"Andy Hall" wrote in message
...
On Thu, 22 Jan 2004 00:02:57 -0000, "G&M" wrote:

"Christian McArdle" wrote in message
. net...
Is there a noticable difference in loft insulation (rockwool rolls)
in
insulating greater than a 4" depth?

Yes. The law of diminishing returns says that 350mm is the best
environmentally speaking. Any more and the environmental cost of
manufacturing and transporting the insulant is higher than the energy
saved.
100mm is definitely on the low side. 200mm would be better. The
difference
between 200mm and 350mm isn't that great.

Are you sure on this. It's just I heard the ODPM people who set the
building regs were talking about as much as 450mm in the next part L.

They talk about all sorts of things. This one is pure pandering to
be seen to be doing something towards the Kyoto protocol. It has no
basis in economics or anything else when put into the context of where
domestic energy should be being saved.

This is ********! The Whole House Book has a graph that says 350-400mm is
the current optimum price/performance. If fuel rises, which it will as
cheap energy is coming to an end, then this is meaningless and 450-500mm is
the optimum. Ecohouse - A Design Guide says there is no upper limit to
insulation, as it will pay for itself eventually. There is also the comfort
factor of high insulation and that it also keeps the house cool from a loft
hat may be 55C in summer.


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