As Britain braces for a potential 39C heatwave this week, which could break the all-time June record, many households without air conditioning are seeking ways to stay cool. A simple DIY hack using two common household items—a one-litre water bottle or a four-pint milk bottle, and water—can transform a standard fan into a makeshift air conditioning unit.
How the DIY air conditioner works
Katie Mortram, writing for Good Housekeeping, shared her experience with the method. She filled a bottle 75% full with water and froze it. Once frozen, she placed the bottle in a short tray to catch condensation, covered it with a damp cloth, and positioned it directly in front of an electric fan. The fan then blows air over the ice, creating a chilled breeze.
Mortram noted that the ice expanded to fill the bottle completely, pushing out the bottom of the packaging but not cracking it. This made the bottle difficult to stand upright. Initially, she was unsure if it was working, but within two hours, the effect was significant. The bedroom felt cooler and breezier than the hallway, which was stuffy and stagnant. The chilled air circulated the room, providing noticeable relief.
Effectiveness and limitations
The DIY unit lasted about four hours before the ice melted completely. While this may not seem long, it can make a difference during the hottest part of the day. Mortram confirmed that the method works as a limited quick fix, but noted it is not entirely free—it requires energy to freeze the water and run the fan, which may need to be on a higher setting.
The current highest June temperature in the UK is 35.6°C, set in Southampton in 1976, but this week's forecast could surpass that. The Met Office has issued a rare red weather warning for extreme heat in central and southern England and Wales on Wednesday and Thursday.
Safety precautions
There are important safety considerations. The tray of ice or water should be kept at least 30cm from the fan to avoid electrical hazards if the fan is knocked over. Additionally, the NHS warns that if indoor temperatures exceed 35°C, fans should not be pointed directly at the body, as they can act like a convection oven and accelerate dehydration. Instead, direct the fan away from yourself to cool the surrounding air.
This hack offers a temporary solution for the millions of British homes without air conditioning, which now number around four million—double the figure from three years ago. As extreme heat becomes more common, such DIY methods are increasingly sought after.
