Heating Degree Days? What are they and how are they calculated?

You may have noticed that most months your statement contains information regarding heating degree days (HDD).  The purpose of providing this information is to help our members understand one reason why their energy consumption for any given month may be different from previous years – be it higher or lower. 

Heating Degree Days help provide indications, for those of us in colder climates, as to how much energy we’ll consume for space heating.  Meteorologists, Utility Companies, and others use a temperature of 65° F as a base temperature. 

The heating degree days are calculated by determining any particular days average temperature and subtracting from 65° F.  Thus, the formula for calculating heating degree days is as follows:

  1. (Daily High Temperature – Daily Low Temperature) / 2 = Average Temperature
  2. 65° F. – Average Temperature = Heating Degree Days

Arrowhead Electric uses National Weather Service data gathered in Duluth (http://www.weather.gov/climate/index.php?wfo=dlh) to calculate heating degree days. 

Watch your monthly billing statement for the heating degree days.

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