"Andy Hall" wrote in message
...
On Mon, 11 Aug 2003 23:28:22 +0100, "IMM" wrote:
In the book EcoHouse - A Design Guide, they gave a study that
calculated
in
1987 200mm was the optimum in walls at the then current fuel prices.
As fuel prices rise and the insulation manufacturing costs too, the
whole
payback calcs were skewed somewhat. So they calculated insulation
levels
on
energy to make insulation. They came to the thickness of 650mm. The
conclusion was that what constrains you is the detailing of the
structure
to
hold as much insulation as possible.
Note: A reputable source is given.
That all assumes a house constructed on some sort of "eco-principle"
from scratch.
No. Any house.
With 650mm wall insulation? Sure...
You don't say who "they" are, so it is not possible to
determine the reputation of the material.
You obviously can't read. The sources were given.
The authors?
Sue Roaf, and the rest can be seen on Amazon.
I did not base my illustration on that, and did not say that I was
doing so.
I clearly stated that the illustration was on the basis of today's
requirements from the Building Regulations and used figures to
illustrate the point that in the overall context of a house built to
those standards, the effect of the amount of insulation in the roof
beyond 100mm becomes negligible.
I then illustrated what the case would be for less well insulated
walls, and that is even less.
These are real-world examples from the typical housing stock of today.
Your material from CAT and elsewhere is interesting I'm sure, but I
don't really think that the average person is going to insulate their
walls with 650mm of material or even their loft with 500mm, so it's
academic.
500mm for a loft? 300-400mm CAT say, as the payback falls right off
after
that. If fuel rises dramatically in the next 3,4,5 years then 500mm is
feasible.
Let me see. In winter the bedrooms 20c and the loft 1C. Hot goes to
cold
so a difference of 19C. the larger the difference the greater the heat
flow. In summer, a loft at 48c and the bedrooms below at 25C, a
difference
of 23C. Appears better pack the loft with insulation in order to cool
the
house.
What kind of calculation is that? All you have mentioned is the
temperature difference. THe heat flow depends on the U value of the
material and the thickness as well. That's the whole point......
The pint was that insulation may be more beneficial in summer than winter.
That was obvious.
snip drivel
---
--
Checked by AVG anti-virus system (
http://www.grisoft.com).
Version: 6.0.507 / Virus Database: 304 - Release Date: 04/08/2003