Energy Smart Solutions
Ventilation and your New Zealand Home

To do this we need to remove all excess moisture as it is being made, stop pollution entering your home, reduce dust levels and give our home a fresh controlled and filtered, dry air supply. This will in-turn, stop our homes from getting damper and damper, reduce mould and allergy problems, and has been shown to reduce asthma symptoms, stop condensation and reduce your energy costs.

In New Zealand we generally live with a damp environment. In Summer most parts of NZ have very high humidity. Spring and Autumn's humidity is not too high, but is often higher than recommended and this does not allow our homes to dry out sufficiently between the damp seasons as happens in some other countries environments. Winter, contrary to some peoples thoughts, can sometimes be drier than the other seasons, but as we tend to keep the windows and doors closed more often, we increase the dampness and humidity in our homes causing condensation, cold beds, illnesses, mould growth and the increasing likelihood of allergy and asthma attacks.

As time has moved on, with both new homes and our Kiwi like of renovations, we are now sealing our homes up with air tight windows (or double glazing) with good insulation and better construction methods, all this is aimed at keeping the 'heat' in our homes, which in turn stops heat loss and air movement, which also keeps the moisture in, and then as we now have a warm, airtight home we get an increase in dampness and mould growth, condensation starts to reappear (yes I have have seen condensation on double glazing in New Zealand) then over time the house becomes less efficient, harder to heat and harder to look after, and you are back to where you started, with a cold, hard to heat damp and mouldy home that is not very old or has been recently renovated.

The more we seal and insulate our homes the more we need to Ventilate our homes to make them healthy, condensation, mould and allergy free.

Positive Pressure Ventilation

Positive Pressure Ventilation systems are the most used ventilation systems in New Zealand, they do suit the NZ climate and house design. This is where a fan unit (or 2 or 3) is placed in your roof cavity and collects the drier and often warmer air from that cavity bringing the air through ducting and diffusers into appropriate rooms. The important parts are 1) the filter - the higher the grade the better, 2) the fan/motor - Long life and well made, 3) The controller - how well it controls the air flow into your home.

When Positive Pressure Ventilation systems were first introduced into NZ they only had 1 diffuser and a single speed motor, this gave air flow but it was either too much or too little and often too cold. With experience and knowledge, the change of motor, controller and diffusers (both the number and the design) has resulted in ventilation systems that are far better at keeping homes in New Zealand drier, warmer and far healthier than they have been.

New Zealand's climate suits the use of a Positive Pressure Ventilation System as our roofs collect large quantities of solar energy, even in the middle of winter. By using mother nature to heat our roof cavity we are also using this free energy to dry and pre heat the air that is entering your home, this is why a modern ventilation system with a well thought out and designed controller is very important.

Heat Recovery Ventilation (HRV)

Heat Recovery Ventilation systems use the 'warm but stale' house air to preheat the incoming fresh air from outside. This is done through a heat exchanger mounted in your roof cavity, these were originally designed for countries that have long winters often with snow outside and heating (radiators or central heating) 24/7. When you live in countries with these conditions opening windows is not an option, and as these houses are very air tight they have a build up of dampness, mould etc, which makes the house and the occupants unhealthy.

As using roof cavity air is not feasible in these cases, engineers had to find a better way, they did this by using a heat exchanger which basically transmitted the warm energy from outgoing air to the cold incoming air and still giving the required fresh and drier air to house.

These, true HRV type systems are best suited to houses that get no sun on the roof - for whatever reason - whether the house and roof is constantly shaded because of trees, being in a valley, or because of the winter weather conditions.