Solar gain... Do I need to worry?

[Orangeinmybluelightcup]

Hello, after any advice on whether I need to worry about solar gain in my new extension, due to start in 2wks. We've planned a skylight/pod and full width glass doors. Width is about 2 double patio doors total, for an idea. Is it going to be too hot?! Tell me about your way facing rooms... We are replacing a conservatory, which is unbearable and heats the rest of the house like an oven!

If anyone has a West facing single storey room, it would be really helpful to hear if it's too hot!

Have you already arranged a supplier for the skylight and doors? If so, look into getting them fitted with solar control glass. We're south-west facing and also replacing a conservatory - it's like a furnace.

No not picked the skylight and doors yet, the builder has a regular supplier and said we can pick anything from their books.

I am wondering whether to get a skylight that opens, and whether to get an overhang built out over the doors onto the garden.

I walk dogs and feed cats for a living. Right now I am visiting many homes with lovely big kitchen extensions, bifolds and skylights.

They are sweltering! I mean really really hot! It is exacerbated by the fact that they have closed all windows so the cool night air doesn't get in. The ones with blinds are much cooler.

We are planning a similar extension and this has convinced me that we absolutely must get blinds.

I’m not good with which way things face… I guess ours is kind of north east facing? (Gets sun in the morning)
We have bifold doors about 4.5m across, plus a glazed apex above, and two normal velux skylights.
Yes it gets very warm, uncomfortably warm when it’s weather like this but would be ok with doors open. Rest of the year it’s fine and is pleasant in winter as has toasty underfloor heating.
Glass is triple glazed

Lovely to be able to open skylight
We can leave ours open at night and also not worry about kitten getting out

We have a south facing glass extension, glazed on two sides, brick on one and the other open to the house (it’s a kitchen extension). We also have a roof lantern with solar glass.

90% of the time the temperature is fantastic- a lovely pleasant warmth even in winter. The other 10% is pretty hot however, but not so much I regret it.

What I’ve learnt in the 8 years we have had it:

• if you have an option for a roof vent, get it - ideally a motorised one. We have one but the motor is broken at the moment and not having that outlet for hot air has been really noticeable over the last few days

• try to design it in some way so that you can get air flowing through the room - either through windows or open doors - the bigger you can make the doors the better

• blinds really do help, if you can install them without running the look of the room. Doubly so if you can get the heat reflective ones.

• An alternative to blinds is an outdoor fixed awning - our neighbours have one and open it to shade their extension on sunny days.

• if money is no object, there’s always air conditioning :-)

Good luck OP, it will be worth it when it’s done.

Also re blinds - solar gain aside, they’re essential if you intend locating a table or chairs anywhere the sun will be shining at some part of the day, unless you want to be blinded while eating your dinner.

Oo good point about being blinded by the sun when eating dinner, will think about this when deciding location of skylight!

We had bifold glass doors and roof lights in my previous SW facing house. It was awful. The kitchen wasn't really bearable on days like today .

Now new house same direction and we have a French doors , roof lights and a bamboo patio awning above the patio which makes a massive difference to the heat inside . Today I was in there wondering how the new owners of my last house were bearing up!!

We had blinds inside the bifolds. Didn't help that much at all

West facing house, with 3m wide glass doors and a large sky light. No blinds on either (rental house, little opportunity to make changes).

It’s like a greenhouse as soon as the sun comes out (yet chilly by the doors in winter). So far I have put up a gazebo to shade the doors, and climbed onto the roof to cover the sky light with a light reflecting cover. It’s much better, but still not great.

I would go for a motorised sky light, and ideally external shading - or at least decent thermal blinds and reflective film on the skylight.

Ah @MyAnacondaMight thank you, you've potentially saved me from a real error! Will defo speak to the builder about adding a roof overhang and pick a skylight that opens.

We're west facing with around 3m of glass and some roof windows. Since we had our old spec roof windows replaced, the heat build up has been noticeably less but I'm about to order some semi opaque blinds for the sunniest days. Having opening roof windows has been fantastic during this heat, it makes the kitchen diner the nicest room in the house as it cools down much faster in the evening than the rest of the house.
The plus side of west facing with lots of glass is lovely sunsets!

Thanks @FuglyHouse so would you say to pick an skylight that opens rather than say a sky lantern design?

It's currently 38° in my south facing kitchen, with patio doors and skylights. The thermometer was over 40 before I moved it out of the sunlight . We can't have a fruit bowl or bread out on the worktops since May ish as it just rots, and we are up North so not generally that hot!

We're planning a similar extension and I'm thinking of erecting a pergola or arbor along the south-facing side and growing a deciduous climbing plant over it, so that in the summer it will have some shade.

This sort of thing

External shading will be much better than internal for keeping heat out - i.e. shutters or an awning. Otherwise you just have a greenhouse. An opening skylight to let the heat out will be good and the aim should be to allow for a cross breeze through the room to help keep things cooler.

We have a south west facing flat roofed extension which has patio doors. It’s boiling!!!

I have a west facing single storey extension with a sky pod and bifold doors. It does get quite hot, maybe 6c more than the outside temperature. So on hot days that are 20c the room will be uncomfortably warm at 26c. On those days I tend to go and sit in the east facing lounge which is cooler. On colder days it’s great because it’s warm and I can open the kitchen door and the excess heat spreads through the house. I don’t need any heating in the house at all from May to October.

@Orangeinmybluelightcup

I think I would pick opening skylights rather than a roof lantern. It's really handy to be able to open a skylight and get good air circulation, even on a relatively still day, as the trapped warm air rises out of them. We quite often open them when cooking to stop the room warming up too much. I've kept ours open for the last few days and although the room has warmed up, it hasn't been as bad as other west facing rooms in the house. I know that some roof lanterns have opening vents but I'm not sure how large the opening is (I suppose it depends upon the size of the lantern), whereas we can open up a substantial area of the roof. Because of the design of our house, we get full sun on the extension roof from late morning, so I'd be worried that a roof lantern would turn our kitchen diner into a big greenhouse.

I know that it's possible to buy internal shades for roof lanterns, but it seems a shame to spend lots of money on a beautiful glass structure that you're going to hide behind a shade when the sun comes out! We don't have external shades on the downstairs rooflights, but we have one on an upstairs Velux, and it's been really effective at limiting the heat gain in that room. It's not at all attractive, but I put up with it rather than have an overheating bedroom.

@WaltzingToWalsingham I'm thinking something like this... But less posh

That sort of overhang looks really nice, but I fear it’s designed for south facing orientations - where the sun is higher in the sky. For west facing doors, the sun is lower by the time it hits the doors, so an overhang might not do much. I currently have a 3m deep gazebo against the doors, and by 4pm it is only just effective at keeping the sun out. I think you might need something more like a pergola, sail shade, awning, or external shutters - in order to be effective.