How warm are Glass roof extensions?

[jenks14]

We are looking at having a single storey extension and can't decide between a glass roof or regular roof with velux's in. The main concern is the room becoming cold in the winter if we have glass and lack of light if we have velux's. Does anyone have any experience of the warmth of a glass roof extension?

[McPhee]

Yes.

Blooming awful. I'm an ex nanny, and one of my familys had one which also had a glass wall. No one could stay in there for very long during warm days for fear of fainting. You could literally stand there and get a sunburn. The condensation used to run off of it as well.

[MulledWineOnTheBusLady]

No experience but marking place cos I wants one! I don't like Veluxes as much, they're a bit ugly, but saying that when I see a house with them I'm always surprised by how much light they give. And I would imagine it's a fair bit cheaper than top of the range glass too.

How old was their extension, McPhee? May be wrong but I get the impression glazing technology has really come on in the last few years (ie as we've started copying everything the Scandinavians have been doing for several decades).

[NotInGuatemalaNowDrRopata]

We have an extension with three large velux windows and bifold glass across the whole back. In summer it gets seriously hot, even with reflective blackout blinds. We got white velux which I think are inoffensive.

Another consideration is the brightness. Yes, it's fab to have a light filled room, but sometimes it's so bright you can't see the tv

And in winter it's cold.

Having said that, I still love it!

[ogredownstairs]

Love ours ( sort of glass cube thing) for the light, and it's perfect at this time of year before it gets too cold. Having said that if I was doing it again I'd probably go for a pitched roof and veluxes as it def. gets too hot in the summer and too cold in the depths of winter - even with specialist blinds and u-floor heating.

[jenks14]

Thanks for the comments, I am sure they will help us make our decision.

[herhonesty]

You can get conservation grade roof lights which are marginally better than velux.

[herethereandeverywhere]

Really depends what direction the roof (and any accompanying glass doors) face.
Also depends what is planned for heating/cooling and insulation.

To reduce the 'greenhouse effect' the optimum position is north facing. We have a north facing side return (glass roof) and bifold doors (west facing/slightly northwest). We get very little direct sunlight onto the glass so there is very little heat magnification. On top of this we have glass which is coated with a solar-reflective layer which reduces the heat by up to 40%.

We have underfloor heating (waterpipe not electric mat) which keeps the place at a constant temperature in the cold months but does take a while to react to variation of temperature (you have to wait hours for it to heat up/cool down).

We also have an air conditioning unit in the room (lovely looking LG mirror one). They are incredibly energy efficient and heat as well as cool (so much so they attract a reduced rate of VAT). The heating mode is invaluable for when there's a sudden drop in temperature and your underfloor heating setting hasn't caught up. I also needed the assurance of not feeling like I would boil to death on a summers day! I don't think the room is that much warmer than velux/regular roof because it happens to be north facing but even so, being able to cool the place in 5 minutes is a luxury worth building into the budget if you can.

[herethereandeverywhere]

Should have said we're comfortable in here year round - it's also our main living room, have sat cosily whilst DH and DD made snowmen a few feet in front of my eyes earlier this year!

[kittycat68]

we have glass extension roof and we are south facing, also have the reflective film on to and would highly recommend this. as we are south facing itd really quite warm in the winter with our heating bills very low beacause of this but i will say we do have to have a fan on sometimes in the summer beacause it gets a bit hot on some days! The reflective film isnt cheap but is well worth the money and you get it back in your heaTING bills. mine was built two years ago lovely and light all my friends love it. Modern double glazed roof units dont loose as much heat as you would think .

[PigletJohn]

of course it will be cold. Unless you constantly pour heat into it to warm the sky.

Consider the roof of your house. As well as tiles, felt, and a plaster ceiling, it has anything up to 250mm of loft insulation. You glass roof will have about the insulating ability of the plaster ceiling.

OOI, I once lived in an old house with no insulation. During the cold winter, a 3kW fan heater running constantly kept the chill off the 12ft square bedroom, but it never got properly warm. When I insulated the loft, a 500W heater kept it warm, and clicked off on its thermostat after a short time.

[FlatCapAndAWhippet]

We have an extension to our kitchen with a glass roof and wall, that opens on to the garden. It has the solar reflective roof which in my opinion, is definately worth the extra cost, it significantly reduces the heat in there during the summer. That said there were a couple of days this year that the heat made in uncomfortable to be in there for too long (south facing). As for the winter, it is never cold, it has a stone floor on which we have a big sisal rug, the kitchen table is in there, big armchair, kids stuff etc but we have two powerful radiators belting out the heat. My absolute dread was that it was going to be flippin freezing, it's the total opposite but you can see the difference in the heating bill!

We love it, it's the heart of the house.

[HECTheHallsWithRowsAndFolly]

you only need to put your hand on one of your windows to know. Glass doesn't keep the heat in at all.

[Sleepwhenidie]

We also have a similar set up to how Kitty and flapjacks sound, (pics on profile) - modern solar reflective glass, sw facing, only too hot on freakishly hot days in summer (say >30deg), but we have some shade from a two and a half storey wall alongside the kitchen though, so its not relentless sun all day.

Re winter, we have underfloor heating (no rads) and the kitchen is open plan, it never feels cold. We love it.

More of a shock then the heating bills was the window cleaning...self cleaning glass just isn't

Re insulation, there won't be a loft on a single storey extensiom as OP describes it with velux windows, so modern glass/plaster and tile probably not so different in terms of heat loss, or am I missing something?

[PigletJohn]

A flat roof can (must) be insulated to modern standards and lose as little heat as a pitched roof with loft. It will be vastly better insulated than a glass roof or a tent.

[DiBaker]

Hi I thought I?d jump in here as we had the same problem with our old conservatory roof (which was plastic). In the summer it got far too hot to relax in and we didn?t use it at all in the winter as it was freezing. We had a new glass roof fitted by a company called Refresh Glass Roofs in August and it?s done the trick. Even when it was sub-zero temperatures the other week the conservatory was lovely and cosy. We?ve got underfloor heating in there and it doesn?t need to be on half as much as we used to have it on for!

[Sportbluehorse0]

I'm thinking of doing what herethereandeverywhere has done. Anyone able to let me know how much it is likely to cost - side return 3.6m x 1.7m and bifold doors approx 2.5m wide (similar to pic in my profile)?

[theflyingpig]

Many apologies to hoof a old thread but it seemed very topical in today's sweltering heat [I googled something like 'velux glass roof too hot' & was brought to this thread].

My two penn'orth - glass as a construction material:

(a) it looks beautiful, no doubt about it, round our way in SW London no recently built side return extension [including ours] is complete without it; but
(b) it's, well, folly basically. almost whatever type of fancy glass you use it'll always be too hot in hot weather & too cold [without adding a few hundred quid to your heating bill] in winter.

My DW loves ours though. Can't resist an opportunity to open the bifold doors in summer. The unspoken truth, however, is that, without opening them fully, the heat in there is unbearable.