The heating degree days declined and the cooling degree days increased in Portugal since the 1950s

08.10.2021

Sources: E-OBS and Banco de Portugal calculations. | Note: Values computed according to the Eurostat methodology.

The increase in average daily temperatures observed in recent decades has had implications for the heating and cooling energy indices calculated for the territory of mainland Portugal. These indices, measured in days-degrees Celsius, reflect the heating needs for buildings during the winter, and cooling requirements during the summer. For example, a one day-degree Celsius increase in the heating index corresponds to a need to raise the temperature by one degree Celsius for one day, or half a degree Celsius for two days, and so on. Both indices reflect energy expenditures, but in opposite directions.

Panel A of the figure shows that there has been a generalized decrease in heating needs in Portugal from the 1950s until now, and such change has been spatially heterogeneous, with greater reductions in the northern region of the country. For the same level of thermal insulation in buildings, this development means a reduction in energy consumption.

Panel B of the figure illustrates the increase in cooling needs observed in the same period, mainly concentrated in the interior and the south of the country. In economic terms, this evolution reflects an increase in energy consumption for a given level of thermal insulation in buildings.

For further details see Special Issue “Climate change and the economy”, October 2021 Economic Bulletin, Banco de Portugal.

Prepared by Bernardino Adão, António Antunes, Nuno Lourenço and João Valle e Azevedo. The analyses, opinions and findings expressed above represent the views of the authors and not necessarily those of Banco de Portugal or the Eurosystem.

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