How to Keep Your Home Cool in a Heatwave Without Air Conditioning

This guide is for renters, homeowners and anyone without air conditioning who dreads the next spell of hot weather. You will learn how heat gets into a home, how to keep it out during the day, how to flush it out at night and how to look after the people most at risk. In an emergency, including signs of serious heat illness, call your local emergency number and follow official emergency services and government heat advice, which always overrides this guide. General information, not professional advice.

How Heat Gets Into Your Home

Before buying anything, it helps to understand where the heat is coming from. In most homes, three things do the damage: sunlight streaming through windows, warm outdoor air drifting in, and heat produced inside by people, cooking and appliances. Walls and roofs also soak up heat during the day and release it slowly into the evening, which is why a top-floor flat can stay hot long after sunset.

The basic strategy is simple. During the hottest part of the day you block heat from getting in. When the air outside becomes cooler than the air inside, usually late evening to early morning, you flush the stored heat out. And all day long you reduce the heat you create indoors. Every tip in this guide fits into one of those three jobs.

Block the Heat During the Day

Windows are usually the biggest source of unwanted heat. Sun shining through glass can warm a room quickly, so shading is the single most effective free action you can take. Shading on the outside of the window works best because it stops the heat before it reaches the glass, but indoor shading still helps a great deal.

1. Close curtains and blinds early Shut them on sun-facing windows before the sun reaches them, not once the room is already hot. East-facing rooms need shading in the morning and west-facing rooms in the afternoon.
2. Use light-coloured or reflective coverings Pale curtains, blackout linings or reflective window film bounce more heat back out. If you rent, use removable options and check your agreement or ask your landlord before fixing anything to frames.
3. Shade from outside where possible External blinds, awnings, shutters or even a temporary sheet hung outside a window can keep a room noticeably cooler. Make sure anything outdoors is secured and will not block an escape route.
4. Keep windows shut while it is hotter outside Opening a window when the outside air is hotter just lets more heat in. Keep it closed and shaded until the evening cools down.
5. Close doors to hot rooms Shut off rooms that get the full afternoon sun so their heat does not spread through the home, and spend the day in the coolest room.

Plants and outdoor surfaces matter too. If you have a balcony, patio or garden, a parasol, a shade sail or potted plants placed in front of a sunny window can cut the amount of direct sun hitting the glass. Watering a paved area or patio in the early evening can help it cool down faster, so less heat radiates towards the house overnight. Follow any local water-use restrictions, which are common during hot, dry spells.

Pay attention to where you spend your time. Ground-floor rooms and those on the shaded side of the building are often several degrees cooler. Moving a work desk, a child's nap or an older relative's chair into the coolest room for a few days costs nothing.