How will this information help you?
Heating degree days can provide an indication of heating requirements. Degree day information, since it is based upon outside temperature statistics, can help explain why gas consumption is high during some periods and low during others. For example, comparing the current month’s degree days to the previous month’s can indicate how much colder (or warmer) it was and why your natural gas consumption would have fluctuated.

What is a heating degree day?
Heating degree day is defined as a measure of the coldness of the weather experienced. Simply put, it’s the difference between 65° F and the average of the high and low temperatures in a given day. The higher the number, the more natural gas will be used in heating your home or building.

Example for any given day:

High Temp = 50° F

Low Temp = 20° F

Average Temperature = 50° + 20° F = 35° F                                               2

Degree Day   =   65°F - 35° F   =   30° F

Therefore, the day was a 30° day.

Although the degree day reading is useful, keep in mind that other factors such as sun load or excessive infiltration due to high wind also affect the heating requirements of a building and are not taken into account by the degree day calculation.

By taking the total Heating Degree Day figures and dividing it by the Days of Service, you arrive at the temperature variance from 65° F.

For example:

507 Heating Degree Days        33 Days of Service        =    Approx. 16

65° F - 16                 =        49°

Therefore, the average temperature for those days of service was 49° F.

Where did 507 come from?
That figure comes from adding the heating degree day for each of the 33 days of service.

For example:

Day 1: 20° day      Day 2: 10° day       Day 3: 8° day         Day 4: 23° day

Day 5: 4° day...     Day 31: 14° day     Day 32: 13° day     Day 33: 12° day

Total for all 33 days   =   507 Heating Degree Days