As Britain braces for its third heatwave of the year, with temperatures forecast to hit 34–35°C later this week, a simple trick using a bowl of cold water on a windowsill has gone viral – and some say it can cut the temperature by 10 degrees.
The technique was shared by Sam Smith, 40, a TV studio floor manager from Peterborough, who learned it from his aunt years ago. In a social media post that has amassed more than 17,000 likes, he explained: “So you just fill a bowl with cold water or ice. When you place the bowl on your window sill, or in front of a fan, the water evaporates into the air. This process absorbs heat, effectively lowering the ambient temperature of the room without electricity.”
“A bowl of cold water on a windowsill can cool a room by up to 10 degrees during the UK's third heatwave.”
Smith described it as “a great little hack” that “could be especially useful for people on a tight budget or elderly people looking for a cheap way to stay cool”. One impressed viewer commented: “Wow. Really worked...dropped my room like 10 degrees…”
The Met Office has confirmed the UK is entering its third heatwave this year, though Deputy Chief Forecaster Steven Keates said it would not be record-breaking compared to May and June. Temperatures are expected to reach 33°C on Wednesday, 34°C on Thursday, and possibly 35°C on Friday and Saturday, particularly in southern England, he added.
During such heat, experts recommend other low-cost measures too. Prof Mike Tipton of the University of Portsmouth advises that “fanning the face improves thermal comfort most, but fanning the whole body helps lower body temperature more”. However, he warns that using a fan when temperatures are above 35°C may worsen things by directing hot air towards the body.
Fans are relatively cheap. According to the Energy Saving Trust, running a freestanding fan for 24 hours costs between 15p and 31p. Placing ice cubes in front of the fan can cool the air further, as can positioning it in front of an open window – as long as it’s cooler outside.
Other simple tips include opening windows on opposite sides of the house to encourage airflow, especially at night or early morning when outdoor air is cooler. In flats with windows on one side only, opening doors and using a fan helps. During the day, keep windows shut and blinds or curtains drawn to keep warmer air out.
Extra insulation can also help keep heat out in summer, while reducing winter energy bills. And avoiding ovens, cookers, washing machines and dishwashers during the hottest hours can stop unnecessary heat building up inside.
With the heatwave about to intensify, Smith’s budget-friendly windowsill hack – costing next to nothing – has struck a chord with households trying to stay cool without sending their energy bills soaring.
