Keep windows and doors shut during the day and air as soon as it gets cooler, e.g. early morning and evening. Create a natural draft, if you can. Simply open the downstairs windows on the shady side of the house and the upstairs windows on the hot side of the house.
Sun reflective window film can easily be applied to your windows, no matter, if you rent or own, and is a great way to keep the heat outside. While still letting in plenty of daylight, the adhesive film reflects around 60% of the heat coming through your windows.
Getting air conditioning fixed can be really expensive. A much cheaper option is a portable air conditioner. They start at around £80 and transport hot air out of the house through a venting hose. Don’t let it run all day though, as they use quite a lot of energy.
Home owners can prepare for the next big heatwave by painting their house in a light colour as opposed to dark shades. These store heat and make it difficult to keep your house cool in the summer months.