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U-Value Calculator

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Last year I trained as a BER assessor and part of the course was to calculate u-values based on different types of construction materials. We were given an Excel spreadsheet to help us do the calculations, but it was an awful thing to use. So, one evening, I decided to do my own in html/javascript so that I could just open up a browser and do the calculations there. I looked around to see if it had been done already, but couldn\'t find anything other than shareware Windows executables. The hardest part was getting a reliable source of thermal efficiency values for the different types of materials, but I eventually found one, and converted as many of the values as I could for this script.


To use it, you simply select a material from the drop down box, and the values for that material will be automatically put into the input boxes, type in the thickness of the material in millimetres, and click add, and it should be added to the table below. Keep doing this until you have all the materials listed. The U-Value calculation will keep automatically updating. It can be downloaded from here

17 Comments

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Submitted by Chris Quinn on Fri 17 Jul 2009 12:57
I tried your U-value calculator and it looked really handy at the start, but no matter what data I entered, the U-value was always 0.18

Is there any way to fix this?
Submitted by paulhan on Tue 28 Jul 2009 10:32
Are you including the thickness of the materials? That's the only thing I can think of off the top of my head.
Submitted by J Max on Tue 18 Aug 2009 15:40
No, there seems to be something wrong with the calculator, the u-value does not change from 0.18, even if thickness and/ or % is modified....any ideas, it would be very useful if it worked?
Submitted by malcolm on Tue 13 Oct 2009 10:38
As other comments u-value always remains at 1.8
Submitted by jason on Sat 17 Oct 2009 11:24
works fine for me guys
Submitted by jason on Sat 17 Oct 2009 11:24
works fine for me guys, thanks
Submitted by Callum on Sun 18 Oct 2009 16:12
Hi,

Just used the calculator OK on IE7, but under Firefox, my usual browser on the interweb I have it more locked down (no script and other stuff) and the total was never updated (even with No-script set to allow scripting), so I then tried it under IE7 and it worked OK (i only use IE7 if I can't get FF to work, which now-a-days is rare), so I suspect the people having problems are using a browser that is more locked down than IE7 in default mode.

Thanks

Callum
Submitted by simon smith on Tue 03 Nov 2009 6:29
yes, i meet the same problems on your calculator.
whatever i put in it, it will be always 1.8.
what is the problem?

simon
Submitted by Chris Thomas on Fri 20 Nov 2009 17:58
Same for me, always 0.18.
Running Windows 7 though?

Thanks
Chris
Submitted by Ernst on Fri 02 Apr 2010 22:54
This seems to be an Firefox based problem - in Explorer works everything fine
Submitted by Dee on Tue 13 Apr 2010 9:44
Hi,

Be careful, if you or anyone using this gets audited by SEAI Quality Managment team, and you can't show correct calculations it will not be good! Will you be blamed for publishing a calculator that is not correct? Have to checked that all the thermal resistances you use are independantly certified, (you are not allowed to use the thermal resistances on trade literature / website made by the manufacturers, you can only use certs from IAB, BAB, etc.

I have made a simple xcel spread sheet for U Value calculations, including roofs etc. It's best to keep a folder of certificats for every job you do.

anyway, just thought it was risky.
Submitted by Dee on Tue 13 Apr 2010 9:59
Hi,

Be careful, if you or anyone using this gets audited by SEAI Quality Managment team, and you can't show correct calculations it will not be good! Will you be blamed for publishing a calculator that is not correct? Have to checked that all the thermal resistances you use are independantly certified, (you are not allowed to use the thermal resistances on trade literature / website made by the manufacturers, you can only use certs from IAB, BAB, etc.

I have made a simple xcel spread sheet for U Value calculations, including roofs etc. It's best to keep a folder of certificats for every job you do.

anyway, just thought it was risky.
Submitted by Alexander on Fri 14 May 2010 15:06
I get .18 for U-Value as well. Internet 7, Firefox and safari all the same... No good

Alex
Submitted by John on Tue 17 Aug 2010 3:09
Your Rsi and Rse don't seem to be changeable..also wrong if its walls were talking about for starters.
Submitted by John on Tue 17 Aug 2010 3:09
Your Rsi and Rse don't seem to be changeable..also wrong if its walls were talking about for starters.
Submitted by John on Tue 17 Aug 2010 3:09
Your Rsi and Rse don't seem to be changeable..also wrong if its walls were talking about for starters.
Submitted by Xavier Valladares on Thu 26 Aug 2010 16:57
It also does not work in google chrome, but do works in Internet Explorer.
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JQuery/PHP Website and Applications Developer, based in Ireland.
Interests: Open Source Software, Supercomputers, Financial Markets, Sport, Science, Sustainable Energy. AGW Skeptic.

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