As the UK braces for a heatwave, with the Met Office warning that a return to heatwave conditions is "increasingly likely" and temperatures set to soar into the 30s this week, many people are wondering whether to keep windows open or closed to stay cool. Last month's record-breaking hot weather saw temperatures peak at a sweltering 37.7°C. After a brief respite, forecasters say high pressure from the Azores is poised to push temperatures up again as early as this weekend.
To settle the age-old conundrum, seven experts were asked for their thoughts. While their answers differed slightly, they all reached broadly the same conclusion: keep windows closed during the day, and open them strategically at night.
Expert Consensus: Keep Windows Closed During the Day
Interior trends expert at Tapi Carpets and Floors, Johanna Constantinou, said keeping windows open all the time is a considerable mistake. She explained: "During a heatwave, one of the biggest mistakes people make is having all the windows open during the hottest part of the day. In most homes, it's actually far more effective to keep windows, curtains and blinds closed from late morning through to early evening to stop warm air and direct sunlight building up indoors."
Martyn Bridges, Director of External Affairs at Worcester Bosch, reinforced this guidance: "During a heatwave, people should generally keep windows closed during the hottest parts of the day, particularly in rooms exposed to direct sunlight. Blinds or curtains should also be kept closed during the day to help block out direct sunlight and prevent rooms from becoming too hot. This helps reduce solar gain, where the sun warms the home and causes indoor temperatures to rise."
Nighttime Strategy: Open Windows for Cross-Ventilation
Once temperatures drop in the evening, experts recommend opening windows to let cooler air circulate. Johanna Constantinou advised: "Then, once temperatures drop in the evening, open windows strategically on opposite sides of the home to create cross ventilation and let cooler air circulate naturally."
Dr Katie Tryon from Vitality Health echoed this: "There are several things you can do to help yourself stay cool at night. Firstly, it's important to keep your bedroom cool. Drawing curtains and blinds during the day and keeping windows closed if in direct sunlight to stop hot air getting in can help. When night comes and the air gets cooler, leaving the window ajar to let a cool breeze in can also make it easier to sleep."
Victoria Robinson, product expert at Hillarys, suggested opening windows on opposite sides of the home during the evening to generate a cross-breeze. She said: "Once temperatures start to drop in the evening, that's the best time to open windows and allow cooler air to circulate through your home. Creating a cross-breeze by opening windows on opposite sides of the house can help cool rooms down more quickly."
Additional Cooling Tips from Experts
Professor Chris Sansom, a specialist in renewable energy storage at the University of Derby, advised a tactical approach: "Give thought to the windows in your house that you're opening. For example, opening windows on the opposite sides of your home can create a much-needed, cooling cross-breeze. For even better results, try opening your windows at night-time and closing them during the day to trap cooler air inside and keep it circulating. During daylight hours, open windows on the shaded side of your home to reduce the amount of heat and sunlight entering your home."
Dr Punam Krishnan, working in association with Stannah, warned against depending entirely on fans or open windows: "While methods such as opening windows and using electric fans to cool your room's temperature are widely recognised, it's important to also focus on cooling down your body, as well as your surroundings, to maintain a high sleep quality during the summer months."
Security Considerations
Craig Andres from The Perspicacity Life highlighted another reason to think twice about leaving windows open: home security. He warned: "Temperatures are set to soar over the bank holiday weekend and while it's tempting for households to leave windows open, it's important not to overlook home security. Simple security mistakes such as leaving keys in locks or within reach of open windows, leaving doors unlocked, or windows ajar create easy opportunities for burglars, and more than a quarter of summer burglaries are linked to these oversights."
Verdict
Whether it's improving sleep quality, keeping your home at a comfortable temperature, or ensuring your property remains secure, there is a strong case for avoiding leaving windows open at all hours. Come nightfall, opening windows on both sides of your home to generate a cross-breeze can be a highly effective method of cooling things down.
