Browse Forums Windows & Doors 1 Jul 26, 2011 10:17 pm Hi, work on my new home has started. This is a 6 star home. The contract has the energy values for windows (U and SHGC). These are on the plans as well as on the energy report produced by the modelling software. Either Low E glass or double glazing is within the values. The specifications say windows with 'Low E glass or equivalent within energy values for the windows'. I understand any window that meets the energy rating can be used under the energy rating arrangements. The builder has advised he is using double glazing, which is more expensive than Low E glass. Can the builder seek extra costs for this? I would think if the builder - not me - is choosing to use a more expensive type (double glazing rather than Low E) than that is his cost? If I agree he can use double glazing can he later seek this as a variation? Low e windows are available from the same window supplier. Any advice? Re: window energy values in contracts - when can builder ext 2Jul 26, 2011 10:32 pm newhomestarted Hi, work on my new home has started. This is a 6 star home. The contract has the energy values for windows (U and SHGC). These are on the plans as well as on the energy report produced by the modelling software. Either Low E glass or double glazing is within the values. The specifications say windows with 'Low E glass or equivalent within energy values for the windows'. I understand any window that meets the energy rating can be used under the energy rating arrangements. The builder has advised he is using double glazing, which is more expensive than Low E glass. Can the builder seek extra costs for this? I would think if the builder - not me - is choosing to use a more expensive type (double glazing rather than Low E) than that is his cost? If I agree he can use double glazing can he later seek this as a variation? Low e windows are available from the same window supplier. Any advice? He is doing you a favour... you really don't want Low-E in single glazed. It may rate in the energy rating but it...
is prone to spontaneous fracture is easily marked and difficult to clean I hope he charges sensibly... 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: window energy values in contracts - when can builder ext 3Jul 27, 2011 10:32 am I see you have 2 threads but I will add my comment here. If the builder uses Low-E, you may have a warranty problem should the glass spontaneously break - another poster has exactly this problem - where the liability bounces between the window supplier, the builder and the glass supplier. So your builder may be taking a sensible option for a reason, and the fact that it is more expensive should be born by you, alternatively you could go with the Low-E option at your liability. Thanks 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: window energy values in contracts - when can builder ext 4Jul 29, 2011 11:47 am Interesting Ed. As a Building Designer & Thermal Assessor I am keen to get first hand knowledge on the ins & outs of single pane low-e. Over the years it has been muted that single pane low-e doesn't perform as accurately as the specs would suggest - can you elaborate on its use & maybe show some price comparisons between sg low-e & a basic dg window (with better U & SHGF) Peter Clarkson - AusDesign Australia www.ausdesign.com.au This information is intended to provide general information only. It does not purport to be a comprehensive advice. Re: window energy values in contracts - when can builder ext 5Jul 29, 2011 2:20 pm ausdesign Interesting Ed. As a Building Designer & Thermal Assessor I am keen to get first hand knowledge on the ins & outs of single pane low-e. Over the years it has been muted that single pane low-e doesn't perform as accurately as the specs would suggest - can you elaborate on its use & maybe show some price comparisons between sg low-e & a basic dg window (with better U & SHGF) Hi Peter, Low-E glass reduces radiant heat transfer, but has no effect on conducted heat. It is prone to breakage in single glazed as the single glazed version of low-E is laminated, one side being low-E and the other clear float. (For others, laminated glass is 2 piece of glass bonded together with a plastic interlayer). The low-E side prevents radiant heat from passing by absorbing it, so it gets hot while the other side remains at ambient. This causes thermal stress with one side trying to expand while the other doesn't and frequent breakage is common. This is especially so in direct sunshine — which is where you would get the most benefit from low-E. In double glazed, the low-E is not laminated, and I have never heard of thermal shock/breakage for double glazed low-E. By far the greatest heat loss from homes is conducted heat, reducing the radiant heat loss has very little effect. Expressing the performance of low-e as a u-value refers only to its radiant heat performance, and double glazing u-values refer only to conducted heat performance. In fact Australia is the only country in the world selling single glazed low-E as an energy saving glass, because it doesn't work... except in the software which uses the u-value irrespective of the fact it refers only to radiant heat transfer. Low-E has value in double glazing, for west and north facing windows to control solar heat gain. The suppliers insist on a "thermal assessment" before the low-E is sold into single glazed, such are their worries about performance. Not to mention that it damages easily and is very difficult to clean... the low-E surface in double glazed is encapsulated within the glazing system, so never needs cleaning. I note that single glazed low-E is referred to in Viridian data as being unsuitable for areas prone to condensation, then they recommend the version that is used only in double glazing... presumably because it will need frequent wiping... Quote: Viridian ComfortPlus™ is a laminated single glazed Low E glass, ... Where condensation may be experienced we recommend Viridian ThermoTech™. 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: window energy values in contracts - when can builder ext 6Jul 29, 2011 4:11 pm Thanks Ed . . . very enlightening. To follow on could you explain (in laymans tems) the correct application configurations for Low-E in double glazing. i.e I assume in 'cooling climates' the Low-E is on the inner pane. Is this always the case & is this how it works ? Peter Clarkson - AusDesign Australia www.ausdesign.com.au This information is intended to provide general information only. It does not purport to be a comprehensive advice. Re: window energy values in contracts - when can builder ext 7Jul 29, 2011 5:21 pm The surface position on which the low-E glass will be placed is dependent on the climate. Ideally for warm climates where summer heat reduction is a priority, the coating should be on surface 2 for maximum performance (Note: the surface number is counted from the external surface of the outer pane [1], right through to the external surface of the inner pane [4]). The coating on surface 2 minimises heat gain because it reduces heat build up in the air gap and heat transfer to the interior. Using surface 3, low-E is most effective for warm climate glazing. But it works both ways, in both positions, just more effective in the positions mentioned. So really it should have two u-values, one for each location. 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: window energy values in contracts - when can builder ext 8Jul 30, 2011 10:25 pm I disagree with you Ed, though I was seeking thoughts from others in the forum. What if my specification was for 1 outdoor tap and the builder installed 16. Would I be expected to pay for 15 extra taps which is a 'favour' from the builder? No. I don't see why it would be any different with windows. Again if the builder put in higher insulation than required to meet the energy requirements why would this be a cost to the buyer? I don't think energy efficiency reports are a license to upgrade and up spec everything... Re: window energy values in contracts - when can builder ext 9Jul 30, 2011 10:53 pm newhomestarted I disagree with you Ed, though I was seeking thoughts from others in the forum. What if my specification was for 1 outdoor tap and the builder installed 16. Would I be expected to pay for 15 extra taps which is a 'favour' from the builder? No. I don't see why it would be any different with windows. Again if the builder put in higher insulation than required to meet the energy requirements why would this be a cost to the buyer? I don't think energy efficiency reports are a license to upgrade and up spec everything... What I am saying is that the offer is not simply a choice of what is cheapest against what is more costly (and who knows which way the price will be between low-E and double glazing for any given supplier), it's a choice of which alternative gives the best quality and performance. You pay your builder to be the expert,he knows what he will stand by in the warranty, he knows what performs. Now if you just want the cheapest outcome irrelevant of performance, then tell him. But he may not agree as he has to guarantee the product. If he gives you 16 taps when you wanted 1, then refuse to pay for 15... if he gives you 20 windows when the plans said 15, then refuse to pay for 5. If he advises you to use a better tap, because it will last a lifetime, or it will not drip, then listen... If he advises you to use a particular window, also listen... (especially if it is EcoClassic ) 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 MBA and HIA both have sub contract agreements, check them out 2 7371 Industry type domestic contracts are prepared by industry bodies for the benefit of the builders. This means that if you are the owner watch out. One of the points is… 0 3262 Hello, I am currently working on a study in regards to building contracts in Australia. I would like to interview people with their building experience in Australia and… 0 264 |