exceptions:
1.
The occupant load is not required to be 
determined 
based on the estimated maximum occupant load rate indi-
cated in Table 403.3
.1.1 wh
ere 
approved statistical data 
documents
the accuracy of an alternate anticipated 
occupant load.
VENTILATION
2.
The occupant load used in computing the required ventilation shall be the maximum number who will occupy 
the room or space simultaneously during any 2
-
hour p
eriod.
3.
Dynamic reset (Demand Controlled Ventilation). The system may be designed to reset the design outdoor air 
intake airflow and/or space or zone airflow as operating conditions change. Dynamic reset shall be designed in 
accordance with ASHRAE 62.1 a
nd comply with footnote k of Table 403.3.1.1.    These conditions include, but 
are not limited to:
3.1.
Variations in occupancy or ventilation airflow in one or more individual zones for which ventilation airflow 
requirements will be reset. Note: Examples of
measures for estimating such variations include: occupancy 
scheduled by time of day, a direct count of occupants, or an estimate of occupancy or ventilation rate per 
person using occupancy sensors such as those based on indoor CO
2
concentrations.
3.2.
Variations in the efficiency with which outdoor air is distributed to the occupants under different ventilation 
system airflows and temperatures.
3.3.
A higher fraction of outdoor air in the air supply due to intake of additional outdoor air for free cooli
ng or 
exhaust air makeup.
TABLE 403.3.1.1
MINIMUM VENTILATION RATES
OCCUPANCY CLASSIFICATION
OCCUPANT DENSITY
#/1000 FT
2a
PEOPLE OUTDOOR
AIRFLOW RATE IN 
BREATHING ZONE, R
p
CFM/PERSON
AREA OUTDOOR
AIRFLOW RATE IN 
BREATHING ZONE R
a 
CFM/FT
2a
EXHAUST 
AIRFLOW
RATE 
CFM/FT
2a
Correctional facilities
Booking/waiting
50
7.5
0.06
—
Cells
without plumbing fixtures
25
5
0.12
—
with plumbing fixtures
g
25
5
0.12
1.0
Day room
30
5
0.06
—
Correctional facilities
Dining halls
(see food and 
beverage service)
—
—
—
—
Guard stations
15
5
0.06
—
Dry cleaners, laundries
Coin
-
operated dry cleaner
20
15
—
—
Coin
-
operated laundries
20
7.5
0.06
—
Commercial dry cleaner
l
30
30
—
—
Commercial laundry
10
25
—
—
Storage, pick up
30
7.5
0.12
—
Education
Art classroom
g
20
10
0.18
0.7
VENTILATION
Auditoriums
150
5
0.06
—
Classrooms (ages 5
-
8)
25
10
0.12
—
Classrooms (age 9 plus)
35
10
0.12
—
Computer lab
25
10
0.12
—
Corridors (see public spaces)
—
—
—
—
Day care (through age 4)
25
10
0.18
—
Lecture classroom
65
7.5
0.06
—
Lecture hall (fixed seats)
150
7.5
0.06
—
Locker/dressing rooms
g
—
—
—
0.25
Media center
25
10
0.12
—
Multiuse assembly
100
7.5
0.06
—
Music/theater/dance
35
10
0.06
—
Science laboratories
g, k
25
10
0.18
1.0
Sports locker rooms
g
—
—
—
0.5
Wood/metal shops
g
20
10
0.18
0.5
Food and beverage service
Bars, cocktail lounges
100
7.5
0.18
—
Cafeteria, fast food
100
7.5
0.18
—
Dining rooms
70
7.5
0.18
—
Kitchens (cooking)
b
—
—
—
0.7
Non
-
tobacco smoking   
establishments
b
70
60
—
—
Hotels, motels, resorts and dormitories 
Bathrooms/toilet
—
private
g
—
—
—
25/50
f
Bedroom/living room
10
5
0.06
—
Conference/meeting
50
5
0.06
—
Dormitory sleeping areas
20
5
0.06
—
Gambling casinos
120
7.5
0.18
—
Lobbies/prefunction
30
7.5
0.06
—
Multipurpose assembly
120
5
0.06
—
Laboratories
j
Biological
—
—
1.0
1.0
VENTILATION
Chemical
—
—
1.0
1.0
Industrial and nonteaching
—
—
1.0
1.0
Nonproduction chemical labs
—
—
1.0
1.0
Offices
Conference rooms
50
5
0.06
—
Main entry lobbies
10
5
0.06
—
Office spaces
5
5
0.06
—
Reception areas
30
5
0.06
—
Telephone/data entry
60
5
0.06
—
Private dwellings, single and multiple
Garages, common for multiple units
b
—
—
—
0.75
Kitchens and Kitchenettes
b
, 
m
—
—
—
25/100
f
Living areas
c, i
Based upon number of 
bedrooms. First bed-
room, 2; each additional 
bedroom, 1
0.35 ACH but not less
than 15 cfm/person
—
—
Toilet rooms and bathrooms
g
—
—
—
20/50
f
Public spaces
Corridors
—
—
0.06
—
Courtrooms
70
5
0.06
—
Elevator car
—
—
—
1.0
Legislative chambers
50
5
0.06
—
Libraries
10
5
0.12
—
Museums (children’s)
40
7.5
0.12
—
Museums/galleries
40
7.5
0.06
—
Places of religious worship
120
5
0.06
—
Public spaces
Shower room (per shower head)
g
—
—
—
50/20
f
Toilet rooms 
–
public
g
—
—
—
50/70
e
VENTILATION
Retail stores, sales floors and 
showroom 
floors
Dressing rooms
—
—
—
0.25
Mall common areas
40
7.5
0.06
—
Sales
15
7.5
0.12
—
Shipping and receiving
—
—
0.12
—
Smoking lounges and non
-
tobacco   
smoking establishments
b
70
60
—
—
Storage rooms
—
—
0.12
—
Warehouses (see storage)
—
—
—
—
Specialty shops
Automotive motor
-
fuel dispensing 
stations
b
—
—
—
1.5
Barber
25
7.5
0.06
0.5
Beauty salons (without nail salon 
services)
b
25
20
0.12
0.6
Nail salons
b, h
25
20
0.12
0.6
Embalming room
b
—
—
—
2.0
Pet shops (animal areas)
b
10
7.5
0.18
0.9
Supermarkets
8
7.5
0.06
—
Sports and amusement
Bowling alleys (seating areas)
40
10
0.12
—
Disco/dance floors
100
20
0.06
—
Game arcades
20
7.5
0.18
—
Gym, stadium, arena (play area)
—
—
0.30
—
Heath club/aerobics room
40
20
0.06
—
Health 
club/weight room
10
20
0.06
—
Ice arenas without combustion engines
—
—
0.30
0.5
Spectator areas
150
7.5
0.06
—
VENTILATION
Swimming pools (pool and deck area)
—
—
0.48
—
Storage
Repair garages, enclosed parking 
garages
b, d
—
—
—
0.75
Warehouses
—
—
0.06
—
Theaters
Auditoriums (see education)
—
—
—
—
Lobbies
150
5
0.06
—
Stages, studios
70
10
0.06
—
Ticket booths
60
5
0.06
—
Transportation
Platforms
100
7.5
0.06
—
Transportation waiting
100
7.5
0.06
—
Workrooms
Bank vaults/safe deposit
5
5
0.06
—
Computer (without printing)
4
5
0.06
—
Copy, printing rooms
4
5
0.06
0.5
Darkrooms
—
—
—
1.0
Meat processing
c
10
15
—
—
Pharmacy (prep. area)
10
5
0.18
—
Photo studios
10
5
0.12
—
For SI: 1 cubic foot per 
minute = 0.0004719 m
3
/s, 1 ton = 908 kg, 1 cubic foot per minute per square foot = 0.00508m
3
/(s • m
2
), 
°C = ((°F) 
-
32)
/
1.8, 
1 square foot = 0.0929 m
2
.
a.
Based upon net occupiable floor area.
b.
Mechanical exhaust required and the 
recirculation of air from such spaces is prohibited (see Section 403.2.1, Item 3).
c.
Spaces unheated or maintained below 50°F are not covered by these requirements unless the occupancy is continuous.
d.
Ventilation systems in enclosed parking garages sh
all comply with Section 404.
e.
Rates are per water closet or urinal. The higher rate shall be provided where 
the exhaust system is designed to operate intermittently. The lower rate 
shall be permitted only where the exhaust system is designed to operate 
continuously while the space served by the toilet facilities is occupied.
f.
Rates are per room unless otherwise indicated. The higher rate shall be provided where the exhaust system is designed to oper
ate intermittently. The 
lower rate shall 
be permitted
only where the exhaust system is designed to operate continuously while the dwelling unit or sleeping unit served by 
the toilet facility is occupied.
g.
Mechanical exhaust is required and recirculation from such spaces is prohibited (see Section 403.2.1,
Item 4).
h.
For nail salons, 
each manicure and pedicure station shall be provided with a source capture system capable of exhausting not less than 50 cfm 
per 
station. Exhaust inlets shall be located in accordance with Section 502.20. Where one or more re
quired source capture systems operate 
‡‡‡ Chapter 4 was amended by 
Local Law 
77 
of 2023
. This law has an effective
 date of June 10, 2023.
CHAPTER 4
VENTILATION 
SECTION MC 401
GENERAL
401.1 Scope.
This chapter shall govern the ventilation of spaces within a building intended to be occupied. Mechanical exhaust 
systems, including exhaust systems serving clothes dryers and cooking appliances; hazardous exhaust systems; dust, stock and 
refuse conveyor systems; subslab soil exhaust systems; smoke control systems; energy recovery ventilation systems and other 
systems specified in Section 502 shall comply with Chapter 5.
401
.2 Ventilation required.
Habitable and occupiable spaces shall be provided with ventilation in accordance with this section.
1.
Every 
occupiable
space shall be:
1.1.
Naturally ventilated in accordance with Section 402 and mechanically exhausted in 
accordance with Table 403.3.1.1; 
or
1.2.
Mechanically ventilated in accordance with Section 403.
2.
All habitable spaces and occupiable spaces provided with air conditioning shall be mechanically ventilated in accordance 
with Section 403.
3.
Every habitabl
e space
shall be naturally ventilated in accordance with Section 402.
4.
Every habitable space shall be mechanically ventilated if required by Section 403
. 
Ambulatory care facilities (Group B) and Group I
-
2 occupancies shall be ventilated by mechanical means in accordance 
with Section 407.
401.3 When required.
Ventilation shall be provided during the periods that the room or space is occupied or during operation 
of gas appliances.
‡‡‡
401.4 Intake opening location.
Ventilation air intake openings shall compl
y with all of
the following:
1.
Intake 
openings
shall be located
not less than 10 feet (3048 mm) from lot lines or buildings on the same lot. For buildings 
on lots measuring less than 20 feet (6096 mm) in width, intake openings shall be located at the cent
erline between lot 
lines. Where openings front on a street or public way, the distance shall be measured to the centerline of the street or 
public way.
2.
Outdoor air intakes for office occupancies having occupied floors located more than 75 feet (22 860 mm) above the 
lowest level of fire department vehicle access serving spaces above the second story and serving spaces greater than 
10,000 square feet (929 m
2
) of floor area shall be located at least 20 feet (6096 mm) above ground level, at least 30 feet 
(91
44 mm) from exhaust outlets and other exhaust discharges, and at least 20 feet (6096 mm) from areas that may collect 
vehicular exhaust, such as off street loading bays.
3.
Mechanical and gravity outdoor air intake openings shall be located not less than 10
feet (3048 mm) horizontally from 
any hazardous or noxious contaminant source, such as vents, exhausts (including but not limited to exhaust from dry 
cleaning establishments, spray booths, and cooling towers), streets, alleys, parking lots and loading dock
s, except as 
specified in Item 3 
of 
Section 501.3.1. Outdoor air intake openings shall be permitted to be located less than 10 feet (3048 
mm) horizontally from streets, alleys, parking lots and loading docks provided that the openings are located not less 
than 
25 feet (7620 mm) vertically above such locations. Where openings front on a street or public way, the distance shall be 
measured 
to the centerline 
of the street or public way.
4.
Where the requirements of Item 3 above cannot be achieved, 
intake
openings shall be located not less than 3 feet (914.4 
mm) below contaminant sources where such sources are located within 10 feet (3048 mm) of the opening. 
5.
Intake openings in Group I occupancies shall comply with ANSI/ASHRAE/ASHE 170, as require
d.
VENTILATION
6.
Intake openings on structures in flood hazard areas shall comply with the additional requirements of Appendix G of the 
New York City Building Code.
Exception: 
Group R
-
3 occupancies are not required to comply with Section 401.4. 
401.4.1 Required damp
ers in intake openings.
Outdoor air intakes shall be provided with dampers in accordance with 
Chapter 6.
401.5 Intake opening protection.
Air intake openings that terminate outdoors shall be protected with 
corrosion
-
resistant 
screens, louvers or grilles. O
penings in louvers, grilles and screens shall be sized in accordance with Table 401.5, and shall be 
protected against local weather conditions. Outdoor air intake openings located in exterior walls shall meet the provisions f
or 
exterior wall opening protec
tives in accordance with Section 705 of the 
New York City 
Building Code.
TABLE 401.5
OPENING SIZES IN LOUVERS, GRILLES AND SCREENS 
PROTECTING OUTDOOR EXHAUST AND AIR INTAKE 
OPENINGS
OUTDOOR OPENING TYPE
MINIMUM AND MAXIMUM 
OPENING SIZES IN 
LOUVERS, 
GRILLES AND SCREENS 
MEASURED IN ANY 
DIRECTION
Intake openings in
residential oc-
cupancies
Not < 
1
/
4
inch and not > 
1
/
2
inch
Intake openings in other
than resi-
dential occupancies
> 
1
/
4
inch and not > 1 inch
For SI: 1 inch = 25.4 mm.
401.6 
Contaminant sources.
Stationary local sources 
producing
air
-
borne particulates, heat, odors, fumes, spray, vapors, 
smoke or gases in such quantities as to be irritating or injurious to health shall be provided with an exhaust system in 
accordance
with Chap
ter 5 or a means of collection and removal of the contaminants. Such exhaust shall discharge directly to an approved 
location at the exterior of the building.
401.6.1 Wind
-
driven rain.
All exterior louvers for building ventilation systems shall conform to the requirements of Chap-
ter 16 of the 
New York City Building Code
, where applicable, and the following:
1.
Comply with the requirements of AMCA 550. Louvers shall comply with the intru
sion requirements of wind
-
driven 
rain without the use of a damper. Outdoor air intake openings located in exterior walls shall meet the provisions for 
exterior wall opening protectives in accordance with Chapter 16 of the 
New York City Building Code
; 
or
2.
Be installed on a plenum configured to intercept any wind
-
driven rain penetrating the louver and to prevent the rain 
from entering the building ductwork system. Such plenum shall be waterproofed and equipped with a drainage system 
to convey water penetrat
ing the louver directly to the outdoors or in accordance with the 
New York City Plumbing 
Code
.
SECTION MC 402
NATURAL VENTILATION
402.1
General.
Natural ventilation of occupiable and habitable spaces
shall comply with Chapter 12 of the 
New York City 
Build
ing Code.
402.2 Reserved.
402.3 Reserved.
402.4 Reserved.
SECTION 
MC 
403
MECHANICAL VENTILATION
VENTILATION
403.1 Ventilation system.
Mechanical ventilation shall be 
provided
by a method of supply air and return or exhaust air. The 
amount of supply air shall be approximately equal to the amount of return and exhaust air. The system shall not be 
prohibited
from producing negative or positive pressure; such pressures shall not r
esult in door opening forces in excess of those indicated 
in the 
New York City Building Code
and shall not prevent doors from closing as required by the 
New York City Building Code
. 
The 
method
to convey ventilation air shall be designed and installed in ac
cordance with Chapter 6.
403.2 Outdoor air required.
The minimum outdoor airflow rate shall be determined in accordance with Section 403.3.1.1.
Exception:
The minimum required rate of outdoor air may be reduced where the registered design professional demo
nstrates 
that an engineered ventilation system is designed in accordance with ASHRAE 62.1 
Indoor Air Quality Procedure
.
403.2.1 Recirculation of air.
The outdoor air required by Section 403.3.1.1 shall not be recirculated. Air in excess of that 
required by
Section 403.3.1.1 shall not be prohibited from being recirculated as a component of supply air to building spaces, 
except that:
1.
Ventilation air shall not be recirculated from one dwelling 
unit 
to another or to dissimilar occupancies.
2.
Supply air to a
swimming pool and associated deck areas shall not be recirculated unless such air is 
dehumidified
to 
maintain the relative humidity of the area at 60 percent or less. Air from this area shall not be recirculated to other 
uses or occupancies
.
3.
Where mech
anical exhaust is required by Note b in Table 403.3.1.1, recirculation of air from such spaces shall be 
prohibited. Recirculation of air that is contained completely within such spaces shall not be prohibited. Where recir-
culation of air is prohibited, all 
air supplied to such spaces shall be exhausted, including any air in excess of that 
required by Table 403.3.1.1.
4.
Where mechanical exhaust is required by Note g in Table 403.3.1.1, mechanical exhaust is required and recirculation 
is prohibited. Recircula
tion of air that is contained completely within such spaces shall not be prohibited.
403.2.2 Transfer air.
Except where recirculation from such spaces is prohibited by Table 403.3.1.1, air transferred from 
occupiable spaces is not prohibited from serving a
s makeup air for required exhaust systems in such spaces as kitchens, 
baths, toilet rooms, elevators and smoking lounges. The amount of transfer air and exhaust air shall be sufficient to provide
the flow rates as specified in Section 403.3.1.1. The requir
ed outdoor airflow rates specified in Table 403.3.1.1 shall be 
introduced directly into such spaces or into the occupied spaces from which air is transferred or a combination of both.
403.3 Outdoor air and local exhaust airflow rates. 
Buildings that are no
t more than three stories in height above grade plane, 
and that (i) are within Occupancy Group R
-
2 or Occupancy Group R
-
3, (ii) are adult homes or enriched living housing as 
described in Section 308.3.1 of the 
New York City Building Code,
within Occupancy 
Group I
-
1 and have 16 occupants or fewer, 
or (iii) are community residences or intermediate
-
care facilities as described in Section 308.3.2 of the 
New York City Building 
Code,
shall be provided with outdoor air and local exhaust in accordance with Section 
403.3.1.1.2. All other buildings intended 
to be occupied shall be provided with outdoor air and local exhaust in accordance with Sections 403.3.1.1 through 403.3.1.6.
403.3.1 Reserved.
403.3.1.1 Outdoor airflow rate. 
Ventilation systems shall be designed t
o have the capacity to supply the minimum 
outdoor airflow rate determined in accordance with this section. In each occupiable space and, where required, each 
habitable space, the ventilation system shall be designed to deliver the required rate of outdoor 
airflow to the breathing 
zone. The occupant load utilized for design of the ventilation system shall be
not less than the number 
determined
from 
the estimated maximum occupant load rate 
indicated
in Table 403.3.1.1
. 
Ventilation rates for 
occupancies not represented 
in Table 403.3.1.1
shall be those for a listed occupancy classification that is most similar in terms of occupant density, 
activities and building construction; or shall be determined by an approved engineering analysis. The ven
tilation system 
shall be designed to supply the required rate of ventilation air continuously 
during
the period the building is occupied, 
except as otherwise stated in other provisions of the code.
With the exception of non
-
tobacco hookah establishments, t
he ventilation rates in Table 403.3.1.1
are based on the 
absence of smoking in occupiable spaces. Where smoking is anticipated in a space other than a non
-
tobacco hookah 
establishment, the ventilation system serving the space shall be designed to provide v
entilation over and above that re-
quired by Table 403.3.1.1
in accordance with accepted engineering practice.
Exceptions:
1.
The occupant load is not required to be 
determined 
based on the estimated maximum occupant load rate indi-
cated in Table 403.3
.1.1 wh
ere 
approved statistical data 
documents
the accuracy of an alternate anticipated 
occupant load.
VENTILATION
2.
The occupant load used in computing the required ventilation shall be the maximum number who will occupy 
the room or space simultaneously during any 2
-
hour p
eriod.
3.
Dynamic reset (Demand Controlled Ventilation). The system may be designed to reset the design outdoor air 
intake airflow and/or space or zone airflow as operating conditions change. Dynamic reset shall be designed in 
accordance with ASHRAE 62.1 a
nd comply with footnote k of Table 403.3.1.1.    These conditions include, but 
are not limited to:
3.1.
Variations in occupancy or ventilation airflow in one or more individual zones for which ventilation airflow 
requirements will be reset. Note: Examples of
measures for estimating such variations include: occupancy 
scheduled by time of day, a direct count of occupants, or an estimate of occupancy or ventilation rate per 
person using occupancy sensors such as those based on indoor CO
2
concentrations.
3.2.
Variations in the efficiency with which outdoor air is distributed to the occupants under different ventilation 
system airflows and temperatures.
3.3.
A higher fraction of outdoor air in the air supply due to intake of additional outdoor air for free cooli
ng or 
exhaust air makeup.
TABLE 403.3.1.1
MINIMUM VENTILATION RATES
OCCUPANCY CLASSIFICATION
OCCUPANT DENSITY
#/1000 FT
2a
PEOPLE OUTDOOR
AIRFLOW RATE IN 
BREATHING ZONE, R
p
CFM/PERSON
AREA OUTDOOR
AIRFLOW RATE IN 
BREATHING ZONE R
a 
CFM/FT
2a
EXHAUST 
AIRFLOW
RATE 
CFM/FT
2a
Correctional facilities
Booking/waiting
50
7.5
0.06
—
Cells
without plumbing fixtures
25
5
0.12
—
with plumbing fixtures
g
25
5
0.12
1.0
Day room
30
5
0.06
—
Correctional facilities
Dining halls
(see food and 
beverage service)
—
—
—
—
Guard stations
15
5
0.06
—
Dry cleaners, laundries
Coin
-
operated dry cleaner
20
15
—
—
Coin
-
operated laundries
20
7.5
0.06
—
Commercial dry cleaner
l
30
30
—
—
Commercial laundry
10
25
—
—
Storage, pick up
30
7.5
0.12
—
Education
Art classroom
g
20
10
0.18
0.7
VENTILATION
Auditoriums
150
5
0.06
—
Classrooms (ages 5
-
8)
25
10
0.12
—
Classrooms (age 9 plus)
35
10
0.12
—
Computer lab
25
10
0.12
—
Corridors (see public spaces)
—
—
—
—
Day care (through age 4)
25
10
0.18
—
Lecture classroom
65
7.5
0.06
—
Lecture hall (fixed seats)
150
7.5
0.06
—
Locker/dressing rooms
g
—
—
—
0.25
Media center
25
10
0.12
—
Multiuse assembly
100
7.5
0.06
—
Music/theater/dance
35
10
0.06
—
Science laboratories
g, k
25
10
0.18
1.0
Sports locker rooms
g
—
—
—
0.5
Wood/metal shops
g
20
10
0.18
0.5
Food and beverage service
Bars, cocktail lounges
100
7.5
0.18
—
Cafeteria, fast food
100
7.5
0.18
—
Dining rooms
70
7.5
0.18
—
Kitchens (cooking)
b
—
—
—
0.7
Non
-
tobacco smoking   
establishments
b
70
60
—
—
Hotels, motels, resorts and dormitories 
Bathrooms/toilet
—
private
g
—
—
—
25/50
f
Bedroom/living room
10
5
0.06
—
Conference/meeting
50
5
0.06
—
Dormitory sleeping areas
20
5
0.06
—
Gambling casinos
120
7.5
0.18
—
Lobbies/prefunction
30
7.5
0.06
—
Multipurpose assembly
120
5
0.06
—
Laboratories
j
Biological
—
—
1.0
1.0
VENTILATION
Chemical
—
—
1.0
1.0
Industrial and nonteaching
—
—
1.0
1.0
Nonproduction chemical labs
—
—
1.0
1.0
Offices
Conference rooms
50
5
0.06
—
Main entry lobbies
10
5
0.06
—
Office spaces
5
5
0.06
—
Reception areas
30
5
0.06
—
Telephone/data entry
60
5
0.06
—
Private dwellings, single and multiple
Garages, common for multiple units
b
—
—
—
0.75
Kitchens and Kitchenettes
b
, 
m
—
—
—
25/100
f
Living areas
c, i
Based upon number of 
bedrooms. First bed-
room, 2; each additional 
bedroom, 1
0.35 ACH but not less
than 15 cfm/person
—
—
Toilet rooms and bathrooms
g
—
—
—
20/50
f
Public spaces
Corridors
—
—
0.06
—
Courtrooms
70
5
0.06
—
Elevator car
—
—
—
1.0
Legislative chambers
50
5
0.06
—
Libraries
10
5
0.12
—
Museums (children’s)
40
7.5
0.12
—
Museums/galleries
40
7.5
0.06
—
Places of religious worship
120
5
0.06
—
Public spaces
Shower room (per shower head)
g
—
—
—
50/20
f
Toilet rooms 
–
public
g
—
—
—
50/70
e
VENTILATION
Retail stores, sales floors and 
showroom 
floors
Dressing rooms
—
—
—
0.25
Mall common areas
40
7.5
0.06
—
Sales
15
7.5
0.12
—
Shipping and receiving
—
—
0.12
—
Smoking lounges and non
-
tobacco   
smoking establishments
b
70
60
—
—
Storage rooms
—
—
0.12
—
Warehouses (see storage)
—
—
—
—
Specialty shops
Automotive motor
-
fuel dispensing 
stations
b
—
—
—
1.5
Barber
25
7.5
0.06
0.5
Beauty salons (without nail salon 
services)
b
25
20
0.12
0.6
Nail salons
b, h
25
20
0.12
0.6
Embalming room
b
—
—
—
2.0
Pet shops (animal areas)
b
10
7.5
0.18
0.9
Supermarkets
8
7.5
0.06
—
Sports and amusement
Bowling alleys (seating areas)
40
10
0.12
—
Disco/dance floors
100
20
0.06
—
Game arcades
20
7.5
0.18
—
Gym, stadium, arena (play area)
—
—
0.30
—
Heath club/aerobics room
40
20
0.06
—
Health 
club/weight room
10
20
0.06
—
Ice arenas without combustion engines
—
—
0.30
0.5
Spectator areas
150
7.5
0.06
—
VENTILATION
Swimming pools (pool and deck area)
—
—
0.48
—
Storage
Repair garages, enclosed parking 
garages
b, d
—
—
—
0.75
Warehouses
—
—
0.06
—
Theaters
Auditoriums (see education)
—
—
—
—
Lobbies
150
5
0.06
—
Stages, studios
70
10
0.06
—
Ticket booths
60
5
0.06
—
Transportation
Platforms
100
7.5
0.06
—
Transportation waiting
100
7.5
0.06
—
Workrooms
Bank vaults/safe deposit
5
5
0.06
—
Computer (without printing)
4
5
0.06
—
Copy, printing rooms
4
5
0.06
0.5
Darkrooms
—
—
—
1.0
Meat processing
c
10
15
—
—
Pharmacy (prep. area)
10
5
0.18
—
Photo studios
10
5
0.12
—
For SI: 1 cubic foot per 
minute = 0.0004719 m
3
/s, 1 ton = 908 kg, 1 cubic foot per minute per square foot = 0.00508m
3
/(s • m
2
), 
°C = ((°F) 
-
32)
/
1.8, 
1 square foot = 0.0929 m
2
.
a.
Based upon net occupiable floor area.
b.
Mechanical exhaust required and the 
recirculation of air from such spaces is prohibited (see Section 403.2.1, Item 3).
c.
Spaces unheated or maintained below 50°F are not covered by these requirements unless the occupancy is continuous.
d.
Ventilation systems in enclosed parking garages sh
all comply with Section 404.
e.
Rates are per water closet or urinal. The higher rate shall be provided where 
the exhaust system is designed to operate intermittently. The lower rate 
shall be permitted only where the exhaust system is designed to operate 
continuously while the space served by the toilet facilities is occupied.
f.
Rates are per room unless otherwise indicated. The higher rate shall be provided where the exhaust system is designed to oper
ate intermittently. The 
lower rate shall 
be permitted
only where the exhaust system is designed to operate continuously while the dwelling unit or sleeping unit served by 
the toilet facility is occupied.
g.
Mechanical exhaust is required and recirculation from such spaces is prohibited (see Section 403.2.1,
Item 4).
h.
For nail salons, 
each manicure and pedicure station shall be provided with a source capture system capable of exhausting not less than 50 cfm 
per 
station. Exhaust inlets shall be located in accordance with Section 502.20. Where one or more re
quired source capture systems operate 
VENTILATION
continuously during occupancy, the exhaust rate from such systems shall be permitted to be applied to the exhaust flow rate required by Table 
403.3.1.1 for the nail salon.
i.
For each dwelling unit within R
-
2 occupancies, outdoor ventilation air shall be provided by mechanical means when the sum of all exhaust air flow rates, 
whether continuous or intermittent, is designed to exceed 75 cfm. When provided, mechanical ventilation
air flow rate shall be approximately equal to the 
exhaust air flow rate in accordance with Section 403.1 and shall not be less than that required by the air flow rates prescribed in Table 403.3.1.1. For such 
dwelling units, manually operated openable exte
rior wall openings shall not be used to provide required mechanical ventilation air. 
j.
During unoccupied hours the ventilation rate and exhaust rates may be reduced to 0.5 cfm/ft
2
.
k.
When an educational science laboratory is occupied and hoods are 
not in use and hazardous materials are not present, then ventilation rates shall be 
consistent with actual use of the space, but not less than 0.5 cfm/ft
2
.
l.
See Section 502.6 for additional requirements.
m.
Exception: kitchens and kitchenettes in dwelli
ng units of R
-
2 occupancy may be naturally ventilated in accordance with Section 402.
403.3.1.1.1
Zone outdoor airflow.
The minimum outdoor airflow required to be supplied to each zone shall be de-
termined as a function of occupancy classification and space
air distribution effectiveness in accordance with Sections 
403.3.1.1.1.1
through 403.3.1.1.1.3.
403.3.1.1.1.1 Breathing zone outdoor airflow.
The outdoor airflow rate required in the breathing zone 
V
bz
of the 
occupiable space or spaces in a zone shall be determined in accordance with Equation 4
-
1.
V
bz
= R
p
P
z
+ R
a
A
z 
(Equation 4
-
1)
where:
A
z  
= 
Zone floor area: the net occupiable floor area of the space or spaces in the zone.
p
z
= Zone population: the number of people in the space or spaces in 
the zone.
R
p
= 
People outdoor air rate: the outdoor airflow rate required per person from Table 403.3.1.1.
R
a
     = 
Area outdoor air rate: the outdoor airflow rate required per unit area from Table 403.3.1.1.
403.3.1.1.1.2 Zone air distribution effectiveness
.
The zone air distribution effectiveness (E
z
) shall be determined 
using Table 403.3.1.1.1.2.
TABLE 403.3.1.1.1.2
ZONE AIR DISTRIBUTION EFFECTIVENESS
a, b, c, d 
AIR DISTRIBUTION CONFIGURATION
E
z
Ceiling or floor supply of cool air
1.0
 e
Ceiling or 
floor supply of warm air and floor return
1.0
Ceiling supply of warm air and ceiling return
0.8
 f
Floor supply of warm air and ceiling return
0.7
Makeup air drawn in on the opposite side of the 
room from the exhaust and/or return
0.8
Makeup air 
drawn in near to the exhaust and/or re-
turn location
0.5
For SI: 1 
foot = 304.8 mm, 1 foot per minute = 0.00506 m/s, 
°C = ((°F) 
– 
32) /1.8
. 
a. “Cool air” is air cooler than space temperature.
b. “Warm air” is air warmer than space temperature.
c. 
“Ceiling” includes any point above the breathing zone.
d. “Floor” includes any point below the breathing zone.
e. 
Zone air distribution effectiveness of 1.2 shall be permitted for systems with a floor supply of cool air and ceiling return,
provided that lo
w- 
velocity 
dis
-
placement
ventilation achieves unidirectional flow and thermal 
stratification.
f. 
Zone air distribution effectiveness of 1.0 shall be permitted for systems with a ceiling supply of warm air, provided that su
pply air temperature is less 
than 
15°F above space temperature and provided that the 150
foot
-
per
-
minute supply air jet reaches to within 
4
1
/
2
feet of floor level.
403.3.1.1.1.3 Zone outdoor airflow.
The zone outdoor airflow rate (V
oz
), shall be determined in accordance with 
Equation 
4-
2.
V
oz
=  
V
bz
E
z
(Equation 4
-
2)
VENTILATION
403.3.1.1.2 System outdoor airflow.
The outdoor air required to be supplied by each ventilation system shall be 
determined in accordance with Sections 403.3.1.1.2.1 through 403.3.1.1.2.3 as a function of system 
type and zone 
outdoor airflow rates.
403.3.1.1.2.1 Single zone systems.
Where one air handler supplies a mixture of outdoor air and recirculated return 
air to only one zone, the system outdoor air intake flow rate (V
ot
) shall be determined in accordance wi
th Equation 
4
-
3.
V
ot
= V
oz 
(Equation 4
-
3)
403.3.1.1.2.2 100
-
percent outdoor air systems.
Where one air handler supplies only outdoor air to one or more 
zones, the system outdoor air intake flow rate (V
ot
) shall be determined using Equation 4
-
4.
V
ot
=
∑
V
oz
all
zones
(Equation 4
-
4)
403.3.1.1.2.3 Multiple zone recirculating systems.
Where one air handler supplies a mixture of outdoor air and 
recirculated return air to more than one zone, the system outdoor air intake flow rate (V
ot
) shall be 
determined in 
accordance with Sections 403.3.1.1.2.3.1 through 403.3.1.1.2.3.4.
403.3.1.1.2.3.1 Primary outdoor air fraction.
The primary outdoor air fraction (Z
p
) shall be determined for 
each zone in accordance with Equation 4
-
5.
Z
p
= V
oz
/V
pz 
(Eq
uation 4
-
5)
where:
V
pz
= 
Primary airflow: The airflow rate supplied to the zone from the air
-
handling unit at which the outdoor air 
intake is located. It includes outdoor intake air and recirculated air from that air
-
handling unit but does 
not include a
ir transferred or air recirculated to the zone by other means. For design purposes, V
pz
shall 
be the zone design primary airflow rate, except for zones with variable air volume supply and V
pz
shall 
be the lowest expected primary air
-
flow rate to the zone w
hen it is fully occupied.
403.3.1.1.2.3.2 System ventilation efficiency.
The system ventilation efficiency (E
v
) shall be determined using 
Table 403.3.1.1.2.3.2 or Appendix A of ASHRAE 62.1.
TABLE 403.3.1.1.2.3.2
SYSTEM VENTILATION EFFICIENCY
a, b
Max (Z
p
)
E
v
≤ 
0.15
1
≤ 
　⸀(特)
　⸹
≤ 
　⸀㌵
　⸸
≤ 
　⸀㐵
　⸷
≤ 
　⸀㔵
　⸶
≤ 
　⸀㘵
　⸵
≤ 
　⸀㜵
　⸴
㸀‰⸀㜵
　⸳
愮⁍愀砀 
⠀
娀
瀀
⤀⁩猀⁴栀攠氀慲最敳琀⁶慬甀攠漀昀 
娀
瀀
挀愀氀挀甀氀愀琀攀搀⁵猀椀渀最⁅焀甀愀琀椀漀渀′′′
ⴀ
㔀⁡洀漀渀最⁡氀氀 
琀栀攀⁺潮攀猀⁳攀爀瘀攀搀⁢礀 琀栀攀⁳礀猀琀攀洀⸀
戀⸠䤀渀琀敲瀀漀氀慴椀渀最 戀攀琀眀攀敮⁴愀戀氀攠
瘀愀汵攀猀⁳栀愀汬⁢攀 瀀攀爀洀椀瑴攀搀⸀
403.3.1.1.2.3.3 Uncorrected outdoor air intake.
The uncorrected outdoor air intake flow rate (V
ou
) shall be 
determined in accordance with Equation 4
-
6.
V
ou
=
D
∑
R
p
P
z
all
zones
+
∑
R
a
A
z
all
zones
(Equation 4
-
6)
where:
D
=
Occupant diversity: the ratio of the system population to the sum of the zone populations, determined in 
accordance with Equation 4
-
7.
VENTILATION
D =  
P
s
∑
P
z
all
zones
(Equation 4
-
7)
where:
P
a
= System population: The total number of occupants in the area served by the system. For design purposes, 
P
s
shall be the maximum number of occupants expected to be concurrently in all zones served by the 
system.
403.3.1.1.2.3.4 Outdoor air intake flow ra
te.
The outdoor air intake flow rate (
V
ot
) shall be determined in 
accordance with Equation 4
-
8.
V
ot
= V
ou
/E
v
(Equation 4
-
8)
403.3.1.2 
Short
-
term conditions.
If it is known that peak occupancy will be of short duration and/or ventilation will 
be varied or interrupted for a short period of time, the design may be based on the average conditions over a time 
period T determined by Equation 4
-
9.
T = 3V/V
bz
(Equation 4
-
9) 
(US)
T = 50V/V
bz
(Equation 4
-
9) 
(SI)
where:
T 
= 
averaging time period, minutes
V 
= 
the volume of the zone of which averaging is being applied, cubic feet
V
bz
= 
the breathing zone outdoor airflow calculated using Equation 4
-
1 and design valve of the zone pop-
ulation P
z
, cfm
Acceptable design adjustments based on this optional provision include the following:
1.
Zone with fluctuating occupancy: the zone population (
P
z
) may be averaged over time, T.
2.
Zone with intermittent interruption of supply air: the average outdoor airflow supplied to breathing zone over 
time, T, shall be no less than the breathing zone outdoor airflow (
V
bz
) calculated using Equation 4
-
1.
3.
A 
system with intermittent closure of outdoor air intake: the average
outdoor air intake over time, T, shall be no 
less than the minimum outdoor air intake (
V
ot
) calculated using Equation 4
-
3, 4
-
4 or 4
-
8, as appropriate. 
403.3.1.3 Exhaust ventilation.
Exhaust airflow rate shall be provided in accordance with the requirements of Table 
403.3.1.1.
Exhaust makeup
air shall be 
permitted
to 
be any combination of
outdo
or 
air, recirculated air and transfer air, 
except as limited in accordance with Section 403.2.
403.3.1.4 System operation.
The minimum flow rate of outdoor air that the ventilation system must be capable of sup-
plying during its operation shall be permitted
to be based on the rate per person indicated in Table 403.3.1.1 and the 
actual number of occupants present.
403.3.1.5 Variable air volume system control.
Variable air volume air distribution systems, other than those designed 
to supply only 100
-
percent ou
tdoor air, shall be provided with controls to regulate the flow of outdoor air. Such control 
system shall be designed to maintain the flow rate of outdoor air at a rate of not less than that required by Section 403.3.1
.1 
over the entire range of supply air
operating rates.
403.3.1.6 Balancing.
The ventilation air distribution system shall be provided with means to adjust the system to achieve 
not less than the minimum ventilation airflow rate as required by Sections 403.3.1.1 and 403.3.1.2. Ventilation syst
ems 
shall be balanced by an approved method. Such balancing shall verify that the ventilation system is capable of supplying 
and exhausting the airflow rates required by Sections 403.3.1.1 and 403.3.1.2.
SECTION 
MC 
404
ENCLOSED PARKING GARAGES
404.1 Enclosed parking garages.
Where mechanical ventilation 
systems
for enclosed parking garages operate intermittently
, 
such operation shall be automatic by means of carbon monoxide detectors applied in conjunction with nitrogen dioxide detec-
tors. Such detectors sha
ll be installed in accordance with their manufacturers’ instructions. Such systems shall operate auto-
matically upon detection of a concentration of carbon monoxide of 25 parts per million (ppm) or nitrogen dioxide of 500 parts
per billion (ppb).
‡‡‡ Chapter 4 was amended by 
Local Law 
77 
of 2023
. This law has an effective
 date of June 10, 2023.
CHAPTER 4
VENTILATION 
SECTION MC 401
GENERAL
401.1 Scope.
This chapter shall govern the ventilation of spaces within a building intended to be occupied. Mechanical exhaust 
systems, including exhaust systems serving clothes dryers and cooking appliances; hazardous exhaust systems; dust, stock and 
refuse conveyor systems; subslab soil exhaust systems; smoke control systems; energy recovery ventilation systems and other 
systems specified in Section 502 shall comply with Chapter 5.
401
.2 Ventilation required.
Habitable and occupiable spaces shall be provided with ventilation in accordance with this section.
1.
Every 
occupiable
space shall be:
1.1.
Naturally ventilated in accordance with Section 402 and mechanically exhausted in 
accordance with Table 403.3.1.1; 
or
1.2.
Mechanically ventilated in accordance with Section 403.
2.
All habitable spaces and occupiable spaces provided with air conditioning shall be mechanically ventilated in accordance 
with Section 403.
3.
Every habitabl
e space
shall be naturally ventilated in accordance with Section 402.
4.
Every habitable space shall be mechanically ventilated if required by Section 403
. 
Ambulatory care facilities (Group B) and Group I
-
2 occupancies shall be ventilated by mechanical means in accordance 
with Section 407.
401.3 When required.
Ventilation shall be provided during the periods that the room or space is occupied or during operation 
of gas appliances.
‡‡‡
401.4 Intake opening location.
Ventilation air intake openings shall compl
y with all of
the following:
1.
Intake 
openings
shall be located
not less than 10 feet (3048 mm) from lot lines or buildings on the same lot. For buildings 
on lots measuring less than 20 feet (6096 mm) in width, intake openings shall be located at the cent
erline between lot 
lines. Where openings front on a street or public way, the distance shall be measured to the centerline of the street or 
public way.
2.
Outdoor air intakes for office occupancies having occupied floors located more than 75 feet (22 860 mm) above the 
lowest level of fire department vehicle access serving spaces above the second story and serving spaces greater than 
10,000 square feet (929 m
2
) of floor area shall be located at least 20 feet (6096 mm) above ground level, at least 30 feet 
(91
44 mm) from exhaust outlets and other exhaust discharges, and at least 20 feet (6096 mm) from areas that may collect 
vehicular exhaust, such as off street loading bays.
3.
Mechanical and gravity outdoor air intake openings shall be located not less than 10
feet (3048 mm) horizontally from 
any hazardous or noxious contaminant source, such as vents, exhausts (including but not limited to exhaust from dry 
cleaning establishments, spray booths, and cooling towers), streets, alleys, parking lots and loading dock
s, except as 
specified in Item 3 
of 
Section 501.3.1. Outdoor air intake openings shall be permitted to be located less than 10 feet (3048 
mm) horizontally from streets, alleys, parking lots and loading docks provided that the openings are located not less 
than 
25 feet (7620 mm) vertically above such locations. Where openings front on a street or public way, the distance shall be 
measured 
to the centerline 
of the street or public way.
4.
Where the requirements of Item 3 above cannot be achieved, 
intake
openings shall be located not less than 3 feet (914.4 
mm) below contaminant sources where such sources are located within 10 feet (3048 mm) of the opening. 
5.
Intake openings in Group I occupancies shall comply with ANSI/ASHRAE/ASHE 170, as require
d.
VENTILATION
6.
Intake openings on structures in flood hazard areas shall comply with the additional requirements of Appendix G of the 
New York City Building Code.
Exception: 
Group R
-
3 occupancies are not required to comply with Section 401.4. 
401.4.1 Required damp
ers in intake openings.
Outdoor air intakes shall be provided with dampers in accordance with 
Chapter 6.
401.5 Intake opening protection.
Air intake openings that terminate outdoors shall be protected with 
corrosion
-
resistant 
screens, louvers or grilles. O
penings in louvers, grilles and screens shall be sized in accordance with Table 401.5, and shall be 
protected against local weather conditions. Outdoor air intake openings located in exterior walls shall meet the provisions f
or 
exterior wall opening protec
tives in accordance with Section 705 of the 
New York City 
Building Code.
TABLE 401.5
OPENING SIZES IN LOUVERS, GRILLES AND SCREENS 
PROTECTING OUTDOOR EXHAUST AND AIR INTAKE 
OPENINGS
OUTDOOR OPENING TYPE
MINIMUM AND MAXIMUM 
OPENING SIZES IN 
LOUVERS, 
GRILLES AND SCREENS 
MEASURED IN ANY 
DIRECTION
Intake openings in
residential oc-
cupancies
Not < 
1
/
4
inch and not > 
1
/
2
inch
Intake openings in other
than resi-
dential occupancies
> 
1
/
4
inch and not > 1 inch
For SI: 1 inch = 25.4 mm.
401.6 
Contaminant sources.
Stationary local sources 
producing
air
-
borne particulates, heat, odors, fumes, spray, vapors, 
smoke or gases in such quantities as to be irritating or injurious to health shall be provided with an exhaust system in 
accordance
with Chap
ter 5 or a means of collection and removal of the contaminants. Such exhaust shall discharge directly to an approved 
location at the exterior of the building.
401.6.1 Wind
-
driven rain.
All exterior louvers for building ventilation systems shall conform to the requirements of Chap-
ter 16 of the 
New York City Building Code
, where applicable, and the following:
1.
Comply with the requirements of AMCA 550. Louvers shall comply with the intru
sion requirements of wind
-
driven 
rain without the use of a damper. Outdoor air intake openings located in exterior walls shall meet the provisions for 
exterior wall opening protectives in accordance with Chapter 16 of the 
New York City Building Code
; 
or
2.
Be installed on a plenum configured to intercept any wind
-
driven rain penetrating the louver and to prevent the rain 
from entering the building ductwork system. Such plenum shall be waterproofed and equipped with a drainage system 
to convey water penetrat
ing the louver directly to the outdoors or in accordance with the 
New York City Plumbing 
Code
.
SECTION MC 402
NATURAL VENTILATION
402.1
General.
Natural ventilation of occupiable and habitable spaces
shall comply with Chapter 12 of the 
New York City 
Build
ing Code.
402.2 Reserved.
402.3 Reserved.
402.4 Reserved.
SECTION 
MC 
403
MECHANICAL VENTILATION
VENTILATION
403.1 Ventilation system.
Mechanical ventilation shall be 
provided
by a method of supply air and return or exhaust air. The 
amount of supply air shall be approximately equal to the amount of return and exhaust air. The system shall not be 
prohibited
from producing negative or positive pressure; such pressures shall not r
esult in door opening forces in excess of those indicated 
in the 
New York City Building Code
and shall not prevent doors from closing as required by the 
New York City Building Code
. 
The 
method
to convey ventilation air shall be designed and installed in ac
cordance with Chapter 6.
403.2 Outdoor air required.
The minimum outdoor airflow rate shall be determined in accordance with Section 403.3.1.1.
Exception:
The minimum required rate of outdoor air may be reduced where the registered design professional demo
nstrates 
that an engineered ventilation system is designed in accordance with ASHRAE 62.1 
Indoor Air Quality Procedure
.
403.2.1 Recirculation of air.
The outdoor air required by Section 403.3.1.1 shall not be recirculated. Air in excess of that 
required by
Section 403.3.1.1 shall not be prohibited from being recirculated as a component of supply air to building spaces, 
except that:
1.
Ventilation air shall not be recirculated from one dwelling 
unit 
to another or to dissimilar occupancies.
2.
Supply air to a
swimming pool and associated deck areas shall not be recirculated unless such air is 
dehumidified
to 
maintain the relative humidity of the area at 60 percent or less. Air from this area shall not be recirculated to other 
uses or occupancies
.
3.
Where mech
anical exhaust is required by Note b in Table 403.3.1.1, recirculation of air from such spaces shall be 
prohibited. Recirculation of air that is contained completely within such spaces shall not be prohibited. Where recir-
culation of air is prohibited, all 
air supplied to such spaces shall be exhausted, including any air in excess of that 
required by Table 403.3.1.1.
4.
Where mechanical exhaust is required by Note g in Table 403.3.1.1, mechanical exhaust is required and recirculation 
is prohibited. Recircula
tion of air that is contained completely within such spaces shall not be prohibited.
403.2.2 Transfer air.
Except where recirculation from such spaces is prohibited by Table 403.3.1.1, air transferred from 
occupiable spaces is not prohibited from serving a
s makeup air for required exhaust systems in such spaces as kitchens, 
baths, toilet rooms, elevators and smoking lounges. The amount of transfer air and exhaust air shall be sufficient to provide
the flow rates as specified in Section 403.3.1.1. The requir
ed outdoor airflow rates specified in Table 403.3.1.1 shall be 
introduced directly into such spaces or into the occupied spaces from which air is transferred or a combination of both.
403.3 Outdoor air and local exhaust airflow rates. 
Buildings that are no
t more than three stories in height above grade plane, 
and that (i) are within Occupancy Group R
-
2 or Occupancy Group R
-
3, (ii) are adult homes or enriched living housing as 
described in Section 308.3.1 of the 
New York City Building Code,
within Occupancy 
Group I
-
1 and have 16 occupants or fewer, 
or (iii) are community residences or intermediate
-
care facilities as described in Section 308.3.2 of the 
New York City Building 
Code,
shall be provided with outdoor air and local exhaust in accordance with Section 
403.3.1.1.2. All other buildings intended 
to be occupied shall be provided with outdoor air and local exhaust in accordance with Sections 403.3.1.1 through 403.3.1.6.
403.3.1 Reserved.
403.3.1.1 Outdoor airflow rate. 
Ventilation systems shall be designed t
o have the capacity to supply the minimum 
outdoor airflow rate determined in accordance with this section. In each occupiable space and, where required, each 
habitable space, the ventilation system shall be designed to deliver the required rate of outdoor 
airflow to the breathing 
zone. The occupant load utilized for design of the ventilation system shall be
not less than the number 
determined
from 
the estimated maximum occupant load rate 
indicated
in Table 403.3.1.1
. 
Ventilation rates for 
occupancies not represented 
in Table 403.3.1.1
shall be those for a listed occupancy classification that is most similar in terms of occupant density, 
activities and building construction; or shall be determined by an approved engineering analysis. The ven
tilation system 
shall be designed to supply the required rate of ventilation air continuously 
during
the period the building is occupied, 
except as otherwise stated in other provisions of the code.
With the exception of non
-
tobacco hookah establishments, t
he ventilation rates in Table 403.3.1.1
are based on the 
absence of smoking in occupiable spaces. Where smoking is anticipated in a space other than a non
-
tobacco hookah 
establishment, the ventilation system serving the space shall be designed to provide v
entilation over and above that re-
quired by Table 403.3.1.1
in accordance with accepted engineering practice.
Exceptions:
1.
The occupant load is not required to be 
determined 
based on the estimated maximum occupant load rate indi-
cated in Table 403.3
.1.1 wh
ere 
approved statistical data 
documents
the accuracy of an alternate anticipated 
occupant load.
VENTILATION
2.
The occupant load used in computing the required ventilation shall be the maximum number who will occupy 
the room or space simultaneously during any 2
-
hour p
eriod.
3.
Dynamic reset (Demand Controlled Ventilation). The system may be designed to reset the design outdoor air 
intake airflow and/or space or zone airflow as operating conditions change. Dynamic reset shall be designed in 
accordance with ASHRAE 62.1 a
nd comply with footnote k of Table 403.3.1.1.    These conditions include, but 
are not limited to:
3.1.
Variations in occupancy or ventilation airflow in one or more individual zones for which ventilation airflow 
requirements will be reset. Note: Examples of
measures for estimating such variations include: occupancy 
scheduled by time of day, a direct count of occupants, or an estimate of occupancy or ventilation rate per 
person using occupancy sensors such as those based on indoor CO
2
concentrations.
3.2.
Variations in the efficiency with which outdoor air is distributed to the occupants under different ventilation 
system airflows and temperatures.
3.3.
A higher fraction of outdoor air in the air supply due to intake of additional outdoor air for free cooli
ng or 
exhaust air makeup.
TABLE 403.3.1.1
MINIMUM VENTILATION RATES
OCCUPANCY CLASSIFICATION
OCCUPANT DENSITY
#/1000 FT
2a
PEOPLE OUTDOOR
AIRFLOW RATE IN 
BREATHING ZONE, R
p
CFM/PERSON
AREA OUTDOOR
AIRFLOW RATE IN 
BREATHING ZONE R
a 
CFM/FT
2a
EXHAUST 
AIRFLOW
RATE 
CFM/FT
2a
Correctional facilities
Booking/waiting
50
7.5
0.06
—
Cells
without plumbing fixtures
25
5
0.12
—
with plumbing fixtures
g
25
5
0.12
1.0
Day room
30
5
0.06
—
Correctional facilities
Dining halls
(see food and 
beverage service)
—
—
—
—
Guard stations
15
5
0.06
—
Dry cleaners, laundries
Coin
-
operated dry cleaner
20
15
—
—
Coin
-
operated laundries
20
7.5
0.06
—
Commercial dry cleaner
l
30
30
—
—
Commercial laundry
10
25
—
—
Storage, pick up
30
7.5
0.12
—
Education
Art classroom
g
20
10
0.18
0.7
VENTILATION
Auditoriums
150
5
0.06
—
Classrooms (ages 5
-
8)
25
10
0.12
—
Classrooms (age 9 plus)
35
10
0.12
—
Computer lab
25
10
0.12
—
Corridors (see public spaces)
—
—
—
—
Day care (through age 4)
25
10
0.18
—
Lecture classroom
65
7.5
0.06
—
Lecture hall (fixed seats)
150
7.5
0.06
—
Locker/dressing rooms
g
—
—
—
0.25
Media center
25
10
0.12
—
Multiuse assembly
100
7.5
0.06
—
Music/theater/dance
35
10
0.06
—
Science laboratories
g, k
25
10
0.18
1.0
Sports locker rooms
g
—
—
—
0.5
Wood/metal shops
g
20
10
0.18
0.5
Food and beverage service
Bars, cocktail lounges
100
7.5
0.18
—
Cafeteria, fast food
100
7.5
0.18
—
Dining rooms
70
7.5
0.18
—
Kitchens (cooking)
b
—
—
—
0.7
Non
-
tobacco smoking   
establishments
b
70
60
—
—
Hotels, motels, resorts and dormitories 
Bathrooms/toilet
—
private
g
—
—
—
25/50
f
Bedroom/living room
10
5
0.06
—
Conference/meeting
50
5
0.06
—
Dormitory sleeping areas
20
5
0.06
—
Gambling casinos
120
7.5
0.18
—
Lobbies/prefunction
30
7.5
0.06
—
Multipurpose assembly
120
5
0.06
—
Laboratories
j
Biological
—
—
1.0
1.0
VENTILATION
Chemical
—
—
1.0
1.0
Industrial and nonteaching
—
—
1.0
1.0
Nonproduction chemical labs
—
—
1.0
1.0
Offices
Conference rooms
50
5
0.06
—
Main entry lobbies
10
5
0.06
—
Office spaces
5
5
0.06
—
Reception areas
30
5
0.06
—
Telephone/data entry
60
5
0.06
—
Private dwellings, single and multiple
Garages, common for multiple units
b
—
—
—
0.75
Kitchens and Kitchenettes
b
, 
m
—
—
—
25/100
f
Living areas
c, i
Based upon number of 
bedrooms. First bed-
room, 2; each additional 
bedroom, 1
0.35 ACH but not less
than 15 cfm/person
—
—
Toilet rooms and bathrooms
g
—
—
—
20/50
f
Public spaces
Corridors
—
—
0.06
—
Courtrooms
70
5
0.06
—
Elevator car
—
—
—
1.0
Legislative chambers
50
5
0.06
—
Libraries
10
5
0.12
—
Museums (children’s)
40
7.5
0.12
—
Museums/galleries
40
7.5
0.06
—
Places of religious worship
120
5
0.06
—
Public spaces
Shower room (per shower head)
g
—
—
—
50/20
f
Toilet rooms 
–
public
g
—
—
—
50/70
e
VENTILATION
Retail stores, sales floors and 
showroom 
floors
Dressing rooms
—
—
—
0.25
Mall common areas
40
7.5
0.06
—
Sales
15
7.5
0.12
—
Shipping and receiving
—
—
0.12
—
Smoking lounges and non
-
tobacco   
smoking establishments
b
70
60
—
—
Storage rooms
—
—
0.12
—
Warehouses (see storage)
—
—
—
—
Specialty shops
Automotive motor
-
fuel dispensing 
stations
b
—
—
—
1.5
Barber
25
7.5
0.06
0.5
Beauty salons (without nail salon 
services)
b
25
20
0.12
0.6
Nail salons
b, h
25
20
0.12
0.6
Embalming room
b
—
—
—
2.0
Pet shops (animal areas)
b
10
7.5
0.18
0.9
Supermarkets
8
7.5
0.06
—
Sports and amusement
Bowling alleys (seating areas)
40
10
0.12
—
Disco/dance floors
100
20
0.06
—
Game arcades
20
7.5
0.18
—
Gym, stadium, arena (play area)
—
—
0.30
—
Heath club/aerobics room
40
20
0.06
—
Health 
club/weight room
10
20
0.06
—
Ice arenas without combustion engines
—
—
0.30
0.5
Spectator areas
150
7.5
0.06
—
VENTILATION
Swimming pools (pool and deck area)
—
—
0.48
—
Storage
Repair garages, enclosed parking 
garages
b, d
—
—
—
0.75
Warehouses
—
—
0.06
—
Theaters
Auditoriums (see education)
—
—
—
—
Lobbies
150
5
0.06
—
Stages, studios
70
10
0.06
—
Ticket booths
60
5
0.06
—
Transportation
Platforms
100
7.5
0.06
—
Transportation waiting
100
7.5
0.06
—
Workrooms
Bank vaults/safe deposit
5
5
0.06
—
Computer (without printing)
4
5
0.06
—
Copy, printing rooms
4
5
0.06
0.5
Darkrooms
—
—
—
1.0
Meat processing
c
10
15
—
—
Pharmacy (prep. area)
10
5
0.18
—
Photo studios
10
5
0.12
—
For SI: 1 cubic foot per 
minute = 0.0004719 m
3
/s, 1 ton = 908 kg, 1 cubic foot per minute per square foot = 0.00508m
3
/(s • m
2
), 
°C = ((°F) 
-
32)
/
1.8, 
1 square foot = 0.0929 m
2
.
a.
Based upon net occupiable floor area.
b.
Mechanical exhaust required and the 
recirculation of air from such spaces is prohibited (see Section 403.2.1, Item 3).
c.
Spaces unheated or maintained below 50°F are not covered by these requirements unless the occupancy is continuous.
d.
Ventilation systems in enclosed parking garages sh
all comply with Section 404.
e.
Rates are per water closet or urinal. The higher rate shall be provided where 
the exhaust system is designed to operate intermittently. The lower rate 
shall be permitted only where the exhaust system is designed to operate 
continuously while the space served by the toilet facilities is occupied.
f.
Rates are per room unless otherwise indicated. The higher rate shall be provided where the exhaust system is designed to oper
ate intermittently. The 
lower rate shall 
be permitted
only where the exhaust system is designed to operate continuously while the dwelling unit or sleeping unit served by 
the toilet facility is occupied.
g.
Mechanical exhaust is required and recirculation from such spaces is prohibited (see Section 403.2.1,
Item 4).
h.
For nail salons, 
each manicure and pedicure station shall be provided with a source capture system capable of exhausting not less than 50 cfm 
per 
station. Exhaust inlets shall be located in accordance with Section 502.20. Where one or more re
quired source capture systems operate 
VENTILATION
continuously during occupancy, the exhaust rate from such systems shall be permitted to be applied to the exhaust flow rate required by Table 
403.3.1.1 for the nail salon.
i.
For each dwelling unit within R
-
2 occupancies, outdoor ventilation air shall be provided by mechanical means when the sum of all exhaust air flow rates, 
whether continuous or intermittent, is designed to exceed 75 cfm. When provided, mechanical ventilation
air flow rate shall be approximately equal to the 
exhaust air flow rate in accordance with Section 403.1 and shall not be less than that required by the air flow rates prescribed in Table 403.3.1.1. For such 
dwelling units, manually operated openable exte
rior wall openings shall not be used to provide required mechanical ventilation air. 
j.
During unoccupied hours the ventilation rate and exhaust rates may be reduced to 0.5 cfm/ft
2
.
k.
When an educational science laboratory is occupied and hoods are 
not in use and hazardous materials are not present, then ventilation rates shall be 
consistent with actual use of the space, but not less than 0.5 cfm/ft
2
.
l.
See Section 502.6 for additional requirements.
m.
Exception: kitchens and kitchenettes in dwelli
ng units of R
-
2 occupancy may be naturally ventilated in accordance with Section 402.
403.3.1.1.1
Zone outdoor airflow.
The minimum outdoor airflow required to be supplied to each zone shall be de-
termined as a function of occupancy classification and space
air distribution effectiveness in accordance with Sections 
403.3.1.1.1.1
through 403.3.1.1.1.3.
403.3.1.1.1.1 Breathing zone outdoor airflow.
The outdoor airflow rate required in the breathing zone 
V
bz
of the 
occupiable space or spaces in a zone shall be determined in accordance with Equation 4
-
1.
V
bz
= R
p
P
z
+ R
a
A
z 
(Equation 4
-
1)
where:
A
z  
= 
Zone floor area: the net occupiable floor area of the space or spaces in the zone.
p
z
= Zone population: the number of people in the space or spaces in 
the zone.
R
p
= 
People outdoor air rate: the outdoor airflow rate required per person from Table 403.3.1.1.
R
a
     = 
Area outdoor air rate: the outdoor airflow rate required per unit area from Table 403.3.1.1.
403.3.1.1.1.2 Zone air distribution effectiveness
.
The zone air distribution effectiveness (E
z
) shall be determined 
using Table 403.3.1.1.1.2.
TABLE 403.3.1.1.1.2
ZONE AIR DISTRIBUTION EFFECTIVENESS
a, b, c, d 
AIR DISTRIBUTION CONFIGURATION
E
z
Ceiling or floor supply of cool air
1.0
 e
Ceiling or 
floor supply of warm air and floor return
1.0
Ceiling supply of warm air and ceiling return
0.8
 f
Floor supply of warm air and ceiling return
0.7
Makeup air drawn in on the opposite side of the 
room from the exhaust and/or return
0.8
Makeup air 
drawn in near to the exhaust and/or re-
turn location
0.5
For SI: 1 
foot = 304.8 mm, 1 foot per minute = 0.00506 m/s, 
°C = ((°F) 
– 
32) /1.8
. 
a. “Cool air” is air cooler than space temperature.
b. “Warm air” is air warmer than space temperature.
c. 
“Ceiling” includes any point above the breathing zone.
d. “Floor” includes any point below the breathing zone.
e. 
Zone air distribution effectiveness of 1.2 shall be permitted for systems with a floor supply of cool air and ceiling return,
provided that lo
w- 
velocity 
dis
-
placement
ventilation achieves unidirectional flow and thermal 
stratification.
f. 
Zone air distribution effectiveness of 1.0 shall be permitted for systems with a ceiling supply of warm air, provided that su
pply air temperature is less 
than 
15°F above space temperature and provided that the 150
foot
-
per
-
minute supply air jet reaches to within 
4
1
/
2
feet of floor level.
403.3.1.1.1.3 Zone outdoor airflow.
The zone outdoor airflow rate (V
oz
), shall be determined in accordance with 
Equation 
4-
2.
V
oz
=  
V
bz
E
z
(Equation 4
-
2)
VENTILATION
403.3.1.1.2 System outdoor airflow.
The outdoor air required to be supplied by each ventilation system shall be 
determined in accordance with Sections 403.3.1.1.2.1 through 403.3.1.1.2.3 as a function of system 
type and zone 
outdoor airflow rates.
403.3.1.1.2.1 Single zone systems.
Where one air handler supplies a mixture of outdoor air and recirculated return 
air to only one zone, the system outdoor air intake flow rate (V
ot
) shall be determined in accordance wi
th Equation 
4
-
3.
V
ot
= V
oz 
(Equation 4
-
3)
403.3.1.1.2.2 100
-
percent outdoor air systems.
Where one air handler supplies only outdoor air to one or more 
zones, the system outdoor air intake flow rate (V
ot
) shall be determined using Equation 4
-
4.
V
ot
=
∑
V
oz
all
zones
(Equation 4
-
4)
403.3.1.1.2.3 Multiple zone recirculating systems.
Where one air handler supplies a mixture of outdoor air and 
recirculated return air to more than one zone, the system outdoor air intake flow rate (V
ot
) shall be 
determined in 
accordance with Sections 403.3.1.1.2.3.1 through 403.3.1.1.2.3.4.
403.3.1.1.2.3.1 Primary outdoor air fraction.
The primary outdoor air fraction (Z
p
) shall be determined for 
each zone in accordance with Equation 4
-
5.
Z
p
= V
oz
/V
pz 
(Eq
uation 4
-
5)
where:
V
pz
= 
Primary airflow: The airflow rate supplied to the zone from the air
-
handling unit at which the outdoor air 
intake is located. It includes outdoor intake air and recirculated air from that air
-
handling unit but does 
not include a
ir transferred or air recirculated to the zone by other means. For design purposes, V
pz
shall 
be the zone design primary airflow rate, except for zones with variable air volume supply and V
pz
shall 
be the lowest expected primary air
-
flow rate to the zone w
hen it is fully occupied.
403.3.1.1.2.3.2 System ventilation efficiency.
The system ventilation efficiency (E
v
) shall be determined using 
Table 403.3.1.1.2.3.2 or Appendix A of ASHRAE 62.1.
TABLE 403.3.1.1.2.3.2
SYSTEM VENTILATION EFFICIENCY
a, b
Max (Z
p
)
E
v
≤ 
0.15
1
≤ 
　⸀(特)
　⸹
≤ 
　⸀㌵
　⸸
≤ 
　⸀㐵
　⸷
≤ 
　⸀㔵
　⸶
≤ 
　⸀㘵
　⸵
≤ 
　⸀㜵
　⸴
㸀‰⸀㜵
　⸳
愮⁍愀砀 
⠀
娀
瀀
⤀⁩猀⁴栀攠氀慲最敳琀⁶慬甀攠漀昀 
娀
瀀
挀愀氀挀甀氀愀琀攀搀⁵猀椀渀最⁅焀甀愀琀椀漀渀′′′
ⴀ
㔀⁡洀漀渀最⁡氀氀 
琀栀攀⁺潮攀猀⁳攀爀瘀攀搀⁢礀 琀栀攀⁳礀猀琀攀洀⸀
戀⸠䤀渀琀敲瀀漀氀慴椀渀最 戀攀琀眀攀敮⁴愀戀氀攠
瘀愀汵攀猀⁳栀愀汬⁢攀 瀀攀爀洀椀瑴攀搀⸀
403.3.1.1.2.3.3 Uncorrected outdoor air intake.
The uncorrected outdoor air intake flow rate (V
ou
) shall be 
determined in accordance with Equation 4
-
6.
V
ou
=
D
∑
R
p
P
z
all
zones
+
∑
R
a
A
z
all
zones
(Equation 4
-
6)
where:
D
=
Occupant diversity: the ratio of the system population to the sum of the zone populations, determined in 
accordance with Equation 4
-
7.
VENTILATION
D =  
P
s
∑
P
z
all
zones
(Equation 4
-
7)
where:
P
a
= System population: The total number of occupants in the area served by the system. For design purposes, 
P
s
shall be the maximum number of occupants expected to be concurrently in all zones served by the 
system.
403.3.1.1.2.3.4 Outdoor air intake flow ra
te.
The outdoor air intake flow rate (
V
ot
) shall be determined in 
accordance with Equation 4
-
8.
V
ot
= V
ou
/E
v
(Equation 4
-
8)
403.3.1.2 
Short
-
term conditions.
If it is known that peak occupancy will be of short duration and/or ventilation will 
be varied or interrupted for a short period of time, the design may be based on the average conditions over a time 
period T determined by Equation 4
-
9.
T = 3V/V
bz
(Equation 4
-
9) 
(US)
T = 50V/V
bz
(Equation 4
-
9) 
(SI)
where:
T 
= 
averaging time period, minutes
V 
= 
the volume of the zone of which averaging is being applied, cubic feet
V
bz
= 
the breathing zone outdoor airflow calculated using Equation 4
-
1 and design valve of the zone pop-
ulation P
z
, cfm
Acceptable design adjustments based on this optional provision include the following:
1.
Zone with fluctuating occupancy: the zone population (
P
z
) may be averaged over time, T.
2.
Zone with intermittent interruption of supply air: the average outdoor airflow supplied to breathing zone over 
time, T, shall be no less than the breathing zone outdoor airflow (
V
bz
) calculated using Equation 4
-
1.
3.
A 
system with intermittent closure of outdoor air intake: the average
outdoor air intake over time, T, shall be no 
less than the minimum outdoor air intake (
V
ot
) calculated using Equation 4
-
3, 4
-
4 or 4
-
8, as appropriate. 
403.3.1.3 Exhaust ventilation.
Exhaust airflow rate shall be provided in accordance with the requirements of Table 
403.3.1.1.
Exhaust makeup
air shall be 
permitted
to 
be any combination of
outdo
or 
air, recirculated air and transfer air, 
except as limited in accordance with Section 403.2.
403.3.1.4 System operation.
The minimum flow rate of outdoor air that the ventilation system must be capable of sup-
plying during its operation shall be permitted
to be based on the rate per person indicated in Table 403.3.1.1 and the 
actual number of occupants present.
403.3.1.5 Variable air volume system control.
Variable air volume air distribution systems, other than those designed 
to supply only 100
-
percent ou
tdoor air, shall be provided with controls to regulate the flow of outdoor air. Such control 
system shall be designed to maintain the flow rate of outdoor air at a rate of not less than that required by Section 403.3.1
.1 
over the entire range of supply air
operating rates.
403.3.1.6 Balancing.
The ventilation air distribution system shall be provided with means to adjust the system to achieve 
not less than the minimum ventilation airflow rate as required by Sections 403.3.1.1 and 403.3.1.2. Ventilation syst
ems 
shall be balanced by an approved method. Such balancing shall verify that the ventilation system is capable of supplying 
and exhausting the airflow rates required by Sections 403.3.1.1 and 403.3.1.2.
SECTION 
MC 
404
ENCLOSED PARKING GARAGES
404.1 Enclosed parking garages.
Where mechanical ventilation 
systems
for enclosed parking garages operate intermittently
, 
such operation shall be automatic by means of carbon monoxide detectors applied in conjunction with nitrogen dioxide detec-
tors. Such detectors sha
ll be installed in accordance with their manufacturers’ instructions. Such systems shall operate auto-
matically upon detection of a concentration of carbon monoxide of 25 parts per million (ppm) or nitrogen dioxide of 500 parts
per billion (ppb).
VENTILATION
404.2 Mini
mum ventilation.
Automatic operation of the 
system
shall not reduce the ventilation airflow rate below 0.05 cfm 
per square foot (0.00025 m
3
/s • m
2
) of the floor area and the system shall be capable of producing a ventilation airflow rate of 
0.75 cfm per 
square foot (0.0038 m
3
/s • m
2
) of floor area.
404.3 Occupied spaces accessory to public garages. 
Connecting
offices, waiting rooms, ticket booths and similar uses that 
are accessory to a public garage shall be maintained at a positive pressure and shall be
provided with ventilation in accordance 
with Section 403.3.
SECTION 
MC 
405
SYSTEMS CONTROL
405.1 General.
Mechanical ventilation systems shall be provided with manual or automatic controls that will operate such 
systems whenever the spaces are occupied. A
ir
-
conditioning systems that supply required ventilation air shall be provided with 
controls designed to automatically maintain the required outdoor air supply rate during occupancy.
405.2 Manual control.
Each air distribution system shall be provided with
not less than one manual control to stop the 
operation of the supply, return, and exhaust fans(s) in an emergency. The manual control shall be provided at an approved 
location. A disconnect switch shall not be considered a manual control.
405.2.1 Office b
uildings.
Any building where the main use or dominant occupancy is classified in Occupancy Group B 
having occupied floors located more than 75 feet (22 860 mm) above the lowest level of fire department vehicle access, 
where a system serves a floor or floor
s other than the floor on which the equipment is located, shall be provided with the 
following controls, in addition to the controls required by this chapter:
1.
Manual controls for operating individually each air supply and each exhaust or return fan in t
he system located as 
follows:
1.1.
At the Fire Command Center, and
1.2.
In the room containing the affected air
-
handling fans.
2.
Manual controls for operating individually or in groups each remote control reversible fire shutter, when such shutters 
are provided in accordance with the provisions of the 
New York City Building Code
, or each smoke damper provided 
in accordance with the 
provisions of the 
New York City Building Code
. Such controls shall be located at the Fire 
Command Center.
SECTION 
MC 
406
VENTILATION OF UNINHABITED SPACES
406.1 General.
Uninhabited spaces, such as crawl spaces and attics, shall be provided with natural ventilation openings as 
required by the 
New York City 
Building Code
or shall be 
pro
-
vided
with a mechanical exhaust and supply air system. The 
mechanical exhaust rate shall
be not less than 0.02 cfm per square foot (0.00001 m
3
/s • m
2
) of horizontal area and shall be 
automatically controlled to operate when the relative humidity in the space served exceeds 60 percent.
406.1.1 Methane and radon venting.
The design and material
s used in the installation of the methane and radon vent 
systems shall be approved by the commissioner and shall comply with all applicable rules of the Fire Department.
SECTION MC 407
AMBULATORY CARE FACILITIES AND GROUP I
-
2 OCCUPANCIES
407.1 General. 
Mec
hanical ventilation for ambulatory care facilities (Group B) and Group I
-
2 occupancies shall be designed 
and installed in accordance with all applicable federal, state and local regulations.
SECTION MC 408
VENTILATION OF NONPRODUCTION CHEMICAL
LABORATORIES
VENTILATION
408
.1 General. 
Nonproduction chemical laboratories complying with the hazardous materials quantity limitations of Section 
427 of the 
New York City Building Code
shall provide a mechanical ventilation system in accordance with NFPA 45 and Table 
403.3.1.1 o
f this code, except that ducts constructed of combustible materials shall not be permitted.