How good is modern glass thermally?

[JP_]

I have always been against conservatories - cold in winter, boiling in summer! But after having my loft done a learned a thing or two about u values, and modern glass is pretty low - but is it low enough. What I cannot find is a guide to u-value comfort, e.g. room with u-values X will cost £y/hr to keep cosy at zero degrees. Have been looking at these Solarlux conservatories and they look perfect - but how can I be sure I won't regret it when the mercury hits minus five? The room will be a living room / dining room, not a fair weather one.

Basically, building regs says U Value of greater than 1.8 (I think that is currently the case), which I think these windows achieve, but is that enough for comfort in harsh conditions? I assume U-values are applied to windows in general - but an insulated wall and roof with a window is not the same as a wall and roof made entirely of glass!

(I was about to say, I bet most people will reply with "just build an extension" - so a poll! )

 

[chappers]

Exactly.
Uvakues are about conservation of energy. Sitting in a glass box will be much hotter in the summer due to UV penetration.
Imagine this in a hot sunny day would you rather sit in a tent or a greenhouse.
Well the glass probably has a much lower u value than the tent fabric.
Not sure where you got your info from the regs state a u value of 0.18 for an extension roof or 0.28 for a wall. A std double glazed unit is around 1.1 to 1.5. God knows what conservatory glass is.
Just had a look at what your looking at. Thats a bit more than a conservatory. How much are they? Will still cost more to heat than an extension and be hotter in the summer.

 

[JP_]

No idea about cost, not enquired. Might see if I can find a Solarlux installer / builder closer to home, they are a long way from here.

 

[Rad1o]

If you get them to use triple glazing the insulation improves again, but this may come at a price. The summer is always a problem unless you can keep the sun out.

 

[chappers]

If you get them to use triple glazing the insulation improves again,

But only if you up the unit thickness and the air gaps. For example take a 28mm unit 4-20-4 if you introduced a third pane so 4-8-4-8-4 then the triple glazed unit would have a higher u-value about 1.1 compared to 1.2
Though this could be counteracted by using better glass in the triple unit for example adding a second layer of low-E glass which would bring it down to around 0.9.
To be honest I doubt the cost would justify it, also this would reduce any solar gain you might get in the winter, but conversely might be beneficial in the summer.
There is no simple answer

 

[Gazman16]

Have a look at Ultraframe's Livin roofs too

 

[God]

Most of the issue with a cold or hot conservatory will be with the roof material used. that's why they are pushing these for connie roofs
https://www.guardianroof.co.uk/