With our summers feeling more Mediterranean, finding ways to stay comfortable indoors is becoming less of a luxury and more of a necessity. There are no legally-defined upper temperature limits, but experts suggest an optimum of 20 to 23 degrees Celsius for living areas and workplaces. Each degree above can impact both health and productivity.

The challenge is keeping cool without adding to the environ-mental burden. Read on for some of the most economical and sustainable methods.

Cooling appliances

Fans remain one of the cheapest options, with a typical tower, desktop or pedestal fan costing just 15 to 31p for 24 hours of continuous use (Energy Saving Trust). Their low energy use also means minimal CO2 emissions.

Portable air conditioning units are significantly more expensive to run – typically £4.84 to £6 for 24 hours – and produce considerably more CO2. If you do need one, make sure it’s the right size for the room you’re using it in.

Evaporative air coolers offer a middle ground, using a fan to move air over water rather than a refrigerant chemical. Running costs are similar to a fan at 28p to 40p per 24 hours, although the units themselves cost more to buy. Keep internal doors closed when in use, and unplug when not in use to avoid using energy when on standby. These tips apply to air conditioning, too.

How to cool your home for free

Timing is important. Keep your windows closed during the hottest times of the day, but when the air is cooler outside than inside, open windows on opposite sides of your home to let the air flow through. Close blinds and curtains when the sun is shining directly through the glass and open them again when the sun has moved.

Longer-term solutions

Topping up your loft insulation is one of the most effective investments you can make. It acts as a thermal barrier in both directions, keeping heat in during winter and slowing its entry during summer.

Adding solar control film to your most sun-exposed windows, particularly south-facing ones, can significantly reduce the heating effect of sunlight through the glass. For a budget-friendly alternative, try lining sunny windows with newspaper.

Keeping cool doesn’t have to come at great cost to you or the planet. By combining simple methods, such as opening windows and drawing curtains at the right time of day, with smarter appliance choices and some home improvements, it is possible to stay comfortable through even the hottest days of summer.

Small adjustments, made consistently, really do add up and could help you save on your energy bills.

Sara Chardin is a freelance writer and content creator who specialises in writing thoughtful articles about sustainability, travel and home interiors.