As a fourth heatwave approaches and wildfires continue across parts of the UK, energy experts suggest a simple trick to keep bedrooms cool at night: placing a bowl of water on the windowsill.
Wales has had just 5% of its usual rainfall for July after a string of heatwaves and a dry spring. North Wales and the Upper Severn were the first parts of the UK to declare drought status, and parts of Usk met their heatwave threshold for 20 days in a row.
Emergency crews are tackling blazes in Wales, and homes were evacuated after a fire swept through the Cairngorms National Park, which Police Scotland declared a major incident.
Evaporative cooling hack
Energy specialists at the Local Energy Advice Partnership (LEAP) say the method is "surprisingly effective" and that bowls of water placed around the home can help cool the air and lower indoor temperatures. When warm air passes over the water, the water absorbs the heat and slowly evaporates. This is known as evaporative cooling, and it lowers the temperature of the air around it.
Adding ice cubes makes the trick even more effective. Pointing a fan at the bowl speeds up evaporation and spreads the cooler air around the room. LEAP say it works best when the bowl is placed near an open window or in front of a fan. They suggest filling a bowl with ice and cold water and putting it in front of a fan to act as a homemade, DIY air-conditioner.
User testifies to effectiveness
Instagram user Samsmith1986, who has over 2,000 followers, backs the hack and calls it a "simple life hack that can really make a difference." In a video posted during the June heatwave, he said: "You have to try this if you can't sleep during this heatwave. Grab yourself a bowl of cold water. Place it on the windowsill at night time. Now, the cold water draws in the heat and converts it into vapour. How cool is that?"
The video got a strong response. One user said: "Just tried this now and it's defo cooled the room." Another added: "Put a bowl of cold water behind an electric fan. As it evaporates, the fan blows the cold vapour at you! It's fabulous!"
Lost archaeology revealed
The dry weather has also uncovered unexpected archaeological sites. Lost Roman buildings and World War 1 practice trenches have appeared in grasslands across Wales, with the prolonged heat revealing hidden remains. Many are only visible from the air, and some have not been seen for "two or three decades", according to the Royal Commission on the Ancient and Historical Monuments of Wales (RCAHMW).
Bear in mind that the effect is modest compared to air conditioning and may be less noticeable in humid conditions or rooms with little airflow.
