The need to heat a given building has decreased over time: the heating degree days (HDD) value decreased by 19% between 1979 (3 510 degree days) and 2022 (2 858) in the EU. In other words, only 81% of the heating needs were required in 2022 compared with 1979. 

In contrast, the cooling degree days (CDD) value was almost four times higher in 2022 (140) than in 1979 (37), indicating that the need for cooling (air conditioning) significantly increased over the last decades.

Heating degree days and cooling degree days are weather-based technical indexes designed to describe the energy requirements of buildings in terms of heating or cooling. However, HDD and CDD alone should not be used as a proxy for energy consumption or greenhouse gas emissions. These also depend on other factors, such as the location and orientation of the building, design, insulation, usage, as well as the heating/cooling system and type of energy that is used (e.g. fossil fuels or renewable energy).

Heating degree days almost ten times higher in Finland than in Malta

Heating degree days vary considerably across the EU members. In 2022, Finland recorded the highest annual heating degree days value (5 277), in contrast to the lowest value observed in Malta (544). This means that for a given building, the need for heating was almost ten times higher in Finland than in Malta. For annual HDD, Finland was closely followed by Sweden (4 919), ahead of Estonia (4 118), Latvia (4 026) and Lithuania (3 773).

In 2022, the EU members with the lowest number of annual heating degree days were Malta (544) as mentioned above, Cyprus (696), Portugal (968), Spain (1 478) and Greece (1 538).

Source dataset: nrg_chddr2_a

Highest HDD in Sweden’s Norrbottens län 

Among EU regions (NUTS 3), Norrbottens län in Sweden had the highest annual average of heating degree days value (6 647) for all available data spanning across 43 years, from 1979 to 2022, while the lowest value was observed in Fuerteventura in Spain (17). 

Norrbottens län in Sweden was followed by Lappi in Finland (6 640) and Västerbottens län in Sweden (6 077).

On the other hand, the lowest values which followed Fuerteventura were also in Spain: La Gomera (38), Lanzarote (53), Gran Canaria (150) and La Palma (250).

Malta and Cyprus had the highest cooling degree days 

In the EU, in 2022, for annual cooling degree days, the highest values at national level were in: Malta (842), followed by Cyprus (698), Spain (384), Italy (375) and Greece (372). The lowest values were recorded in Ireland (0.03 CDD), Sweden (1.6), Finland (2.5), Denmark (3.4) and Latvia (13.6).

On the NUTS 3 regional level, the annual averages for all available data spanning across 43 years, from 1979 to 2022, show that the highest cooling degree days were observed in the Gozo and Comino islands in Malta (594) followed by Cyprus (580), Malta (577), Notios Tomeas Athinon (567) and Peiraias, Nisoi (566), both in Greece.

Source dataset: nrg_chddr2_a