Anybody got any figures for these (and ideally pointers to sources of such
figures)? I can't find them in Part L or BS5449(1990). The BS has values for
floors with Bare boards and "Parquet, lino, rubber" (rubber?!): I wouldn't
have expected them to have laminate in 1990, but I'm sure we had carpets
even back in those days!

I know I could calculate the U of the flat roof from its component
materials - I'm just being lazy! I am surprised they don't include it
though.

--
John Stumbles
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-+
I've got a book about motivation but I've never got round to reading it

On Sun, 4 Jan 2004 15:22:15 -0000, "John Stumbles"
] wrote:

Anybody got any figures for these (and ideally pointers to sources of such
figures)? I can't find them in Part L or BS5449(1990). The BS has values for
floors with Bare boards and "Parquet, lino, rubber" (rubber?!): I wouldn't
have expected them to have laminate in 1990, but I'm sure we had carpets
even back in those days!

There are tables in the help files of the Myson and the Barlo heatloss
calculating software. If you want the Myson one (their web site is
under construction) I can mail it to you.
There is also a good table and sets of numbers the HVCA Central
Heating Design Guide.

For the roof, the main factor is going to be the amount of insulation.

Figures I have are 2.04 for uninsulated, 0.80 for 25mm and 0.54 for
50mm. Probably after that, the figure is going to tend towards the
U value of the insulation and the rest becomes almost irrelevant.


For the floor, you have to take into account the perimeter/area factor
if it is a ground floor so there are tables of numbers rather than
single figures.



I know I could calculate the U of the flat roof from its component
materials - I'm just being lazy! I am surprised they don't include it
though.

..andy

To email, substitute .nospam with .gl

Andy Hall wrote:



For the floor, you have to take into account the perimeter/area factor
if it is a ground floor so there are tables of numbers rather than
single figures.


In any case teh tables are not hugely accurate. In my case they are
probabvly accurate for a floor that is unvented underneath, but when the
east wind blows and the stupid an unncessary underfloor vents (its a
suspended block and beam floor) let oit all in, it drops in temperature
a LOT even WITH insulation.

Anyone know what a rotless suspebed concrete floor has to have
underfloor vents? The Building inspector muttered something about
letting flood water out...Oh well. At least it allows me to pick up air
for open fires by punching down a foot into the void...

"Andy Hall" wrote in message
...
On Sun, 4 Jan 2004 15:22:15 -0000, "John Stumbles"
] wrote:

Anybody got any figures for these (and ideally pointers to sources of
such
figures)? I can't find them in Part L or BS5449(1990). The BS has values
for
floors with Bare boards and "Parquet, lino, rubber" (rubber?!): I
wouldn't
have expected them to have laminate in 1990, but I'm sure we had carpets
even back in those days!

There are tables in the help files of the Myson and the Barlo heatloss
calculating software. If you want the Myson one (their web site is
under construction) I can mail it to you.

Yes please; I thought I had a copy somewhere but can't find it now I need it
:-(

The Barlo one's tables seem to be cribbed straight from the BS.

There is also a good table and sets of numbers the HVCA Central
Heating Design Guide.

"Domestic Heating Design Guide", £20, treeware perhaps?

For the roof, the main factor is going to be the amount of insulation.

Figures I have are 2.04 for uninsulated, 0.80 for 25mm and 0.54 for
50mm. Probably after that, the figure is going to tend towards the
U value of the insulation and the rest becomes almost irrelevant.

I'd expect it to have 100mm glass fibre but I'd need to ask the guy who put
it up. I'll shoot for 0.5 which should be close enough for jazz.


For the floor, you have to take into account the perimeter/area factor
if it is a ground floor so there are tables of numbers rather than
single figures.

The BS just has a couple of fudge factors for different floor areas of solid
floors (reflected in Barlo's 110sqm, 50sqm and Terraced house options).



--
John Stumbles
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-+
Thank God I'm an atheist

On Sun, 04 Jan 2004 23:21:28 +0000, The Natural Philosopher
wrote:

Andy Hall wrote:



For the floor, you have to take into account the perimeter/area factor
if it is a ground floor so there are tables of numbers rather than
single figures.


In any case teh tables are not hugely accurate. In my case they are
probabvly accurate for a floor that is unvented underneath, but when the
east wind blows and the stupid an unncessary underfloor vents (its a
suspended block and beam floor) let oit all in, it drops in temperature
a LOT even WITH insulation.

I suppose you could then treat it as though the entire floor was
exposed to outside temperatures (i.e. like a wall) and ignore the
periphery effect.
For the purposes of a heating requirement calculation, and assuming no
draught through the floor adding to air changes, this would give a
conservative figure (i.e. worse heat loss than it probably is).


Anyone know what a rotless suspebed concrete floor has to have
underfloor vents? The Building inspector muttered something about
letting flood water out...Oh well.

Do they have four toes? I know that there's strange tales from those
parts..... :-)

At least it allows me to pick up air
for open fires by punching down a foot into the void...

You should have built the floor stronger....... ;-)



..andy

To email, substitute .nospam with .gl

On Sun, 4 Jan 2004 23:23:59 -0000, "John Stumbles"
] wrote:

"Andy Hall" wrote in message
.. .
On Sun, 4 Jan 2004 15:22:15 -0000, "John Stumbles"
] wrote:

Anybody got any figures for these (and ideally pointers to sources of
such
figures)? I can't find them in Part L or BS5449(1990). The BS has values
for
floors with Bare boards and "Parquet, lino, rubber" (rubber?!): I
wouldn't
have expected them to have laminate in 1990, but I'm sure we had carpets
even back in those days!

There are tables in the help files of the Myson and the Barlo heatloss
calculating software. If you want the Myson one (their web site is
under construction) I can mail it to you.

Yes please; I thought I had a copy somewhere but can't find it now I need it

On its way to you....


:-(

The Barlo one's tables seem to be cribbed straight from the BS.

There is also a good table and sets of numbers the HVCA Central
Heating Design Guide.

"Domestic Heating Design Guide", £20, treeware perhaps?

Yep. www.hvca.org.uk

£19.50

It has a bunch of other useful data as well such as pipe sizing,
radiator derating, pressure vessel sizing. I found it useful to
have everything in one place.


For the roof, the main factor is going to be the amount of insulation.

Figures I have are 2.04 for uninsulated, 0.80 for 25mm and 0.54 for
50mm. Probably after that, the figure is going to tend towards the
U value of the insulation and the rest becomes almost irrelevant.

I'd expect it to have 100mm glass fibre but I'd need to ask the guy who put
it up. I'll shoot for 0.5 which should be close enough for jazz.


Certainly at 100mm and up figures get quite close to the material's U
value. In reality the loss will be a shade less, but that goes in
the right direction for a heating design.



For the floor, you have to take into account the perimeter/area factor
if it is a ground floor so there are tables of numbers rather than
single figures.

The BS just has a couple of fudge factors for different floor areas of solid
floors (reflected in Barlo's 110sqm, 50sqm and Terraced house options).

For a boarded floor (non T&G), I suppose one should consider the
draught proofing effect of the carpet as well, but that is pretty hard
to assess.....

..andy

To email, substitute .nospam with .gl

"Andy Hall" wrote in message
...
On Sun, 4 Jan 2004 23:23:59 -0000, "John Stumbles"
] wrote:

"Andy Hall" wrote in message
.. .
On Sun, 4 Jan 2004 15:22:15 -0000, "John Stumbles"
] wrote:

Anybody got any figures for these (and ideally pointers to sources of
such
figures)? I can't find them in Part L or BS5449(1990). The BS has
values
for
floors with Bare boards and "Parquet, lino, rubber" (rubber?!): I
wouldn't
have expected them to have laminate in 1990, but I'm sure we had
carpets
even back in those days!

There are tables in the help files of the Myson and the Barlo heatloss
calculating software. If you want the Myson one (their web site is
under construction) I can mail it to you.

Yes please; I thought I had a copy somewhere but can't find it now I need
it

On its way to you....


Thanks


---8---


For the floor, you have to take into account the perimeter/area factor
if it is a ground floor so there are tables of numbers rather than
single figures.

The BS just has a couple of fudge factors for different floor areas of
solid
floors (reflected in Barlo's 110sqm, 50sqm and Terraced house options).

For a boarded floor (non T&G), I suppose one should consider the
draught proofing effect of the carpet as well, but that is pretty hard
to assess.....

Well it's all pretty approximate (unless you get into the sort of detail in
Part L1) so I'm surprised they haven't at least included some average-ish
sort of figures e.g. cheap'n'nasty rubber-backed | deluxe thick pile on
cushioned underlay.

I see Barlo's help file also refers to the BS and shows the same table (as
also in the Barlo) but then goes on to describe the P/A method. However
their calcs seem to just use the BS table - no P/A.

I suppose for uninsulated suspended floors the heat loss through the floor
vastly exceeds the loss round the peripheries so you can in practice pretty
much ignore P/A - ?



--
John Stumbles
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-+
Women always generalise

On Mon, 5 Jan 2004 01:51:08 -0000, "John Stumbles"
] wrote:




For the floor, you have to take into account the perimeter/area factor

if it is a ground floor so there are tables of numbers rather than
single figures.

The BS just has a couple of fudge factors for different floor areas of
solid
floors (reflected in Barlo's 110sqm, 50sqm and Terraced house options).

For a boarded floor (non T&G), I suppose one should consider the
draught proofing effect of the carpet as well, but that is pretty hard
to assess.....

Well it's all pretty approximate (unless you get into the sort of detail in
Part L1) so I'm surprised they haven't at least included some average-ish
sort of figures e.g. cheap'n'nasty rubber-backed | deluxe thick pile on
cushioned underlay.

I see Barlo's help file also refers to the BS and shows the same table (as
also in the Barlo) but then goes on to describe the P/A method. However
their calcs seem to just use the BS table - no P/A.

I suppose for uninsulated suspended floors the heat loss through the floor
vastly exceeds the loss round the peripheries so you can in practice pretty
much ignore P/A - ?

This is basically what TNP said. For a suspended block floor, you
could effectively treat it as a wall on the basis that the outside
temperature is across the entire underside. This would give a worse
heat loss calculation than using the P/A factor, but for a heating
design will mean that you err on the side of more heat provision.

For timber floors, possibly the U values published assume no P/A
anyway.

Obviously it's a different situation if you are trying to demonstrate
that a new house construction falls within energy consumption
guidelines as opposed to a heating design for an existing property
where you want to make sure that there is adequate heat provisioning.
Generally on a property without cavity insulation, the largest heat
losses tend to be through the walls anyway, and the floors about third
on the pecking order.

Another factor is how does one treat party walls? Should it be to
assume that next door has no heating and that therefore the party wall
is effectively external, or that next door has heating and that
therefore there is a net zero transfer - or something in between?
If you consider a typical terraced property, they are often three
times as deep as wide, so the party wall areas are substantial in
comparison to the external.




..andy

To email, substitute .nospam with .gl

Andy Hall wrote:

On Mon, 5 Jan 2004 01:51:08 -0000, "John Stumbles"
] wrote:




For the floor, you have to take into account the perimeter/area factor


if it is a ground floor so there are tables of numbers rather than
single figures.

The BS just has a couple of fudge factors for different floor areas of

solid

floors (reflected in Barlo's 110sqm, 50sqm and Terraced house options).

For a boarded floor (non T&G), I suppose one should consider the
draught proofing effect of the carpet as well, but that is pretty hard
to assess.....

Well it's all pretty approximate (unless you get into the sort of detail in
Part L1) so I'm surprised they haven't at least included some average-ish
sort of figures e.g. cheap'n'nasty rubber-backed | deluxe thick pile on
cushioned underlay.

I see Barlo's help file also refers to the BS and shows the same table (as
also in the Barlo) but then goes on to describe the P/A method. However
their calcs seem to just use the BS table - no P/A.

I suppose for uninsulated suspended floors the heat loss through the floor
vastly exceeds the loss round the peripheries so you can in practice pretty
much ignore P/A - ?


This is basically what TNP said. For a suspended block floor, you
could effectively treat it as a wall on the basis that the outside
temperature is across the entire underside. This would give a worse
heat loss calculation than using the P/A factor, but for a heating
design will mean that you err on the side of more heat provision.

For timber floors, possibly the U values published assume no P/A
anyway.

Obviously it's a different situation if you are trying to demonstrate
that a new house construction falls within energy consumption
guidelines as opposed to a heating design for an existing property
where you want to make sure that there is adequate heat provisioning.
Generally on a property without cavity insulation, the largest heat
losses tend to be through the walls anyway, and the floors about third
on the pecking order.


Yes, that is more or less my subjective experience.

However raised woden floors with underfloor ventilation - good for rot -
can be extremely draughty. Even with carpets. I acheved considerable
gains by hardboarding such a floor and actually laying vinyl and a
non-fixed carpet.

If airflow beneath the floor is restricted, is hugely warmer. The air is
locked, and very little transfer to the soil takes place, and, over a
period, the soil under the house becomes warm anyway. 2-3m of wet soil
is still an effective insulator.



Another factor is how does one treat party walls? Should it be to
assume that next door has no heating and that therefore the party wall
is effectively external, or that next door has heating and that
therefore there is a net zero transfer - or something in between?
If you consider a typical terraced property, they are often three
times as deep as wide, so the party wall areas are substantial in
comparison to the external.


Ther are two aspects to heat calculations that need to be done.

Worst case - how much power do you need running flat out to heat a house
on the three really cold days a year. That determines boiler and
radiator sizes.

Average losses - which dictate the overall annual heating cost.

I think my house seems to be rated as needing 12Kw to fully heat it but
the average yearly bill would reflect about 1.2kw averaged over the
year. hether a 10:1 peak to mean ratio is typical I do not know, but its
a benchmark anyway.

Finally, when calaculating heat reqiremenst, practical limitations often
outweigh theory. My UF heating for example could be laid on one of two
grids only - I picked the looser grid, which was supposed to give about
50w/sq m, and this has proved entirely adequate. Corresponding to about
1.5Kw per large room (6x5 meters). It seems small but it works. Likewise
in wet radiator territory, how much psacehave you got?

Over engineering the heating system gives you rapid wram up, and,
provided you have proper temperature control, I do not think a larger
boiler operating on 20:1 duty cycle is MUCH less efficient than a
tiddler working on 5:1.

Additionally, if CH pipes are routed as much as possible inside the
insulation barrers, the losses from them are not overall losses, but
serve to het the house anyway. One is left with overall heat leakage and
the hot flue gases as the major heat losses from the house.

Returning to the original posters question, if the floor has underfloor
draughts, I would seal it with hardboard, and mastic around the
skirting, and assume a U value of about 5 for the wood floor, and then
calculate the carpet as somehwat similar to rockwool and get the U value
from rockwool conductivity over the thickness of both carpet an underlay.







.andy

To email, substitute .nospam with .gl

"Andy Hall" wrote in message
...

Another factor is how does one treat party walls? Should it be to
assume that next door has no heating and that therefore the party wall
is effectively external, or that next door has heating and that
therefore there is a net zero transfer - or something in between?

The HVCA guide reckons you should treat adjacent property as unheated, but
then half the U value for the wall because the adjacent property probably
will be heated.

I think this rather bizarre alternative to using the real U value and
changing the temperature drop is just because that's the way their example
worksheet does things. (It does a single temperature drop multiplcation at
the end of everything.)

If you consider a typical terraced property, they are often three
times as deep as wide, so the party wall areas are substantial in
comparison to the external.

Having just done a complete heat-loss for my house, and realised that the
fabric loss was about 55% of the total, with the vent loss being 45%, it
does seem that there's a slightly misplaced obsession with exact 'U' values
when vent rates are basically picked from a list of 1,1.5,2 or 3.

For example, disregarding all the windows (i.e. treating them as wall) in
this house makes about 5% difference to the total loss. As you're probably
going to be adding 10-20% of hand-wavy 'distribution loss' and 'intermittent
heating factors' at the end of the whole process, I did finish up wondering
why I'd bothered measuring everything so carefully.

JOOI, what do other people who've done detailed heat-loss calcs come up with
for vent vs. fabric loss?

Will

In article ,
The Natural Philosopher writes:

Returning to the original posters question, if the floor has underfloor
draughts, I would seal it with hardboard, and mastic around the
skirting, and assume a U value of about 5 for the wood floor, and then

When I moved in to a 1900 house 18 years ago, you could see where
the drafts came through the floor as it had left a dirty mark on
the carpet. In this case, it was all round the edge of the room
where there was a 1/4" gap between the bottom of the skirting and
the floorboards. After that carpet had been ripped out, I repainted
the skirting, and deliberately spilled over 2" onto the floorboards
too. When the paint was dry, I bought a very wide roll of good
quality sellotape, and stuck it carefully along the gap between the
skirting and the floor, rising to about 20mm above the floor so it
would be hidden by the new carpet which was subsequently installed.
18 years on, that's still doing fine and has to this day stopped any
draft coming up through the edge of the carpet, at least to the
extent that there is no discolouration caused by the carpet filtering
dust out as the previous carpet had done.

--
Andrew Gabriel

On Mon, 5 Jan 2004 11:11:15 -0000, "Will Dean"
wrote:

"Andy Hall" wrote in message
.. .

Another factor is how does one treat party walls? Should it be to
assume that next door has no heating and that therefore the party wall
is effectively external, or that next door has heating and that
therefore there is a net zero transfer - or something in between?

The HVCA guide reckons you should treat adjacent property as unheated, but
then half the U value for the wall because the adjacent property probably
will be heated.

I think this rather bizarre alternative to using the real U value and
changing the temperature drop is just because that's the way their example
worksheet does things. (It does a single temperature drop multiplcation at
the end of everything.)

I'm sure it is. I think that you have to look at the circumstances
and come to a decision based on what you want to achieve.

For example, in one house that we had, an old lady lived next door and
we knew that she only heated one room. I therefore treated that
party wall as being external.

In a more rigorous calculation, one should also account for internal
heat transfers if the rooms are maintained at different temperatures.
In the same house, I had a large bathroom which had a wall adjoining a
bedroom. THe bathroom design temperature was 23, while the bedroom was
16. In that scenario, the transfer was significant. The radiator
manufacturer programs take heatlosses via this route into account but
not usually heat gains - presumably because you'll buy a larger
radiator.



If you consider a typical terraced property, they are often three
times as deep as wide, so the party wall areas are substantial in
comparison to the external.

Having just done a complete heat-loss for my house, and realised that the
fabric loss was about 55% of the total, with the vent loss being 45%, it
does seem that there's a slightly misplaced obsession with exact 'U' values
when vent rates are basically picked from a list of 1,1.5,2 or 3.

Like any other engineering exercise, it is important to look at what
are the significant factors and what are not.

To some extent, you have control over the rate of air change in that
you can go round and hermetically seal the place if you're stupid.

Fabric heat losses may be less easily controlled.

For example, in older properties with solid walls, the heat loss
through them is substantial, yet people fuss about whether there is
100mm or 200mm of roof insulation.

By doing the sums, you gain an appreciation of what the factors
actually are, what is important and what is not and how you are going
to deal with them - i.e. with insulation or more heat.



For example, disregarding all the windows (i.e. treating them as wall) in
this house makes about 5% difference to the total loss. As you're probably
going to be adding 10-20% of hand-wavy 'distribution loss' and 'intermittent
heating factors' at the end of the whole process, I did finish up wondering
why I'd bothered measuring everything so carefully.

JOOI, what do other people who've done detailed heat-loss calcs come up with
for vent vs. fabric loss?

Depending on the property, anything from 25%/75% to 75%/25%.


Will







..andy

To email, substitute .nospam with .gl

"Andy Hall" wrote in message
news

Like any other engineering exercise, it is important to look at what
are the significant factors and what are not.

To some extent, you have control over the rate of air change in that
you can go round and hermetically seal the place if you're stupid.

Fabric heat losses may be less easily controlled.

For example, in older properties with solid walls, the heat loss
through them is substantial, yet people fuss about whether there is
100mm or 200mm of roof insulation.

Yes, it was interesting - having done it in Excel rather than one of the
radiator mfg's programs, it's particularly easy to look at what the effect
of double glazing or cavity wall insulation is.

By doing the sums, you gain an appreciation of what the factors
actually are, what is important and what is not and how you are going
to deal with them - i.e. with insulation or more heat.

Sure. Along that lines, are you aware of any standard methods of converting
heat loss rates into annual heating costs? (Or at least, total annual
energy consumption.)

There must be some rules of thumb used to calculate pay-back times on
additional insulation, for example.

Obviously, there's a regional variation, but I have got rather stuck at
'degree day' figures, which don't seem to mesh well with 'U x area' figures.

Depending on the property, anything from 25%/75% to 75%/25%.

Interesting. Maybe I should go and measure a brand-new house, to see what
that works out at...

Will

On Mon, 5 Jan 2004 13:06:22 -0000, "Will Dean"
wrote:

"Andy Hall" wrote in message
news

Like any other engineering exercise, it is important to look at what
are the significant factors and what are not.

To some extent, you have control over the rate of air change in that
you can go round and hermetically seal the place if you're stupid.

Fabric heat losses may be less easily controlled.

For example, in older properties with solid walls, the heat loss
through them is substantial, yet people fuss about whether there is
100mm or 200mm of roof insulation.

Yes, it was interesting - having done it in Excel rather than one of the
radiator mfg's programs, it's particularly easy to look at what the effect
of double glazing or cavity wall insulation is.

By doing the sums, you gain an appreciation of what the factors
actually are, what is important and what is not and how you are going
to deal with them - i.e. with insulation or more heat.

Sure. Along that lines, are you aware of any standard methods of converting
heat loss rates into annual heating costs? (Or at least, total annual
energy consumption.)

I did it once using tables of daily temperatures sent to me by the Met
Office. I assumed two types of day - weekend and weekday, and then
made actual measurements of gas use by my boiler. I then factored
for the other days based on the temperature. In the end I was about
5% high on my estimate,

You could try making contact with the people who do the SEDBUK work.
They will likely have a better model to use. Whether that is based
on measurements, mathematical modelling or both I am not sure.



There must be some rules of thumb used to calculate pay-back times on
additional insulation, for example.

You can do that reasonably easily based on looking at the element
involved. One approach is to take monthly average temperatures and
compute the heat loss through the surface for the month and then the
energy used based on your heating patterns.
Then you just add the numbers.

Last time I did this, I remember that cavity insulation looks pretty
good on an ROI basis, double glazing rather less so.






Obviously, there's a regional variation, but I have got rather stuck at
'degree day' figures, which don't seem to mesh well with 'U x area' figures.

Depending on the property, anything from 25%/75% to 75%/25%.

Interesting. Maybe I should go and measure a brand-new house, to see what
that works out at...




Will



..andy

To email, substitute .nospam with .gl

Will Dean wrote:

"Andy Hall" wrote in message
...


Another factor is how does one treat party walls? Should it be to
assume that next door has no heating and that therefore the party wall
is effectively external, or that next door has heating and that
therefore there is a net zero transfer - or something in between?


The HVCA guide reckons you should treat adjacent property as unheated, but
then half the U value for the wall because the adjacent property probably
will be heated.

I think this rather bizarre alternative to using the real U value and
changing the temperature drop is just because that's the way their example
worksheet does things. (It does a single temperature drop multiplcation at
the end of everything.)


If you consider a typical terraced property, they are often three
times as deep as wide, so the party wall areas are substantial in
comparison to the external.


Having just done a complete heat-loss for my house, and realised that the
fabric loss was about 55% of the total, with the vent loss being 45%, it
does seem that there's a slightly misplaced obsession with exact 'U' values
when vent rates are basically picked from a list of 1,1.5,2 or 3.

For example, disregarding all the windows (i.e. treating them as wall) in
this house makes about 5% difference to the total loss. As you're probably
going to be adding 10-20% of hand-wavy 'distribution loss' and 'intermittent
heating factors' at the end of the whole process, I did finish up wondering
why I'd bothered measuring everything so carefully.

JOOI, what do other people who've done detailed heat-loss calcs come up with
for vent vs. fabric loss?



I forget, but at building reg sort of U values, the vent loss is getting
close to dominating IIRC.


Will

In article ,
Andy Hall writes:

For example, in one house that we had, an old lady lived next door and
we knew that she only heated one room. I therefore treated that
party wall as being external.

In a more rigorous calculation, one should also account for internal
heat transfers if the rooms are maintained at different temperatures.
In the same house, I had a large bathroom which had a wall adjoining a
bedroom. THe bathroom design temperature was 23, while the bedroom was
16. In that scenario, the transfer was significant. The radiator
manufacturer programs take heatlosses via this route into account but
not usually heat gains - presumably because you'll buy a larger
radiator.

A couple of related things...

In a multi-zone system, don't forget that you might choose to have
an adjacent zone switched off, which could radically change the
temperature differential.

Normally, a good amount of the upstairs heat actually comes through
the ceiling/floor from downstairs. However, this takes time from a
standing start (i.e. at least the time for the downstairs to warm up),
so if you want to be able to get the upstairs up to temperature without
having to wait for the downstairs to first heat up, you should probably
assume the floor of the upstairs is rather more like a suspended
downstairs floor.

These points are probably most relevant where you have a zoned heating
system controlled by occupancy where rapid response is required, rather
than just a heating system blindly switched by a timeswitch with no
idea if or when or which parts of a house are occupied.

--
Andrew Gabriel

I forget, but at building reg sort of U values, the vent loss is
getting close to dominating IIRC.

This can be easily sorted with heat recovery ventilation, though.

Also, at least you gain something through ventilation losses, as you get
nice fresh air. Losing heat through the walls or roof gains you nothing
other than damp insulation if you don't have a vapour barrier.

Christian.

Christian McArdle wrote:

I forget, but at building reg sort of U values, the vent loss is
getting close to dominating IIRC.


This can be easily sorted with heat recovery ventilation, though.


Capital cost is an issue.
Sometimes its easier to pay for the fuel.



Also, at least you gain something through ventilation losses, as you get
nice fresh air. Losing heat through the walls or roof gains you nothing
other than damp insulation if you don't have a vapour barrier.



No argument there.

However the point was, that beynd a certain point, insulation is
ineffective, unless you also deal with the ventilation issue as (e.g.)
you suggest.


Christian.

Christian McArdle wrote

Also, at least you gain something through ventilation losses, as you get
nice fresh air.

Not if you live east of London!! Fresh air does not exist!
Regards
Capitol

"Will Dean" wrote in message
.. .
"Andy Hall" wrote in message
...

Another factor is how does one treat party walls? Should it be to
assume that next door has no heating and that therefore the party wall
is effectively external, or that next door has heating and that
therefore there is a net zero transfer - or something in between?

The HVCA guide reckons you should treat adjacent property as unheated, but
then half the U value for the wall because the adjacent property probably
will be heated.

I think this rather bizarre alternative to using the real U value and
changing the temperature drop is just because that's the way their example
worksheet does things. (It does a single temperature drop multiplcation
at
the end of everything.)

If you consider a typical terraced property, they are often three
times as deep as wide, so the party wall areas are substantial in
comparison to the external.

Having just done a complete heat-loss for my house, and realised that the
fabric loss was about 55% of the total, with the vent loss being 45%, it
does seem that there's a slightly misplaced obsession with exact 'U'
values
when vent rates are basically picked from a list of 1,1.5,2 or 3.

For example, disregarding all the windows (i.e. treating them as wall) in
this house makes about 5% difference to the total loss. As you're
probably
going to be adding 10-20% of hand-wavy 'distribution loss' and
'intermittent
heating factors' at the end of the whole process, I did finish up
wondering
why I'd bothered measuring everything so carefully.

JOOI, what do other people who've done detailed heat-loss calcs come up
with
for vent vs. fabric loss?

In the one I'm working on atm (see the heat loss terraced house thread) I'm
getting ~2.6kW vent loss to ~4.3kW fabric



--
John Stumbles
-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-+
bitwise, bytefoolish