Brits are being urged to close their windows between specific hours of the day on Tuesday. Temperatures are climbing again with the fourth heatwave of the summer set to affect parts of the country.
The hottest conditions are expected to meet the official heatwave threshold for at least three consecutive days, potentially reaching a peak of 34C. The UK Health Security Agency has issued heat health alerts for all of England, starting on Tuesday morning and continuing through Wednesday. With homes to be sweltering hot, many households may instinctively open all their windows.
While ventilation is important, this doesn’t always work – and the timing of when you open your windows makes a big difference.
According to energy experts at Grant Store, ventilation works best when the outside air is cooler than the inside. If both are the same temperature, you’re just swapping warm air for warm air.
“The best times to open windows are early morning and late evening, when the outside air is cooler,” the expert explained.
“Opening windows between 11am and 3pm should be avoided, as this is typically the hottest period of the day.”
To maximise the effect, open windows on opposite sides of the house to create cross-ventilation, allowing a breeze to pass through.
“For an added cooling effect, try hanging a damp sheet in front of an open window. As air passes through the fabric, it cools slightly before entering the room.”
Households can also keep their curtains or blinds closed to keep the heat at bay. It may feel counterintuitive, especially after a long, grey winter, but letting the sun pour in during the warmest part of the day can drastically raise indoor temperatures.
“Keeping blinds or curtains closed during the hottest hours – particularly on south- or west-facing windows – helps reduce heat build-up inside your home,” Grant Store’s expert advised.
“If you want to enjoy the light, open your curtains in the early evening once temperatures have dropped.”
Using thermal or blackout curtains can further reduce heat entering your living space and help trap cooler air from overnight.
Household gadgets like ovens, tumble dryers, and even TVs can raise the ambient temperature in your home more than you might expect.
“Avoid using heat-producing appliances during the daytime wherever possible,” said the Grant Store expert. “Dry your clothes outdoors on the line, skip the oven in favour of no-cook meals, and switch off unused electronics completely.”
Even devices left on standby can generate unnecessary heat and waste energy over time.
