Overview

• The Flaschentrick involves partially filling 1.5-liter plastic bottles with water, freezing them overnight and placing them high in a room to lower air temperature through evaporative cooling.
• Users say the cooling effect around each bottle lasts only a few hours before the ice melts and the chill dissipates.
• Deploying multiple frozen bottles can extend the cooling period but increases electricity use and reduces overall sustainability.
• Hanging damp towels or sheets indoors offers a low-cost, equipment-free way to generate evaporative cooling throughout living spaces.
• Homeowners can further cut indoor heat by closing blinds during the day, ventilating in cooler hours and pairing reflective window films with fans and water basins.