greenhouses

[gardenmad]

Does anyone know if polycarbonate glass in grrenhouses is as good as horticultural glass - will it be as efficient in keeping the greenhouse frost free with a heater, of course?

[buildersmate]

The main benefit of glass (over polycabonate) is its ability to transmit infrared frequencies from the sun - thus warming the inside the glasshouse.
Single glass (or indeed single polycarbonate) are both pretty useless at avoiding conduction of heat - which is how the inside gets cold in winter. Any one with single glazing in their house windows will vouch for that. That's why one resorts to a heater.
Plastic (polycarbonate) is marginally better, but not the reason for shifting to ploycarbonate from glass - which is surely to do with avoiding breakage/sharp glass edges.

[gardenmad]

Thankyou, buildersmate for your answer - I was hoping to avoid buying glass as it is so expensive - to replace my existing (over 50 years old) Alton greenhouse will cost over �2000, which I do not want to pay at the moment - a polycarbonate one would be about �600. I have got a lean-to glass extension to the house but it is only single glazed - could I get those triple poly somethings to double glaze it, if they would fit? Anyway, thanks again.