Glossary of Terms

Cooling/Heating Degree Days

Although degree-days are most commonly used in agriculture, they are also useful in building design and construction, and in fuel use evaluation. The construction industry uses heating degree-days to calculate the amount of heat necessary to keep a building, be it a house or a skyscraper, comfortable for occupation. Likewise, cooling degree-days are used to estimate the amount of heat that must be removed (through air-conditioning) to keep a structure comfortable. Heating and cooling degree-days are based on departures from a base temperature, typically 65F (18C).

One heating degree-day is the amount of heat required to keep a structure at 65F when the outside temperature remains one degree below the 65F threshold for 24 hours. One heating degree-day is also the amount of heat required to keep that structure at 65F when the temperature remains 24F below that 65 threshold for 1 hour.

>Likewise, one cooling degree-day is the amount of cooling required to keep a structure at 65F when the outside temperature remains one degree above the 65F threshold for 24 hours. One cooling degree-day is also the amount of cooling required to keep that structure at 65F when the temperature remains 24F above that 65 threshold for 1 hour.

Depending on the calculation method, both heating and cooling degree-days can accumulate in the same day. Also, note that there are no negative degree-days. If the temperature remains below the threshold, there is no degree-day accumulation.

Rain

Yearly rain follows the traditional storm year of July 1 - June 30.