East Village flats are brilliant in winter and stubbornly warm in summer. A new EVH tool tells you, hour by hour, whether to open up or seal in. And it started with a tip in a neighbour's WhatsApp.

If you live in East Village, you know the summer routine. A flat that held its warmth beautifully in January turns into a greenhouse by July. New-build, airtight and district-heated, our homes are designed to keep heat in, which is exactly the problem once the weather turns.

The honest fix isn't air conditioning, it's timing. On a hot day the air outside is often warmer than your flat right through the afternoon, so throwing the windows open just lets more heat in. The trick is the night purge: keep everything shut while it's hotter outside than in, then open up once the evening cools to flush the day's heat out, and close up again before the morning warms. Get that timing right and it's the difference between a comfortable night and a restless one.

So we built a tool to make the call for you. Should I open my windows? gives one clear answer, open or closed, for East Village right now, plus when it's due to change and whether it's worth leaving the windows open overnight. It reads the Met Office forecast for E20 and weighs more than temperature: rain, wind and local air quality all feed into each hour's verdict. During hot spells it switches into heatwave mode, with night-purge guidance built in.

You'll find it on the EVH home screen as a quick open-or-closed line, and in full at eastvillagehub.co.uk/apps/windows, where a tap-through 24-hour outlook shows you the shape of the day.

The best part is where it came from. Mathilde shared a window-timing app in one of the E20 WhatsApp groups a few weeks ago, and enough of us found it handy that we built an East Village version, one that knows our postcode, our airtight flats and our heatwaves. That's how EVH is meant to work: a good tip from a neighbour, turned into something the whole village can use.

Give it a try next time the temperature climbs.