Heatwave tips from a Danish professor to cool your home

As Denmark swelters under a heatwave, many are struggling to keep their homes cool. Steffen Petersen, a professor of indoor climate at Aarhus University’s Department of Civil and Architectural Engineering, offers practical advice.

Open windows at night and close them by day. Denmark’s evenings and nights remain relatively cool, so leaving windows open overnight helps lower indoor temperatures. Petersen advises closing them once indoor and outdoor temperatures align to trap the cool air inside.

Block sunlight before it enters. Outdoor shading—such as awnings, external blinds, or even a sheet hung outside a window—is far more effective than indoor curtains. Windows are the primary culprit for letting heat in, Petersen notes.

Turn off heat-generating appliances. Computers, TVs, and other electronics contribute to indoor warmth. Reducing their use helps keep spaces cooler.

Avoid common myths. Fans do not cool rooms; they only create airflow that feels cooling on the skin. Reversing a fan to blow air outward has no cooling effect, as fans generate heat regardless of direction.

Finally, wear light clothing and stay hydrated. These simple steps, combined with smart ventilation and shading, can make a significant difference.