Adam Smith Posted September 11, 2019 Author Share Posted September 11, 2019 4 minutes ago, SteamyTea said: That is just the steady state value. There are surface affects that will increase the losses. I think they are in the Building Regs. That is exactly the time I see spelling and grammar errors. I don’t know what surface effects you can be referring to here. Heat can only be lost to conduction, convection or radiation. All these will be rolled up into the U-value. A much more likely caveat is the degradation of the seal and leakage of the argon over time. I wouldn’t be surprised if the glass has to be replaced every few years – but it’s very difficult to get reliable information. Link to comment Share on other sites More sharing options...
SteamyTea Posted September 11, 2019 Share Posted September 11, 2019 (edited) 14 minutes ago, Adam Smith said: convection It is those loses. I can't remember where the figures are published, but a few online calculators state it. I am not 100% sure that just the u-value of a window takes this into account. Here is one: https://insulationcart.com/knowledge/u-value-calculations/what-is-a-u-value-and-how-to-calculate-it/130 Edited September 11, 2019 by SteamyTea Link to comment Share on other sites More sharing options...
Adam Smith Posted September 11, 2019 Author Share Posted September 11, 2019 12 minutes ago, SteamyTea said: It is those loses. I can't remember where the figures are published, but a few online calculators state it. I am not 100% sure that just the u-value of a window takes this into account. Here is one: https://insulationcart.com/knowledge/u-value-calculations/what-is-a-u-value-and-how-to-calculate-it/130 Okay, but the assumption of the measurement is that a temperature difference is maintained either side of the glass by whatever means. If you are saying that convection could make a difference, it could only make a difference by changing the air temperature on one side of the glass – which has already been defined. Link to comment Share on other sites More sharing options...
SteamyTea Posted September 11, 2019 Share Posted September 11, 2019 Never looked into it too closely. There is evaporation losses, which are disproportionately high for and semi absorbent material, not that glass should be. May have to spend a few minutes looking it up. A friend of mine has a similar type house. She had a similar conversion done, may ask her what calculations were done. She did not have to worry about neighbours wall as her place is end of terrace. Link to comment Share on other sites More sharing options...
Adam Smith Posted September 19, 2019 Author Share Posted September 19, 2019 Thanks to everyone who replied to this topic. Having considered this I think the best choice is wooden joists with OSB and tiles. My main considerations are – I want to do it all myself and I don’t have the money or the strength to start moving tons of spoil/hard-core. The minimum depth of concrete would be something like 450 mm, so that somehow I would have to order skips, which costs a fortune in London. If I had 6 inch joists then I could fit the insulation and UFH between the joists and the total depth would be about 250 mm, which I could achieve by spreading everything around. Tiling on top of wood can work out very well. If I have concrete I would need a pour of oversight and another pour of screed, during which I would need another couple of guys helping. The thing about concrete is that you can’t change your mind. You have to get the level right first time and it’s difficult and expensive to break up and get rid of. With wooden joists and OSB I could manage it on my own and work at my own pace. I can always decide to poke a water pipe or an electrical cable underneath at a later stage. Over such a small area I can make a wooden floor as firm as you like and I can hang the joists off the brick wall. The total kitchen/conservatory floor will end up being a patchwork of three floors - a Victorian floor, a bathroom floor from 20 years ago and whatever I do. As Russell Griffiths was saying, the proper job would be to replace the whole lot - which someone may want to do at a later stage - but since what I am doing is an add-on, there’s no point doing anything too expensive or too permanent. Link to comment Share on other sites More sharing options...
Jeremy Harris Posted September 19, 2019 Share Posted September 19, 2019 On 11/09/2019 at 12:11, Adam Smith said: I don’t know what surface effects you can be referring to here. Heat can only be lost to conduction, convection or radiation. All these will be rolled up into the U-value. A much more likely caveat is the degradation of the seal and leakage of the argon over time. I wouldn’t be surprised if the glass has to be replaced every few years – but it’s very difficult to get reliable information. Just to clarify, there are two surface resistance elements that have to be taken into consideration, in addition to the U value of the materials, to get the total U value. They are the surface thermal resistance on the inside and outside surfaces respectively, and they attempt to sweep up the conductivity of the air in the surface layer and the emissivity of the material at those surfaces, along with some degree of forced convection on each. For a wall, for example, the surface thermal resistance is usually taken to be 0.13 m².K/W for the external surface and 0.04 m².K/W for the internal surface thermal resistance. These thermal resistances need to be added to the other thermal resistances in the build up of the element and then the reciprocal of the result take as the U value. Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now