Daily HDD = 65 - daily average temperature
For example, HDD for a day with daily average temperature of 55°F is computed as:
Daily HDD = 65 - 55 = 10 HDD
When the daily average temperature is higher than the base temperature (65°F), CDDs will be calculated as:
Daily CDD = daily average temperature - 65
For example, CDD for a day with daily average temperature of 75°F is computed as:
Daily CDD = 75 - 65 = 10 CDD