Browse Forums Windows & Doors 1 Mar 02, 2014 10:36 pm Hi, after some advice on double glazing. Have spent many fascinating hours perusing this forum and the Viridian website but I think I'm getting information overload and need to sort out all this information! We're looking to build a project home in Sydney and have asked the builder to price DG windows, and we've been asked to let them know which particular window(s) we would like. Our main living areas to the back face NE, with one bedroom, one bathroom and the laundry having NW glazing. If our primary aim in having DG is to keep heat out in summer while not blowing the budget, how would you rank in order of importance: Thickness of glass Different thickness of the two panes of glass Width of gap between the panes Low E coating Air vs argon fill Thermal break for aluminium frames Tint Anything I've forgotten? I'm thinking low E for the NE and NW windows, but a little stuck on the other details. Is having thicker glass panes more important/better bang for the buck than a thermal break, for instance? Thanks! Re: Double glazing to keep heat out - what's most important? 2Mar 02, 2014 10:55 pm 1) Get low-E as you say, included in the DG. 2) For the remainder, check out www.wers.net Glass thickness is irrelevant for energy efficiency, it only affects acoustic properties. Thermal break is only as effective as the WERS result... but always compare clear glass results between different products. 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: Double glazing to keep heat out - what's most important? 3Mar 02, 2014 11:21 pm ed @ ecoclassic 1) Get low-E as you say, included in the DG. 2) For the remainder, check out http://www.wers.net Glass thickness is irrelevant for energy efficiency, it only affects acoustic properties. Thermal break is only as effective as the WERS result... but always compare clear glass results between different products. Ed Thanks Ed for the link. Trying to filter the results so I don't have to compare over 30,000 windows! So a thermal break is not as important as the other factors then? We get some aircraft noise, it's noticeable rather than being intrusive so I'm hoping that whatever we pick for energy efficiency will be sufficient to block the noise. Re: Double glazing to keep heat out - what's most important? 4Mar 03, 2014 6:04 am AvaG ed @ ecoclassic 1) Get low-E as you say, included in the DG. 2) For the remainder, check out http://www.wers.net Glass thickness is irrelevant for energy efficiency, it only affects acoustic properties. Thermal break is only as effective as the WERS result... but always compare clear glass results between different products. Ed Thanks Ed for the link. Trying to filter the results so I don't have to compare over 30,000 windows! So a thermal break is not as important as the other factors then? We get some aircraft noise, it's noticeable rather than being intrusive so I'm hoping that whatever we pick for energy efficiency will be sufficient to block the noise. Welcome... Our standard product (we have TB as well) beats a famous TB for energy efficiency. The best aluminium U value is 3.5 - that's us. It is verified by WERS in an email to me, after heaps of people said theirs was better - some try it on with different glazing types and using fixed windows instead of opening to say - "see, ours is best". But it isn't. So close to 3.5 would be good... use that as your guide - remember, clear glass only, this is your leveller. Std DG will take care of 80-90% of your noise. 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: Double glazing to keep heat out - what's most important? 5Mar 03, 2014 9:56 pm Still confusing but as the builder uses Viridian as their supplier, I guess I'll start with comparing just their products! At the end of the day it will come down to cost... Sigh... Need to get hold of a price list, so I can just compare the windows that come within budget. Thanks again Ed Re: Double glazing to keep heat out - what's most important? 6Mar 04, 2014 5:12 pm AvaG Still confusing but as the builder uses Viridian as their supplier, I guess I'll start with comparing just their products! At the end of the day it will come down to cost... Sigh... Need to get hold of a price list, so I can just compare the windows that come within budget. Thanks again Ed Your builder won't be using Viridian, they are the glass supplier, though they may be supplying his window supplier... all glazing other than clear float adds considerable cost. 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: Double glazing to keep heat out - what's most important? 7Mar 04, 2014 11:33 pm ed @ ecoclassic AvaG Still confusing but as the builder uses Viridian as their supplier, I guess I'll start with comparing just their products! At the end of the day it will come down to cost... Sigh... Need to get hold of a price list, so I can just compare the windows that come within budget. Thanks again Ed Your builder won't be using Viridian, they are the glass supplier, though they may be supplying his window supplier... all glazing other than clear float adds considerable cost. Ed Started to realise that last night! What do you mean by clear float Ed? Does that just refer to clear glass rather than tinted, or something else? Compared the Viridian DG products - is it fair to say that thickness of the glass makes a difference to solar heat gain, more so than argon fill over air? Re: Double glazing to keep heat out - what's most important? 8Mar 05, 2014 6:23 am AvaG ed @ ecoclassic AvaG Still confusing but as the builder uses Viridian as their supplier, I guess I'll start with comparing just their products! At the end of the day it will come down to cost... Sigh... Need to get hold of a price list, so I can just compare the windows that come within budget. Thanks again Ed Your builder won't be using Viridian, they are the glass supplier, though they may be supplying his window supplier... all glazing other than clear float adds considerable cost. Ed Started to realise that last night! What do you mean by clear float Ed? Does that just refer to clear glass rather than tinted, or something else? Compared the Viridian DG products - is it fair to say that thickness of the glass makes a difference to solar heat gain, more so than argon fill over air? Clear float is standard clear glass, not toughened, not tinted and not treated in any way... float refers to the method of manufacture. The thickness of the glass is not relevant for energy efficiency. Optimum air gap (or argon) is 12mm, more is worse, less is worse. 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: Double glazing to keep heat out - what's most important? 9Mar 05, 2014 7:11 am We've got standard double glazing and it definitely cuts the noise. We're amazed at what we can hear with the windows open, that we just aren't aware of with them closed. Re: Double glazing to keep heat out - what's most important? 10Mar 05, 2014 9:17 pm Trying to get this straight Ed. What is the single most important feature of a double glazed unit for keeping heat out of the house? And is a 12mm gap also ideal for air? catjim, I'm looking forward to not hearing planes at 6am! To be fair, they don't wake me, I hear them if I'm awake, but I'd rather not be reminded that I'll need to be up soon Re: Double glazing to keep heat out - what's most important? 11Mar 06, 2014 6:04 am AvaG Trying to get this straight Ed. What is the single most important feature of a double glazed unit for keeping heat out of the house? And is a 12mm gap also ideal for air? Optimum air gap or argon gap is 12mm. Given glass is the leveller, being the same available for all windows, then the frame is the next most important feature, this is shown in WERS as the combined U value for frame and glass by manufacturer, called Uw. You compare frames by comparing the same glazing, e.g. clear float, in each, to reveal the underlying performance of the whole system. The star rating in WERS combines Uw SHGC and air infiltration. Then you choose the glass... if you need low-E or tint. 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: Double glazing to keep heat out - what's most important? 12Mar 06, 2014 9:57 pm Thanks ed, that was very helpful. I guess I should check with the builder whether we can use any supplier or just their preferred supplier, so I don't spend hours comparing different windows only to find I can't use any of them anyway! Have learnt a lot from you though, thanks again. Re: Double glazing to keep heat out - what's most important? 13Mar 27, 2014 4:26 pm My understanding is the following ranking when considering stopping heat from entering your home. This is from looking at Ed's results on WERS so he may be able to correct me if I am wrong or have misunderstood his first two lots of ratings 1.Thermal break for aluminium frames - important as the frame can make up between 10-30% of the entire window so should be considered - can change overall performance by 10% 2. Low e & tint - for simplicity I have grouped these as both will reject heat based on the reflection and darkness of the coating / tint. Important to see the final product and not judge off a specification sheet as different coatings/films have different aesthetics and visual light transmittance. Seems to change the results by about 8-9% 3.Air vs argon fill - Argon is more dense than air so will reduce the flow of heat across the window. Seems to affect the results by about 2% 4.Width of gap between the panes - I have always understood that larger is better. Given 12mm gap and 10mm gap seem to be Ed's standard range and he says 12mm, I would trust Ed and go with the larger gap 5. Thickness of glass - mainly relates to noise. Confusingly the WERS results with a thicker glass and smaller gap actually perform slightly better. (4/12/4 vs 5/10/5) same frame just different insert? I would think the larger gap is less expensive as the glass is thinner - Ed any insight? 6. Different thickness of the two panes of glass - mainly relates to noise and reverberation hope this helps. Re: Double glazing to keep heat out - what's most important? 14Mar 29, 2014 8:52 pm Thanks Adrian. I think I am a little confused about the thermal break - I took Ed to mean that other aspects of the window/frame are more important, but I probably misunderstood. I'm waiting to hear back about the window supplier and size of the windows before I make any decisions about double glazing. It didn't fill me with confidence when I said I would like double glazed windows with low-E coating and I was asked if I meant Comfort glass. Re: Double glazing to keep heat out - what's most important? 15Mar 31, 2014 6:51 am AvaG Thanks Adrian. I think I am a little confused about the thermal break - I took Ed to mean that other aspects of the window/frame are more important, but I probably misunderstood. I'm waiting to hear back about the window supplier and size of the windows before I make any decisions about double glazing. It didn't fill me with confidence when I said I would like double glazed windows with low-E coating and I was asked if I meant Comfort glass. Sorry guys, very busy at the moment, will respond properly over the next few days. THE most important thing about window performance as far as energy is concerned is the WERS results ( www.wers.net ) for clear glazing... Thermal break does not necessarily beat non-broken windows... our unbroken window rates Uw 3.5 with clear glass. Check others with CLEAR glass... Then of course you need to think about wind and rain performance (unpublished) and then acoustics (again unpublished). 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: Double glazing to keep heat out - what's most important? 16Apr 04, 2014 10:10 am Hi AvaG, Ed was commenting that his windows perform very well without a thermal break - which they do with a low u-value of 3.5 which is excellent for an aluminium framed window. What I was pointing out was that his windows with a thermal break perform even better so a thermal break (thermal frame UPVC) does make a difference and up to 10% in Ed's case but may be more with other suppliers depending on their quality of frame design. Ed may be able to shed more light on this when he has the time. I am also happy to be corrected and Ed may flip my number 1 & 2 and feel the tint / low e is more important when considering heat rejection. I simply looked at the Eco Classic WERS results and % comparisons. I would think that the size of the window may also affect this. smaller windows will have more emphasis on the frame performance and large windows will be skewed by glass performance as the glass makes up a large portion of the window. in relation to the supplier mentioning Comfort Plus when you asked about low e glass. You can still have confidence in them as Comfort Plus is a low e glass made by Viridian. Comfort Plus is simply the brand name of their range of Low e glass. regards Adrian Re: Double glazing to keep heat out - what's most important? 17Apr 05, 2014 9:25 pm That makes sense Adrian, thanks. I'll have to wait to decide about windows though, to see if I have to stick to their preferred supplier who doesn't have a huge range of double glazed windows and might not offer windows with thermal breaks. I'll have to give the sales person the benefit of the doubt, when I've mentioned double glazed windows with a different sales person before, she tried to talk me out of it and suggested laminated or comfort glass instead. So I assumed that when this one said comfort glass, I took her to mean just single glazing with low E coating. Could be why she looked a little confused! Re: Double glazing to keep heat out - what's most important? 18Apr 07, 2014 7:32 am Adrian Lafleur My understanding is the following ranking when considering stopping heat from entering your home. This is from looking at Ed's results on WERS so he may be able to correct me if I am wrong or have misunderstood his first two lots of ratings 1.Thermal break for aluminium frames - important as the frame can make up between 10-30% of the entire window so should be considered - can change overall performance by 10% hope this helps. The relative performance of thermal break compared to unbroken windows is mainly as a the result of good thermal design, As I say, our unbroken window beats many broken windows. So thermally broken can be WORSE than unbroken. Check WERS. Quote: 2. Low e & tint - for simplicity I have grouped these as both will reject heat based on the reflection and darkness of the coating / tint. Important to see the final product and not judge off a specification sheet as different coatings/films have different aesthetics and visual light transmittance. Seems to change the results by about 8-9% This is a complicated question because low-E and DG have totally different applications. Low-E acts only on radiant heat, and DG acts only on conducted heat. But in the tables, using EcoClassic as a reference, then adding low-E improves the theoretical U value by 23%. (3.5:2.7) Quote: 3.Air vs argon fill - Argon is more dense than air so will reduce the flow of heat across the window. Seems to affect the results by about 2% Argon makes a difference of U value = 0.2, or roughly 5%. However, it does deplete to about 50% over 20 years. Quote: 4.Width of gap between the panes - I have always understood that larger is better. Given 12mm gap and 10mm gap seem to be Ed's standard range and he says 12mm, I would trust Ed and go with the larger gap Yes, 12mm is the optimum. More than 12mm or less then 12mm is worse. Quote: 5. Thickness of glass - mainly relates to noise. Confusingly the WERS results with a thicker glass and smaller gap actually perform slightly better. (4/12/4 vs 5/10/5) same frame just different insert? I would think the larger gap is less expensive as the glass is thinner - Ed any insight Thickness of glass is to do with the standards for glazing where we are required to use thicker glass due to the area. The relative cost of glass between 4mm and 5mm is not really relevant, as most manufacturers have a small rebate for their double glazing due to the window really being designed for single glazing, so when you add up the glass and gap, it tells you how much space they have. Thinner glass allows a bigger air gap for those with narrow rebates. We designed for 4mm glass and 12mm gap = 20mm rebate. Quote: 6. Different thickness of the two panes of glass - mainly relates to noise and reverberation Correct. And even better if they are not parallel (not practical in a home). 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 The worst thing you can do is sign a building contract without a pre contract review. Over the years many people have come to me with disputes where they just signed… 0 8338 This is one of the reasons I decided to go overseas for my double glazed windows. As the builder indicated, he's worked on many upmarket builds, these were the most well… 13 19080 Thank you. That is really helpful. Once we get the place done and passed for OC we can upgrade in the future once we get back on our feet and not paying mortgage and rent. 4 5713 |