Should I open my windows?

Why E20 flats overheat

East Village was built new, sealed tight and wrapped in insulation. That's brilliant for holding winter warmth but awkward in summer, when the same airtightness traps heat you'd rather be rid of. Add large windows, a lot of glass, and communal district-heating pipes running warm through the building, and a flat can sit hotter than the street outside for hours.

What to do about it. On a hot day the outdoor air is often warmer than your flat through the afternoon, so throwing the windows open just invites more heat in. The move is a night purge. Keep windows shut and blinds down while it's hotter outside than in, then open up once the evening air drops below your indoor temperature to flush the day's heat out, and close everything again before the morning warms up. This page makes that call for you, hour by hour, using the Met Office forecast for E20.

A note on MVHR. Many East Village flats have MVHR (mechanical ventilation with heat recovery), which keeps fresh air moving with the windows closed. If yours does, you can seal up through the hottest part of the day without the air going stale.