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What are Heating Degree Days / Cooling Degree Days? Follow

Heating/Cooling Degree Days measure the amount of heating or cooling necessary at your property. Degree days are measured relative to a base of 65oF. Above 65oF it is assumed that your property will need to have cooling, and below 65oF it is assumed that your property will need to have heating.

  • Heating Degree Days (HDD) - HDD is the equivalent number of days you would have to heat your building by 1 degree to accommodate the heating requirement. For example, if you have a day on which the temperature is 55oF degrees, that day is worth 10 Heating Degree Days because it is 10 degrees below 65oF. HDD is calculated in this way for each day of the year and summed up to get the total annual HDD.
  • Cooling Degree Days (CDD) - CDD is the equivalent number of days you would have to cool your building by 1 degree to accommodate the cooling requirement. For example, if you have a day on which the temperature is 80oF degrees, that day is worth 15 Cooling Degree Days because it is 15 degrees above 65oF. CDD is calculated in this way for each day of the year and summed up to get the total annual CDD.

If you're interested in seeing more, we also have an online calculator that will show you your heating and cooling degree days (HDD and CDD)--from more than 900 weather stations around the United States and Canada. You can also download the HDD and CDD for your buildings into Portfolio Manager custom reports when selecting metrics under the Property Information section:

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