When it is cold and humid: short damp airing
Damp cold is common on Atlantic coasts. Rooms can feel clammy without being icy. Air briefly when it is not raining, then close. This is not a mold diagnosis.
Damp cold is common on Atlantic coasts: the UK, the Netherlands, Brittany, northern Portugal. Rooms can feel clammy even when the thermometer is not that low. A short opening still swaps stale indoor air for outdoor air. This is not a mold diagnosis, and this app does not measure indoor humidity.
If glass is running with condensation, a brief airing on a drier spell, then closing, is usually better than leaving a window cracked all day in the rain.
The damp-cold checklist
- Air briefly when it is not raining, then close to keep warmth
- Do not dry laundry in front of a wide-open window in wet cold
- Wipe condensation; lingering wet glass is a comfort problem
- Keep airing short; humidity is a reason to stay brief, not to skip airing forever
Brief, then shut
The cold-weather rule still holds: you are keeping paid-for heat. Humidity only makes the opening shorter, and it is a reason to wait for a drier hour when you can.
A cracked window all afternoon in driving rain cools the room and loads the air with outdoor moisture. That is the opposite of a useful airing.
Dew point still describes how heavy the air feels. In winter it is a comfort signal, not a heatwave flush signal. See dew point.
What this page will not do
Ventilate will not tell you that you have mold, and it will not read a sensor in the wall. If you have a damp-building problem, that is a building or health issue beyond window timing.
Use indoor temperature, local weather, and a short timed opening. Then close.
This is not medical advice. If cold, damp, or condensation is making you unwell, follow your local health agency.