Aluminium, Alu clad timber or timber windows?

[Indy]

In the process of speccing out a new build which is being built to a higher level of thermal efficiency than our current one. Most likely ICF and SIPS roof, and one of the areas we're now looking at is glazing.

 

On the initial designs that we have from the architect, she has recommended powder coated aluminium windows. Speaking to a friend, that would be a bad choice as they are not as thermally efficient as timber, alu clad timber or even UPVC.

 

What should I be looking at? Is there a clear favourite? Obviously funds are not limitless, but Ok to spend more to get better quality and looks are also important. 

[nod]

Just had a quote from Ratinal Ali clad 

£58000 Supply only 

Ouch

[ProDave]

Window pricing is very much like kitchen pricing, a random number generator followed by negotiating.  I like a few others found Rationel to give the cheapest of the quotes we received and then they negotiated down a but from that.  I am certainly happy with their ali clad windows and it should mean no painting.

[Russell griffiths]

Your friend is correct. 

[saveasteading]

56 minutes ago, Indy said:

not as thermally efficient as timber, alu clad timber or even UPVC.

 

Yes they are.

An aluminium window with the same U value as a timber or upvc window has the same thermal efficiency.

There is a thermal break in the construction so that the aluminium on the inside is joined to a separate section on the outside by a plastic link....there is no continuity.

Some are better than others.

That is much easier to achieve with upvc, which is a very large factor in the cost.

Wood is not great at thermal resistance so a good timber window also needs complex construction.

Check the U values for the type of window you want.

 

57 minutes ago, nod said:

£58000 Supply only 

Ouch

Nod, what is that roughly £/m2 if you don't mind?

[Nick Laslett]

Aluminium windows with U value 0.8, Passhive House certified. Filter by material. 
 

https://database.passivehouse.com/en/components/list/window?lat=52.283209228571344&lon=0.9176330340150688&cz=3

 

The frame depth will be 80mm approx. 
 

Aluminium windows used to use a hard plastic polyamide for the thermal break. Newer designs use PU-foam. Origin do a frame using an aerogel thermal break, which gets you a U value 0.9, just outside the PH threshold. 

 

Edited February 25, 2022 by Nick Laslett

[Indy]

22 minutes ago, Nick Laslett said:

Aluminium windows with U value 0.8, Passhive House certified. Filter by material. 
 

https://database.passivehouse.com/en/components/list/window?lat=52.283209228571344&lon=0.9176330340150688&cz=3

 

The frame depth will be 80mm approx. 
 

Aluminium windows used to use a hard plastic polyamide for the thermal break. Newer designs use PU-foam. Origin do a frame using an aerogel thermal break, which gets you a U value 0.9, just outside the PH threshold. 

 

 

That's good to know that it can be done with aluminium.

 

What U-value should I be aiming at, which is at that inflection point between cost and efficiency? Not really fussed about reaching true PH levels, as long as I get good performance out of them.

[JohnMo]

Triple aim for 0.8 on an opening window, for the whole window not the glazing.

Double 1.2, but they are difficult to find.

 

Ask for full u value calcs before you agree to buy, as many salesmen try to talk glazing u value, not whole window.

[Shoestring]

A lot will depend on the look you want to achieve.  I loathe uPVC and wanted timber, my husband didn't want the maintenance of timber so we went with aluclad (best of both worlds).  We looked at aluminium as a cost comparison, and it seemed that good efficient alu products are pretty compatible to aluclad timber price wise and I didn't like the look of aluminium internally.  I looked at loads and loads of options and chose Nordan.  A big factor for us was the cost, Nordan came out ahead of competitors there.  I really liked the profile externally - it wasn't just plain and boxy.  They do not have in house fitters so you'll need to do the leg work there, although they have a list of recommended installers (but do your own due diligence on them).  We wanted to celebrate the timber internally and Nordan offer a clear lacquered timber (other stains etc available too), the timber is engineered to make it stronger and take out the knots so looks a bit like a solid wooden counter top, with lots of small rectangular pieces finger jointed together.  If natural/stained timber look appeals to you, don't go with Rational as it's not done well.  We went for a classic profile inside, which again stopped it from looking square and boxy & gave more of a traditional feel.  We had double glazing but they do triple glazing and loads of different opening options and products with varying u-values I think they offer PH products too but don't quote me on that.  Their website lacked information as did their brochure and we struggled a bit with logistics, they weren't faultless by any means.  We have a showroom local to us which was really helpful & well worth a visit.  We're really, happy now everything is fitted, it looks great, and it was good value compared to many other companies.  Also, when there were issues, they were pretty good at sorting things out.  I will also mention Norrsken who came a close second to Nordan but were more expensive, they do however offer an in-house installation.  Hope that is helpful to you in making a decision!