Overview
- Homes are often the deadliest place in a heat wave because building materials store daytime heat and stop nights from cooling, a pattern linked by the Robert‑Koch‑Institut to rising mortality when weekly mean temperatures exceed about 20°C.
- Keep windows closed during hot daytime hours when outside air is warmer than inside and do major ventilation by opening windows wide for cross‑breeze at night or early morning when outdoor temperatures fall.
- External sun protection such as awnings, outside roller shutters or external blinds blocks heat much more effectively than internal curtains, though renters may need landlord approval to install them.
- Use low‑cost, practical tricks that help now: run fans to move air (they cool people not rooms), open wardrobe doors during ventilation to avoid heat traps, and use the car door‑swing and footwell AC techniques to purge hot air before driving.
- Balance health and energy choices by limiting indoor–outdoor temperature gaps to about 5–6°C, avoiding indoor wet laundry that raises humidity and mold risk, checking medications that affect heat tolerance, and supporting cooling spaces and outreach for vulnerable people.