On Tue, 29 Mar 2005 17:24:15 +0100, "Doctor Evil"
wrote:


"Andy Hall" wrote in message


No, I am simply pointing out that
there is no point in going to
extremes on loft insulation

Lord Hall, 12" is not extreme. In fact, there is no such thing as extreme
in insulation. Put is as much as you can, with 12" being the minimum.

I think that you've just demonstrated my point exactly.



as opposed to a reasonable provisioning
when in comparison large amounts of heat
are going out through the
walls.

It is terraced. At least half the walls is not outside wall.

You don't know that. Some mid terraced houses are narrow and deep,
some are not. Some have substantial rear extensions which have large
areas of outside wall. I once owned a house which was exactly like
that.




For one thing
the ceilings are very high in comparison
to many properties so loss
through them is greater in proportion.

..in proportion to what?


Obviously in proportion to the losses from houses with lower ceilings
and walls...........



Most wall area most probably
will be party wall.

It may or may not be.

You have an odd idea of how terraced houses are built.

Not really. I have owned a practical example where there were
substantial areas of external wall due to a rear extension. This is
a very typical construction if the property is not a two up/two down.



This doesn't alter the amount going
out through the front and back walls
which is likely to be an order of magnitude
greater than that through the roof even
if you were to only put 100mm
of insulation there.

Because more is going out through the outside wall the roof should neglected
then. What logic.

I didn't say that at all but simply highlighted looking at things in
proportion. You have demonstrated that you are incapable of doing
that, so there's no real point in discussing it.



It is best to
make the ceiling air-tight by using
silicon to block any holes and have an
insulated and sealed trap door, and
12" of Rockwool.

It would be if it were a more modern house.
This property is over 150 years old and
unless one were to implement modern insulation
standards on it comprehensively, there is little
or no value in going mad as you are suggesting
on one aspect.

Mad about what? Insulating the loft to 12" is hardly going mad. The house
will be reasonably air-tight as two sides are not outsides walls.

Going over the top with one aspect while doing nothing about the rest.
This is what the OP has said that he will do for cost reasons.


When
replacing windows and doors obviously install sealed units to make the house
more air-tight.

Obvious to who? Not everybody want to replace the character sash
windows with plastic hermetically sealed ones.
Window replacement wasn't on the agenda anyway


The walls will not be cavity, so pretty well air tight
there too.

The losses through solid brick walls in comparison even with
uninsulated cavity are huge. Have you ever looked at a table of U
values? Do you know what they mean?



It is air leakages that cost in heating fuel. It is well worth
having sealed doors and windows and ensuring the ceiling is air-tight too.

It is one of the reasons. Heating designs are based around an
assumed number of air changes per hour. Not everybody wants to live
in a sealed box as you seem to advocate.


Then the 12" of insulation will have a great effect.

IN comparison to the heat loss through the walls, the difference
between 150 and 300mm of loft insulation is negligible.

Do I need to do the sums again to remind you?


So, in time new sealed windows would be installed. Having the sealed loft
ceiling and 12" of insulation would compliment that and already be in place.


Who said anything about even wanting to replace windows?




If we were talking about a modern
house with cavity walls, cavity
insulation and double glazing, then
there is a marginal case for going
to thicker insulation.

You really don't know do you.

The problem for you is that I do and can easily demonstrate it.




The case you are making is equivalent
to arguing for a 40W bulb rather
than a 60W bulb when there is a 3kW
fire in the room.

What a mad analogy.


On the contrary. It describes the situation that you are advocating
perfectly.

--

..andy

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