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Ventilation is the most important element in your "healthy home, healthy living strategy. If you are experiencing condensation or mold growth anywhere in your home it is directly related to your environment being stale and polluted with bad air.  If your home was full of clean air then these problems would not exist and you would not be reading this. Because you are considering a ventilation system then think about it carefully and make sure it complies with fresh air standards and heat recovery otherwise you will be wasting heat, energy and your money.

Don't be fooled, don't let anyone tell you that dry air is healthy air.

Only clean air is healthy air, and can only come directly from outside as required  under NZ Standard 4303 "Ventilation for Acceptable Indoor Air Quality" it is not recommended to be sourced from your roof space.

A recent Consumer Institute panel heating test suggested that a dehumidifier and a heater was the best combination to create a faster and more efficient heating time. This is evidence that internal air that has relatively low moisture levels uses less energy to heat. Air that contains high levels of moisture requires more energy to heat and takes longer to raise the temperature. Of coarse we don’t suggest that a dehumidifier/heater solution would be practical because the capital and energy cost would be very high. So the more effective solution is to dehumidify the whole house with a single system using a heat recovery unit using fresh outside air.

Ventilation of homes is of coarse essential for the replacement of stale, polluted indoor air with fresh outside air and for the removal of moisture generated in the home. Combining a heat recovery ventilation system with high levels of insulation and heating completely changes the indoor environment to an extremely healthy environment. Traditionally New Zealand homes were ventilated by natural ventilation, i.e. infiltration through open doors and windows, which can be characterized as ventilation by coincidence but often does not provide adequate air change to provide a healthy indoor environment.

Straight to Genuine Heat Recovery Ventilation

Understanding more about moisture and mold growth

Household Moulds Linked to Childhood Asthma

Latest research regarding positive pressure (forced air) ventilation systems released by the New Zealand Government Department EECA May 13 2011. "The report recommends that this type of ventilation system - known as a "positive pressure" or "roof cavity" system - is not promoted or installed based on potential heating or cooling benefits." 
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