Browse Forums Eco Living Re: Roof space heat - eave vents and whirlybirds ... 18Oct 26, 2009 10:10 pm We have chosen an Ironstone roof (dark grey) and while it looks terrific it will obviously get hot, we have opted for a couple of whirly birds and the whole house is insulated but we now wish we spent the extra (about $3500) and got the sarking, I was up in the roof last week with our Air Con friend and it was only mid 20's and it was VERY hot up there, admittedly the Whirly Birds are in yet but a high 30's + it will be an oven up there! We might go through a season and after that see if it's worth getting sarking, does anyone know if it's MORE expensive getting it done post building ? Re: Roof space heat - eave vents and whirlybirds ... 19Oct 27, 2009 8:09 am From The Your Home Technical Manual - Common Myths (click on link) "Myth: Roof ventilators will keep your house significantly cooler. Fact: Roof ventilators do not make an appreciable difference to house temperatures if the roof is insulated, particularly if reflective insulation is installed. If your ceiling is uninsulated a ventilator might make a small difference, but insulation is a better investment. There may, however, be other valid reasons for installing roof ventilators such as moisture removal." Re: Roof space heat - eave vents and whirlybirds ... 20Oct 28, 2009 7:24 pm dymonite69 In the absence of a radiant barrier, ventilating a roof space with a whirly is insignificant. - Natural convection in the roof space results in a much cool boundary layer at the top surface of the ceiling (lower than the mean air temperature) And guess what will happen to that boundary layer if you introduce enough ventilation to stir up the air space without actually allowing enough air out to take much heat away! I believe an experiment could well find that only having a couple of eave vents or a single small whirlybird could be worse than having none at all. "Now, supposing a house to have a southern aspect, sunshine during winter will steal in under the verandah, but in summer, when the sun traverses a path right over our heads, the roof will afford an agreeable shade, will it not?" -- Socrates, ca. 400 BC Shade the brick with large eves. Since going to minimum of 600mm eaves on my build, I've noticed much improved cooling off the house after hot summer days. Can see the… 1 3930 Old Home Restoration / Renovation Cheers mate! This is exactly what I was thinking but wasn't sure if it was something I'd find on the shelf. I agree with you, fixing the brackets to the board will look… 2 4060 retail its around double the price of a similar sized actron/dakin system from memory, They are excellent systems though. But with how builder gouge on AC/heating, you… 4 16528 |