On 30/12/17 01:19, Tricky Dicky wrote:
The heat loss through a glazed roof will be horrendous even if double glazed if our old conservatory roof was anything to go by. We replaced it with a lightweight insulated roof and so far through the coldest parts of winter the temperature has stayed about 1C at most below the temperature of the lounge where the thermostat is situated this is despite a considerable amount of glazing remaining. If you feel you need some light coming through the roof then I would limit it to smaller roof lights.

Richard


You can get to 0.6W/mK with this:

file:///home/tw/Downloads/Pilkington_energiKare_Triple_and_Pilkington_Insuli ght_Triple_High_WER_Scores.pdf

That's worse than the recommended for roofs. However, it equates, on a
15m2 room, to a loss of 189W if heated to 21C inside and freezing outside.

The recommended value is 0.15W/mK so the loss there would be: 47W

So a triple glazed glass roof is losing an extra 142W which is about 2p
per hour at 13p/kWhr electrical heating - ie bugger all.


It also fails to take into account solar gain (a positive) in winter.


I would say: talk to the BCO. They may allow it, or may allow it with
compensatory improvements elsewhere in the building.