Browse Forums General Discussion Re: Are whirlybird extractors worth it? 21Mar 28, 2012 11:23 pm Ian its nice to see you have finally, and hopefully, abandoned your usual drearily-long posts which contained much about nothing, to one unfortunately smeared with sarcasm because someone just does not agree with your blinkered opinion. Arfur Re: Are whirlybird extractors worth it? 22Mar 29, 2012 9:18 am Okay, can we please stop with the thinly veiled insults and barbs? Honestly, I thought this was a forum for adults and I am over the 'conversation' in this thread where some people seem to want to have the last word. Good grief, all I want was some feedback on whirlybirds. Uncle Arfur - point taken, you think they are useless in most cases. Ian, point taken, you think they are useful. If you don't have anything more to contribute constructively to the thread topic, hands off the keyboard and go look elsewhere. 2010, June : Land bought (1700sqm, battleaxe block). That's it so far! We're in the design phase .... Re: Are whirlybird extractors worth it? 24Apr 10, 2012 1:45 pm Our house in Sydney had a tiled roof, ducted air, pool pump, solar power heated water for pool, 2 underground tanks and my last electricty bill for the summer period there was $1,050. OUCH! I wanted this house to be cheaper to run and somebody recommended 4 vents per w/bird so I thought why not give them a try just in case they do work so we had 2 w/birds and eight eave vents installed. Do they work? Don't know and probably wont til next summer but every time I look at them they're spinning so I assume hot air is going out of the roof space. I haven't had a full summer bill yet but it has been cold and wet so you couldn't compare anyhow. I think if you want them give them a go, maybe if you know someone who can do it cheaper than the building company instal them after you move in. Regards, Grumbles Re: Are whirlybird extractors worth it? 25Apr 15, 2012 10:26 pm Whirlybirds do make a difference to the heat in your roof cavity and unless you have whirlymates in the plaster lining of your ceiling the benefit is only in your roof space. Venting your roof space increases the energy efficiency of your ducted a/c because it doesn't work as hard or as long to get cooler air into the home. Eave vents is the 3rd piece of effective ventilation. You need more than 1 whirlybird for larger roof spaces. If you wanted a solar powered ventilator that can be retrofitted, look at the Edmonds Maestro. There is another product by Edmonds called Airomatic and this needs electricity in the roof to power it. It has a low profile and a clear domed top to let light into the roof space which vermin don't like. I'm owner building and am doing everything possible for energy efficiency so have done my research. Re: Are whirlybird extractors worth it? 26Apr 16, 2012 1:39 am As a tradie who gets up in roofs now and then I can safely say the roof vents do lower the temperature in the roof space! (even kicking up two or three tiles takes a roof from unbearable to hot) Inside the roof space it gets very warm even on mild days when the sun is out, the vents don't require wind to turn, especially the non moving type, they use thermal convection, or hot air rises! Even a hot wind on a 40'c day has a good chance of being cooler than inside the roof on a sunny day, the sun is the key, try it out, open your man hole and sick your head in side! Insulation only slows the movement of heat, not stops it, so a cooler roof can make inside cooler, although the difference would be greater on several hot days in a row where the insulation has been 'compromised' by constant heat. They would probably have a greater function at ventilation to remove moisture etc especially if fans in bathrooms etc are not vented outside. 2 Re: Are whirlybird extractors worth it? 27Apr 16, 2012 5:23 pm stormjr, "as a tradie who gets up in rooves now and then", I was wondering if our tiler was correct when he said our choice of the light colour would be noticeably cooler inside than dark tiles. Heat reflection and all that..... Has your experience confirmed this, or is it probably a "feel good" type of thing ! Re: Are whirlybird extractors worth it? 28Apr 16, 2012 10:26 pm Love the old whirlybird argument I don't have access to the research behind this, but I can guarantee there will be some. The BCA 2011 has the following to say about ventilated roof spaces under Table 3.12.1.1 Total R-value for typical roof and ceiling construction: ... (c) Pitched roof with flat ceiling - Tiled roof - ventilated (down 0.74; up 0.23); unventilated (down 0.56; up 0.41) ... (d) Pitched roof with flat ceiling - Metal roof - ventilated (down 0.72; up 0.21); unventilated (down 0.54; up 0.39) A tiled roof need only be unsarked for it to be considered "ventilated" for the purposes of that Table. So this tells us that the Australian Building Codes Board consider that (in the absence of roof insulation) ventilation of the roof space (1) provides around 33% better insulation against summer heat and (2) provides around 45% worse insulation against loss of winter heating energy. This is with the minimal ventilation provided by an un-sarked tiled roof. This implies that a whirlybird (or just a covered hole in the roof even) is likely to assist in controlling temperatures in the roof during summer. My experience working in roofs is that ventilation via whirlybirds or lifting a few tiles makes a big difference to in-roof temperature, but remember that this is still above the insulation. If you have R3.5 batts installed (for example) then the difference in total R-value between ventilated and non-ventilated during summer conditions would be less than 5%, which means minimal effect on internal temperatures. --- With respect to roof colour, the BCA 2011 states "A light coloured roof reduces the flow of heat from solar radiation better than a dark colour roof". It then provides a table of typical absorptance values ranging from slate grey (0.9) through to galvanized steel (0.55) through to light cream (0.30). It has been my experience that the roof spaces of light coloured roofs do tend to be cooler than those of dark coloured roofs, though I haven't had the chance to do a "back to back" comparison of two otherwise identical roofs with different coloured claddings on the same day. Are whirlybird extractors worth it? 29Apr 17, 2012 2:55 am We had 2 of the solar powered whirly birds installed (so they will still turn on them stinking hot/no wind perth summer days) but haven't seemed to have noticed a difference yet. Abit strange considering the cost, but I have heard of them working wonders on others houses. Re: Are whirlybird extractors worth it? 30Apr 17, 2012 7:52 am Thanks Integrity, interesting stuff..some personal research and a gut feel..not much more one can do ! In fairness nobody gave a crap about the ACCC and the gag clauses continued in the pro forma templates of a few other builders after the ACCC took on Wisdom, and more… 19 73284 Hi I am wanting some opinions about the build of a steel shed I am going to get one about 4.5 x 2.5 m steel shed and the height will be about 2.3-2.4m high The one I am… 0 14434 Hi everyone. I am a single mother with little daughter, living in a small tourist town in WA Australia. 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