Eurocell profile: Can someone interpret this u-value calculation

[MoDo]

For a SIPS building with brick skin. Walls/roof aiming for 0.12 u-value - so fairly decent thermal performance and MVHR. Trying to decide between uPVC and alu-clad. We are fairly desperate to reduce cost (thanks to budget overruns at the foundation stage) but for such an integral part of the building not sure if this is a compromise worth making. A trusted local window firm can produce (and fit) the Eurocell Modus which claims u-values as low as 0.7. I asked Eurocell whether this refers to the glass or the glass/frame combo but only received the attached as a reply. I admit to being unable to determine from the document whether this profile would be a match for the 0.8 alu-clad products at more than double the cost. 

If someone interpret the attached - I'd be very grateful.

M75-207 Calculation Summary.pdf

[JohnMo]

Last page bottom left just above the black section where it says 3 A, there is a box saying U window.  That is the overall U value of the window, either as plain glass or different window bars options.

[MoDo]

Thanks for that - so it would seem there are indeed budget uPVC options available that can indeed match the performance of the far more expensive alu-clad products. At least 'on paper'.

[Mr Punter]

uPVC is a better insulator than aluminium, so no real surprise.  It is not as strong, so often has chunkier section sizes and often needs reinforcing with steel.

[MikeGrahamT21]

I was going down the modus route, but when I finally got to placing my order, they didn't do the glass anymore that got it down to 0.7Uw, was nearer 1.0Uw, so I decided to go elsewhere. If you are buying from a uPVC wholesaler you may well be able to mix and match frame and glass, but unless things have changed, Eurocell now supply AGC glass, which isn't as good on the uvalue front.

[MoDo]

That's interesting - I'll check with the supplier, but my understanding is that they do manufacture the frames in-house using the profiles. So hopefully they can mix-and-match glass like you say.

[craig]

uPVC can and will perform better but it depends on the profile (how man chambers etc.) - not all uPVC profiles will be better than timber aluminium windows. Just to let you know, the test performed was using a 44mm glazing unit, using 4/16/4/16/4 glass/spacer and Krypton filled gas. 

You will receive a different performance if that glass was Argon filled and I would suspect a Ug value of 0.64 or thereabouts and a Uw value of approx. 0.85 / 0.9Uw possibly higher.