Browse Forums Heating, Cooling & Insulation 1 Jul 23, 2010 9:23 am I've tried some searching on here, and also on the greater interwebbie, but can't find much specifics. Come May 2011, all new homes built will have to conform to 6 star specifications for energy ratings. However I cannot find anything about this. Attending a ArchiCentre meeting Tuesday night the presenter mentioned 7 star and even said 8 star! (dunno if that was just a brain fart or what, but still). Is there a list of 'prescriptions' to achieve 6? 6.5? 7+? stars for energy rating? I couldn't find anything on any of the state government websites in regards to homes, sustainability, dse, etc. We are close to going to an architect, scrapping the entire drawings and concepts i've done, and let them have free reign on our front-facing-north block and say we must have 1) 3 bedrooms 2) 2 - 2.5 bathrooms 3) be complimentary to the surrounding street (california bungalows for the most part) 4) energy efficient 7stars ideally I guess 5) be as carbon neutral as possible (eg: construction using components should be sourced from as local as possible, components should be created in an energy efficient and preferably renewable way, etc). 6) stick to the budget Then let them have their way with it. But for my own curiousity i'm wondering what actually makes up the energy ratings... Re: 6+ Star Energy Rated Homes 2Jul 23, 2010 9:52 am Not exactly my field of expertice but... The componants are formed around the need to heat & cool, recycling water, energy efficent white goods, lighting. orientation of the build makes a big diff, roof construction has an effect on light entry and will increase or decrease the positive effect the sun will have in winter/summer. The building matrix with embodied energy will effect the carbon foot print. In short that is the point of the rating scheme, that we reduce the input of power to keep the comfort level, Ummm comfortable. Sorry about the technical speak Onc Where you are coming from is where you are going to... Re: 6+ Star Energy Rated Homes 3Jul 23, 2010 10:38 am My understanding is that the star rating is purely based on estimated energy energy use for heating and cooling - at least in terms of AccuRate or NATHERS. It doesn't consider other appliances such as lighting. However, it must be remembered that conditioning contributes to around 50% of total household energy use (more than any other appliance). If the house is intrinsically uncomfortable it is less remediable than changing to CFLS or an efficient fridge. There are other rating system looking at water use of appliances. They do not consider reuse of water. Embodied energy of the construction materials is generally not considered, nor is any independent energy that you generate on site. Of course if you build a McMansion of low-energy materials it might still use more resources than a modest home with conventional masterials. Similarly, you could afford an entire windmill farm for your energy needs but it doesn't show how much wasteful energy you use in your home. All of these are relevant but they aren't measured by assessors. It must be remembered that actual energy use is significantly related to occupancy behaviours e.g. leaving the thermostat on too high, heating the home when you are away, not opening curtains to let the sun in, putting on a jumper instead of turning on the heater It thus can be seen that there are so many factors that indicate a 'green' build of which star ratings comprise but one (though important) factor. The idea of energy star ratings is to just assess how 'efficient' the house in staying within a comfortable temperature range without additional heating or cooling. It is obviously up to the occupant if they still want to condition the house during the extremes. The NATHERS/AccuRate dataset describes 66 climatic locations and tries to predict the energy use for heating/cooling. They attribute a 0-10 star rating based on MJ/m2 of house. You can find the table here: Star bands Finally I am a bit dubious about the methods they used and the accuracy of the day. I posted a discussion here Deriving star ratings What your house actually uses could vary 2 fold depending on your tolerance levels for hot and cold. Re: 6+ Star Energy Rated Homes 4Jul 23, 2010 10:52 am To give a rough idea of what you need to do to reduce your energy use (each half star is a 15% reduction) Existing house 1-3 stars (******* insulation, leaky windows and doors) New house 5 stars (good insulation and sealing) Super-efficient house 7.5 stars (good orientation, sealing, insulation and double glazing) Passivhaus 10 stars (R 12 insulation, triple glazing, heat recovery ventilator) Re: 6+ Star Energy Rated Homes 5Jul 23, 2010 11:13 am Thanks for the great explanation, so it isn't necessarily a checkbox way to select components to build up to an efficient house, but it isn't exactly scientific or holistic either. You are right about dealing with cooling of a property. Being able to keep heat out so you don't have to chill (or reduce the need to chill) the interior would be a great target. Thanks for the links too - some good reading in there too. Re: 6+ Star Energy Rated Homes 6Jul 23, 2010 11:23 am The authorities would like to make it a checklist to make it easier for the industry to follow. Unfortunately, it requires a bit more thought than this. You need to take in consideration the site and the local climate to take best advantage of the situation. Half of energy efficient building is getting orientation right to take advantage of the sun or the wind. If you want to delve into the nuances read this practical guide: Your Home Technical manual It also includes a section of rating systems. Re: 6+ Star Energy Rated Homes 7Jul 25, 2010 2:13 pm I read an article in AFR (23 April 2010) that 9 star rated home has been developed in Perth. Re: 6+ Star Energy Rated Homes 8Jul 25, 2010 2:51 pm more than one Where you are coming from is where you are going to... Re: 6+ Star Energy Rated Homes 9Jul 25, 2010 3:40 pm A 9 star in Perth would use 17MJ/m2/year in heating and cooling So a 200m2 house would use 3400MJ/m2/year (944 Kwh). That would amount less than $188 in electricity per year, $43 of gas or 250kg of wood. Re: 6+ Star Energy Rated Homes 10Jul 25, 2010 4:08 pm add to that: rain water collection, solar grid feed, backyardaquaponics(fish, fruit and veg), recycling water to soil gardens, SHWS, black water treatment onsite, recycled materials during construction(recycled concrete, glass, steel) Seems a bit more sustainable Where you are coming from is where you are going to... Re: 6+ Star Energy Rated Homes 11Aug 18, 2010 5:09 pm I found this blog in the "home building blogs" thread in the "building a new house" forum: http://buildingour9starhome.blogspot.com/ Yes you read that correctly... 9 star ... 9.1 star in fact! I think it will be a VERY interesting blog to follow! Built 3br house in Glenorchy, Tas in 2001 * * * Built 5br courtyard house in Lenah Valley, Tas in 2011 - Homeone thread / Blog Re: 6+ Star Energy Rated Homes 13Aug 20, 2010 9:30 pm My big gripe with the star ratings is that we rely on computer modelling that is not based on hard factual experience. Some things to think about - solar orientation and eaves. Convention says that the living areas should have the best solar access, ie kitchen+family+dining room. Experience says that most homes are dormitories with families out at school or work in the day, home in the kitchen/family for a few hours and then the majority of in-home time is spent in the bedrooms. The coldest rooms in my house are the bedrooms, and that's where most of our heating costs go. Contrarian conclusion is that bedrooms should get most solar access. Insulation - this works, no doubts. Should we also have reflective foil under the roof as well as "pink batts" on top of the ceiling? Dunno - its never been studied in Australia. Look at the online controversy on keeping roofs cool in summer by using whirly birds vs foil. My guess is that you should try for both foil and batts, and that should be one of the smaller costs involved. Roof vents/whirlybirds don't seem to have had any real study in Australia. Cavity wall insulation is also a must for brick veneer, but not such an issue for double brick, unless you're trying for 6+. Roof colour - light is better for keeping cool in summer, and it's cheap to do. Some shires have a stupid attitude that you have to have a dark roof because it looks good. Dark is good for the few parts of OZ that are truly cold in winter, and there aren't too many of those. Windows - double glazed if you can get them at a sensible price. I'm in Perth and the suppliers for the project home market just don't(won't) supply them. Ed from Eco Classic should take note of this - there's a market niche just waiting for a good supplier. DONT INSTALL REVERSE CYCLE AIRCONDITIONING IF YOU WANT TO BE GREEN. You can keep your house cooler in summer by doing easy things such as roof colour, eaves, and insulation. Shut the curtains and windows on hot summer days. Use evap aircon if you must have something. Solar Hot Water works and will pay for itself in a relatively short time and is a genuinely good green choice. That's my distilled knowledge based on a year of research into designing my home. Real improvements beyond this require unconventional wall construction methods that don't have known track-record of durability. Re: 6+ Star Energy Rated Homes 14Aug 20, 2010 10:37 pm By late next year future home buildings will be looking more at regs for 7 star rating as minimum. ... and owners will start to realize the benefit of having eco (real) friendly homes. Wait til you see the next spate of home styles built in 6-8 weeks all up... low maintenance, smaller foot print, lower VOC's and less energy used to keep comfortable. Where you are coming from is where you are going to... Re: 6+ Star Energy Rated Homes 15Aug 20, 2010 11:46 pm SouthFreo DONT INSTALL REVERSE CYCLE AIRCONDITIONING IF YOU WANT TO BE GREEN. What if you live in a state that is 95% powered by hydro and wind? Built 3br house in Glenorchy, Tas in 2001 * * * Built 5br courtyard house in Lenah Valley, Tas in 2011 - Homeone thread / Blog Re: 6+ Star Energy Rated Homes 16Aug 21, 2010 12:31 am SouthFreo, Being in a mixed climate we used both batts and foil. In most parts of Australia south of Brisbane and north of Hobart this would be appropriate. We hardly heat our bedrooms. A short burst just before the kids go to bed and just before rising. They play in the living areas of the house for most of the day. They don't have many toys in their rooms. We never heat or cool our bedrooms overnight. Having north facing living areas makes sense not only from a point of heating but also daylighting - unless you study in your bedroom during the day. If you don't have access to cheap wood or town gas then RCAC is the next best thing. As mentioned if it is running off Green Energy then it is GH neutral (better than the aforementioned). In the future we will run out of gas. That leaves wood, which is impractical in an urban setting. I agree that Solar HWS is very cost-effective. Re: 6+ Star Energy Rated Homes 17Aug 24, 2010 12:07 am My current builder quoted $16000 to whack in reverse cycle aircon, but baulked at the idea of adding reflective foil to the roof as well as batts for a cost of a few grand. Small upfront cost for insulation, big lifetime gain in cost-savings, but he didn't see it that way. The market says a good home should have RC, so that's what the industry caters for. Nice bloke, very capable builder, but the whole industry suffers from lack of hard knowledge about what really works. Too many nice guys with computers and not enough hard-a***es asking difficult questions and expecting real proof. Re Tassie and green energy - yes, heat pumps are probably a good choice for heating, but I can't conceive of the typical Tassie summer day that would require aircon for cooling. Aussies are too in love with black roofs - a great big whack of peak day time electricty load could be trimmed if the roofs were light coloured and properly insulated. Re: 6+ Star Energy Rated Homes 18Aug 24, 2010 7:15 am And keep the walls and windows shaded from summer sun. Re: 6+ Star Energy Rated Homes 19Aug 29, 2010 9:03 am I'm glad i found this forum, In regards to solar panels is a 3kw going to be sufficient for the future? also for those that have solar hot water how well do they heat in winter? (i'm in Melbourne, from what i understand they aren't that efficient in the winter months) we are planning on using evac tubes for the panels. Re: 6+ Star Energy Rated Homes 20Aug 29, 2010 9:37 am A twin flat plate provides about 3000 kwh per year (150 L/day average of hot water ). A 30 tube evacuated plate provides about 3500 kWh per year (185L/day average of hot water). However the outpu range between winter and summer is 3x difference Because ET is more efficient in winter you might get 90L per day instead of 60L. By late spring, the FP catches up considerably and both will be giving you more than 300L/day by summer. Average hot water daily use is 50L/person. 10 years ago was a different software than we use now. it has had a lot of changes over the past years. Improvments to the software and changes to how Nathers models need… 8 1547 go upvc window frames ensure insulation under colorbond. not just sarking, lighter color roof also not sure if you have seen this viewtopic.php?t=5823 last couple of pages… 4 110591 Ask for references and speak to them. If they are defensive or try to avoid the request, walk. 1 74717 |