Which is the more effective conservatory glass

[RobFJ]

Can SKS help me with an independent view. I've got 2 quotes in to completely replace conservatory glass. The brief was, as far as feasible, to extend the months we can use the conservatory by controlling the high temps/ ideally glare in summer and maximising light and heat retention in the darker/cooler months - no tints.

The two companies have both quoted for St Gobain glass - one Cool-lite SKN176, the other Planitherm 4S. Both say their choice is the best one for us

The St Gobain leaflets don't help as Cool-lite has the Tech Spec (not that I understand it all), Planitherm does not.

Any thoughts/advice will be much appreciated.

 

[Notch7]

planitherm 4S is a low emissivity coating and is on face 3 (counting from outside).

Cool lite is a solar control tint that is in the external pane of the glass.

So 2 different things, doing different jobs!

 

[RobFJ]

Tx Notch 7 for the explanation of the difference - much appreciated

I managed to find a Tech Spec for Planitherm. Looks like Planitherm has up to double internal and external light reflectance values over Cool Lite and double the u-value.

I'm swaying towards Cool-Lite on the basis of lower heat loss as there are blinds already in the conservatory to cope with reflectance

 

[big-all]

is it already double glazed

 

[RobFJ]

is it already double glazed

Yes, about 15yrs old, with several blown panels

 

[big-all]

probably minimum difference in overall winter usage as heat loss will still be significant

 

[crank39]

probably minimum difference in overall winter usage as heat loss will still be significant

I agree, glass has moved on tenfold since even the 90's but glass alone will not give you what you want, you have to change some anyway due to failure and you've decided to do all of them which is good as you'll get the same spec/colour throughout but please don't expect miracles. I've spec'd it, I've fitted it and I've given the customers the exact same spiel the manufacturer gave me, but to no avail.

If you really want all year round use then you'll need to think about swapping to a solid warm roof......they work!

 

[Gazman16]

^^^what Crank said^^^^

 

[RobFJ]

Tx all for the contributions - much appreciated.

We had to rule out a solid roof at the start on the basis of that the adverse impact on direct light into the house would be far too great. (The joy of living in a 300 year old cottage with tiny windows

So it's doing the best we can with that constraint as a given.

 

[Notch7]

As others have said, the glass will make a noticeable difference, but your conservatory will still suffer significant temperature variations. It is because the latest glass has a u value of say 1.2 wheras a flat roof to current regs has a u value of 0.18

You will notice a worthwhile improvement though, but perhaps not the magic solution the salesmen are implying.

For a few more options see
http://www.tuffxglass.co.uk/ambience.html
To confuse things they use a mixture of Saint Gobain, pilks and guardian.

Many conservatory companies brand these glasses as their own special 'brand' -but there are only 2 main manufacturers really.

Roof glass does a few things:

-the outer pane has a solar control tint to reduce solar gain and glare
-outer pane may also have self clean coating
-inner pane has a low emissivity coating to reflect heat back in (known as a low e coat)
-spacer bar may be a warm bar to reduce thermal bridging
-gas may be argon to reduce conductivity / convection in the cavity


many conservatories have floors with no insulation and walls the same -so that also impacts on heat loss.

 

[Gazman16]

Tx all for the contributions - much appreciated.

We had to rule out a solid roof at the start on the basis of that the adverse impact on direct light into the house would be far too great. (The joy of living in a 300 year old cottage with tiny windows

So it's doing the best we can with that constraint as a given.

Have you looked at the partially solid roofs?
https://www.ultraframe-conservatories.co.uk/solid-roofs/livinroof

You can have glass or veluxs anywhere you like to still get the light in but the rest is all fully insulated and plastered