Why hot weather feels even hotter in Danish buildings

While July has generally been one of the cooler summer months you’re likely to experience in Denmark, June was hot and dry.

In fact, last month’s high temperatures in Denmark may have felt particularly punishing because they were in Denmark rather than in a country better equipped to cope with hot weather.

Buildings and houses in the Nordic nation are relatively poorly equipped when it comes to high temperatures – something that could play an increasing role given changes to the climate expected in coming years.

A new report from Oxford University places Denmark among the countries which are the most poorly prepared for increasing global temperatures.

That is due in no small part to the construction of Denmark’s buildings, which historically has been with a different climate in mind to the one considered in the report, according to an expert who spoke to broadcaster DR.

“We design our buildings to keep the heat in for long periods and that’s why we have buildings that might not be ready for a future in which there’s a need for cooling,” Steffen Petersen, professor at Aarhus University’s Department of Civil and Architectural Engineering, told DR.

The use of glass in Danish buildings from the 1960s onwards is one important factor in this regard.

“We insulate well and also have large window panes which provide a good heat benefit, which is an important element in the winter to keep our energy consumption down. But it has the opposite effect in the summer where we don’t need a heat benefit, on the contrary it causes overheating,” Petersen said.

“Experts have always criticised this trend because it will end up with what we have now, a need for cooling in a country where we actually a characterised by temperatures that shouldn’t give the need for cooling,” he said.

The summer of 2018, which saw long unbroken spells of hot weather, brought the issue to the fore with reports of residents in newly-built developments in places like Aarhus Ø and the Nordhavn district of Copenhagen who found their homes so hot they were unable to stay in the living rooms, including at night.

What can be done to avoid overheated homes in the summer?

“There’s a risk that when people feel uncomfortable in their own homes with these temperatures, that they will invest in modern pumps that are relatively cheap and install them in urban areas to cool their homes, which gives increased energy use and noise pollution and would be bad for green transition,” Petersen said.

An expert with housing thinktank Bolius said that the problem was known in the real estate sector but there are steps residents can take.

That includes checking the size of west and south-facing windows and choosing home with a north-facing bedroom if possible.

“It’s this unfortunate problem that our houses are built like a thermos. They can keep the heat in during winter but also keep it inside once it’s already got in during the summer. Whereas old houses are a bit more draughty and are without such big windows,” Tue Patursson of Bolius told DR.

If you already live in an apartment that traps summer heat, there are mitigating steps advised by Patursson.

“Make sure the sun doesn’t get into the house. Look at what they do in the south. Use sun shades, parasols and curtains. They close off their houses during the daytime in summer with outside shutters, and doors and windows are closed so you keep inside the relatively cold temperature that you have in the evening and at night,” he said.