Browse Forums Heating, Cooling & Insulation 1 May 30, 2012 4:00 pm It seems the home-builder we're most-likely going with puts R3.5 batts in the ceiling & R2.0 batts in the walls, by default. We intend on getting double-glazed windows where appropriate, and probably putting at least some insulation in garage walls & ceiling as well. However - does anyone have a handle on how much difference an R-rating increase would make to liveability & comfort ... and I guess heating/cooling cost? eg. going from R2.0 --> R3.0 in the walls, or R3.5 --> R4.0 in the ceiling? Or more increase than that? And while I'm here ... what sort of cost's usually involved? [I know I can probably search for that ... but I couldn't see any answers to the "main" question] Re: Anyone have a "feel" for improvement by R-rating increas 2May 30, 2012 4:50 pm Hi Forg, You could look at this engineer's webpage: http://fricker.net.au/ At the bottom he has a PDF technical paper entitled: The diminishing benefit of extra home insulation. It is from 2002 so the costs might be a little out but it gives you an idea of how much insulation is optimal without too many added costs. Hope this helps. Re: Anyone have a "feel" for improvement by R-rating increas 3May 30, 2012 5:09 pm Basically extra insulation saves you heating and cooling costs. As long as your heater, and cooling system are powerful enough it won't make much difference to the comfort. Going up from R2.0 to R3.0 will save you .17 watt/degree c/m2 So say you have 100m2 of outside wall and its 12 degrees outside and you want it to be 22degree inside. The extra insulation will save you 0.17 watt x 100 x 10 degree = 0.17 kilowatts every hour. For the roof the change will save you around 0.04watts/degree c/m2 So say you have a 200m2 roof the saving would be 0.04 x 200 x 17 = 0.134kw/hour Doesn't sound a lot but there are a lot of hours in a heating or cooling season and the difference in temperature can be a lot more than 10 degrees There is some more info on my blog here: http://www.anewhouse.com.au/?p=63 For the roof it would be 1/2 watt for your suggested increase The Harder You Try - the Luckier You Get ! Web site http://www.anewhouse.com.au Informative, Amusing, and Opinionated Blog - Over 600 posts on all aspects of building a new house. Re: Anyone have a "feel" for improvement by R-rating increas 4May 31, 2012 7:52 am Interesting links ... thanks folks! The summary of what I've found makes me thing maybe it's not worth upgrading from what's standard; diminishing-returns makes me [nearly] believe what Choice says about the recommended R-value for Sydney (R3.0 for roof and 1.5 for walls), and the builders already exceed that. Plus there's the wall-thickness issue, it looks like there aren't many products that're going to allow the wall to remain the same thickness yet allow better insulation to fit; there do look like there're two fairly commonly used products that'll fit in what looks like a standard wall, one is R2.0 the other R2.5 so I might ask whether it's possible to go to R2.5 for the walls. Looks to me, though, as if the money might be better spent with sun shades &/or paying the drafties to get the cornice & awning sizes right according to sun-angles etc, applying film to the very few west-facing windows, etc. And making sure they seal doors & windows properly. Really tight at the top of the stairs- how to get furniture into those rooms? Study books - does anyone really use them these days? Large storage closet would be more functional. 2 6894 Hi, Looking to add an ensuite to one of the bedrooms and make it a Master BR. Please see the attached current floorplan. Need suggestions on what's the best way to do… 0 7341 In my opinion just a few more indoor plants and you're done. It's already a lovely space, you've managed a classic style without being too cluttered and that creates a… 1 19557 |