do you mean 4-12-4-12-4 ?

It ain't that simple either! as there are low E films, gas fillings, type of glass low iron or etc to think about

Have you heard of, or tried ProFin, from Finland funily enough...?

See : http://www.profin.fi/en/main

I am about to see them installed in a timber-framed project, with a claimed Uw-value of 0.97

When they are in, I will try to get some jpegs posted up...

Cheers

Can I just butt in quickly to ask if there's a link to somewhere that explains what any of this means?

We're all GBS here for our last few orders of 3G (krypton filled, low e etc).
Mainly because of the fit of opening parts TBH - everything they've done seals really well.
We did have a few teething probs with glazing but they always sort them out.
In comparison others have seemed leakier. I'd be scared to switch to something else unless it can be demonstrated that they are suitably "schnick".

Posted By: palebluedotCan I just butt in quickly to ask if there's a link to somewhere that explains what any of this means?

They're talking about triple glazed (3G) windows - 4-15-4-15-4 is the glazing spec - 4mm glass/15mm space/4mm glass/15mm space/4mm glass.
Inward opening is the norm in europe. space can be various gasses and the spacer material is important as the aluminium spacers typically used in standard glazing units acts as a thermal bridge reducing the benefit of the window.

Uw is a specific way of measuring U value for windows.

seascape, thanks for the NorDan tip. See http://www.greenbuildingforum.co.uk/forum114/comments.php?DiscussionID=3691&page=2#Comment_131875 . I'm adding them to the quote invite list.

Not having looked at NorDan lately, they seem to have 3 ranges, not just the 2 shown online.
All-timber or aluminium clad externally. All have clip-in aluminium glazing beads all round, even the all-timber windows.

The 2 online ones are
N-tech 1.2, 2G, max Uw 1.2
N-tech 0.7, Passivhaus 3G 16 gap with insulated frames
Both offer inward and outward opening compatibly interchangeable.

There's also still N-tech 0.9, 3G 12 gap with uninsulated frames - but only outward opening.
Pity, because that's just what I wanted, but inward opening. Still, will seek quote, for comparison.

Fostertom - I had an excellent response from Skaala UK office. Prices appeared competitive and the windows were very good quality, well, they are Finnish and they have slightly worse winters than over here! We visited their office in Suffolk and looked at the windows and doors there.
Project died - but - looks as if it may get going again! We'll probably stay with Skaala for supply only. Strangely we had a Finnish family staying in our holiday cottage and they had a beautiful timber house with Skaala windows - spooky!
Regards, Jonathan

I thought I would share this with you - many windows are sold on U-value but there is a mutch more subtle g value (not Ug which is the U value of the glass). Although U value is important its only part of the storey

SF = Solar Factor, commonly used in Europe sometimes known as ‘g’ value is the same as Solar Heat Gain Coefficient (SHGC) used in the USA. The Solar Factor is the ratio of the total solar energy entering through the glass compared to the incident solar energy. This total energy is the sum of the solar energy entering by direct transmittance and the part of the energy absorbed by the glass and re radiated to the inside.

U value = the relevant insulation value of the glass as per EN673 calculated as Heat transfer through the glass

For a build it can make an amazing difference

Glass A : 0.6 U value – 37% g value
Glass B : 0.7 U value – 61% g value

Note: For DEAP changing values is harder to do as you have to also update the overall window U-value – so I have just altered the g value for purposes of demonstration
Glass A :
PHPP: 19Kwh/M2
DEAP: 3667 Kwh/Annum heat use
Glass B :
PHPP: 14Kwh/M2
DEAP: 2205 Kwh/Annum heat use

So a 66% reduction from DEAP calcs and 35% reduction via PHPP – WOW!!!!!!!

(just adding for those who do not know - DEAP is the Irish calculation s/w for working out a building energy rating based)

Fostertom,

+1 that...!

Ok - thanks for the feedback - I have been driving these numbers out of PHPP.

So are we saying that using PHPP to bring down ones heat demand via tweeking the g value might not be the best approch

Overheating worries me - but PHPP is showing that my building overheats for less than 5% of the time (it is Ireland !!!)

I thought PHPP allows for orientation and regional situation... so that you can model the dwelling exactly in it's proposed location?.. and then specify the overshading for each opening??

Cheers and good luck..

As far as solar gain is concerned PHPP is in full defensive mode - concentrating on avoiding danger of summer overheating (and in the process discounting the simple possibility that people can open windows and thro-ventilate in summeer - PHPP seems to keep on assuming closed windows and MHVR all summr long). Having thereby strictly limited south window area, PHPP does take account of the remaining dribble of solar gain for winter heating.

It's defensive - very far from positively taking max. advantage of winter solar gain. In that respect, PHPP is old-fashioned, based on Dr Feist's research of 25yrs ago, whose considered priorities and 'not worth its' (prob sound then) are still taken as almost religious article of faith (try saying what I'm saying now on AECB.net - the reactions are ... reactive!).

One consequence is that, as PHPP is only interested in summer sun as an overheating threat, it only models the shading of same that the building itself creates, by deep reveals, overhangs etc. It ignores the shading caused by lower external features, like surrounding buildings, trees, horizon in general. Tho the latter are mostly out of the picture as far as high summer sun is concerned, these lower obstructions are all-important to low winter sun. PHPP ignores them.

So these comments are a bit short of the mark:

Posted By: DarylPPHPP allows for orientation and regional situation... so that you can model the dwelling exactly in it's proposed location?.. and then specify the overshading for each opening??

Posted By: wookeyPHPP allows for reveal depth so I'm assuming it does something sensible about orientation and g-value

PHPP needs a major overhaul, or will be superseded.

I'm at home now, so I have PHPP in front of me, and I don't agree either. PHPP does have inputs for specific factors such as reveals and brise soleils, and surrounding buildings, but it also has a general override on the Shading worksheet to allow for any other factors. It does treat E, W, N, S and horizontal windows differently for radiation as well, and is based on local climate data if available. It does allow you to enter figures for open window ventilation and for night cooling and there's a special SummVent worksheet. As well as the Shading worksheet, there is also the Shading-S worksheet, specifically for summer shading such as blinds and trees.

So I'm not sure where your very negative view comes from, Tom?

Posted By: fostertomWhat you've both said doesn't much reassure me.

What is your better suggestion, Tom, of a suitable method (i.e. program) that is tested and so known to be accurate? i.e. not your ideas of what ought to be done and could be developed, but a useful program I can use today to design a house with the same confidence that the house as built will perform approximately the same as the model?

Got an amazingly low price from Munster Joinery, as recommended by VikingHouse, but impossible to pin down exactly what's being offered, either online, by phone or in stuff they've sent me - so awaiting a rep visit with samples on Feb 7. I'm v hopeful.