Secondary windows and U values

descol

Hi

Would anyone there be able to give me an indication of the improved U value for a PVC 16 mm double glazed Unit (U value of 2.0) - if a secondary glazed single glass sliding window was to be fitted internally ? 

thanks  

sydthebeat

https://www.boards.ie/discussion/2058260842/secondary-windows-and-u-values

as far as i know, according to the methodology, there would be no difference, as the default value for ANY window with secondary glazing is 2.4

to input values different from the default, you would need to have the situation tested and certified.

descol

Sydthebeat

Thanks for your helpfull comments

I have another query if you could offer advice it would be apparecaited

In a situation with single glazed timber sash windows in a proptected structure - the default U value is often 4.8.

If the glass panels were removed and energy glass such as Fineo fitted - the light transmitenace etc would obiviously improve -

but what might the U value improve to - if at all ?

thanks

descol

sydthebeat

tough one

a window u value is a measurement of the WHOLE window, including the glazing and frame

so if you improve the glazing to double glazing, but not the frame, you are certainly improving the u value but i couldn't say exactly what the new u value would be.

the BER would default to a 3.1 if its a 6mm gap with no argon

descol

thanks Syd

Yes - I agree - I suspect there is lttle change in the U value overall - simply better "performing " glass