The researchers tested a new way to reduce heat from the sun coming through windows in hot climates without blocking out natural light. They used a thin film of flowing water on the windows to cool them down and found that it lowered indoor temperatures by 2.2 to 4.1 degrees Celsius. The water film absorbed some of the sun's heat, but still let in more light compared to dry glass. This method could help keep buildings cooler without sacrificing daylight.