Conservatory solar gain reduction

[Frazer Jolly Goodfellow]

At present we have pleated fabric roof blinds in our conservatory that cost a fortune, don't really work very well in keeping solar temperature gain down on sunny days and have become tatty in only a few years use. So I'm considering 'solar foil inserts' slotted inside the polycarbonate panels of the conservatory roof.

Product suppliers claim 80% and upwards "solar heat rejection" which sounds a lot but how effective are they in practice?

Are they as easy to fit as claimed?

Any 'gotchas' to be wary of?

Recommendations re products and suppliers?

Alternatives to achieve the goal of making the conservatory more usable in mid-summer?

[dennis]

That's because internal blinds don't keep the solar gain down (much).

They are less inside so will work better. The best is an external blind or shade.

Drink plenty of water.

[andrew]

White canvas awning *outside* the glazing?

AJH

[pete]

Roof vent? Not got one myself, but this one looks interesting

[meow2222]

Deciduous climbing plants on the outside will provide shade in summer, plus fruit, and drop their leaves off for winter sun. The leaves will make a mess of course.

Ventilation went interior temp is greater than exterior.

Ventilation at night to cool the thermal storing floor so the daytime temp rises later and less. This works well, but requires a fan to run most of the night. Ajar windows are inadeqaute.

Silvered mylar curtains.

Those are a good start, and probably plenty.

NT

[The Natural Philosopher]

The whole point of consrvatories is to be sat in in spring and fall whn its too cold outside.

If you want a cool room in summer, build a basement or cellar.

[dennis]

Runner beans are quite good and you remove them in winter.

[meow2222]

Wouldnt it take all summer for them to cover the roof?

NT

[Frazer Jolly Goodfellow]

The solar foil insert products are described as:

"biaxially oriented polyester film with a sputter-coated metalized layer"

"advanced, ultra-clear micro-thin metalised polyester"

Is that anything more effective than tinted plastic?

[pete]

I guess you could save a packet (when I enquired of the manufacturers, they were quite expensive) by cutting up some foil strips and using them. The only difficult bit would be inserting them all the way into the polycarbonate panels without tearing or breaking them.

[Synapse Syndrome]

That's Mylar - the most light reflective stuff you can get. It's used extensively to protect satellites and space vehicles from the sun. People that grow special herbs hydroponically indoors also use it to line the grow-room, so that all the light ends up being absorbed by the plants.

Mylar is nearly perfectly light reflective - much much more than aluminium foil or glass mirrors. It's also totally flexible and very hard to tear.

ss.

[meow2222]

Silvered mylar film comes in 2 grades. Space blanket reflects... not sure but somewhere vaguely around 66%, and costs peanuts. The very high reflectivity stuff is used for sun pipes, and is close to 100% reflective.

NT

[Frazer Jolly Goodfellow]

Performance figures quoted by one supplier for its solar foil products: UV rejection 99% Solar rejection 80% - 88% Light transmission 14% - 10% Glare reduction 80% - 87%

... and claims solar rejection for fabric blind: 17%

Improving solar rejection by a factor of 5 times sounds like it may be very effective. Can anyone can confirm that from real-life experience of it?

[Bruce]

I don't have personal experience, but an office building I used to visit regularly had a large waiting area in a lightwell that had been covered in with a conservatory-like structure.

On my early visits the waiting area was insufferably hot and stuffy despite some roof vents. The owners decided to take professional advice and an architect advised a reflective solar film (foil?) which was expensive and took several weeks to apply - this was over quite a large area and quite high, needing scaffold towers to fit.

On my later visits, after the work was done, the waiting area was completely transformed. It was much cooler but at the expense of losing quite a lot of light. But waiting there was a much more pleasant and comfortable experience.

[David]

We have this kind of system at our school, if you go past on a summers night you will see all the windows wide open, all the windows have been placed in specific areas, so some classrooms have stack ventilation and others cross ventilation.

The building felt really nice and fresh in the morning sometimes almost too cool, at around 1500 it began to get a bit hot but other than that it works great.

All windows are opened by electric motors which are controlled by the advanced ventilation control software (like a BMS but it is specifically for the ventilation)

There is also a weather station on the roof which closes certain windows when it rains or gets too windy.

During school hours the windows will not close on anyone's fingers but at night if any movement is detected the windows close.

You could leave the windows open at night but you will have to worry about burglars etc.

[PCPaul]

We fitted solar powered roof fans in ours. Worked surprisingly well for knocking the top 10C off the temperature, the only problem was the only ones we could find at the time (10 years ago?) were a bit flimsy and not that well balanced so they made the roof buzz when on full chat.

Two 8" fans near the ridge of a 16'x9' conservatory did make it a sensible temperature, though. I was surprised how much effect they had.