Don’t sweat it: Keeping cool sustainably in a heatwave

Keele’s Dr Sharon George offers tips on how to beat the heat, without contributing to further climate change.

As temperatures in the UK soar and records are broken, we are reminded that climate change is pushing temperatures and our weather to extremes. Hotter, drier summers are becoming more likely and so it makes sense to think about how to prepare for a heatwave, both now and in the future.

Air conditioning, while convenient, and pleasantly cooling, uses a lot of energy. A rise in outdoor temperatures increases energy use from air conditioning producing more greenhouse gases, which in turn drives climate change.

There are things we can do to stay cooler during a heatwave, without costing the earth, both in the short term and on a bigger scale going forward.

1. Natural, cooling ventilation

We can encourage a cool breeze through our homes by using natural ventilation, opening windows and doors, especially to create a natural air flow. Opening windows at the top and bottom of your home will help hot air escape and will draw in fresh air. However, if outside temperatures are very high, you could just be drawing in warm air. It will help if spaces around doors and windows are shaded, keeping out those intense rays so that you draw in cooler air. Closing shutters, blinds, and curtains if you have them will help. A damp towel on a windowsill where air is coming in might help, with heat being used up in evaporating moisture, cooling the air, however, this only works if the ventilation is good, or you could end up with too much humidity. This will feel worse as your natural perspiration will not work as well, and you could end up even warmer.

2. Use appliances sparingly

Living in our homes, we produce heat when we use appliances, and cook and heat our water. Turning off the hot-water system in the day and not cooking hot food will prevent our homes storing heat up, and often giving us uncomfortably hot evenings. Many of us have been working from home on computers. These, and other electrical appliances often generate a lot of heat. The harder the appliance is working the more heat it will generate. Having smaller, more efficient fridges and freezers will help, as will turning off lights when they are not in use to reduce extra heat being reduced. Fans, while using electricity, are less energy intensive than air conditioning. You can get a fast immediate cooling effect by moistening your skin and using a fan to dry off. The water molecules need energy to evaporate and so will absorb heat from your skin and the air next to it. The faster air flow will keep the concentration of water vapour lower allowing faster evaporation, and more efficient, fantastic cooling.

3. More trees please

Evaporation coupled with shading mean trees can have a significant cooling effect on buildings and spaces. Leafy canopies provide much needed shade, preventing ground heating. Often trees are cut down to let in more light, but their role in providing shade, and absorbing water is important in a changed climate future where we are likely to need more shading, and drainage and absorption by our trees of increased rainfall.

4. Reflect the solar energy

Making surfaces white or light can have a cooling effect by reflecting sunlight, rather than absorbing it. When the sunlight is absorbed by a dark surface, it then gets re-emitted as longer wavelength radiation that we feel as heat. Painting buildings and walls around buildings white can prevent heating, and using blinds and curtains to reflect light away from windows will help.

5. Plan our buildings from scratch

Insulated buildings not only help keep heat in, they keep heat out. In the UK, most of the year we focus on keeping spaces warm, and many of us have well-insulated homes, which is great in winter, but at times when air temperature is high, and the sun is blazing our homes can overheat. South-facing windows allow sunlight to warm our homes in the winter but can create a problem in summer with overheating. Creating homes designed with good ventilation and shutters, shades and efficient technology will help.