Condensation forms when warm, moist indoor air meets a cold surface such as a window. To stop it: create less moisture, extract it where it's made, heat the home evenly, and ventilate with fresh, drier air. A heat pump and a ventilation system together give the best result.
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Waking up to windows dripping with water is a familiar New Zealand winter sight. Condensation isn't just annoying. Over time it leads to mould, musty smells and damp, unhealthy air.
Why do NZ homes get so much condensation?
Everyday living puts a lot of moisture into the air: showers, cooking, drying washing indoors and even breathing. Many homes have cold surfaces, such as single-glazed windows and poorly insulated walls. When warm, moist air touches those cold surfaces, the moisture turns back into water.
Step 1: Create less moisture
- Dry washing outside or in a vented dryer.
- Put lids on pots when cooking.
- Avoid unflued gas heaters, which add a lot of moisture to the air.
Step 2: Extract moisture where it's made
Use extractor fans in the bathroom and kitchen, and leave them running for a while after showering or cooking. Fans should be ducted to the outside, not into the roof space.
Step 3: Keep the home evenly warm
Warmer surfaces mean less condensation. A heat pump keeps rooms at a steady temperature, and its dry mode removes moisture from the air on damp days. See the best heat pump settings for winter.
Step 4: Ventilate with a home ventilation system
Opening windows works, but not on a frosty night. A whole-home ventilation system brings in fresh air all year round:
- Positive-pressure ventilation pushes filtered air into the home, usually from the roof space, and moves damp air out through small gaps around windows and doors. An affordable option for many homes.
- Balanced heat recovery ventilation supplies fresh outside air and extracts stale air through ducts, transferring warmth from the outgoing air to the incoming air. Ideal for well-sealed and new homes.
Heat pump or ventilation system?
They do different jobs. A heat pump heats and dries the air in the room it's in. A ventilation system replaces damp, stale air with fresh air throughout the home. For a home with ongoing condensation, the best result usually comes from both.
Rental properties
Landlords also need to meet the Healthy Homes standards for heating and ventilation. Read our guide to the Healthy Homes heating standard.
Get advice for your home
We install heat pumps and home ventilation systems across Hamilton, the Waikato and Auckland. Book a free in-home assessment and we'll recommend the right fix for your home.
Frequently asked questions
How do I stop condensation on my windows in winter?
Reduce the moisture you create indoors, extract it where it is produced and keep the home evenly warm. Use extractor fans when showering and cooking, dry washing outside or in a vented dryer, heat the home consistently, and consider a whole-home ventilation system if the problem continues.
Does a heat pump help with condensation?
Yes, a heat pump keeps rooms warmer, which reduces condensation, and its dry mode removes moisture from the air. On its own it does not bring in fresh air, which is what a ventilation system does.
What is the difference between positive pressure and heat recovery ventilation?
A positive-pressure system pushes filtered air into the home, usually from the roof space, and moves damp air out through gaps around windows and doors. A balanced heat recovery system supplies fresh outside air and extracts stale air through ducts, transferring warmth from the outgoing air to the incoming air.
Ready for a comfortable home all year?
Book a free in-home assessment and get a fixed-price written quote from our local team in Hamilton, the Waikato and Auckland.