High temperatures affect more than just what clothes you wear — they also affect your energy use. Heating and cooling costs account for up to 50 percent of a home’s energy use and rise or fall in direct response to the weather. Even just a few days of extreme temperatures can cause your electric bill to be noticeably higher.
Weather specialists have a way of comparing year-over-year temperatures to know when we’re experiencing a particularly hot summer. Using a formula representing the amount of cooling needed to keep a home comfortable, they assign a magnitude to the weather. This unit of measurement is called a cooling degree day (CDD).
Since a typical home doesn’t need to be heated or cooled when the outside temperature is 65 degrees, the CDD for a given day is equal to the difference between the day’s average temperature and 65 degrees. Without degree days, comparing the energy use over two periods would be like calculating the miles per gallon for your car without knowing how many miles you had driven.
Using CDDs, Idaho Power can see that the average summer months in 2017 are 30 percent warmer than they were in 1990, requiring significantly more energy to cool our homes. And records indicate July 2017 was the second hottest July the Treasure Valley has seen since 1877.