Good Repair Guide: Improving internal ventilation

All houses need a constant supply of fresh outdoor air to replenish indoor oxygen levels and replace stale, moisture-laden air that is generated by household activities.

Poor indoor air quality comes from a range of sources, including:

• high indoor moisture levels from unvented kitchen or bathroom steam, unvented gas heaters or clothes dryers
• pollutants and discharges from solid-fuel burners, open fires, gas heaters and cookers, and occupant activity such as smoking inside
• volatile organic compounds (VOCs) given off by new building materials, paint and carpets
• outdoor sources of pollution such as vehicle emissions or fireplace emissions.

In most New Zealand homes, opening windows will be sufficient to meet most air quality requirements, so long as this is used in conjunction with localised externally vented air extraction systems such as kitchen rangehoods and bathroom extractor fans to remove moisture and pollutants. Where the occupants are not able or choose not to open windows regularly, there is likely to be a need for other means of ventilation.

This Good Repair Guide outlines strategies for maintenance tradespeople to improve the ventilation of spaces within a domestic building.