Energy Efficiency Buzzwords De-Buzzed: Heating Degree Days

Thu, 02/12/2015 - 8:45am
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Every industry does it. We use words that mean so much to us that we don’t realize that they’re meaningless to the rest of the world. This series - Energy Efficiency Buzzwords De-Buzzed – attempts to change that. Have a “green” word or phrase you want de-buzzed? Let Evergreen Home Performance know and we’ll add it to the series!

Today’s buzzword: Heating Degree Days

The colder it is outside, the harder our heating systems have to work to make our homes comfortable. Energy advisors and heating engineers quantify this common sense with something called heating degree days (HDD). Don’t be fooled by their name: heating degree days are calculated by subtracting the day’s average outside temperature from a base inside temperature of 65 degrees, so every winter day will equal many HDD.

Adding heating degree days over the course of the winter tells us what kind of heating season we’re having, and lets us compare one season to the next, but this statistic is more than just a fun fact. HDD are a quick indication of how the weather impacts our energy needs, because it takes more energy to keep your house warm when the temperature is 10 (65-10 = 55 HDD) than it does when it’s 40 (65-40=25 HDD).

Keeping track of HDD is how your fuel provider knows when to take more oil or propane to customers with automatic delivery. Comparing your energy use to HDD patterns can help you and your energy advisor evaluate your home’s efficiency – and the impact of any efficiency improvements you make.

Want to learn more? Schedule a FREE one-hour energy consult and learn how home performance can help you gain comfort and cut costs, no matter how many heating degree days this winter has in store.