| Webster's Online Dictionary |
| Expressions | Definition | ||
| Heating degree day | Heating degree day (HDD) is a quantitative index demonstrated to reflect demand for energy to heat or cool houses and businesses. This index is derived from daily temperature observations at nearly 200 major weather stations in the contiguous United States. The "heating year" during which heating degree days are accumulated extends from July 1 to June 30 and the "cooling year" during which cooling degree data are accumulated extends from January 1 to December 31. A mean daily temperature (average of the daily maximum and minimum temperatures) of 65 °F is the base for both heating and cooling degree day computations. Heating degree days are summations of negative differences between the mean daily temperature and the 65 °F base; cooling degree days are summations of positive differences from the same base. For example, cooling degree days for a station with daily mean temperatures during a seven-day period of 67,65,70,74,78,65 and 68, are 2,0,5,9,13,0 and 3, for a total for the week of 32 cooling degree days. (references) | ||
Source: compiled by the editor from various references; see credits. | Top | ||
| Expressions | Domain | Definition | |
| Heating degree day | Energy | The number of degrees per day that the daily average temperature (the mean of the maximum and minimum recorded temperatures) is below a base temperature, usually 65 degrees Fahrenheit, unless otherwise specified; used to determine indoor space heating requirements and heating system sizing. Total HDD is the cumulative total for the year/heating season. The higher the HDD for a location, the colder the daily average temperature (s). (HDD). (references) | |
| Heating degree day | Physics | A unit that measure the space heating needs during a given period of time. (references) | |
| Heating degree day | Weather | 1: See Degree Day. (references) | |
| 2: A form of degree day used to estimate the required energy for heating. One heating degree day occurs for each degree the daily mean temperature is below 65 degrees Fahrenheit. (references) | |||
Source: compiled by the editor from various references; see credits. | Top | ||
