IMM wrote:

"Rick Dipper" wrote in message
...
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.
snip
There is no problem of overheating. Where do they come from?

Unless you are insane, there is no point in insulating better
than where the minimum solar gain plus energy emitted by the house
equipment and householders causes a temperature rise high enough over
ambient that it'll be warm enough even on the coldest blizzard.

Adding more just reduces habitable volume, and adds cost.
You've also got to consider on whether you want to hit this level.

At what point does the income of just sticking the money in the bank of
a portion of your insulation at base-rate exceed the savings on possibly
rising energy costs.