Posted by harry on June 24, 2009, 7:28 pm
It is an existing house I modified. It had external walls of solid
brick construction 8" thick. I put up another masonary skin of
insulating blocks spaced 20" away from the existing wall & filled with
mineral wool bats. I also extened the place & all the new internal
partitions were 8" concrete blockwork.
The extension is earth shielded ie below ground. (The site is
I made the windows myself, they are quadruple glazed ie two double
glazed units in timber frames. I suspect this may actually keep the
heat out in sunny weather so I'm not really sure if it was a good idea
or not given we have the shutters on the windows.
We've had one Winter here but it wasn't that cold really to test it
We have a very small wood stove (potbellied type) for prolonged cold
weather. I can usually scrounge up waste wood. We had it on for a
few hours during sunless spells.
Most of our heat comes from our large South facing windows &
conservatory. We open the doors linking the house & conservatory
when it warms up in there.
Posted by News on June 25, 2009, 8:30 am
I assume the floor was dug out and insulation below the floor? The existing
inner wall will be a cold bridge attacked to the ground. Did you insulate
the outside of the new walls below ground level to prevent the cold earth
from acting as a heat sink?
I assume a new roof was added. Is there a cold bridge where roof meets the
I would have thought you would want to keep heat out in sunny weather. One
window can be left open in winter if facing south to gain solar. The
internal insulated shutters should be enough to ensure heat is kept in with
only double glazing.
Wise to have a conservatory on the south side. It also acts as another
Posted by harry on June 26, 2009, 5:13 pm
The extension I put 4" of ridgid insulation under the concrete. The
old bit has a suspended timber floor. I was able to get underneath
and put insulation between the joists.
The wall insulation meets up with the roof insulation. There are some
cold bridges, I decided to leave some of them in view of the work
involved in fixing the problem. They're fairly minor though.
You might be right. Hard to say. Idon't have the instrumentato t
oprove itone way or the other.
We have a "Winter room" that has no outer walls (there is a sun tube
for illumination) Plus some borrowed light from the conservatory.
Posted by News on June 27, 2009, 9:29 am
Nice harry, nice. :)
Posted by Jim Wilkins on June 27, 2009, 1:04 pm
I stick black tape to the indoor side and measure its temperature with
an IR thermometer. With storm windows and two layers of clear
polyester film the inside of the window is no more than a few degrees
colder than the same tape on the adjacent wall.
You can track convection and infiltration losses with a helium balloon
ballasted to neutral buoyancy. If you can get it right it will rise to
the ceiling, move to the wall, drop down with the colder air and float
on top of it back to the heat source.
Mylar balloons hold the helium longer, but latex ones work pretty well
if you ballast them slightly light with paper and wet it to neutral.
Evaporation more or less balances helium loss.
I estimate the insulation efficiency by measuring the cool-down rate
at night with the stove off, and the temperature rise rate vs weight
of wood burned. There isn't much more I can economically do to improve
the insulation but the measurements tell me that the stove will have
to run flat out all day if the temperature drops to -20F, and how long
I can plan to be away, without turning on electric backup heat, before
the pipes freeze.
Solar is pathetic here in winter; my (drained) solar water heater
barely warms above freezing. Right now it's at 78F due to the stalled
storm over New England; in normal summer weather it would be 120-130F
full and 190F empty.