Moisture in the home - it's there all year round | Blog | Unovent

Moisture in the home - it's there all year round

27 October 2015
Moisture in the home - it's there all year round Moisture in the home - it's there all year round Blog

The existence of moisture in the home is well known by scientists but little understood by homeowners. The Energy Efficiency and Conservation Authority (EECA) advise 30% of New Zealand homes are damp and many more suffer from mould and mildew.

It’s accepted everyone living in a home generates moisture but not widely understood this moisture contributes to the house being cold and difficult to heat as well as being an unhealthy environment to live in. Most people will be aware that EECA has been widely promoting improvements in insulation and providing suggestions to make houses healthier and more energy efficient.

A BRANZ Survey found 40% of timber-framed houses had poor or seriously inadequate under-floor ventilation.


How much moisture does your home produce in a day?

It’s obvious that leaky homes have moisture problems but typical well-constructed homes of any age are also likely to suffer from dampness caused by normal everyday living activities On their website, EECA says, “The average NZ family produces around 8 litres of moisture in the home each day from activities like cooking, showers and breathing. This is normal and can be managed with the right balance of insulation, heating and ventilation.”

A healthy home has 3 elements – adequate insulation, sufficient heating when required and good ventilation all year around. The insulation will make the heating process more energy efficient (cheaper). An adequately ventilated house will also be cheaper to heat.

Moisture isn’t always visible

Moisture exists in the air. It is unseen until it becomes steam or condensation. Steam is water in gas form (water above 100 degrees Celsius). Condensation is the conversion of steam back to liquid. Moisture also exists unseen in the air as humidity. The higher the air temperature the more moisture in the air. An example of this can be seen in the sky. The sun warms up water which vaporises and rises into the air. When it reaches a height that sufficiently cools the moisture it condenses into clouds – visible moisture.

The same process occurs inside homes. Moisture is generated from many sources and exists unseen in the rooms until it touches a cool surface such as windows where it condenses into water.  Moist air and weeping windows feed mould and mildew. The warmer the air in your home the more moisture will be held in the air. The highest humidity in the world is around the equator and the lowest is at the poles. Obviously the equatorial areas are warmer than the polar regions. There’s lots of mould at the equator but none at the poles.

Replace stale air with fresh dry air

Using a positive ventilation system such as Unovent pushes stale moist air out of the house by drawing fresh dryer air down from the roof space. The stale moist air is pushed out through gaps under and around doors and windows, up chimneys, through range hood and expel air vents, etc.  The dryer fresher air in the home is warmer and healthier.

Summer air temperatures create more moisture than winter

In winter it is easier and more economical to heat an adequately ventilated home. However, it’s just as important in summer. The summer air temperatures are higher therefore holding more moisture. You are not aware of this moisture because it isn’t condensing on windows or tiled bathroom walls – but it is there and it’s feeding the moulds and mildews. Installing and running a ventilation system is just as important in summer as it is in winter.