"m Ransley Dec 27, 8:58 p
Is it 10% more, optimal wall insulation is well below ceiling ratings,
from what I have read at different sites even SIP construction by near
50%. Alot is construction techniques but still retings are much lower
Here's a good link that has some real data:
It looks like a skylight has roughly 2X the heat loss of a similar
vertical window, so you are right. They also explain why. It seems
the main effect is that with a skylight being installed close to flat,
the gas between panes circulates bottom to top, carrying heat from the
inner pane to the outer. With a vertical window, the gas between panes
doesn't move directly from pane to pane, so less energy is transferred.
Kind of strange, as I would think that would be a second order kind
of effect, but apparently it makes a big difference.
I'm sure there is some heat gain from the sun during winter that helps
offset some of this. It might even offset all of the difference in
some climates. Of course in the summer you have the opposite effect,
where now the heat is working against you. Still, if the differential
is 2X, it's still not all that bad.