Degree Days are a measure of how cold (or hot) it was over a period of time, and correspondingly how much energy is needed for heating (or cooling) a building.
Degree Days are a measure of how cold (or hot) it was over a period of time, and correspondingly how much energy is needed for heating (or cooling) a building. The degree days can help consumers in comparing energy consumption per month or year with a normal month or year.
Calculating degree days is done by measuring both the lowest and highest outside temperature (Tmin and Tmax) for a particular day (midnight to midnight). A mean temperature for that day is estimated based on these measurements and used in calculations together with a base temperature (Tbase). This temperature (Tbase), which is different from region to region, represents a temperature where it is not necessary to either cool or heat a building. For example, 17 °C is typically used in Denmark, whereas 15.5 °C is standard in UK.
The individual day’s degree days are added together, forming weekly, monthly, annual and seasonal values.
Calculation of heating degree days for a given day is performed using the formula to the right, where Dh and Dc denotes heating degree days and cooling degree days, respectively.