Update data/climate_data.py

data/climate_data.py

@@ -117,10 +117,13 @@ class ClimateLocation:
         self.summer_design_temp_db = round(np.nanpercentile(dry_bulb, 99.6), 1)
         self.summer_design_temp_wb = round(np.nanpercentile(wet_bulb, 99.6), 1)
         
-        # Calculate degree days
-        daily_temps = np.nanmean(dry_bulb.reshape(-1, 24), axis=1)
-        self.heating_degree_days = round(np.nansum(np.maximum(18 - daily_temps, 0)))
-        self.cooling_degree_days = round(np.nansum(np.maximum(daily_temps - 18, 0)))
+        # Calculate degree days using (T_max + T_min)/2
+        daily_temps = dry_bulb.reshape(-1, 24)
+        daily_max = np.nanmax(daily_temps, axis=1)
+        daily_min = np.nanmin(daily_temps, axis=1)
+        daily_avg = (daily_max + daily_min) / 2
+        self.heating_degree_days = round(np.nansum(np.where(daily_avg < 18, 18 - daily_avg, 0)))
+        self.cooling_degree_days = round(np.nansum(np.where(daily_avg > 18, daily_avg - 18, 0)))
         
         # Calculate summer daily temperature range (June–August, Southern Hemisphere)
         summer_mask = (months >= 6) & (months <= 8)