Reducing conservatory solar gain

[Roly]

I need to re-roof a lean-to conservatory, it's south facing and gets no shade, so summertime heat build-up is something that needs to be controlled.

When asking for advice, the consensus seems to be that a tinted solar glass roof is going to reduce the heat more effectively than any other material.

However, other people advise that opening roof vents would be a better solution as they allow the heat to escape.

Obviously the best solution appears to be a glass roof with opening vents, but that wouldn't be possible within the budget we have.

So what is likely to be our best value solution ?

One option might be a glass roof, the other would be a polycarbonate roof with vents - possibly automatic vents.

On a related subject, if we were to have roof vents, the natural ventilation would be better if there were controllable vents near floor level, so that air would enter and rise to the roof. The science seems fine, but I'm unclear about the practicalities. We have a brick dwarf wall and the vents would need to be fitted through the brickwork. What would be the best hardware to use, bearing in mind that we get ants trying to get into the house and would prefer something ant-proof ?

[Andy Hall]

Vents and blinds.

Polycarbonate roofs are a really bad idea, especially when it rains - very noisy

[Roly]

Noise under those circumstances isn't a particularly serious consideration. for us Are there other significant drawbacks to a polycarbonate roof ?

[Andy Dingley]

Solar gain and heat build-up isn't the same thing as excess temperature. Vents let you reduce this only when you need to, at the height of Summer and the peak of temperature. For the rest of the year, any heat gain is usually welcome.

Extra wall layers reduce the rain noise on polycarbonate substantially. You don't have to use the cheapest coldframe grade.

[manatbandq]

External blinds.

MBQ

[AJH]

This strikes me as a sensible idea, remember the blinds that used to be pulled down in front of butchers and greengrocers?

This whole point about greenhouse effect is that direct solar radiation passes through glass but once it strikes a surface and is re radiated the glass doesn't transmit it, so heat builds up inside and has to be vented. So theoretically a blind pulled over outside should be far more effective, having said that I had a land rover with a "safari" roof, basically a plain metal sheet over the normal roof with an air gap, this was supposed to intercept direct sunlight but didn't have a noticeable effect.

AJH

[Roly]

Are you thinking of any specific types of blinds that are designed for this particular purpose, or or you thinking of those awnings that are offered for sale, which extend out from the wall ?

[manatbandq]

I was thinking of whatever you can find or make that is external. I don't know if anything is commercially available.

MBQ