"..... But also has a much lower transmission, so you get less heat in the
first place ......."

Well .........horticultural glass has a light transition of around 90%
whilst triple walled poly carb has a transition of 84%. this is normally
compensated for by having less glazing bars and other structure as there is
so much more strength in the polycarb sheeting also it if far lighter than
glass.

--
David Hill
Abacus nurseries
www.abacus-nurseries.co.uk