Ventilation

Adequate ventilation of your home is critical to maintain a dry healthy indoor environment. Ventilation removes stale air containing moisture, odours and indoor pollutants and replaces this with fresh outdoor air. The building code requires new homes in New Zealand to have one complete air change every three hours or 0.33 air changes per hour.

Most homes can be ventilated adequately by opening windows to provide air changes. It is important to open windows and doors to ventilate even in winter to prevent moisture and other indoor pollutants from building up inside your home. Open wide at least one window  in each room of the house and leave all internal doors open for around 5 - 10 minutes to allow a cross draught to flow throughout.   Read more on how to ventilate your home.

The bathroom, kitchen and laundry produce a lot of moisture, mainly from showering and cooking. In these areas it is recommend provide additional ventilation in the form of extractor fans or range hood to remove the moisture produced before it can escape to other areas of the home. Extractor fans and range hoods should always be vented to the exterior of the home and will work best if a window in the room is left slightly open to provide a source of replacement air. Read more about extractor fans.

Home ventilation systems have become increasingly popular in recent years to increase ventilation and reduce problems with dampness and condensation.  While these systems can be very effective, adequate ventilation can usually be achieved without installing a ventilation system. Read more about home ventilation systems.

FAQs

Won't my house get cold if I open the windows in winter?  You only need to ventilate the house for short periods of 5-10 minutes at a time to provide an air change, even less on a windy day. While the fresh outdoor air will be cold the walls, ceiling and furnishings will retain their heat and help to warm the incoming air. The incoming air will also be drier making it easier to heat.

I have a fan heater in the bathroom, why do I need an extractor fan as well?  While fan heaters help to keep your bathroom warm and dry, they do not actually remove the water vapour. Once the heater is turned off the air will cool and the moisture will condense on cool surfaces. Often the condensation may appear in other rooms as the warm moist air escapes from the bathroom before cooling. An extractor fan will remove moisture before it can condense. Running the extractor fan and the heater together will remove moisture even more effectively than running an extractor fan alone.

My house is very draughty, do I still need to open windows to ventilate?  Draughts around windows, doors and floor boards do provide considerable ventilation, but cannot be controlled. The rate of air change will depend mainly on the wind conditions; on a calm frosty night there may not be enough ventilation, on a cold windy day there will be too much. Excessive ventilation due to draughts is a major cause of heat loss in homes as warm air escapes and is replaced by cold outdoor air. It is preferable to draught proof your house so you can have greater control over ventilation rates.