A Dachgeschosswohnung is the hardest flat in Germany to keep cool — charming in winter, brutal in a heatwave. The heat comes from a specific source, and once you address it, even an attic room becomes liveable. Here's how.
Why attic flats overheat
Top-floor flats sit directly under a roof that bakes in the sun all day, and that heat radiates downward into your rooms for hours, even after sunset. Roof windows (the Velux-style kind) let in strong, direct sunlight, and there's little mass above you to buffer the temperature. The result is a space that keeps heating through the afternoon and holds that warmth into the night — a fundamentally tougher job than cooling a lower floor.
Shade the roof windows — the biggest lever
In an attic, shading matters more than anywhere else, and roof windows are the priority. Sunlight stopped before it enters never becomes indoor heat, so external blinds or shades on roof windows make a dramatic difference. Shade wall windows from outside too where you can. Without shading, you're fighting a losing battle all day; with it, everything else you do actually works.
Ventilate hard at night
Because an attic stores so much heat, aggressive night ventilation is essential. Once the outside air finally drops below your indoor temperature, open windows on opposite sides for a strong cross-breeze, and use a fan at a window to push hot air out. Flush as much stored heat as possible overnight, then seal and shade again before the day heats up.
Concentrate cooling in one room
Don't try to cool the whole attic — pick one room as your retreat, close it off, shade it, and focus your cooling there. A single comfortable room to sleep or work in is achievable; a comfortable whole attic usually isn't. Close interior doors to contain the cool and keep the hot, sunny rooms sealed off.
Use cooling gear that copes
In an attic, undersized cooling won't keep up. If you use a mobile AC, size it generously for the room's high heat load — see our PortaSplit attic guide and BTU sizing guide. In dry heat, an air cooler helps as a lower-cost option, though an attic's intensity often calls for an AC. A fan supports either by moving air across you.
Put it together
To cool a Dachgeschosswohnung: shade roof and wall windows from outside, ventilate hard at night, concentrate cooling in one sealed room, and use generously sized gear. Get the shading right and the rest follows. Check which cooling units are in stock near you that can handle the heat up top.