Browse Forums Building A New House 1 Feb 18, 2021 8:42 pm Hi all, Our house plans finally got approved after sitting in the too-hard basket at the council for the last 3 months and we also got advice from the builder today that the energy efficiency came in at only 4.1 which is pretty poor. They advice including cavity insulation to bring it up to 6. The cost of this is just under $3k which I am happy enough with. Are there any other options we should consider that give decent bang for buck? I looked briefly at double glazing etc. but the cost is prohibitive and I am putting external roller shutters on most of the north facing windows anyway. The house is long and skinny on an east-west facing block so we have long walls and a decent number of windows on both the north and south side (only one window each facing east and west). We are also considering roof colours. Most of the house is white but we picked a Colorbond Night Sky roof which I am thinking is maybe a bad idea. I looked at the solar absorbance after we picked the Night Sky and saw that it is 0.96 for Night Sky and only 0.73 for Monument which seems like a pretty decent improvement for a colour which would still give us the look we want as I think it would look a little boring with the walls and roof all white (or close to). The builder says that the colour of the rood actually doesn't make that much difference to the temperature inside the house, especially with decent insulation in the ceiling. I would also be open to getting fans in the roof if it would help. The house is in Perth and less than a 1km to the beach so hopefully we will enjoy a decent sea breeze most afternoons and a good portion of the roof (maybe 30%) will be coated in solar panels anyway. Happy to listen to any advice. Phil Re: Energy Efficiency Advice 2Feb 18, 2021 9:25 pm I increased the energy stars by reducing the size of the windows by raising the sill height; which was a zero cost modification. This can make a big difference if you have windows that start close to the floor. 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: Energy Efficiency Advice 3Feb 20, 2021 11:04 am " The builder says that the colour of the rood actually doesn't make that much difference to the temperature inside the house, especially with decent insulation in the ceiling. " As you have found out by your own research, the difference in the two colours - " I looked at the solar absorbance after we picked the Night Sky and saw that it is 0.96 for Night Sky and only 0.73 for Monument " is quite substantial and would help reduce a lot of the heat buildup in the roof space. By adding the cavity insulation plus the above, a lot of incremental changes can add up to a big difference. What type of cavity insulation were you looking at? Stewie Re: Energy Efficiency Advice 4Feb 20, 2021 11:26 am Stewie D By adding the cavity insulation plus the above, a lot of incremental changes can add up to a big difference. What type of cavity insulation were you looking at? Stewie Thanks Stewie I can tell of course that the solar absorbance can decrease significantly with different roof colours, but don't really know how much difference it actually makes in the real world, especially if there is good quality ceiling insulation and potentially some ventilation in the roof space. I'd consider adding anticon too but all these additional costs for more insulation are starting to add up. I really don't want to spend thousands more on this if the difference it makes is not huge. I know it's not taken into account in the energy assessment, but we are getting a 6 kW solar system and reverse cycle air conditioning. Since you get basically nothing for sending excess solar to the grid these days, I'll probably end up using the AC quite a bit during the hot days anyway since it will effectively cost almost nothing to run while the sun is shining. I'm not sure if the type of cavity insulation yet. When the energy assessment was done they said it came in at 4.1, and the addition of cavity insulation will bring it up to the 6 required. I'd say they will be using whatever minimum type would bring it to over 6. Re: Energy Efficiency Advice 5Feb 21, 2021 4:39 pm Choosing to use AC over insulating correctly is your first mistake. Your AC will ALWAYS cost you to run. Tin roof and no anticon......? Are you mad? Pay for the additional insulation (assuming your talking about external wall insulation), reduce window sizes to a max total glazed area of 20% of total m² of floor area, raise sills, add eaves if you dont have already, add anticon and invest in double glazed, low SHGC windows. The windows only need to go on the elevations that will benefit from having them, not on all windows as most builders will tell you. Its you house and your money but a small investment at the start will save you lots throughout your investments lifecycle. Re: Energy Efficiency Advice 6Feb 21, 2021 5:35 pm A small investment? Thanks for the advice but you've probably added about $30k worth of modifications. The double glazing alone would be tens of thousands. Unfortunately I do not have unlimited money. A decent amount of glazing is necessary at my place since it's a very narrow block (only 8.5m wide) and the place would feel really claustrophobic if it didn't have decent sized windows. I'm putting roller shutters over most of the windows on the north side though so can have them closed during the hot summer days. I'll consider anticon if it's recommended in the efficiency report. Re: Energy Efficiency Advice 7Feb 21, 2021 6:57 pm I have to agree with Bimbob on this one. A metal roof gets really hot and your roof space in summer will be like the surface of the sun if you don't have Anticon at a minimum and preferably a decent foil blanket insulation under the roof sheeting. Stewie Re: Energy Efficiency Advice 9Feb 24, 2021 10:56 am Stewie D I have to agree with Bimbob on this one. A metal roof gets really hot and your roof space in summer will be like the surface of the sun if you don't have Anticon at a minimum and preferably a decent foil blanket insulation under the roof sheeting. Stewie The quote for Antico 50 was only about $2300 so I reckon we will go for it. Thanks for the advice. Re: Energy Efficiency Advice 10Mar 10, 2021 1:12 pm Stewie D I have to agree with Bimbob on this one. A metal roof gets really hot and your roof space in summer will be like the surface of the sun if you don't have Anticon at a minimum and preferably a decent foil blanket insulation under the roof sheeting. Stewie I finally got my energy efficiency report and it came in at 6 stars 38.8 mJ/m². About 30 mJ of that is for HEATING, and only around 9 mJ for cooling. Re: Energy Efficiency Advice 11Mar 10, 2021 7:33 pm Yes, ours was combined heating and cooling at 64.6mJ and rated at 5.1 stars. The thing that perplexes me is that despite all our insulation , orientation etc etc, we only have a rating at 5.1 whereas I've seen a lot of homes built lately with far less of the above that achieve a rating quite above ours. Stewie Re: Energy Efficiency Advice 12Mar 11, 2021 7:00 am Large areas of glazing will reduce your overall rating such as sliding/stacking doors. Windows with low sills, lack of shading, type of opening sash the type of room these windows are in and the direction they face and these factors are just for windows. Then add construction materials, downlights, ceiling fans etc plus all the points you mentioned above and ofcourse location. Its great fun to model homes and see the difference a small change can make. For instance I modeled my house at the concept stage and returned a rating of 7.5 stars. A few changes later and Im at 9.2 which afforded me the opportunity to delete the aircon and save thousands from the build and thousands more on future living expenses. Re: Energy Efficiency Advice 13Mar 11, 2021 7:46 am Philsta Hi all, Our house plans finally got approved after sitting in the too-hard basket at the council for the last 3 months and we also got advice from the builder today that the energy efficiency came in at only 4.1 which is pretty poor. They advice including cavity insulation to bring it up to 6. The cost of this is just under $3k which I am happy enough with. Are there any other options we should consider that give decent bang for buck? I looked briefly at double glazing etc. but the cost is prohibitive and I am putting external roller shutters on most of the north facing windows anyway. The house is long and skinny on an east-west facing block so we have long walls and a decent number of windows on both the north and south side (only one window each facing east and west). We are also considering roof colours. Most of the house is white but we picked a Colorbond Night Sky roof which I am thinking is maybe a bad idea. I looked at the solar absorbance after we picked the Night Sky and saw that it is 0.96 for Night Sky and only 0.73 for Monument which seems like a pretty decent improvement for a colour which would still give us the look we want as I think it would look a little boring with the walls and roof all white (or close to). The builder says that the colour of the rood actually doesn't make that much difference to the temperature inside the house, especially with decent insulation in the ceiling. I would also be open to getting fans in the roof if it would help. The house is in Perth and less than a 1km to the beach so hopefully we will enjoy a decent sea breeze most afternoons and a good portion of the roof (maybe 30%) will be coated in solar panels anyway. Happy to listen to any advice. Phil If you cant afford double glazing then the cheapest options are: 1. Anticon blanket 2. Get your entire house sarked and have them tape every single join in the sarking with insulation tape ( we do this and for a 2 story house it costs less then $2k) 3. Get them to fill every penetration with expandable foam 4. Put acoustic foam under the bottom plates of your external walls 5. Get them to seal the gap between the bottom plate and the slab with acoustic sealant 6. Invest in a decent set of roller blinds This will stop the cold are escaping and hot air coming in. You should be able to all of that for under $12k Cheers Simeon Simeon McGovern Affordable Custom Homes, We design and build to your budget Ashington Homes www.ashingtonhomes.com.au Re: Energy Efficiency Advice 15Mar 11, 2021 8:22 am Bimbob Just a tip: drapes and pelmets work way better than rollers but rollers are good too fair call was just thinking of a more modern look but you are correct Simeon McGovern Affordable Custom Homes, We design and build to your budget Ashington Homes www.ashingtonhomes.com.au Re: Energy Efficiency Advice 17Mar 11, 2021 8:33 am Bimbob I agree with you but strictly performance-wise, uglier is better, sort of like the Queensland state of origin team.... very funny!!! Simeon McGovern Affordable Custom Homes, We design and build to your budget Ashington Homes www.ashingtonhomes.com.au Re: Energy Efficiency Advice 18Mar 11, 2021 8:55 am "For instance I modeled my house at the concept stage and returned a rating of 7.5 stars." What did you model it in ? Or I should ask how did you work out the energy efficiency of your proposed house? Stewie 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 110524 Versaloc is a mortarless besser block system that still needs a properly engineered footing. If you just do a 400x200 footing it will fail in time. At 17m long you need it… 1 15635 Thank you so much for the effort. We will use it to talk with builder. We also had idea of building duplex instead and seeking suggest ions. viewtopic.php?f=31&t=106744 11 13817 |