Reply To: What impact do ventilation systems have on heating performance

[Vicki Cowan]

Nik
I’ll find and attach the presentation Lisa Burrough did on the BRANZ study. As Andrew says (since he did a lot of the work) essentially the air was warmer in the roof space during the day when it was sunny – but it was wetter than inside the house. And at night time the air was much colder inside the roof than in the house. So the forced air systems were pumping damp air into the houses during the day and cold air at night. Not at all an ideal situation, and certainly not one leading to an overall warmer drier home. So not really a positive upside in the day time.
The study recommended that the thermostats be humidistats as well so that the systems only operated when the roof air was warmer AND drier than that in the house. I’m not aware that any manufacturer has actually done that.

Norman, I tried the links you suggested, but they don’t work? I am aware of Robyn’s study and have a copy of her paper, but I didn’t see the presentation at SB10. From what

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