Heating degree days (HDD): these refer to the intensity of cold over a certain period of time, taking into account the outside temperature and the average ambient temperature (i.e. they indicate the amount of heating needed). The basic temperature value depends on various factors related to the building and its surroundings, but by using a general climatological approach, the basic temperature is set at a constant value of 15ºC to calculate HDD. Therefore, the heating degree days (HDD) determined for the Basque Country and for the EU27 between 1979 and 2023 indicate how the intensity of cold has changed over the years.
Taking as a reference the Basque Country and the EU27, two points appear clearly. On the one hand, throughout this period there has been less need for heating in the Basque Country than across the EU27. And above all, both in the Basque Country and throughout the EU27, since 1979 the need to use heaters has gradually declined. Apart from short-term annual variations, the overall trend clearly shows this: the Basque Country went from 2,197.2 HDD in 1979 to 1,585.1 HDD in 2023. the EU27 had 3,509.57 HDD in 1979 and 2,820.92 HDD in 2023.
In short, there has been less intense cold in the Basque Country in recent years. The averages across the EU27 are higher than in the Basque Country. This indicates that in other European countries heating needs are greater than in the Basque Country, but the trend is the same, as there is less and less need to use heating.
Analysed by regions, the southern regions are of course the ones that need least heating (the Canary Islands, Ceuta, Malta, the Southern Aegean, Cyprus, Melilla and Algarve), and the northern one those that need the most (Northern and Eastern Finland, Innlandet, Northern Norway and Upper Norrland). The Basque Country is closer to those with less needs.