Browse Forums Heating, Cooling & Insulation 1 Oct 24, 2009 9:26 pm Guys, I heard higher the R value , better protection u get from heat ?? is it true ?? do we know whats required R value as per Building codes\standards ?? I have R 2.5 in my roof , was wondering if upgrading it to 4 will help me or not ? Any advices.. cheers!! Re: How much R Value is good for roof insulation ? 2Oct 24, 2009 11:29 pm We have R4.1, they are good enough. I wouldn't think 2.5 would be enough! Building Thread viewtopic.php?f=31&t=13002 Site start: 8th July 2009 Handover: 11/12/2009! 5 months total build time. 40 sqs of luxuary...Bliss! Re: How much R Value is good for roof insulation ? 3Oct 25, 2009 8:55 am pinkfairymagic We have R4.1, they are good enough. I wouldn't think 2.5 would be enough! The difference between R2.5 & R4.1 is 156 Watts/hour for a 10 degree temperature difference between outside and inside, for 100 sq.m. of ceiling. That is the same as running 2 incandescent light globes. Or roughly 3 cents per hour while you're heating or cooling. If you heat/cool 50 hours/week, it's $1.50/week, or $75/year. So if it costs more than say $400 (5 yrs pay back) to pay the difference between R2.5 & R 4.1, you need to think about it. Ed "ECOECO" At 'EcoEco', we design windows, we design the best windows, we do it for you, so that when you’re happy we are happy. Tel. 1800 326 326 Re: How much R Value is good for roof insulation ? 4Oct 25, 2009 9:44 am It all depends on your climate: The most cost-effective R value recommendations can be found here: INSULATION LEVELS FOR YOUR CLIMATE Read this (based on a Melbourne climate): The Diminishing Benefit Of Extra Home Insulation Re: How much R Value is good for roof insulation ? 5Oct 25, 2009 9:49 am ed @ EcoClassic pinkfairymagic We have R4.1, they are good enough. I wouldn't think 2.5 would be enough! The difference between R2.5 & R4.1 is 156 Watts/hour for a 10 degree temperature difference between outside and inside, for 100 sq.m. of ceiling. That is the same as running 2 incandescent light globes. Or roughly 3 cents per hour while you're heating or cooling. If you heat/cool 50 hours/week, it's $1.50/week, or $75/year. So if it costs more than say $400 (5 yrs pay back) to pay the difference between R2.5 & R 4.1, you need to think about it. Ed so whats the moral of story ? whats better and whats expensive in long run? Re: How much R Value is good for roof insulation ? 6Oct 25, 2009 10:45 am namz ed @ EcoClassic pinkfairymagic We have R4.1, they are good enough. I wouldn't think 2.5 would be enough! The difference between R2.5 & R4.1 is 156 Watts/hour for a 10 degree temperature difference between outside and inside, for 100 sq.m. of ceiling. That is the same as running 2 incandescent light globes. Or roughly 3 cents per hour while you're heating or cooling. If you heat/cool 50 hours/week, it's $1.50/week, or $75/year. So if it costs more than say $400 (5 yrs pay back) to pay the difference between R2.5 & R 4.1, you need to think about it. Ed so whats the moral of story ? whats better and whats expensive in long run? It's not a critical decision... maybe $75/yr saving if you improve insulation, versus maybe $400 cost... not a big difference whether you do or whether you don't. The first R2.5 is important though. "ECOECO" At 'EcoEco', we design windows, we design the best windows, we do it for you, so that when you’re happy we are happy. Tel. 1800 326 326 Re: How much R Value is good for roof insulation ? 7Oct 25, 2009 9:08 pm ^^^ Ed, Even IF this is all you are saving (which I highly doubt) your $400 upgraded batts have paid themselves off in 5 months, big gain if you intend on staying in said house for decades to come. Building Thread viewtopic.php?f=31&t=13002 Site start: 8th July 2009 Handover: 11/12/2009! 5 months total build time. 40 sqs of luxuary...Bliss! Re: How much R Value is good for roof insulation ? 8Oct 26, 2009 5:09 am pinkfairymagic ^^^ Ed, Even IF this is all you are saving (which I highly doubt) your $400 upgraded batts have paid themselves off in 5 months, big gain if you intend on staying in said house for decades to come. Your maths is wrong... unless you pay $30 total extra for the upgraded batts. In my example I gave $75/yr saving, so it would take just over 5 yrs to get back $400 ($400 ÷ $75). Yes, the R values look like big numbers but heat flow is 1 ÷ R = Watts/m²/ºC. So the performance differences between R values are tiny. R 2.5 = 1÷ 2.5 = 0.4 Watts/m²/ºC and R4.1 1 ÷ 4.1 = 0.244 Watts/m²/ºC so you save 0.156 Watts/m²/ºC (so 100m² @ 10ºC = 156 Watts/hr). I put forward the ingoing economic argument, not the whole argument and energy prices will increase disproportionately in future, so you should take that into account. But ceiling insulation can be easily increased later so also take that into account. At the start, it's better to put money into extra wall insulation and energy efficient windows which are difficult to improve IMO. Just make sure you don't pay too much for the upgrades, or they won't make sense economically. That said, I would upgrade insulation before I bought a Caesarstone benchtop... Ed "ECOECO" At 'EcoEco', we design windows, we design the best windows, we do it for you, so that when you’re happy we are happy. Tel. 1800 326 326 Re: How much R Value is good for roof insulation ? 9Oct 26, 2009 7:51 am Namz, As Ed points out, you can lose heat via a number of locations. For instance it would not be advantageous to insulate the ceiling to R12 if your walls remained uninsulated. Due consideration should also be made regarding weathersealing and appropriate window coverings. If funds allow then double glazing should be considered. This is not even addressing areas of heat gain. Radiant barriers such as foil to roof and walls are very effective at blocking direct solar radiation. At the design stage, good orientation allows you heat the house for free with direct sunlight yet block it out during the hotter months and reduce your artificial heating and cooling requirements. Re: How much R Value is good for roof insulation ? 12Oct 26, 2009 10:30 am Namz where are you? This is the most important. The cost of insulation is normally about half in the actual install, I would always go for the 4 over the 2.5. Relative to what else you could spend money on (eg double glazing, sorry Ed!) you will get good bang for your buck. Alternatively, you could put concertina foil batts on top of the 2.5s giving about r4, but including a reflective foil barrier (ie preventing heat ingress). Re: How much R Value is good for roof insulation ? 13Oct 26, 2009 10:43 am lambchoppa Namz where are you? This is the most important. The cost of insulation is normally about half in the actual install, I would always go for the 4 over the 2.5. Relative to what else you could spend money on (eg double glazing, sorry Ed!) you will get good bang for your buck. Alternatively, you could put concertina foil batts on top of the 2.5s giving about r4, but including a reflective foil barrier (ie preventing heat ingress). I am in Point Cook , VIC , any idea how much would concertina foil batts cost ?? Re: How much R Value is good for roof insulation ? 14Oct 26, 2009 6:26 pm Namz, if you'r getting heat build up and you already have r2.5 then putting in more is most likely not going to fix the issue. It is more likely that you have a heat entry via another part of the house, windows, non insulated walls or similar nad IMO your be best off determining where this is entering the house, and either trying to stop it getting in via this area - perhaps external shading on the troublesome window etc. Or if that cannot be done for whatever reasons, then installing this type of device is the enxt best where the hot air inside the hoseu is drawn up and out of the room. http://www.edmonds.com.au/html/products/vent_a_room_system_250mm.htm The vents are closable so heat lose in winter is reduced. Cheers Re: How much R Value is good for roof insulation ? 15Oct 28, 2009 4:31 pm There are handy calculators to help you work out what you need - under "resources" on the Bradford Insulation website at www.bradfordinsulation.com.au Re: How much R Value is good for roof insulation ? 16Oct 28, 2009 6:15 pm Namz Try and look at it in multiple perspectives. Insulating a great big wall is one thing to protect from summer heat but not the only thing. Can you use small trees or grape vines? Would adding some kind of timber panel as a decoration help? Can you extend your roof into a gable or veranda that covers summer sunlight? Is radiant heat being reflected from other surrounding structures or surfaces? If so can you reduce it - remove it - shield it? Do you have concrete paving surrounding the house or parts of it - radiating heat. If the garage or other structures nearby acting like giant heat banks again radiating heat. Can you remove or shield that heat source? Would a combination of all of these help? The house I am in currently has a Cement render wall - 2 inches of concrete strung up to timber. I intend to replace it with an insulation system that will actually cool it on hot days passively. Until then I am using grape vines to cover the walls on the East, West and North sides. It actually works reducing the walls surface temperatures to less than surrounding air. Last summer I could bake an egg on it. That heat then went into the ceiling mostly but the North West room was toxic to be in. It won't be this year. I have strung a grape to the West wall corner. It grows about 3^3 meters a month once its roots get down. After 6 months it will easily cover 10 meters^2. In the next year and then on it will cover 30 or 40 meters square. No need to water, just a couple of rail spikes in the ground, food scraps and some compost. And I get 6 weeks of table grapes to browse and suck up to neighbors with. Ed, You are correct but only on linear terms. If someone spent $4000 insulating their home with a total envelope of 3.5 to 6.0 then that is going to make a difference but as you stated it may not pay off. The trick from that point is managing air flow through the roof cavity on hot days and eliminating air leaks through doors and windows etc. Assuming you did that and the house was air tight you could heat your entire house using 10 -100 watt light globes or 1kw p/h. If you took advantage of passive design principals or solar hot water and used that to heat the house your investment would save you nearly 100% of your heating costs by making passive and solar energy highly effective. No point investing in solar electricity if you have 400 watts of downlights in your lounge alone.. Re: How much R Value is good for roof insulation ? 17Oct 29, 2009 6:56 am Redman Ed, You are correct but only on linear terms. If someone spent $4000 insulating their home with a total envelope of 3.5 to 6.0 then that is going to make a difference but as you stated it may not pay off. The trick from that point is managing air flow through the roof cavity on hot days and eliminating air leaks through doors and windows etc. Hi Red, The other influences you mention actually dilute the economic argument to marginally improve insulation... the more the other issues affect your home, the less the improvement from increased insulation. Redman Assuming you did that and the house was air tight you could heat your entire house using 10 -100 watt light globes or 1kw p/h. If you took advantage of passive design principals or solar hot water and used that to heat the house your investment would save you nearly 100% of your heating costs by making passive and solar energy highly effective. This would only be the case where inside and outside temperatures were so close as to be irrelevant. And since you have minimum 10% of floor area as windows, and the U value of a single glazed window is say 6, then the windows alone in a 20 square home would lose 111 Watts/ºC. A 10ºC differential is 1.1kW. Added to that you conduction through walls and ceilings, which even insulated would add about double the window figure. And then there's air leakage... Ed "ECOECO" At 'EcoEco', we design windows, we design the best windows, we do it for you, so that when you’re happy we are happy. Tel. 1800 326 326 Re: How much R Value is good for roof insulation ? 18Oct 29, 2009 11:33 am yeah i do have concrete around my house..specially next to windows in west side.. Redman Namz Try and look at it in multiple perspectives. Insulating a great big wall is one thing to protect from summer heat but not the only thing. Can you use small trees or grape vines? Would adding some kind of timber panel as a decoration help? Can you extend your roof into a gable or veranda that covers summer sunlight? Is radiant heat being reflected from other surrounding structures or surfaces? If so can you reduce it - remove it - shield it? Do you have concrete paving surrounding the house or parts of it - radiating heat. If the garage or other structures nearby acting like giant heat banks again radiating heat. Can you remove or shield that heat source? Would a combination of all of these help? The house I am in currently has a Cement render wall - 2 inches of concrete strung up to timber. I intend to replace it with an insulation system that will actually cool it on hot days passively. Until then I am using grape vines to cover the walls on the East, West and North sides. It actually works reducing the walls surface temperatures to less than surrounding air. Last summer I could bake an egg on it. That heat then went into the ceiling mostly but the North West room was toxic to be in. It won't be this year. I have strung a grape to the West wall corner. It grows about 3^3 meters a month once its roots get down. After 6 months it will easily cover 10 meters^2. In the next year and then on it will cover 30 or 40 meters square. No need to water, just a couple of rail spikes in the ground, food scraps and some compost. And I get 6 weeks of table grapes to browse and suck up to neighbors with. Ed, You are correct but only on linear terms. If someone spent $4000 insulating their home with a total envelope of 3.5 to 6.0 then that is going to make a difference but as you stated it may not pay off. The trick from that point is managing air flow through the roof cavity on hot days and eliminating air leaks through doors and windows etc. Assuming you did that and the house was air tight you could heat your entire house using 10 -100 watt light globes or 1kw p/h. If you took advantage of passive design principals or solar hot water and used that to heat the house your investment would save you nearly 100% of your heating costs by making passive and solar energy highly effective. No point investing in solar electricity if you have 400 watts of downlights in your lounge alone.. Re: How much R Value is good for roof insulation ? 19Oct 29, 2009 11:45 pm ed @ EcoClassic This would only be the case where inside and outside temperatures were so close as to be irrelevant. And since you have minimum 10% of floor area as windows, and the U value of a single glazed window is say 6, then the windows alone in a 20 square home would lose 111 Watts/ºC. A 10ºC differential is 1.1kW. Added to that you conduction through walls and ceilings, which even insulated would add about double the window figure. And then there's air leakage... Ed Thanks Ed Air leakage is easily solved. The argument for wanting to maximise insulation during construction in Australia as worthy and it does pay off. Temperature variability and heat gain / loss is minimal with the relative outside gradient as you mentioned and you are correct. We are lucky in that our climate is relatively mild, even Hobart has a welcoming climate compared to say New York state or Colorado. In Colorado, you can spend a winter heating a home by 50 degrees or more. -30 outside 20 inside. -30 is where you fingers hurt in about 3 minutes and turn blue in 5, after 30 you no longer have fingers. Ever tripped on a dog doo doo? One thing to learn from the Americans is methods and technology to insulate with. No one has written a bible on this, few studies have been performed but there is a gathering recourses of literature and product variations to work off and the insulation products make pink batts look amateurish. When Americans want insulation they are talking about R 30 or R 40. Even their roof coverings are sealed ceramic paints that you can hold a blow torch to with about 2% conductivity and non flammable. Australian products are a joke actually but we stand to gain the most. I think this is the same product http://www.lizardskin.com/pages/ceramic.php Referring to this -> http://www.eaglecoatings.net/ Product Video And this tolerable enthusiast.. http://www.youtube.com/watch?v=hYR2X5o3 ... r_embedded http://www.superiorcoatings.net.au/html ... therm.html Australian link? http://www.mathews.com.au/blanket.htm Another NASA product before Airogel. IN any case this is standard practice in the states. The equivalent of 250mm of rockwool or pink batts. Melbourne winter 12c and summer 28 c Average - Your house is 21 winter and 26 summer, The input is normally 10 degrees so why are we using so much energy needlessly? RE: House sealing. To test if you have reduced / eliminated as much air leakage as possible . http://www.youtube.com/watch?v=kNOfSYgt ... re=related namz yeah i do have concrete around my house..specially next to windows in west side.. I would try to cover it in summer using trees if I could. But this depends on space and other factors. If you need deciduous trees keep in mind they are from wetter climates and have shallow root forms similar to rain forest trees which could lift concrete. If you have a fence line that shades it part of the day and there is no space for shrubs or trees. Raise the fence height and plant something like Bougainvillea which looks great - thins out in cooler climates during winter is 100% natural barbed wire and uses almost no water. http://mallorcaphotoblog.files.wordpress.com/ Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ Extreme Like ⋅ Add a comment ⋅ Pin to Ideaboard ⋅ http://www.skopelos.net/ Flowers from September to April Re: How much R Value is good for roof insulation ? 20Oct 30, 2009 6:17 am Redman One thing to learn from the Americans is methods and technology to insulate with. No one has written a bible on this, few studies have been performed but there is a gathering recourses of literature and product variations to work off and the insulation products make pink batts look amateurish. When Americans want insulation they are talking about R 30 or R 40. Don't be fooled. Official recommendations do not always correlate with actual practice. Our friends worked and traveled across the US and weren't particularly impressed by construction methods or detailing. As with all things, these items cost money. BTW Imperial R values is about 5 1/2 x SI unit R values. The equivalent are R 6-7 batts (which are available here locally). 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