joker97: 1) are there any other alternative ventilation systems that is cheaper than DVS?
2) ... in Dunedin?
3) any ventilation systems that recycles and reconditions rather than PPV? (would it be better?)
The university of Otago tested a couple of houses in Dunedin with respect to roof cavity heat recovery with DVS and "HRV" systems. They found that there were virtually no days in the year when running such a system would provide heat to the house.