- Cooling Degree Day (CDD) : A Cooling Degree Day (CDD) is
Cooling degree days are used to estimate how hot the climate is and how much energy may be needed to keep buildings cool. CDDs are calculated by subtracting a balance temperature from the mean daily temperature, and summing only positive values over an entire year. The balance temperature used can vary, but is usually set at 65_F (18_C), 68_F (20_C), or 70_F (21_F).