As the UK swelters in a heatwave, many people will be looking for ways to keep their homes cool
Forget about opening your windows when it’s warm(Image: PeopleImages via Getty Images)
With another blistering day predicted for Sunday, millions of people across Scotland and the rest of the UK will be seeking methods to maintain cool homes. However, one of the most widespread practices during an intense heatwave could actually be making matters significantly worse.
Throwing windows wide open the instant temperatures start to soar may seem like the natural response. Yet specialists warn that doing so during the warmest period of the day – between 11am and 6pm – when outdoor air frequently exceeds indoor temperatures, can push home temperatures higher rather than lowering them.
When the air outside is hotter than inside, opening windows simply permits that heat to flood into your property. Rather than generating a refreshing breeze, it can function more like a fan-assisted oven, capturing warm air indoors and making rooms progressively suffocating.
Instead, homeowners are urged to keep their windows firmly closed throughout the warmest stretch of the day, particularly those on whichever side of the building is exposed to direct sunlight. The Energy Saving Trust (EST) advises closing curtains or blinds at the same time to stop solar heat from pouring through the glass and causing rooms to warm up further.
The EST recommends opening windows once outdoor temperatures drop below those indoors, such as late evening, overnight or early morning. This permits cooler air to circulate through the property and helps dispel heat that has accumulated during the day.
Creating a cross-breeze by opening windows on opposing sides of your property can significantly improve ventilation, allowing fresher air to move more effectively throughout. The Energy Saving Trust also suggests keeping internal doors open where possible to promote air circulation between rooms.
The UK Health Security Agency (UKHSA) advises minimising additional heat sources within the home by restricting oven usage and other heat-producing appliances during the warmest periods of the day. Switching off electrical equipment when not needed can similarly help reduce unnecessary warmth indoors.
While fans can provide some relief, they perform most effectively once external temperatures begin to decrease and cooler air can be brought inside. The UKHSA cautions against relying solely on fans as a cooling solution when indoor temperatures surpass 35C, making overnight ventilation especially crucial during extended periods of hot weather.
While it might appear counterintuitive, experts recommend keeping windows and curtains shut on the sun-facing side of your property during the peak heat of the day, before ventilating the home overnight – a proven method for maintaining lower indoor temperatures during periods of extreme heat.