How your apartment layout sets the cooling ceiling
Two flats on the same street can be several degrees apart. The difference is usually layout, not luck.
The outdoor forecast is shared. Your indoor temperature is not. A ground-floor courtyard and a top-floor studio on the same block can be several degrees apart by late afternoon, even when they opened and closed at the same clock times.
Layout is the reason. It decides whether air can actually leave, which façade is the cooler intake, how much sun the roof dumps into the rooms, and whether a balcony door is a gift or a radiator.
Start with the façades
Look at where the windows are, not how many you have.
Single-sided homes have every opening on one wall. Cross-ventilated homes have openings on two different sides. That split is the first thing the Ventilate engine asks, because fan placement and flush speed both hang on it. See single-sided or cross-ventilation.
Then look at what is outside each window. A courtyard with plants is usually a better intake than a sun-baked street. See courtyard or street.
Height, night, and the size of the opening
Top floors sit under the roof. They heat faster by day and give the heat back all night. See why the top floor stays hot.
Night flush is the only free cooling most European flats get. It only works if outdoor air is actually cooler, and in a city heat island that stretch is shorter. See how to flush heat at night.
Balcony doors move a lot of air when they should be open, and a lot of sun when they should be shut. Small high windows do the opposite. See balcony doors and small windows.
What the app does with this
Onboarding maps layout, window type, and what sits outside each pane. Advice is per window, not one rule for the whole home. Fan placement still lives with the timing guide: where to place a fan.
Once layout is working, the next question is whether that cooler outdoor air is worth letting in.
In this guide
Single-sided flats versus cross-ventilation
Windows on one façade cannot flush a home the way opposite façades can. Here is how to tell which layout you have, and what to do with a fan in each case.
Courtyard windows versus the street
The cooler intake is usually the greener, shadier, more sheltered side. Street façades hold heat, noise, and often worse air. Use them as exhaust when you can.
Why top-floor flats stay hotter
The roof takes the sun all day and radiates into the rooms all night. Top floors need stricter daytime shading and a longer night flush than the flats below.
How to flush heat out of a flat at night
Night ventilation is the only free cooling most homes without AC get. It only works when outdoor air is cooler than indoor air, and city heat islands make that window shorter.
Balcony doors versus small high windows
A sliding door moves a lot of air, and a lot of sun. A small high window does neither well. Match the opening you have to intake, exhaust, and daytime shade.
Common questions
- What is a single-sided flat?
- Every openable window is on the same façade. Air has no natural path through the home, so an open window mostly exchanges air with itself. You need a fan to create a pressure difference, and you need patience.
- What is cross-ventilation?
- You have openable windows on two different façades, ideally opposite ones. Air can enter one side and leave the other. Once outdoor air is cooler, a through-draught can flush hot air in minutes.
- Why is the top floor hotter?
- The roof takes the full sun load and radiates it down all night. Top-floor flats also sit above the rest of the building's stored heat. Daytime shading and a long night flush matter more here than on a shaded ground floor.
- When should I do a night flush?
- Only when outdoor air is cooler than indoor air. Open as wide as safety allows, keep going overnight if the air stays cooler, and close before the morning crossover. In a heat island that window starts later and ends earlier.
These guides are informational and are not medical advice. If heat is making you unwell, follow your local health agency’s guidance.
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