Which? scientific advisers have examined various heatwave cooling methods, distinguishing between those supported by science and those that offer limited or negative effects. Among the tips reviewed are using aluminium foil on windows, placing ice in front of a fan, and taking cold showers.
According to Dr. Neal Rimmer, a Which? senior scientific adviser, applying aluminium foil to the outside of windows is effective at reflecting heat and light, preventing solar energy from entering and warming the house. Heat-reflective window film, which works on a similar principle, is presented as a less conspicuous alternative.
Olivia Pratt, a Which? scientific adviser, states that placing ice in front of an electric fan can reduce the immediate air temperature, helping to cool individuals by replacing warm air against the skin. However, this method becomes less effective in humid conditions as melting ice increases humidity, hindering natural sweat evaporation.
Monika Gil, another Which? senior scientific adviser, advises against cold showers before bed during a heatwave. She explains that cold water can trigger a reflex that constricts blood vessels, making one feel warmer. A lukewarm shower is suggested as a better alternative, as it can open blood vessels and allow heat to escape more easily. Leaving skin damp after a lukewarm shower can also provide an additional cooling effect as water evaporates.
Jacob Compton, a Which? scientific adviser, highlights that blackout blinds can prevent heat build-up by blocking solar radiation when closed on sun-facing windows during peak daylight hours. Additionally, Which? advises keeping windows closed during the hottest parts of the day if the outside air is warmer than indoors, and only opening them in the late evening or early morning when external temperatures drop.