What are heating and cooling degree days?
Heating and cooling degree days are a measure of how much the average daily temperature deviates from a baseline of 65 degrees. The average temperature is crudely computed by averaging the high and low temperatures for the day, so a high of 70 and a low of 50 would result in an average daily temperature of 60 and 5 heating degree days. Conversely, a high of 90 and a low of 65 ((90 + 65)/2 = 78 rounded up) results in 13 cooling degree days for that particular day. These degree days are sometimes used by utility companies to get a rough idea of how much you may by using your heating or air conditioning.
Heating and cooling degree days used to determine how much power people should be using on the average to cool/heat their homes and businesses. Degree days are calculated by using the average temperature for the day and its difference from the number 65. The number 65 is used as the base number because most buildings and homes would be most comfortable and energy efficient around 65 degrees. Example: • On a summer day the high was 90 and the low 70 = average 80. 80 (average) – 65 (base) = 15 cooling degree days. • On a winter day the high was 40 and the low was 0 = average 20. 65 (base) – 20 (average) = 45 heating degree days.
