Skip to main content
Select Source:

degree-day

degree-day, a unit of measure used to estimate the fuel and power requirements in heating and cooling a building; it is equal to a difference of 1 degree between the outdoor daily average temperature (the mean of the maximum and minimum daily dry-bulb temperatures) and a reference temperature. Degree-days are an indicator of how far the average temperature departs from a human comfort level called the base. In the United States the base is generally 65°F (18°C), although in very warm or cold locations an alternative may be used, while in Great Britain the base is 15.5°C (60°F).

Each degree of outside average temperature below the base is one heating degree-day (HDD), and each degree above the base is one cooling degree-day (CDD). To calculate the number of heating degree-days in a month, for example, the outdoor average temperature for each day is subtracted from the base, and the results for each day are added (with negative remainders being treated as 0).

Heating degree-days are a measure of the severity and duration of cold weather; the colder the weather over a given period the higher the cumulative heating degree-day value. Similarly, the warmer the weather over a given period, the higher the cumulative cooling degree-day value. The ability to compare one week, month, or other period with another using degree-days permits the analysis of seasonal patterns of energy consumption, enables the setting and tracking fuel and power budgets, and can be used to verify that projected economies are achieved by energy-saving measures.

The growing degree-day (GDD), an extension of the degree-day concept, is defined as a day on which the mean daily temperature is one degree above the minimum temperature required for the growth of a particular crop. The GDD is used as a guide to planting times and for determining the approximate dates when a crop will be ready for harvesting.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"degree-day." The Columbia Encyclopedia, 6th ed.. . Encyclopedia.com. 23 Aug. 2017 <http://www.encyclopedia.com>.

"degree-day." The Columbia Encyclopedia, 6th ed.. . Encyclopedia.com. (August 23, 2017). http://www.encyclopedia.com/reference/encyclopedias-almanacs-transcripts-and-maps/degree-day

"degree-day." The Columbia Encyclopedia, 6th ed.. . Retrieved August 23, 2017 from Encyclopedia.com: http://www.encyclopedia.com/reference/encyclopedias-almanacs-transcripts-and-maps/degree-day

day degrees

day degrees The departure of the average daily temperature from a defined base, e.g. 4°C, the minimum recognized temperature for the growth of many plant species. The number of day degrees may be totalled to assess the accumulated warmth of a particular year's growing season for crops. See also ACCUMULATED TEMPERATURE; AGROMETEOROLOGY; and MONTH DEGREES.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"day degrees." A Dictionary of Earth Sciences. . Encyclopedia.com. 23 Aug. 2017 <http://www.encyclopedia.com>.

"day degrees." A Dictionary of Earth Sciences. . Encyclopedia.com. (August 23, 2017). http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/day-degrees

"day degrees." A Dictionary of Earth Sciences. . Retrieved August 23, 2017 from Encyclopedia.com: http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/day-degrees

day degrees

day degrees The departure of the average daily temperature from a defined base (e.g. the minimum recognized temperature for the growth of a plant species). The number of day degrees may be totalled to assess the accumulated warmth of a particular year's growing season for crops. See also accumulated temperature; agrometeorology; and month degrees.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"day degrees." A Dictionary of Ecology. . Encyclopedia.com. 23 Aug. 2017 <http://www.encyclopedia.com>.

"day degrees." A Dictionary of Ecology. . Encyclopedia.com. (August 23, 2017). http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/day-degrees-0

"day degrees." A Dictionary of Ecology. . Retrieved August 23, 2017 from Encyclopedia.com: http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/day-degrees-0

day degrees

day degrees The departure of the average daily temperature from a defined base (e.g. the minimum recognized temperature for the growth of a plant species). The number of day degrees may be totalled to assess the accumulated warmth of a particular year's growing season for crops. See also ACCUMULATED TEMPERATURE; AGROMETEOROLOGY; and MONTH DEGREES.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"day degrees." A Dictionary of Plant Sciences. . Encyclopedia.com. 23 Aug. 2017 <http://www.encyclopedia.com>.

"day degrees." A Dictionary of Plant Sciences. . Encyclopedia.com. (August 23, 2017). http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/day-degrees-1

"day degrees." A Dictionary of Plant Sciences. . Retrieved August 23, 2017 from Encyclopedia.com: http://www.encyclopedia.com/science/dictionaries-thesauruses-pictures-and-press-releases/day-degrees-1

degree day

de·gree day • n. a unit used to determine the heating requirements of buildings, representing a fall of one degree below a specified average outdoor temperature (usually 18°C or 65°F) for one day.

Cite this article
Pick a style below, and copy the text for your bibliography.

  • MLA
  • Chicago
  • APA

"degree day." The Oxford Pocket Dictionary of Current English. . Encyclopedia.com. 23 Aug. 2017 <http://www.encyclopedia.com>.

"degree day." The Oxford Pocket Dictionary of Current English. . Encyclopedia.com. (August 23, 2017). http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/degree-day

"degree day." The Oxford Pocket Dictionary of Current English. . Retrieved August 23, 2017 from Encyclopedia.com: http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/degree-day