Browse Forums Heating, Cooling & Insulation 1 Jan 19, 2009 8:24 am Hi guys,
We are close to signing with a builder and thanks to this forum and the internet have been researching energy efficiency for a long time however I am keen to find out from those that have a full double glazed house how often (or at what outside temperatures) do you actually switch on your heating and cooling. All our living areas will be north facing, bedrooms at the south, light coloured colorbond roof, brick veneer, our builder includes a Brivas gas ducted heating system however we were thinking of getting a credit for this and was looking into the HRV Ventilation Systems and getting thermostat controlled roof ventilators, then see how we go and maybe get a small split system installed if we only ever required it on a ridiculously hot/cold day. Cheers Bailey. Energy efficient custom built house - Moving In 3 Weeks Re: Type of heating/cooling required for a double glazed hou 2Jan 19, 2009 9:38 am Bailey Hi guys, full double glazed house living areas will be north facing bedrooms at the south light coloured colorbond roof, brick veneer HRV Ventilation Systems thermostat controlled roof ventilators maybe get a small split system installed if we only ever required it on a ridiculously hot/cold day. Dear Bailey, Good on you for going for an energy efficient design. Most things you are doing will work well. Your question is how much supplementary and cooling and heating will be required for your house. The answer is a bit complex as it depends on how you 'operate' the building e.g. open windows, pull curtains during the day and what you will tolerate. However, you should be able to use half to 2/3 rds the energy of a average dwelling. That could be as low as 10Wh/day. This assumes you are doing everything else well - insulating the walls and ceiling with batts and foil, weatherproofing, insulating window coverings and correct shading. Why don't you get a house energy rating from a reputable and experienced assessor to calculate the predicted energy cost of heating and cooling. But you probably couldn't achieve zero requirements (this is quite difficult). I woudn't ditch an additional heating system but good design could mean eliminating the need for air con most or all days. I would also add ceiling fans to help cool people. Also make sure the windows are well positioned to catch cooling breezes in summer and that they open in the correct direction. Windows need to be both upwind and downwind to funnel the air through the house. Check with the Bureau of Meteorology to get a windrose for your area. Forget about roof ventilators unless you are ventilating directly from your living area to the outside. http://forums.envirotalk.com.au/Whirlyb ... t8445.html I am doubtful that an HRV could substitute for a gas heater. It has been suggested that HRV only become economical in extreme weather eg. Northern Europe, Canada. Passivhaus systems in Europe complement the HRV with insulation levels 3-4x the Australian minimum standard. The systems are seen more in commercial applications locally. It is quite difficult to find a domestic one in Australia. Venmar is the only brand I have found. Here are some good factsheets on heating and cooling systems. It gives pros and cons, efficiencies and running costs: http://www.sustainability.vic.gov.au/ww ... sheets.asp Re: Type of heating/cooling required for a double glazed hou 3Jan 19, 2009 1:34 pm Bailey Hi guys, We are close to signing with a builder and thanks to this forum and the internet have been researching energy efficiency for a long time however I am keen to find out from those that have a full double glazed house how often (or at what outside temperatures) do you actually switch on your heating and cooling. All our living areas will be north facing, bedrooms at the south, light coloured colorbond roof, brick veneer, our builder includes a Brivas gas ducted heating system however we were thinking of getting a credit for this and was looking into the HRV Ventilation Systems and getting thermostat controlled roof ventilators, then see how we go and maybe get a small split system installed if we only ever required it on a ridiculously hot/cold day. Cheers Bailey. Hi Bailey, Your biggest issue is radiant heat through your North facing windows which double glazing alone cannot affect. Great in winter - but terrible in summer, but note that nothing beats double glazing so this must come first. I suggest you have Low-E glass installed at the same time within the double glazing - this will shield you from most of the infra red and will make a huge difference (do not listen to anyone who says it is a replacement for double glazing - it can only supplement it). On the North face, you need Low-E installed to keep the heat OUT. Ask you builder to have this installed on surface 2 on North facing windows. If you want to keep the South facing bedrooms warm, have Low-E installed on surface 3, this will keep the radiant heat IN. Low-E is a virtually invisible layer of metal which coats one side of the glass and in double glazing is in between the 2 pieces of glass. On the practical side, I have said before that I would NEVER buy ducted heating EVER again - it is just too dusty (and we live in the country on 25 acres!!!). PM me if you need more detailed info... Ed Re: Type of heating/cooling required for a double glazed hou 4Jan 19, 2009 1:51 pm Hi EcoClassic,
Your mention of Low-E caught my attention. I too have a large north facing (probably more NNW) living room window. I am concerned about the heat coming thru during summer. I don't want to put a pergola outside because I want to keep the light coming in. Is Low-E some kind of coating that I can apply to standard window glass? Thanks. Building Clarendon Brighton - Done and moved in Sept 2009 Re: Type of heating/cooling required for a double glazed hou 5Jan 19, 2009 1:56 pm eho Hi EcoClassic, Your mention of Low-E caught my attention. I too have a large north facing (probably more NNW) living room window. I am concerned about the heat coming thru during summer. I don't want to put a pergola outside because I want to keep the light coming in. Is Low-E some kind of coating that I can apply to standard window glass? Thanks. No, Low-E glass is manufcatured but you could reglaze in Low-E... although in a single glazed situation it is not so effective, I have no doubt you will feel a substantial difference. 3M do solar control films which can be applied to your existing window, I have no experience of them but they rate in WERS and 3M is a very good company. Ed Re: Type of heating/cooling required for a double glazed hou 6Jan 19, 2009 2:05 pm eho Your mention of Low-E caught my attention. I too have a large north facing (probably more NNW) living room window. I am concerned about the heat coming thru during summer. North-facing windows are the best aspect for a passive solar design. If you have a correctly sized eaves, you can exclude the high summer sun yet allow the low winter sun to let light in. There are lots of solutions for this: a) Fixed length conventional eaves b) Uptilt eaves which get better winter exposure c) Louvred pergola c) Adjustable awnings or adjustable pergola e.g. Vergola Here are some ideas from the Your Home technical manual: http://www.yourhome.gov.au/technical/pubs/fs44.pdf I would say that reflective or heat-selective windows have a greater role on aspects which cannot be shaded adequately wihtout extremely long eaves or overhangs e.g. west or east aspects Re: Type of heating/cooling required for a double glazed house 7Jan 19, 2009 7:03 pm How about low-e on surface 2 and surface 3. Would this not give a really nifty solution. Demolition August 2009, Construction Started September 2009, Completed December 2010 Re: Type of heating/cooling required for a double glazed house 9Jan 19, 2009 7:32 pm EcoClassic Casa2 How about low-e on surface 2 and surface 3. Would this not give a really nifty solution. Yes, I believe so... Ed So, is it ever done? Demolition August 2009, Construction Started September 2009, Completed December 2010 Re: Type of heating/cooling required for a double glazed house 10Jan 19, 2009 7:47 pm I have never heard of it. Maybe because it would be a higher cost.
I think homes are predominantly heating or cooling and people configure Low-E to suit. I will see if I can ask WERS... Ed Re: Type of heating/cooling required for a double glazed hou 11Jan 19, 2009 7:56 pm dymonite69 North-facing windows are the best aspect for a passive solar design. If you have a correctly sized eaves, you can exclude the high summer sun yet allow the low winter sun to let light in. There are lots of solutions for this: a) Fixed length conventional eaves b) Uptilt eaves which get better winter exposure c) Louvred pergola c) Adjustable awnings or adjustable pergola e.g. Vergola Here are some ideas from the Your Home technical manual: http://www.yourhome.gov.au/technical/pubs/fs44.pdf I would say that reflective or heat-selective windows have a greater role on aspects which cannot be shaded adequately wihtout extremely long eaves or overhangs e.g. west or east aspects Dymonite69, that's excellent article and great advice! EcoClassic, thanks for the info on the solar film, I will definitely check them out. If not too expensive, sounds like a good additional measure to pergola. I have attached my plan to show where my family room I mentioned about. Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Above the family room at the back are the bedrooms upstairs, though I have eaves, they are for the bedrooms instead. I think lourves pergola outside the family room window will be the way to go. What do you think how far out the pergola should go? The family room window is about 2m high from the floor level. Building Clarendon Brighton - Done and moved in Sept 2009 Re: Type of heating/cooling required for a double glazed house 12Jan 19, 2009 8:08 pm I think your louvre would need to be a length equal to half (the height of the window + the distance to the louvre). But I am sure dynomite69 will give you the trigonometry... Re: Type of heating/cooling required for a double glazed hou 13Jan 19, 2009 10:03 pm eho Above the family room at the back are the bedrooms upstairs, though I have eaves, they are for the bedrooms instead. I think lourves pergola outside the family room window will be the way to go. What do you think how far out the pergola should go? The family room window is about 2m high from the floor level. This is a common problem in two storey houses. Builders will shade the top storey but forget to use something for the bottom one. The minimal distance for the pergola is given by the formula for fixed eaves. You can extend your louvred pergola any distance after that. Because of the design it will still let in the winter sun. Another construction involves a very open pergola with decidous vines planted over the top. These will be bare during in winter but provide a green cover in the warmer months. Re: Type of heating/cooling required for a double glazed house 15Jan 20, 2009 9:14 pm Non conditioned can be done and typically a welldesigned hosue will see 2 weks mid summer and winter that people wished they had heating. Otherwise they get by. But it;s allabout what temp you desire.
Bailiey - thats a lot og paving around the house that is going to heat up a lot in summer - just be carefull - and the back turf seperating fence might affect you airflow throihg the house on you - ie making it hotter as well. Good luck with it all and great for you to be thinking in the right direction. Steve Re: Type of heating/cooling required for a double glazed hou 16Jan 21, 2009 9:59 pm On the practical side, I have said before that I would NEVER buy ducted heating EVER again - it is just too dusty (and we live in the country on 25 acres!!!).
Ed you sound like you know what you're talking about so I'm also interested to know that if you would never go ducted heating again what type of heating would you go with? Re: Type of heating/cooling required for a double glazed house 17Jan 22, 2009 8:16 am Bailey, sorry for hijacking your thread and I guess people got confused with my plan as yours
Yak_Chat thats a lot og paving around the house that is going to heat up a lot in summer - just be carefull - and the back turf seperating fence might affect you airflow throihg the house on you - ie making it hotter as well. Thank you for the idea about paving and heating up around the house. I have never thought of that. I wanted paving on the right side because that would be my main access path from front to back, like pushing garbage bins, etc. My little 2yo may also ride his tricycle along there too Since I won't use the left hand side much, I made it stepping stones on gravels. I probably could put more plants along that side to make it like a tropical jungle (if you know what I mean). But the need of maintenance took this idea out. The separating boundary between the backyard turf and the paving is a retaining wall. There is about 0.5m drop from the house level to the backyard level. I didn't want my backyard to slop down so I created a retaining wall there to make it two levels. Any ideas how I may be able to improve the airflow about the house? Thanks. Building Clarendon Brighton - Done and moved in Sept 2009 Re: Type of heating/cooling required for a double glazed hou 18Jan 22, 2009 10:15 am kristee On the practical side, I have said before that I would NEVER buy ducted heating EVER again - it is just too dusty (and we live in the country on 25 acres!!!). Ed you sound like you know what you're talking about so I'm also interested to know that if you would never go ducted heating again what type of heating would you go with? Hydronic (which I have used before) or reverse cycle a/c... Ed Re: Type of heating/cooling required for a double glazed house 19Jan 22, 2009 2:08 pm Hmmm...thanks for the tip Ed. I have done some googling and made some inquiries with local suppliers, sounds like a really good option. Not on the cheap side to install, but worth it for it's cost effectiveness to run.
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