Passive Design

Designing the building and the spaces within it to benefit from natural light, ventilation and even temperatures.

Controlling indoor air quality

Moisture and contaminants from building materials and activities such as cooking and heating can harm building occupants’ comfort and health.

Moisture generally results from activities such as cooking and washing, as well as from building occupants’ breathing, and from unflued gas heaters.

Common sources of contamination include smoking, building materials giving off volatile organic compounds (VOCs), and combustion (of gas, oil or wood) for cooking and heating, which gives off particulates, carbon, sulphur, nitrogen oxide and complex organic molecules such as polycyclic aromatic hydrocarbons.

Air may also be contaminated by biocontaminants such as mould and fungi spores.

Moisture can affect both thermal comfort and health. Common airborne contaminants have been linked to a range of symptoms such as headaches, sinus congestion, dizziness, nausea, irritations of the eyes, nose and throat, respiratory problems, allergies and neurological disorders.

As far as possible, moisture and contaminants should be eliminated (by removing the source of contamination – for example, removing moulds, and specifying low-VOC building materials) or removed as close as possible to the source (for example, by using range hoods, extractor fans and vents to remove moisture and contaminants from cooking and washing).

BRANZ House Condition Surveys, conducted around every 5 years since 1994, have consistently found poor indoor air quality in New Zealand houses. The 2015/16 survey, for example, found that 11% of owner-occupied and 31% of rental houses felt damp. Assessors found signs of mould in almost half the houses visited.


Updated: 02 May 2017