U values for Velux windows

attic · 26-08-2012 06:39PM #1

Hi,
Just looking thru velux documentation and the U values for most of its windows range between 1.0 and 1.4.

http://www.velux.ie/en-GB/PublishingImages/PDFs/VLX%202272%20.%2036pp%20Trade%20Brochure%202012-ROI-Final.pdf

What is the building reg now for U values for windows?

Thanks.

kieranhr · 27-08-2012 10:19AM

Short answer, the maximum acceptable u-value for windows and rooflights is 1.6 W/m2K, as long as your glazing area does not exceed a quarter of your floor area.

But - achieving the u-value targets in the regulations is easy. The hard part is getting the overall Carbon Performance and Energy Performance Coefficients right. If you get the u-values right but nothing else, there's no doubt your house will fail the regulations check.

attic · 27-08-2012 10:52AM

kieranhr wrote: »

Short answer, the maximum acceptable u-value for windows and rooflights is 1.6 W/m2K, as long as your glazing area does not exceed a quarter of your floor area.

But - achieving the u-value targets in the regulations is easy. The hard part is getting the overall Carbon Performance and Energy Performance Coefficients right. If you get the u-values right but nothing else, there's no doubt your house will fail the regulations check.

Ok, so what other things are biggies: I guess air tightness, anything else?

kieranhr · 27-08-2012 11:49AM

You'll need to get your architect/engineer/BER assessor to carry out a whole house energy analysis to say whether or not the EPC and CPC I mentioned above conform to the regulations. I usually find these to be the most stringent requirements, and if you hit these, everything else will pretty much fall into place.

sydthebeat · 27-08-2012 12:52PM

attic wrote: »

Ok, so what other things are biggies: I guess air tightness, anything else?

yeah... everything.

compliance can only be proven by a DEAP analysis.

U values for Velux windows

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