German heatwave sparks safety warnings for windows, shutters and elevators

Experts warn that applying aluminium foil or rescue blankets to windows during hot weather can backfire. The foil reflects sunlight but quickly heats up, transferring heat to the glass and increasing the risk of thermal stress and, in rare cases, glass breakage. Peter Huber of the German Roller Shutter and Sun Protection Association cautioned, “Grundsätzlich sollte man Fenster innen nicht bekleben.” The German Window + Façade Association adds that poor ventilation behind the foil can cause the glass to overheat.

Similarly, consumer organisations advise against lowering roller shutters completely. Fully closed shutters trap a layer of hot air between the glass and the shutter, creating a heat‑sink that can damage plastic shutters or even cause glass to crack. Keeping the ventilation slits open allows air circulation and prevents the “Hitzestau” (heat buildup).

Elevator manufacturers also note heat‑related operational limits. Schindler explains that when shaft temperatures exceed about 40 °C, safety systems may shut the lift down temporarily. TÜV Rheinland advises passengers to stay calm, use the emergency call and avoid forcing doors open. The risk is higher in glass‑covered shafts, which “erhitzen sich aber viel schneller,” according to Schindler’s Jan Steeger.

Overall, authorities recommend using external shading devices such as awnings or blinds, ensuring proper ventilation, and avoiding DIY foil solutions to mitigate heat stress in homes and public infrastructure.