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.

[Nickfromwales]

11 hours ago, craig said:

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.

What happens if the remit is for these to be (and remain) airtight / as airtight as possible, for 20+ years or more.

 

Does uPVC then still get put on the menu?

[craig]

Good quality systems, will have 15 to 30 year product guarantee. Same question goes to timber / aluminium to be honest.

[Nickfromwales]

1 minute ago, craig said:

Good quality systems, will have 15 to 30 year product guarantee. Same question goes to timber / aluminium to be honest.

Let me rephrase..............boyo.

 

Do any uPVC manufacturers state that their product has been airtight tested, as some of the bigger players kinda suggest at least?

[Big Jimbo]

I think Modern UPVC which has been used by a few bods on here, state. Effective Air leakage = 0

Is that what you mean ?

[Crofter]

7 minutes ago, Big Jimbo said:

I think Modern UPVC which has been used by a few bods on here, state. Effective Air leakage = 0

Is that what you mean ?

That must depend on the product. I've got a set of French doors from them and they're definitely not completely airtight. They were cheap though, and they're on a pretty exposed elevation.

[craig]

1 hour ago, Nickfromwales said:

roduct has been airtight tested, as some of the bigger players kinda suggest at least?

Yes, the likes of Internorm, Aluplast, Gealean,  Kommerling, Dako, Rehau etc. have air permeability test results according to EN 12207.

 

Edited 23 minutes ago by craig

[Nickfromwales]

Just now, craig said:

Yes, the likes of Internorm, Aluplast, Gealean,  Kommerling, Dako, have airtightness test results according to EN 12207.

 

Thanks.

 

Any uPVC ones offering this?

[craig]

They are uPVC systems 😉