Our homes are supposed to be our safe places, but for nearly a third of New Zealanders, damp homes can have a serious effect on our health.

Damp, mouldy houses and the link to respiratory problems

Damp, poorly ventilated houses encourage mould growth. For healthy individuals, mould may not have a significant impact, but if people have underlying health issues, damp, mouldy homes can lead to or worsen breathing problems.

The Asthma and Respiratory Foundation NZ reports that one in six New Zealanders lives with respiratory illness – that equates to 700,000 people. It is estimated that the yearly costs associated with respiratory disease are $5.5 billion. While not all respiratory problems are caused by damp houses, it is best to limit exposure to damp and mould.

Sources of indoor moisture

All occupied homes accumulate moisture – the simple act of breathing contributes 0.2 litres (L) per hour per person. Other sources include normal household activities like cooking, cleaning and bathing. The Energy Efficiency and Conservation Authority (EECA) estimates the average New Zealand family produces around 8 litres of moisture in their homes every day.

Breathing (per person)0.2 L per hour
Perspiration (per person)0.03 L per hour
Shower/bath (per event)1.5 L
CookingUp to 3 L
Dishwasher (per load)1 L
Clothes drying (per load)5 L
Clothes washing (per load)0.5 L
Science Learning Hub

(Figures produced by the University of Otago and reported in the New Zealand Herald and the Science Learning Hub)

Moisture also enters houses from the outside. Leaks in the roof, around windows or in the plumbing allow moisture to get between the walls or floors.

How Passive Houses combat unhealthy environments

An increase in insulation, air tight envelopes and mechanical ventilation all aid in combating dampness in homes and improving quality air.

By adding quality insulation, you are increasing the thermal resistance of your building envelope. Increased thermal resistance means less energy transfer between the outside and inside air, so the air within your home isn’t mimicking the external temperatures. It is important to maintain healthy living temperatures within your home so your immune system isn’t constantly working overtime.

To insure your efforts towards insulation are not in vain, your home needs an air tight & waterproof barrier. By replacing your standard building paper with the likes of the ProClima system, your home will be surrounded by a 100% waterproof, air tight membrane. The ProClima Sysytem prevents any moisture from entering your thermal envelope and therefore keeps your insulation dry and effectively working. Most damp homes do not start damp… Their thermal resistance decreases due to damp, shrunken insulation that no longer performs properly. This damp insulation can begin to grow mould and fungi which attributes to polluted air.

An airtight barrier also prevents your home from losing heat energy through gaps in the building envelope, maintaining your air tempertaure for longer.

Although an air tight barrier prevents external moisture from entering the home, it does not irradicate the internal moisture created by those living in the home – in fact, it makes this moisture worse as it has no where to escape. To combat internal moisture, you need Mechanical Ventilation. Mechanical Ventilation Systems need to be installed within your thermal envelope (insulation layer) to work effectively.

Mechanical Ventilation Systems such as Heat Recovery Units are the best at filtering the air coming into your home, removing moisture and transferring heat simultaneously. By taking the energy from the extracted (damp) air and reintroducing it to the filtered fresh air being brought into your home, you will not need to spend money heating the new air with the likes of a heatpump. Most Heat Recovery Units on the market claim to recover approximately 90% of heat energy (meaning if it is 0°C outside and 20°C inside, the new air being introduced into the home will be approximately 18°C).

We should all be breathing filtered air

Exposure to CO2 and other common pollutants (such as Nitrogen Dioxide) can produce a variety of health effects. These may include headaches, dizziness, restlessness, a tingling or pins or needles feeling, difficulty breathing, sweating, tiredness, increased heart rate, elevated blood pressure, coma, asphyxia, and convulsions. By filtering out CO2 and other pollutants in the air we breath, we can reduce the impact these carbons have on your body, overall improving your quality of life.


Ministry for the Environment – NZ

This article outlines some of the main pollutants that affect our health and environment. It includes information on standards and guidelines for managing levels of pollutants.

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