Turning down the heating at night does not result in more moisture in the home, but it does increase the chance of condensation. Colder air can hold less water vapour, so the relative humidity rises and moisture condenses more quickly on cold windows and walls. Lowering the temperature by a few degrees instead of turning it off completely, ventilating properly and airing the room in the morning will help keep this under control.
What happens to moisture when the heating is turned off at night?
The amount of moisture in the home does not change because of the thermostat. That moisture comes from breathing, cooking, showering and drying laundry. What does change is how much moisture the air can hold. Warm air can contain more water vapour than cold air. If the temperature drops at night, the same amount of moisture remains in the cooler air, making it relatively more humid.
In the coldest places in the home, such as windows, the corners of external walls and the wall behind a wardrobe, the air cools down even further. This is where moisture becomes visible as condensation. In the bedroom, moisture from your breath is added to this, which explains why windows are wet in the morning. As nights according to the KNMI forecast can reach around freezing point, you will notice this effect more quickly.
Is turning down the heating at night a bad idea?
No. Nighttime temperature reduction saves energy, and the moisture risk is easy to manage. Milieu Centraal provides advice on daytime and nighttime temperatures for each heating system. The difference mainly lies in how far you lower the temperature and whether you continue to ventilate.
| Heating system | Milieu Centraal nighttime advice | Moisture |
|---|---|---|
| Central heating boiler with standard radiators | 15 degrees one hour before going to bed | Keep ventilation open, air the room in the morning |
| Hybrid heat pump or district heating | 1 to 2 degrees lower | Smaller temperature difference, lower risk of condensation |
| Fully electric heat pump | Do not lower | Pay particular attention to ventilation in the bedroom |
Turning it off completely during a cold period is somewhat different from lowering the temperature. In a poorly insulated home, walls and windows will cool down much further, and the chance of condensation increases. If you want to heat efficiently, choose to lower the temperature rather than switching it off completely.
How to prevent moisture and condensation when lowering the nighttime temperature
Ventilation is the most important step. Milieu Centraal advises ventilating day and night all year round, even in winter. Leave the vent open in the bedroom at night, even when it is cold. Briefly air the room with the window wide open in the morning and wipe wet windows dry, so that moisture does not penetrate the window frames. Place beds and wardrobes a few centimetres away from the external wall, and do not dry laundry in the bedroom.
If you continue to have wet windows, you will find more background information on why you get condensation on your windows and what you can do about it. If the bedroom is particularly damp in the morning, also read why your bedroom is so damp in the morning.
Does a dehumidifier help when the heating is lower at night?
If you ventilate properly and the humidity remains high anyway, a dehumidifier can help. For example, run it for a few hours in the evening in the bedroom or the room where most condensation occurs, with the door and windows closed while it is running. A dehumidifier does not solve the cause: without ventilation, moisture will continue to build up. You can read about using a dehumidifier and heating together.
Keep in mind that moisture and mould in the home are linked to respiratory problems and an increased risk of asthma according to the RIVM. A device is not a treatment; if you have symptoms, consult your GP.
The AirPure DH251 dehumidifier
The AirPure DH251 is a compact dehumidifier that is also pleasant to use in the bedroom.
Dehumidification: up to 900 ml per day
Water tank: 3800 ml, switches off when the tank is full thanks to the safety sensor
Nighttime use: night mode where the display turns off
Timer: adjustable from 1 to 24 hours
Room and consumption: suitable for rooms up to 55 m², 80W
Size and weight: 24 x 13.4 x 37 cm, 2.51 kg
Direct answer: lowering the heating at night does not create extra moisture, but it does increase the chance of condensation on cold surfaces. Lower it by a few degrees instead of turning it off completely, keep the ventilation open and briefly air the room in the morning.
Suffering from wet windows or a damp bedroom in winter? View the AirPure DH251 dehumidifier or all dehumidifiers from Dynter.
Frequently asked questions
Is it bad to turn off the heating at night?
Turning it off completely is not ideal during a cold period, because walls and windows cool down significantly. Lowering the temperature by a few degrees saves energy and keeps the risk of condensation limited.
Why are my windows wet in the morning?
At night, the glass cools down and you breathe out moisture. That moisture condenses on the cold window. Ventilating during the night and airing the room in the morning helps.
Should the vent in the bedroom be open at night in winter?
Yes. Milieu Centraal advises ventilating all year round, day and night. An open vent removes moisture and CO2 while you sleep.
What temperature should you set the heating to at night?
For a central heating boiler with standard radiators, Milieu Centraal advises 15 degrees one hour before going to bed. For a fully electric heat pump, they advise not to lower the temperature.