Which windows should I choose? Liniar vs Liniar Energy+ 90 vs Rehau

[SSKK]

I'm changing out all my old double glaze windows (with cracked seals etc) on my 1980 double brick detached house (with a single brick + insulation bit where they have converted the garage and I think extended a bit). I have a few different options I am trying to choose between and I was wondering if people could help me decide! Overall, I'm trying to make my house more thermally efficient and warmer but also consider costs. 

• Liniar Energy+ 90  - triple glaze 48mm (4-18-4-18-4) - planiclear / Planitherm Total+ FG / Planitherm Total+ FG - u = 0.77, g = 0.61 wer = 29.47 - £10.3k supply only (I know a window fitter who will fit at a good day rate)
• Liniar Energy+ - triple glaze 36mm (4-12-4-12-4) - optiwhite / k glass s / k glass s - u = 0.97, g = 0.67, wer = 20.99 - about £6.3k supply only
• Rehau Total 70c - triple glaze 42mm (4-16-4-14-4) - optiwhite / k glass s / k glass s - u value just under 1 I think, still getting details £6.1k supply only
• Liniar Energy+ - triple glaze 36mm (4-12-4-12-4) - planiclear / Planitherm Total+ FG / Planitherm Total+ FG- u = 0.98, g = 0.61, wer = 16.2 - about £6.1k supply only

 

In a nutshell, is it worth forking out an extra £4k to get the thicker casements and move u value down from just under 1 to 0.77? If not, which of the other options should I go for? I had been hoping the Rehau would be a better u value than the Liniar as it is 42mm vs the Liniar 36mm, however, the numbers look like they are going to be very similar (I don't know why this is the case?). I'm also getting a quote to fill the 36mm-42mm options with krypton, and this will bring the u value down to about 0.8, but I have no idea currently how much extra this will add to the quote. 

 

Considering my house (80's detached double brick which I hopefully soon will cavity fill), is it worth going for the 48mm casement? Am I going to see much difference in a place like mine?

 

Thanks in advance to anyone who can help me work through my dilemma. 

[Conor]

How my windows is that? We used internorm which seem to be on par with likes of Rationel etc but a lot cheaper. 

[MikeSharp01]

 

9 hours ago, SSKK said:

 

Considering my house (80's detached double brick which I hopefully soon will cavity fill), is it worth going for the 48mm casement? Am I going to see much difference in a place like mine?

This will depend on the rest of the structure - you need to do a full fabric analysis EG get the U values (work them out) for the walls / roof, and see where your heat is all going. That way you can get a feel for the payback time of what looks like an improvement of 23% in your windows and then you can decide if other ways of spending the 4K, EG improving the loft / tank / thin wall insulation would be more effective. I think the general consensus on here would be that just making the windows better without looking at everything else is likely to be wasteful. 

 

12 minutes ago, Conor said:

How my windows is that? We used internorm which seem to be on par with likes of Rationel etc but a lot cheaper. 

Not sure how you managed to get Internorm in under the Rationel price it generally seems the other way around on here.

 

 

[SSKK]

14 hours ago, MikeSharp01 said:

 

This will depend on the rest of the structure - you need to do a full fabric analysis EG get the U values (work them out) for the walls / roof, and see where your heat is all going. That way you can get a feel for the payback time of what looks like an improvement of 23% in your windows and then you can decide if other ways of spending the 4K, EG improving the loft / tank / thin wall insulation would be more effective. I think the general consensus on here would be that just making the windows better without looking at everything else is likely to be wasteful. 

 

Not sure how you managed to get Internorm in under the Rationel price it generally seems the other way around on here.

 

 

How do I do a fabric analysis?

 

I have 200mm loft insulation so I suppose this u value is quite low (<0.2?)

Once we get the cavity wall insulation then I suppose this will also have u values of <0.6?

Floor? Not sure but my googling says this may be up to 1.2. Does this sound right? - If so, I guess the windows don't make sense to go for the extra £4k.

We're changing the front and back doors also. Getting rid of the cat flap and letterbox. 

We're trying to also borrow a thermal camera from the council to look for weak spots. 

 

I also did some calcs later on and if I assume 0.2 delta u value, 20m2 of windows, 20 degrees difference between outside and inside for 3 months, and 10 degrees for 3 months. then 260kWh saving per year or less than £45 at the prices after the price cap goes away. So, on a price basis - not worth it if I've done this right. And I def won't feel warmer if my floor u value is that bad. 

 

So the question is then which of the others? Is there really any difference, or nothing between them I should consider?

 

 

 

[SSKK]

On 16/03/2023 at 06:37, Conor said:

How my windows is that? We used internorm which seem to be on par with likes of Rationel etc but a lot cheaper. 

11 (2 of which are bay windows) and a french door. I got some Rationel quotes but these were £25k-ish. 

[Redbeard]

"Floor? Not sure but my googling says this may be up to 1.2. Does this sound right? - If so, I guess the windows don't make sense to go for the extra £4k."

 

Search Floor Perimeter/Area ration for an expl of how floor U values are calculated. This site (https://warmafloor.co.uk/support-centre/u-values/) has a good explanation. Not sure that in actual 'comfort' performance it's going to seem the same for a solid floor as for a (ventilated) suspended timber floor.