Target U-values… Cost/benefit sense check… What am I missing? 🤷🏻‍♂️

[Iceverge]

20 hours ago, Oz07 said:

I might approach my next place differently instead of fabric first ill do economic fabric first. 

 

Economic fabric first probably wouldn't be very nice to live in. 

 

It would only include the smallest windows necessary for fire escape purposes and they would be the lowest legally acceptable spec. 

 

For comfort I would always upgrade to thermally good windows before going behind Bregs insuation. 

[JohnMo]

1 hour ago, Iceverge said:

upgrade to thermally good windows

One of the main reasons passivhaus specify 3G is based on comfort. The window internal temperature of 3G being very close to room temperature, so isn't uncomfortable to sit next too. The lower the performance the more uncomfortable they are to be near for long periods with it cold outside.

 

We have a bay window, with floor to ceiling glazed and I sit there quite a lot, it's comfortable whatever the weather is doing outside. Not sure I could do that with 2G.

[craig]

I’m at the stage of it works and performs, it doesn’t really matter if it’s uPVC or timber alu. Lot’s of personal preference of course but you can save a lot and obtain the performance with a good uPVC system.