Ventilating your home
It is important to keep your home adequately ventilated - to maintain air quality and remove moisture for a healthy indoor environment.
As we improve air tightness, our homes are becoming easier to heat. However this improved air tightness means it's even more important to make sure you have good ventilation.
How to ventilate your home
Natural ventilation
The simplest and cheapest way to ventilate your home is to open doors and windows regularly to allow fresh air from outside into your home.
In summer, open windows and doors in different parts of your home to create a cross-draught, which will circulate air and help keep your house cool.
In winter, air your house at least once a day for a few minutes with wide open doors and windows to create a cross-draught. This will quickly replace stale indoor air with fresh outdoor air.
Warm inside air holds a lot of moisture, which will form condensation as it cools, unless it is removed from the house.
The best time to do this is when you turn off the heating, e.g. before you leave the house in the morning and just before you go to bed at night.
Depending on how you use the house, your home's air tightness and the wind and temperature conditions outside you may need to repeat this several times a day.
Ventilate overnight
Ventilating your bedroom overnight is also important for maintaining air quality and reducing the risk of excessive moisture and mould growth. You can keep a window slightly ajar on a hinge. Fit security latches if the window can be used to enter the house.
Gas heaters
Avoid using unflued gas heaters. If you are using a gas heater or LPG portable heater without a vent or flue to the outside, always keep at least one window open to allow fresh air to enter the room. Never use unflued gas heaters in bedrooms.
Tackling moisture/dampness problems in your house
If you have dampness or moisture issues in your home, you need to look at three aspects of your home: insulation, heating and ventilation.
Tackle home dampness problems at their source, and ensure adequate home insulation and energy efficient heating. If you are thinking about a home ventilation system, make sure you do these things first.
If you are having issues with excessive moisture/dampness and poor indoor air quality, EECA recommends the following steps (in order of priority):
1. Ensure that there is effective ventilation from wet areas in the home (such as the bathroom, laundry and kitchen) to minimize the moisture that causes the problems. Install externally vented range hoods or extractor fans over your cooker, an externally vented extract fan in your shower / bathroom and exhaust laundry dryers to the outside.
2. Ventilate your home with fresh outdoor air.
3. Ensure there is no moisture entering your home from outside. Check for leaks in pipes, drains and fittings in ceilings, under the floor and walls.
4. If you have an enclosed basement it must be ventilated to New Zealand Building Code requirements - ensure all the vents are open.
5. If the soil under your floor is damp, check for drainage problems (e.g. run off from neighbours properties). Fit drains on the outside of your house to lower the water table and reduce the dampness in the under floor soil.
6. If the sub-floor is still damp, look into fitting a vapour barrier to the ground underneath your floor (i.e. polythene sheeting).
If you are not sure, talk to a qualified builder.
Insulation and heating
At the same time, you need to think about insulation and heating. A cold and damp house won't be improved by ventilation alone.
7. Remove unflued gas heaters which can cause moisture problems in houses.
8. Ensure that your home is adequately insulated.
9. Heat your house. Aim for 18-21° C during the day.
10. Single-glazed windows are areas of high heat loss and will always attract condensation in winter. Consider double-glazing your house.
Once you have looked at all these things, and you still have moisture problems in your home, consider either a dehumidifier or home ventilation system.
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