Monthly degree days below a base temperature - Europe

Resource information

Degree days below a temperature (also called Heating degree days) correspond to the cumulative number of degrees by which the mean daily temperature falls below a given temperature called the "base temperature". This concept has been developed by heating engineers who wanted a way to relate each day's outdoor temperature to the energy required to heat a building. The "base temperature" is usually an indoor temperature of 18°C or 19°C which is adequate for human comfort (internal gains increase this temperature by about 1 to 2°C).

Heating degree days are presented as monthly and annual means over the five years: 1996 to 2000. Base temperatures ranging from 12°C to 22°C are available. The heating degree days for a particular day are based on the average temperature of the day (the sum of the high and low temperatures divided by two). If the average temperature is above the base temperature, there are no heating degree days that day. If it is less than the base temperature, the base temperature is subtracted from it to give the number of heating degree days.


The Satel-Light server delivers daylight and solar radiation information over Western and Central Europe with a high spatial and temporal resolution (every 5 km, every half-hour). It was funded by the European Union (Directorate General XII). Thanks to the SODA project, the information now includes temperatures and covers a total of five years: 1996 to 2000,