A degree day is a unit of measurement that represents how much heat is required to raise the temperature of 1 pound of water by 1 degree Fahrenheit. Cooling degree days estimate how much energy is needed to cool space, while heating degree days measure how much heat is required to make a building comfortable.
Cooling Degree Days
Cooling degree days can be used to calculate the amount of energy required to cool a space.
Cooling degree days measure how hot it is over a period of time. The higher the number, the more cooling is required.
Answered by Kevin Zemanek, OEC Assistant Vice President, Operations
There have been some more over the last 2 years, but they are generally in line with the historical values. As of the end of July 2025 we have had 12 control periods (Peak Alerts) and expect a couple more this summer. We had 14 control periods in 2024.
A lot of this is due to above normal weather over the last 2 summers, so we have seen high loads compared to the initial defer target