Overview
- Coverage this week consolidated guidance from Verbraucherzentrale, Umweltbundesamt and multiple outlets that fully lowered shutters can trap hot air and fail as sun protection.
- Solar radiation heats the sealed air layer between shutter and window so that warm air transfers through the glass and can even overheat or damage panes and deform plastic slats.
- The simple fix is to leave the shutter’s ventilation slits open or a one-hand-width gap at the bottom so air can circulate behind the shutter and prevent a heat build-up.
- Exterior shading such as outside-mounted blinds, shutters or awnings blocks sunlight before it reaches the glass and works far better than interior curtains or inside-mounted blinds.
- Limit ventilation to late evening, night or early morning when outdoor air is cooler, use fans and short targeted airing to control humidity and CO2, and know DIY tricks like frozen bottles give only temporary relief.