Maybe another daft learner question but if you dont ask you dont know !!

Building a Sips house with 142mm kingspan TEK, adding 50mm kingspan to the interior gives me 1.3 (W/m2k). I have been getting quotes for windows with 0.8 which seem expensive. Am i going overboard at 0.8 ? considering the TEK is 1.3 ? I am happy to spend the money if its well spent.

Thank you.

Posted By: CJTBuilding a Sips house with 142mm kingspan TEK, adding 50mm kingspan to the interior gives me 1.3 (W/m2k). I have been getting quotes for windows with 0.8 which seem expensive. Am i going overboard at 0.8 ? considering the TEK is 1.3 ? I am happy to spend the money if its well spent.

I suspect you have an error in your figures. 0.13 W/m²K seems a much more likely U-value for the wall than 1.3.

0.8 is a good figure for the U-value of a window. It's about what mine are. Is that the whole window value, or a value for the glazing? For myself I think the money would be well spent if they are at a good price, but it depends on what the rest of the building is like, and what your overall aims and budget are.

edit: to add that the U-value of a window is not the only criterion to look at. The quality of construction and especially the hardware is important. And stability of course. The finish is important in terms of how much maintenance will be required. Airtightness is very important.

Posted By: djhI suspect you have an error in your figures. 0.13 W/m²K seems a much more likely U-value for the wall than 1.3.

My mistake ! 0.13 I intend to concentrate on airtightness. My aim is to have a comfortable house with low running costs, Budget isn't a massive issue but i feel i have to be sensible as well considering i am not getting any younger. Thank you.

CJT, Russell are hard to deal with, not retail-friendly at all, but if you're confident to go thro the specifying process, the price makes it worth it (also poor in delivering on time!).
If the walls are U.13 nominal, then prob U.8 windows would be justified.