Browse Forums Windows & Doors Re: Double Glazing - Scorched curtains anyone? 3May 09, 2010 8:33 am evie i've been told, but not read anywhere, that the air pocket between DG and blinds can get so hot the blinds can scorch. anyone else heard of this? It's not true... to be hotter than single glazed would mean the whole idea of double glazing would be nonsense... your blinds would be cooler with double glazing... 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 - Scorched curtains anyone? 4May 09, 2010 9:15 am Interesting question. Does double glazing trap more radiant heat than single glazing? Is a double glazed glasshouse hotter during the day? Maybe. You have to reach fairly high temperatures for fabric to actually scorch though. The air has to be higher than an iron! So the heat has to pass in the layer and largely get trapped. You would need a pretty heavy duty insulating curtain to do that. We have synthetic cellular blinds and they look OK after one summer. UV light can bleach colours though - as I found out when I accidentally left a good jumper in my car for a few months. Re: Double Glazing - Scorched curtains anyone? 5May 11, 2010 5:43 pm Quote: i've been told, but not read anywhere, that the air pocket between DG and blinds can get so hot the blinds can scorch. anyone else heard of this? Sounds a bit like that urban myth that your curtains will fade under day light saving. Re: Double Glazing - Scorched curtains anyone? 6May 12, 2010 11:14 pm The technical reason why double glazing makes no difference to your curtains compared to single glazing... The only difference between single glazing and double glazing with regard to heat transfer is in conduction, i.e. the heat which passes by direct transfer from object to object or through contact with the air. Double glazing slows down the conduction through the window by incorporating an insulating barrier of air. Radiant heat transfer, for all intents and purpose, is identical in single glazed and double glazed windows. Double glazing affects the air temperature in a room, either by shielding it from the cooler outside or by shielding it from the warmer outside by using the air barrier between the glass. The only way curtains will get warmer with double glazing, is if the room gets warmer because the air in the room also gets warmer. If this happens then everything in the room will be close to the same temperature, curtains, carpets, furniture - everything. Proximity to the window will make almost no difference. As Dymonite says, UV is an issue for curtains, and there would be a minimal reduction in UV by using double glazing, and that is because glass does stop some UV and with double glazing you have more glass. 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 - Scorched curtains anyone? 8May 13, 2010 10:55 am ed @ EcoClassic Radiant heat transfer, for all intents and purpose, is identical in single glazed and double glazed windows. But what about the variation in spectral emissivity of even normal glass? It can trap heat because it lets in more solar radiant heat then it lets out internal radiant heat. That's partly why glasshouses stay warm and that the inside of a closed car can overheat even on a moderate but sunny day. Re: Double Glazing - Scorched curtains anyone? 9May 13, 2010 12:56 pm dymonite69 ed @ EcoClassic Radiant heat transfer, for all intents and purpose, is identical in single glazed and double glazed windows. But what about the variation in spectral emissivity of even normal glass? It can trap heat because it lets in more solar radiant heat then it lets out internal radiant heat. That's partly why glasshouses stay warm and that the inside of a closed car can overheat even on a moderate but sunny day. The solar heat gain coefficient of double glazed windows is lower than single glazed, so having 2 pieces of glass would not enhance the radiant heating effect, it would only reduce it. The radiant heat entering the room falls on stuff like furnishings and heats these up, it is then no longer radiant heat, but embedded heat as energy. The room and the air inside (just like the greenhouse) become warmer. It does this until the radiation (& conduction & convection) moving outward is in balance with the incoming radiation and then the temperature stabilises, albeit 30 degrees above the outdoor temperature. In the northern hemisphere, greenhouses use automatic (mechanical) vents to let the hot air out, and the greenhouse temperature moderates at a lower temperature. Emissivity occurs where the glass itself heats up and radiates, and would be no worse in double glazing, and in the example of scorched curtains, would have no effect. Double glazing does indeed trap radiant heat, but when it traps radiant heat, it is no longer radiant heat, but heat that has energised the material it fell on, where it dissipates mostly as conducted heat, warming the air and the surroundings. 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 - Scorched curtains anyone? 10May 13, 2010 2:06 pm ed @ EcoClassic Double glazing does indeed trap radiant heat, but when it traps radiant heat, it is no longer radiant heat, but heat that has energised the material it fell on, where it dissipates mostly as conducted heat, warming the air and the surroundings. Any object above -273 degrees Celsius will radiate heat (including the 'energised' objects in the room). As you know this is how low-e windows work - because it further reduces the radiant heat loss from inside the house. Normal glass does this to some degree but not as well as low-e. DG might let less solar radiation enter (Solar Heat Gain Co-efficient - SGHC) but I am wondering if this is offset by also letting less radiant heat out. Anyway the question is largely academic. To reach really high temperatures you would some kind of setup like a solar oven where the material is designed in a way to reach really high temperatures without being losing it's heat. Re: Double Glazing - Scorched curtains anyone? 11May 13, 2010 2:45 pm dymonite69 ed @ EcoClassic Double glazing does indeed trap radiant heat, but when it traps radiant heat, it is no longer radiant heat, but heat that has energised the material it fell on, where it dissipates mostly as conducted heat, warming the air and the surroundings. Any object above -273 degrees Celsius will radiate heat (including the 'energised' objects in the room). As you know this is how low-e windows work - because it further reduces the radiant heat loss from inside the house. Normal glass does this to some degree but not as well as low-e. DG might let less solar radiation enter (Solar Heat Gain Co-efficient - SGHC) but I am wondering if this is offset by also letting less radiant heat out. Anyway the question is largely academic. To reach really high temperatures you would some kind of setup like a solar oven where the material is designed in a way to reach really high temperatures without being losing it's heat. I agree, and I am sure there is some offset with DG by letting less radiant heat out... how much? Not sure... 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 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 19239 have you used any of the motorised curtain systems available from Ebay? Which one and how is it? 0 2431 For your reference Performance Labels: Window assemblies in housing, except timber windows, must be labelled so the label can be seen when it is in situ. For timber… 6 7716 |