Is it worth paying £9000 more for better U value

[Happy Valley]

We have two quotes from well known window suppliers Rationel and Aluhome for our 160 sq m new build home. The sliding doors are pretty large at 5m and 3.8m respectively within the same room.

 

One set of windows have a U value of 0.82 and sliding doors of 0.9.

 

Whilst the other set has a window U value of 1.2 and 1.6 for the sliders.

 

The difference in price is £9000 Ex VAT (both include fitting).

 

We are not building a passive house standard but are building with ICF and have low U values in the walls, roof and foundations.

 

Whilst money is always a consideration and we do have a budget to work to the big question: Is it worth paying the extra amount for these lower U values? 

[ToughButterCup]

11 minutes ago, Happy Valley said:

...  Is it worth paying the extra amount for these lower U values? 

 

In your for-ever home ? Probably, yes.

To sell as soon as finished ? No.

Edited June 8, 2021 by ToughButterCup

[SteamyTea]

Depends on the area and how it affects the overall U-Value.

While the differences look large on the face of it, the price difference does look very large.

 

You can improve other areas to compensate i.e. extra wall insulation on a North wall, better airtightness, better heating system.

 

Or just do a bit more shopping around.

[IanR]

18 minutes ago, Happy Valley said:

We have two quotes from well known window suppliers Rationel and Aluhome for our 160 sq m new build home. 

 

One set of windows have a U value of 0.82 and sliding doors of 0.9.

 

Whilst the other set has a window U value of 1.2 and 1.6 for the sliders.

 

The difference in price is £9000 Ex VAT (both include fitting).

 

£9K difference on a 160 sq m home seems more than just u value.

 

Are you comparing like-for-like, apart from u value, or is one a timber/alu-clad and the other a aluminium frame, or something similar?

 

I couldn't imagine there'd be that much difference between Rationel U 1.2 vs Rationel U 0.82

 

[A_L]

30 minutes ago, Happy Valley said:

One set of windows have a U value of 0.82 and sliding doors of 0.9.

 

Whilst the other set has a window U value of 1.2 and 1.6 for the sliders.

 

The lower U-value windows will lose around 14kWh/yr per m² less than the higher. The lower U-value Sliders will lose about 43kWh/yr per m² less than the higher. The figures are for central England but are indicative for the U.K. This does not include differences in solar gain but this should be small.  

[nod]

NO

[Happy Valley]

Thanks for the responses.

 

Rationel are using Velfac V200E frames for the windows whilst Aluhome are using Origin OW dual flush aluminium casement windows.

 

This is likely to be our home for the next 20 to 30 years all being well. We are near Macclesfield Cheshire.

Edited June 8, 2021 by Happy Valley

[SteamyTea]

So if, for easy of calculation, you loose 100kWh extra a year, and energy cost go bonkers to £1/kWh.

Then in 30 years you will have saved £6k.

[Ferdinand]

How much are your green ethics worth to you?

 

Or can you get a better price?

[Mr Punter]

Definitely no and I think you should get at least 2 more quotes.

 

If there is a difference of £9000, what were the actual quotes?

 

I have found that overheating is a bigger deal in a new house than heat loss.  Look at reducing the glazed areas if possible, especially in bedrooms.

[the_r_sole]

do both work with your SAP calc?

[Happy Valley]

49 minutes ago, Mr Punter said:

Definitely no and I think you should get at least 2 more quotes.

 

If there is a difference of £9000, what were the actual quotes?

 

I have found that overheating is a bigger deal in a new house than heat loss.  Look at reducing the glazed areas if possible, especially in bedrooms.

 

Thanks for the response

 

I have other quotations from Express and one other company but these are the two which I am interested in.

 

One quote is £36000 installed and the other £37800 + £7200 for installation making £45000 ex VAT

 

We have 4 foot overhangs on the roof above the sliders to stop overheating in the summer. 

 

I am yet chip away at their quotes but with prices going up for most materials these prices might have increased since the quote and we are two months off ordering.

Edited June 8, 2021 by Happy Valley

[Mr Punter]

43 minutes ago, Happy Valley said:

We have 4 foot overhangs on the roof above the sliders to stop overheating in the summer. 

 

This will help a bit if they are south facing, but not 100%

 

Here is one we did with an 1800mm overhang, south facing picture at 13:15 on 20 April and the sun is still halfway up the windows:

 

[MortarThePoint]

Based on the U values, I'd say one set is double glazed and the other triple glazed. If so, you might want to take a look at this other thread. Also, the company that's quoted triple glazing may do double glazing option and vice versa.