Cooling Degree Day
A cooling degree day (CDD) is a measure of how hot a location is over a year, expressed as the cumulative degrees above a 65°F base temperature each day, summed over the year. CDD is the standard input for sizing air-conditioning equipment and predicting annual cooling energy use. A 2,000 CDD location (e.g. Phoenix) has more than double the annual cooling load of a 700 CDD location (e.g. Boston) for an identical home.