As the UK experiences another heatwave with temperatures reaching 32°C, experts are unanimous: keep windows, doors, blinds, and curtains firmly closed during the hottest parts of the day. This method reduces solar heat gain and helps rooms stay cooler.
When to Open Windows
Specialists suggest opening windows only in the early morning or late evening, when outside temperatures drop below indoor levels. This allows proper ventilation and cooling.
Tina Loveland, Senior Designer at Appeal Shading, explains: "Once sunlight has passed through a window and converted to heat inside a room, you're fighting a losing battle. Blinds and shutters intercept that heat before it reaches your living space." She adds that a quality fitted blind on a sun-facing window can cut solar heat gain by 40-70%.
Why Opening Windows Can Be Counterproductive
Throwing open windows during a heatwave feels intuitive but is often wrong. Tina says: "If it's hotter outside than inside, opening your windows will warm your home up, not cool it down." During a UK heatwave, outdoor temperatures can stay above 30°C from mid-morning until early evening, while homes may be at 24-25°C.
NHS and Public Health England guidance echoes this: keep windows in sun-facing rooms closed during the hottest part of the day. Treat your home like a cool box—sealed and shaded until outdoor temperatures fall.
Nighttime Ventilation Strategy
Tina recommends opening windows once outdoor temperatures drop below indoor ones, usually from 9pm or 10pm. Open windows fully on opposite sides of the house to create a cross-draught, flushing out built-up heat.
Max Wilson, co-founder of Pocket Storage, agrees, advising to treat your home like a fridge between 10am and 6pm. He warns: "Opening your windows when it is warmer outdoors is no different from opening a door to an oven."
Why UK Houses Get So Hot
Max explains that British houses are built to conserve heat, not repel it. Insulating materials, furniture, and walls absorb heat all day and release it at night. He recommends removing clutter from windows and doors to encourage airflow, and ensuring an unobstructed path between opposite windows for maximum ventilation.
Additional Cooling Tips
John Klee, a heating expert at BestHeating, suggests placing a bowl of ice in front of a fan to circulate a cool breeze. Edward Simon, director at Direct Fabrics, advises closing off sun-exposed rooms during the day and opening internal doors at night. He also recommends reducing indoor heat sources like oven cooking and tumble drying during peak hours.
