Degree Days — How They Figure In Your Energy-Use Calculations

Degree days are a unit of measurement used to relate the day’s temperature to its energy demands.  This unit of measurement was developed by heating engineers who wanted an easy way to determine the demand for fuel to heat buildings by relating it to each day’s temperatures.

As the name suggests, cooling degree days are designated for cooling and estimate air conditioner usage.  For heating degree days, they  estimate gas or heating oil usage.  With the wintry weather that occurs for several months every year in Northeast Ohio, awareness of heating degree days is especially important.

Cooling degree days are calculated by subtracting a base temperature of 65 from a day’s average temperature in a specific geographic location.  For example, if the day’s high temperature is 85 degrees and the day’s low temperature is 65 degrees, the day’s average is 75 degrees.  Seventy-five minus 65 is 10 cooling degree days.  Cooling degree days can be used to compare the existing summer to previous summers (or any comparable period of time).  They can also be used to compare the heat in one region of the country with another.

You can also calculate the heating degree days for a specific day in a similar manner.  If the day’s average temperature is 55 degrees, then you subtract that from the base room temperature of 65 to get 10 heating degree days.

Heating or cooling degree days are a good way of predicting future heating and cooling needs based on the past.  You can also use records of past heating/cooling degree days to see if the money you’ve spent on energy-saving measures like insulation or upgraded equipment has been beneficial.

For more information on degree days or any of your HVAC concerns, contact Geisel Heating, Air Conditioning, and Plumbing.

Our goal is to help educate our customers about energy and home comfort issues (specific to HVAC systems).  For more information about degree days and other HVAC topics, download our free Home Comfort Resource guide.

Geisel Heating, Air Conditioning and Plumbing services Western Cleveland. Visit our website to see our special offers and get started today!