On 20 Aug 2004 20:34:13 GMT, Ian Stirling
wrote:

IMM wrote:

"Ian Stirling" wrote in message
...
Rick Dipper wrote:

I have worked out the U values of the insulation I intend to use in my
cavity walls, I have 2 solutions

1) Blocks -celotex-rockwall = 0.224 W/m2K
2) Blocks -2 * rockwall = 0.255 W/m2K

0.255 is poor. You should be aiming for 0.1ish

It kind of depends on the property.

0.1U would here (on all walls, floor and ceiling) result in overheating
most of the time except in sub-zero temps from the ambient electrical load,
and human inhabitents, not to mention solar gain.

If going from 0.25 to 0.1 costs around 1500 quid extra (and incidentally
knocks 50 cubic meters off the habitable space), saving me no money,
unless it goes below 10C outside (heating set to 20C now) and vanishingly
small amounts if it does. (currently I reckon the overall insulation is
about 900W/K, with the walls having a U of about 2.4)

Which works out at about 10 pence of elcetric an hour, that sounds
good to me, especailly if we go geo-thermal and get it down to 2.5
pence an hour.

Thanks Ian, I now see a second problem of overinsulation, overheating.

Rick