Heating a home hard for an hour and then letting it go cold is a common cause of streaming windows. Here is what a steadier pattern looks like and what to try first.
Condensation forms when warm, moist air meets a cold surface. Steady, gentle background heat keeps walls and windows warmer than short, hot bursts, so less moisture lands on them. Keep every room gently warm, ventilate briefly each day and use extractors. If the home still streams despite good habits, look at leaks, insulation gaps and finally moisture removal.
Windows that run with water on cold mornings, then dry out by afternoon when the heating has been on. Mould that builds in the coldest bedroom or on the north wall. A home that feels warm for an hour after the heating is on and clammy and cold the rest of the time.
GOV.UK guidance says homes that are insufficiently insulated and heated are more prone to moisture and condensation on the inside of external walls and windows.
These steps go from free habit changes to equipment. Heating costs are a real limit for many households, so change what you can afford to change.
Winters in this part of Kent are mild and wet, with long spells of damp air, so a home can sit in cold, humid conditions for weeks. Older houses in the town and villages, and newer estates such as Kennington and Willesborough, all follow the same rule: cold surfaces plus indoor moisture means condensation.
If your home is a tight new-build, read the new-build condensation guide as well, because ventilation matters even more there.
A dehumidifier removes moisture, not cold, and it is not a substitute for heating, fixing a leak or dealing with rising damp. If you rent and cannot make changes to the structure, a portable dehumidifier is a more realistic option than a loft-mounted system. A Dryzen unit needs a loft and is not suitable for rentals unless the landlord authorises the changes. If you cannot afford to heat the home steadily, the ventilation and furniture steps above still help, and it is worth being open about that at survey.
A Dryzen system is a loft-mounted dehumidifier with insulated ductwork to the central area or stairway of the home. Each unit is rated for 150 square metres and has an extraction rate of 12 litres a day, and it uses about 20 pounds a year in energy. It suits owner-occupied homes with a loft, and the target humidity can be set in the app. See the healthy humidity guide for the target range. It does not remove existing mould, which must be cleaned off. A free survey can measure humidity through the day and tell you whether a system would help.
Cambridge City Council advises aiming for between 18 and 21 degrees Celsius with steady, gentle background heat rather than letting rooms cool right down. Your own comfort, health and budget come first, so treat this as a guide.
Heating one room hard and leaving the others cold tends to push moisture into the cold rooms, where it condenses. Keeping every room at least gently warm and closing the door when you cook or shower helps.
A short burst of ventilation costs less than heating a room full of damp air. Open a window for 10 to 15 minutes a day and run extractor fans during and after cooking and bathing.
Sources: Cambridge City Council: A guide to managing condensation and mould in your home; GOV.UK: Understanding and addressing the health risks of damp and mould in the home
Last reviewed 2026-10-07. General guidance only; this is not a survey of your home.