Underfloor heating.

Insulation thoughts... the existing ground floor has 25mm Jablite topped
with 22mm chip. Recommendation is to over fit 25mm of pre-grooved
insulation and a further set of flooring: chip + Vinyl or engineered
hardwood.

Downside is loss of height in doorways.

What is the real energy loss in heating a relatively uninsulated floor
slab in a roughly square building? For 24 hour occupation, doesn't it
come down to what is lost at the edges?
--
Tim Lamb

On 14/06/2016 11:04, Tim Lamb wrote:
Underfloor heating.

Insulation thoughts... the existing ground floor has 25mm Jablite topped
with 22mm chip. Recommendation is to over fit 25mm of pre-grooved
insulation and a further set of flooring: chip + Vinyl or engineered
hardwood.

Downside is loss of height in doorways.

What is the real energy loss in heating a relatively uninsulated floor
slab in a roughly square building? For 24 hour occupation, doesn't it
come down to what is lost at the edges?

Nowhere near what is lost through the roof and walls before insulation.
I would guess at less than 10% before any insulation for a solid floor.
With 25mm of insulation that will take it down to about 2% another 25mm
will take it down to about 1%. Unless the insulation is really cheap and
labour free it will never pay for itself.

On 14/06/16 11:04, Tim Lamb wrote:
Underfloor heating.

Insulation thoughts... the existing ground floor has 25mm Jablite topped
with 22mm chip. Recommendation is to over fit 25mm of pre-grooved
insulation and a further set of flooring: chip + Vinyl or engineered
hardwood.

Downside is loss of height in doorways.

What is the real energy loss in heating a relatively uninsulated floor
slab in a roughly square building? For 24 hour occupation, doesn't it
come down to what is lost at the edges?


Mm. Its a very very complicated calculation as you have to take the mean
path through a variable soil conductivity to the outside air.

And it isn't dominated by edge effects at all.

Plus remember that the hotter the floor is in comparison to the room the
worse will be the heat loss through it.

Don't think 25mm poly is anywhere near enough.

You must have that extra 25mm, and even then Id say its gonna be lossy.



--
€œSome people like to travel by train because it combines the slowness of
a car with the cramped public exposure of €¨an airplane.€�

Dennis Miller

On 14/06/16 11:56, dennis@home wrote:
On 14/06/2016 11:04, Tim Lamb wrote:
Underfloor heating.

Insulation thoughts... the existing ground floor has 25mm Jablite topped
with 22mm chip. Recommendation is to over fit 25mm of pre-grooved
insulation and a further set of flooring: chip + Vinyl or engineered
hardwood.

Downside is loss of height in doorways.

What is the real energy loss in heating a relatively uninsulated floor
slab in a roughly square building? For 24 hour occupation, doesn't it
come down to what is lost at the edges?

Nowhere near what is lost through the roof and walls before insulation.
I would guess at less than 10% before any insulation for a solid floor.
With 25mm of insulation that will take it down to about 2% another 25mm
will take it down to about 1%. Unless the insulation is really cheap and
labour free it will never pay for itself.

Confirming once again that Denise cant read a post before replying.

And has no understanding of heat loss in buildings or why its different
with UFH.

And this is the calibre of mind that thinks staying in the EU is the
right thing to do.

For him it probably is. Unable to think coherently for himself, and must
always buy 'microwave ready' pre-cooked opinion from the Guardian...



--
Canada is all right really, though not for the whole weekend.

"Saki"

On 14/06/2016 12:05, The Natural Philosopher wrote:
On 14/06/16 11:56, dennis@home wrote:
On 14/06/2016 11:04, Tim Lamb wrote:
Underfloor heating.

Insulation thoughts... the existing ground floor has 25mm Jablite topped
with 22mm chip. Recommendation is to over fit 25mm of pre-grooved
insulation and a further set of flooring: chip + Vinyl or engineered
hardwood.

Downside is loss of height in doorways.

What is the real energy loss in heating a relatively uninsulated floor
slab in a roughly square building? For 24 hour occupation, doesn't it
come down to what is lost at the edges?

Nowhere near what is lost through the roof and walls before insulation.
I would guess at less than 10% before any insulation for a solid floor.
With 25mm of insulation that will take it down to about 2% another 25mm
will take it down to about 1%. Unless the insulation is really cheap and
labour free it will never pay for itself.

Confirming once again that Denise cant read a post before replying.

And has no understanding of heat loss in buildings or why its different
with UFH.

You really don't understand physics do you!
If you put pipes onto and they are at 55C that will only about double
the heat loss through the floor and that loss is only the 1% so at best
adding another 25 mm will take it to the same level as a normal room
without UFH.

Just for the understanding.. if you double the temperature difference
you double the loss. If you double the insulation you halve the loss.


And this is the calibre of mind that thinks staying in the EU is the
right thing to do.

For him it probably is. Unable to think coherently for himself, and must
always buy 'microwave ready' pre-cooked opinion from the Guardian...

Whats the Guardian? ;-)

On 14/06/16 13:38, dennis@home wrote:

You really don't understand physics do you!

You might, but you've overlooked one thing - see below:

If you put pipes onto and they are at 55C that will only about double
the heat loss through the floor and that loss is only the 1% so at best
adding another 25 mm will take it to the same level as a normal room
without UFH.

Just for the understanding.. if you double the temperature difference
you double the loss. If you double the insulation you halve the loss.


No - because you've incorrectly assumed the substrate temperature under
the subfloor remains the same (your assumption appearing to be about 0c )


This is true of walls and roofs. But the general mass of earth under the
house will rise in temperature with an increased floor surface
temperature, so it is far from obvious how much difference an extra 25mm
of insulation will make.

I've never understood the details, but I can see enough to know your
argument has an error.

On 14/06/16 13:38, dennis@home wrote:
On 14/06/2016 12:05, The Natural Philosopher wrote:
On 14/06/16 11:56, dennis@home wrote:
On 14/06/2016 11:04, Tim Lamb wrote:
Underfloor heating.

Insulation thoughts... the existing ground floor has 25mm Jablite
topped
with 22mm chip. Recommendation is to over fit 25mm of pre-grooved
insulation and a further set of flooring: chip + Vinyl or engineered
hardwood.

Downside is loss of height in doorways.

What is the real energy loss in heating a relatively uninsulated floor
slab in a roughly square building? For 24 hour occupation, doesn't it
come down to what is lost at the edges?

Nowhere near what is lost through the roof and walls before insulation.
I would guess at less than 10% before any insulation for a solid floor.
With 25mm of insulation that will take it down to about 2% another 25mm
will take it down to about 1%. Unless the insulation is really cheap and
labour free it will never pay for itself.

Confirming once again that Denise cant read a post before replying.

And has no understanding of heat loss in buildings or why its different
with UFH.

You really don't understand physics do you!

I do understand physics

If you put pipes onto and they are at 55C that will only about double
the heat loss through the floor and that loss is only the 1%

No, its noth8ng like as low as that

so at best
adding another 25 mm will take it to the same level as a normal room
without UFH.

Just for the understanding.. if you double the temperature difference
you double the loss. If you double the insulation you halve the loss.


And this is the calibre of mind that thinks staying in the EU is the
right thing to do.

For him it probably is. Unable to think coherently for himself, and must
always buy 'microwave ready' pre-cooked opinion from the Guardian...

Whats the Guardian? ;-)



--
€œit should be clear by now to everyone that activist environmentalism
(or environmental activism) is becoming a general ideology about humans,
about their freedom, about the relationship between the individual and
the state, and about the manipulation of people under the guise of a
'noble' idea. It is not an honest pursuit of 'sustainable development,'
a matter of elementary environmental protection, or a search for
rational mechanisms designed to achieve a healthy environment. Yet
things do occur that make you shake your head and remind yourself that
you live neither in Joseph Stalins Communist era, nor in the Orwellian
utopia of 1984.€�

Vaclav Klaus

On 14/06/2016 13:59, Tim Watts wrote:
On 14/06/16 13:38, dennis@home wrote:

You really don't understand physics do you!

You might, but you've overlooked one thing - see below:

If you put pipes onto and they are at 55C that will only about double
the heat loss through the floor and that loss is only the 1% so at best
adding another 25 mm will take it to the same level as a normal room
without UFH.

Just for the understanding.. if you double the temperature difference
you double the loss. If you double the insulation you halve the loss.


No - because you've incorrectly assumed the substrate temperature under
the subfloor remains the same (your assumption appearing to be about 0c )


This is true of walls and roofs. But the general mass of earth under the
house will rise in temperature with an increased floor surface
temperature, so it is far from obvious how much difference an extra 25mm
of insulation will make.

I've never understood the details, but I can see enough to know your
argument has an error.

Yes but the error is in favour of the insulation making less difference.

You can work it out but its not easy so most people just take the
figures published.

On 14/06/2016 13:59, The Natural Philosopher wrote:
On 14/06/16 13:38, dennis@home wrote:
On 14/06/2016 12:05, The Natural Philosopher wrote:
On 14/06/16 11:56, dennis@home wrote:
On 14/06/2016 11:04, Tim Lamb wrote:
Underfloor heating.

Insulation thoughts... the existing ground floor has 25mm Jablite
topped
with 22mm chip. Recommendation is to over fit 25mm of pre-grooved
insulation and a further set of flooring: chip + Vinyl or engineered
hardwood.

Downside is loss of height in doorways.

What is the real energy loss in heating a relatively uninsulated floor
slab in a roughly square building? For 24 hour occupation, doesn't it
come down to what is lost at the edges?

Nowhere near what is lost through the roof and walls before insulation.
I would guess at less than 10% before any insulation for a solid floor.
With 25mm of insulation that will take it down to about 2% another 25mm
will take it down to about 1%. Unless the insulation is really cheap
and
labour free it will never pay for itself.

Confirming once again that Denise cant read a post before replying.

And has no understanding of heat loss in buildings or why its different
with UFH.

You really don't understand physics do you!

I do understand physics

If you put pipes onto and they are at 55C that will only about double
the heat loss through the floor and that loss is only the 1%

No, its noth8ng like as low as that

Of course it is, just read what I said and think about it.

On 14/06/16 14:21, dennis@home wrote:
On 14/06/2016 13:59, The Natural Philosopher wrote:
On 14/06/16 13:38, dennis@home wrote:
On 14/06/2016 12:05, The Natural Philosopher wrote:
On 14/06/16 11:56, dennis@home wrote:
On 14/06/2016 11:04, Tim Lamb wrote:
Underfloor heating.

Insulation thoughts... the existing ground floor has 25mm Jablite
topped
with 22mm chip. Recommendation is to over fit 25mm of pre-grooved
insulation and a further set of flooring: chip + Vinyl or engineered
hardwood.

Downside is loss of height in doorways.

What is the real energy loss in heating a relatively uninsulated
floor
slab in a roughly square building? For 24 hour occupation, doesn't it
come down to what is lost at the edges?

Nowhere near what is lost through the roof and walls before
insulation.
I would guess at less than 10% before any insulation for a solid
floor.
With 25mm of insulation that will take it down to about 2% another
25mm
will take it down to about 1%. Unless the insulation is really cheap
and
labour free it will never pay for itself.

Confirming once again that Denise cant read a post before replying.

And has no understanding of heat loss in buildings or why its different
with UFH.

You really don't understand physics do you!

I do understand physics

If you put pipes onto and they are at 55C that will only about double
the heat loss through the floor and that loss is only the 1%

No, its noth8ng like as low as that

Of course it is, just read what I said and think about it.


I did, and you are still talking ********.

If the house is even remotely well insulated, the dominant heatloss will
be through the floor.

No if the house is at 20 degrees and its 5C outside, that is 15C across
'whatever the overall path to the outside is' through the soil.

Take that up to 50C with UFH in the floor itself, and its *45C* across
that path, thereby TREBLING the heat loss.

But then I have designed and lived in a house with UFH, have a degree in
engineering, and have done the calculations for heatloss, and you are a
clueless ****, so its all not surprising.


--
"I guess a rattlesnake ain't risponsible fer bein' a rattlesnake, but ah
puts mah heel on um jess the same if'n I catches him around mah chillun".

On 14/06/2016 14:39, The Natural Philosopher wrote:
On 14/06/16 14:21, dennis@home wrote:
On 14/06/2016 13:59, The Natural Philosopher wrote:
On 14/06/16 13:38, dennis@home wrote:
On 14/06/2016 12:05, The Natural Philosopher wrote:
On 14/06/16 11:56, dennis@home wrote:
On 14/06/2016 11:04, Tim Lamb wrote:
Underfloor heating.

Insulation thoughts... the existing ground floor has 25mm Jablite
topped
with 22mm chip. Recommendation is to over fit 25mm of pre-grooved
insulation and a further set of flooring: chip + Vinyl or engineered
hardwood.

Downside is loss of height in doorways.

What is the real energy loss in heating a relatively uninsulated
floor
slab in a roughly square building? For 24 hour occupation,
doesn't it
come down to what is lost at the edges?

Nowhere near what is lost through the roof and walls before
insulation.
I would guess at less than 10% before any insulation for a solid
floor.
With 25mm of insulation that will take it down to about 2% another
25mm
will take it down to about 1%. Unless the insulation is really cheap
and
labour free it will never pay for itself.

Confirming once again that Denise cant read a post before replying.

And has no understanding of heat loss in buildings or why its
different
with UFH.

You really don't understand physics do you!

I do understand physics

If you put pipes onto and they are at 55C that will only about double
the heat loss through the floor and that loss is only the 1%

No, its noth8ng like as low as that

Of course it is, just read what I said and think about it.


I did, and you are still talking ********.

If the house is even remotely well insulated, the dominant heatloss will
be through the floor.

You still haven't bothered to read what I said, just jumped in again and
got it all wrong as usual.

On 14/06/2016 11:04, Tim Lamb wrote:
Underfloor heating.

Insulation thoughts... the existing ground floor has 25mm Jablite topped
with 22mm chip. Recommendation is to over fit 25mm of pre-grooved
insulation and a further set of flooring: chip + Vinyl or engineered
hardwood.

Downside is loss of height in doorways.

What is the real energy loss in heating a relatively uninsulated floor
slab in a roughly square building? For 24 hour occupation, doesn't it
come down to what is lost at the edges?


Firstly are we talking about a solid floor, or suspended - I suspect the
former, but its worth checking since it can make a big difference in
these situations.

The next thing to consider is the overall area of the floor - larger
floors are disproportionately more efficient than smaller ones, and the
centre of the floor better than the edges.

The actual calculation method required is described in BS EN ISO 13370,
and BS EN ISO 6946 will give you appropriate data to play with for U
values of the soil type etc. (I can't find the BSI link on my local
library page the moment to get the docs - your's may be better)

There is also a BRE doc, number 443 that gives some more info on the
process.



--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

In message , The Natural Philosopher
writes
On 14/06/16 11:04, Tim Lamb wrote:
Underfloor heating.

Insulation thoughts... the existing ground floor has 25mm Jablite topped
with 22mm chip. Recommendation is to over fit 25mm of pre-grooved
insulation and a further set of flooring: chip + Vinyl or engineered
hardwood.

Downside is loss of height in doorways.

What is the real energy loss in heating a relatively uninsulated floor
slab in a roughly square building? For 24 hour occupation, doesn't it
come down to what is lost at the edges?


Mm. Its a very very complicated calculation as you have to take the
mean path through a variable soil conductivity to the outside air.

And it isn't dominated by edge effects at all.

Oh. I was rather thinking dry soil might be a reasonable insulator and,
once the slab temperature stabilised, most of the losses would be from
the edge though the brickwork.

Plus remember that the hotter the floor is in comparison to the room
the worse will be the heat loss through it.

Don't think 25mm poly is anywhere near enough.

You must have that extra 25mm, and even then Id say its gonna be lossy.

I suppose I could ditch the intermediate chip.




--
Tim Lamb

In message , The Natural Philosopher
writes
On 14/06/16 14:21, dennis@home wrote:
On 14/06/2016 13:59, The Natural Philosopher wrote:
On 14/06/16 13:38, dennis@home wrote:
On 14/06/2016 12:05, The Natural Philosopher wrote:
On 14/06/16 11:56, dennis@home wrote:
On 14/06/2016 11:04, Tim Lamb wrote:
Underfloor heating.

Insulation thoughts... the existing ground floor has 25mm Jablite
topped
with 22mm chip. Recommendation is to over fit 25mm of pre-grooved
insulation and a further set of flooring: chip + Vinyl or engineered
hardwood.

Downside is loss of height in doorways.

What is the real energy loss in heating a relatively uninsulated
floor
slab in a roughly square building? For 24 hour occupation, doesn't it
come down to what is lost at the edges?

Nowhere near what is lost through the roof and walls before
insulation.
I would guess at less than 10% before any insulation for a solid
floor.
With 25mm of insulation that will take it down to about 2% another
25mm
will take it down to about 1%. Unless the insulation is really cheap
and
labour free it will never pay for itself.

Confirming once again that Denise cant read a post before replying.

And has no understanding of heat loss in buildings or why its different
with UFH.

You really don't understand physics do you!

I do understand physics

If you put pipes onto and they are at 55C that will only about double
the heat loss through the floor and that loss is only the 1%

No, its noth8ng like as low as that

Of course it is, just read what I said and think about it.


I did, and you are still talking ********.

If the house is even remotely well insulated, the dominant heatloss
will be through the floor.

No if the house is at 20 degrees and its 5C outside, that is 15C
across 'whatever the overall path to the outside is' through the soil.

Take that up to 50C with UFH in the floor itself, and its *45C* across
that path, thereby TREBLING the heat loss.

But then I have designed and lived in a house with UFH, have a degree
in engineering, and have done the calculations for heatloss, and you
are a clueless ****, so its all not surprising.

Come on chaps! Keep it clean...

So the 4" concrete pad in the middle of the cottage is in close contact
with piping at 55C. The pipe temperature will vary due to thermostat
demands but should settle at something above say 10C for the surrounding
ground. Slow thermal response is not a huge concern for 24 hour
occupation.

Within the site, I assume there will be a thermal gradient between the
concrete and the subsoil. Is this likely to cause significant losses
other than near the edges?

New work will probably have 4" of insulation under the screed and pipes.




--
Tim Lamb

On 14/06/16 16:37, dennis@home wrote:
On 14/06/2016 14:39, The Natural Philosopher wrote:
On 14/06/16 14:21, dennis@home wrote:
On 14/06/2016 13:59, The Natural Philosopher wrote:
On 14/06/16 13:38, dennis@home wrote:
On 14/06/2016 12:05, The Natural Philosopher wrote:
On 14/06/16 11:56, dennis@home wrote:
On 14/06/2016 11:04, Tim Lamb wrote:
Underfloor heating.

Insulation thoughts... the existing ground floor has 25mm Jablite
topped
with 22mm chip. Recommendation is to over fit 25mm of pre-grooved
insulation and a further set of flooring: chip + Vinyl or
engineered
hardwood.

Downside is loss of height in doorways.

What is the real energy loss in heating a relatively uninsulated
floor
slab in a roughly square building? For 24 hour occupation,
doesn't it
come down to what is lost at the edges?

Nowhere near what is lost through the roof and walls before
insulation.
I would guess at less than 10% before any insulation for a solid
floor.
With 25mm of insulation that will take it down to about 2% another
25mm
will take it down to about 1%. Unless the insulation is really cheap
and
labour free it will never pay for itself.

Confirming once again that Denise cant read a post before replying.

And has no understanding of heat loss in buildings or why its
different
with UFH.

You really don't understand physics do you!

I do understand physics

If you put pipes onto and they are at 55C that will only about double
the heat loss through the floor and that loss is only the 1%

No, its noth8ng like as low as that

Of course it is, just read what I said and think about it.


I did, and you are still talking ********.

If the house is even remotely well insulated, the dominant heatloss will
be through the floor.

You still haven't bothered to read what I said, just jumped in again and
got it all wrong as usual.


I have read what you said, and noted that you have got it it wrong as
usual, as anyone can see,.


--
€œIt is hard to imagine a more stupid decision or more dangerous way of
making decisions than by putting those decisions in the hands of people
who pay no price for being wrong.€�

Thomas Sowell

On 14/06/16 18:44, Tim Lamb wrote:
In message , The Natural Philosopher
writes
On 14/06/16 14:21, dennis@home wrote:
On 14/06/2016 13:59, The Natural Philosopher wrote:
On 14/06/16 13:38, dennis@home wrote:
On 14/06/2016 12:05, The Natural Philosopher wrote:
On 14/06/16 11:56, dennis@home wrote:
On 14/06/2016 11:04, Tim Lamb wrote:
Underfloor heating.

Insulation thoughts... the existing ground floor has 25mm Jablite
topped
with 22mm chip. Recommendation is to over fit 25mm of pre-grooved
insulation and a further set of flooring: chip + Vinyl or
engineered
hardwood.

Downside is loss of height in doorways.

What is the real energy loss in heating a relatively uninsulated
floor
slab in a roughly square building? For 24 hour occupation,
doesn't it
come down to what is lost at the edges?

Nowhere near what is lost through the roof and walls before
insulation.
I would guess at less than 10% before any insulation for a solid
floor.
With 25mm of insulation that will take it down to about 2% another
25mm
will take it down to about 1%. Unless the insulation is really cheap
and
labour free it will never pay for itself.

Confirming once again that Denise cant read a post before replying.

And has no understanding of heat loss in buildings or why its
different
with UFH.

You really don't understand physics do you!

I do understand physics

If you put pipes onto and they are at 55C that will only about double
the heat loss through the floor and that loss is only the 1%

No, its noth8ng like as low as that

Of course it is, just read what I said and think about it.


I did, and you are still talking ********.

If the house is even remotely well insulated, the dominant heatloss
will be through the floor.

No if the house is at 20 degrees and its 5C outside, that is 15C
across 'whatever the overall path to the outside is' through the soil.

Take that up to 50C with UFH in the floor itself, and its *45C* across
that path, thereby TREBLING the heat loss.

But then I have designed and lived in a house with UFH, have a degree
in engineering, and have done the calculations for heatloss, and you
are a clueless ****, so its all not surprising.

Come on chaps! Keep it clean...

So the 4" concrete pad in the middle of the cottage is in close contact
with piping at 55C. The pipe temperature will vary due to thermostat
demands but should settle at something above say 10C for the surrounding
ground. Slow thermal response is not a huge concern for 24 hour occupation.

Within the site, I assume there will be a thermal gradient between the
concrete and the subsoil. Is this likely to cause significant losses
other than near the edges?


Yes. Due to the fact that its HOT and worst of all, when its coldest
outside is when you want the most heat in that slab, and its hottest,
and loses the most.




New work will probably have 4" of insulation under the screed and pipes.

At LEAST.







--
€œIt is hard to imagine a more stupid decision or more dangerous way of
making decisions than by putting those decisions in the hands of people
who pay no price for being wrong.€�

Thomas Sowell

On 14/06/2016 18:44, Tim Lamb wrote:


Come on chaps! Keep it clean...

You have no chance TNP has lost it.


So the 4" concrete pad in the middle of the cottage is in close contact
with piping at 55C. The pipe temperature will vary due to thermostat
demands but should settle at something above say 10C for the surrounding
ground. Slow thermal response is not a huge concern for 24 hour occupation.

What happened to the 25 mm jabalite (expanded poly)?


Cast concrete 100mm + 25 mm expanded poly has a U value of about 0.6 wm2/k

Cast concrete 100mm has a U value of about 1 wm2/k

Cast concrete 100mm with 50 mm expanded poly has a U value of about 0.4
Wm2/k

So the extra 25mm will save you about 0.2 Wm2/k
While the first 25 mm will save you about twice that.


PIR foam is slightly better with the additional 25mm giving a U value of
about 0.33 Wm2/k


Within the site, I assume there will be a thermal gradient between the
concrete and the subsoil. Is this likely to cause significant losses
other than near the edges?


New work will probably have 4" of insulation under the screed and pipes.

PIR foam would give a U value of about 0.16 Wm2/k.
Expanded poly would be about 0.25Wm2/k

In message , John
Rumm writes
On 14/06/2016 11:04, Tim Lamb wrote:
Underfloor heating.

Insulation thoughts... the existing ground floor has 25mm Jablite topped
with 22mm chip. Recommendation is to over fit 25mm of pre-grooved
insulation and a further set of flooring: chip + Vinyl or engineered
hardwood.

Downside is loss of height in doorways.

What is the real energy loss in heating a relatively uninsulated floor
slab in a roughly square building? For 24 hour occupation, doesn't it
come down to what is lost at the edges?


Firstly are we talking about a solid floor, or suspended - I suspect
the former, but its worth checking since it can make a big difference
in these situations.

Solid.

The next thing to consider is the overall area of the floor - larger
floors are disproportionately more efficient than smaller ones, and the
centre of the floor better than the edges.

Roughly 8mx9m

The actual calculation method required is described in BS EN ISO 13370,
and BS EN ISO 6946 will give you appropriate data to play with for U
values of the soil type etc. (I can't find the BSI link on my local
library page the moment to get the docs - your's may be better)

There is also a BRE doc, number 443 that gives some more info on the
process.

Right. I had a poke around. Installed Silverlight as requested and then
failed to make head or tail of the options offered. There are free
calculators out there but beyond my limited skill to use:-(




--
Tim Lamb

"dennis@home" wrote in message
web.com...
On 14/06/2016 13:59, The Natural Philosopher wrote:
On 14/06/16 13:38, dennis@home wrote:
On 14/06/2016 12:05, The Natural Philosopher wrote:
On 14/06/16 11:56, dennis@home wrote:
On 14/06/2016 11:04, Tim Lamb wrote:
Underfloor heating.

Insulation thoughts... the existing ground floor has 25mm Jablite
topped
with 22mm chip. Recommendation is to over fit 25mm of pre-grooved
insulation and a further set of flooring: chip + Vinyl or engineered
hardwood.

Downside is loss of height in doorways.

What is the real energy loss in heating a relatively uninsulated
floor
slab in a roughly square building? For 24 hour occupation, doesn't it
come down to what is lost at the edges?

Nowhere near what is lost through the roof and walls before
insulation.
I would guess at less than 10% before any insulation for a solid
floor.
With 25mm of insulation that will take it down to about 2% another
25mm
will take it down to about 1%. Unless the insulation is really cheap
and
labour free it will never pay for itself.

Confirming once again that Denise cant read a post before replying.

And has no understanding of heat loss in buildings or why its different
with UFH.

You really don't understand physics do you!

I do understand physics

If you put pipes onto and they are at 55C that will only about double
the heat loss through the floor and that loss is only the 1%

No, its noth8ng like as low as that

Of course it is,

Nope. It wouldnt be as low as 2% with 25mm of insulation.

just read what I said

That was always wrong.

and think about it.

Did that, you are wrong.

In message , The Natural Philosopher
writes

So the 4" concrete pad in the middle of the cottage is in close contact
with piping at 55C. The pipe temperature will vary due to thermostat
demands but should settle at something above say 10C for the surrounding
ground. Slow thermal response is not a huge concern for 24 hour occupation.

Within the site, I assume there will be a thermal gradient between the
concrete and the subsoil. Is this likely to cause significant losses
other than near the edges?


Yes. Due to the fact that its HOT and worst of all, when its coldest
outside is when you want the most heat in that slab, and its hottest,
and loses the most.

Yebbut. We are discussing losses to subsoil which is not intimately
linked to air temperature fluctuations.

New work will probably have 4" of insulation under the screed and pipes.

At LEAST.

--
Tim Lamb

In message . com,
lid writes
On 14/06/2016 18:44, Tim Lamb wrote:


Come on chaps! Keep it clean...

You have no chance TNP has lost it.

But we are not discussing Brexit:-)


So the 4" concrete pad in the middle of the cottage is in close contact
with piping at 55C. The pipe temperature will vary due to thermostat
demands but should settle at something above say 10C for the surrounding
ground. Slow thermal response is not a huge concern for 24 hour occupation.

What happened to the 25 mm jabalite (expanded poly)?

I was considering removing it to avoid chopping bits off doors. The JG
Speedfit slabs will have about 10mm of PIR foam between the pipes and
concrete slab.


Cast concrete 100mm + 25 mm expanded poly has a U value of about 0.6 wm2/k

Cast concrete 100mm has a U value of about 1 wm2/k

Cast concrete 100mm with 50 mm expanded poly has a U value of about 0.4
Wm2/k

So the extra 25mm will save you about 0.2 Wm2/k
While the first 25 mm will save you about twice that.


PIR foam is slightly better with the additional 25mm giving a U value
of about 0.33 Wm2/k

Hmmm... cost a bit to replace the Jablite though.


Within the site, I assume there will be a thermal gradient between the
concrete and the subsoil. Is this likely to cause significant losses
other than near the edges?


New work will probably have 4" of insulation under the screed and pipes.

PIR foam would give a U value of about 0.16 Wm2/k.
Expanded poly would be about 0.25Wm2/k

PIR for new fit. The pipes clip to the surface.


--
Tim Lamb

On 14/06/2016 19:54, dennis@home wrote:
On 14/06/2016 18:44, Tim Lamb wrote:


Come on chaps! Keep it clean...

You have no chance TNP has lost it.


So the 4" concrete pad in the middle of the cottage is in close contact
with piping at 55C. The pipe temperature will vary due to thermostat
demands but should settle at something above say 10C for the surrounding
ground. Slow thermal response is not a huge concern for 24 hour
occupation.

What happened to the 25 mm jabalite (expanded poly)?


Cast concrete 100mm + 25 mm expanded poly has a U value of about 0.6 wm2/k

Cast concrete 100mm has a U value of about 1 wm2/k

Cast concrete 100mm with 50 mm expanded poly has a U value of about 0.4
Wm2/k

So the extra 25mm will save you about 0.2 Wm2/k
While the first 25 mm will save you about twice that.


PIR foam is slightly better with the additional 25mm giving a U value of
about 0.33 Wm2/k


Within the site, I assume there will be a thermal gradient between the
concrete and the subsoil. Is this likely to cause significant losses
other than near the edges?


New work will probably have 4" of insulation under the screed and pipes.

PIR foam would give a U value of about 0.16 Wm2/k.
Expanded poly would be about 0.25Wm2/k

Building regs approved doc part L1B (conservation of fuel etc), has the
following to say on floors:

"The cost-effectiveness of floor insulation is complicated by the impact
of the size and shape of the floor (Perimeter/Area ratio). In many cases
existing uninsulated floor U-values are already relatively low when
compared with wall and roof U-values. Where the existing floor U-value
is greater than 0.70W/m2-K, then the addition of insulation is likely to
be cost-effective. Analysis shows that the cost-benefit curve for the
thickness of added insulation is very flat, and so a target U-value of
0.25W/m2-K is appropriate subject to other technical constraints
(adjoining floor levels, etc.)"

Having UFH pushes the U value threshold down some from the 0.7 mentioned.

I have not tried it, but the following might suit Tim's needs:

http://www.kingspaninsulation.co.uk/...alculator.aspx

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On Tuesday, 14 June 2016 11:04:22 UTC+1, Tim Lamb wrote:
Underfloor heating.

Insulation thoughts... the existing ground floor has 25mm Jablite topped
with 22mm chip. Recommendation is to over fit 25mm of pre-grooved
insulation and a further set of flooring: chip + Vinyl or engineered
hardwood.

Downside is loss of height in doorways.

What is the real energy loss in heating a relatively uninsulated floor
slab in a roughly square building? For 24 hour occupation, doesn't it
come down to what is lost at the edges?
--
Tim Lamb

Only a couple of inches makes a big difference in a doorway hieght usagewise.
Is there a damp proof membrane under the floor already?
If not, it needs to be taken up and remedied along with insulation.
Lot of work.

On Tuesday, 14 June 2016 13:59:25 UTC+1, Tim Watts wrote:
On 14/06/16 13:38, dennis@home wrote:

You really don't understand physics do you!

You might, but you've overlooked one thing - see below:

If you put pipes onto and they are at 55C that will only about double
the heat loss through the floor and that loss is only the 1% so at best
adding another 25 mm will take it to the same level as a normal room
without UFH.

Just for the understanding.. if you double the temperature difference
you double the loss. If you double the insulation you halve the loss.


No - because you've incorrectly assumed the substrate temperature under
the subfloor remains the same (your assumption appearing to be about 0c )


This is true of walls and roofs. But the general mass of earth under the
house will rise in temperature with an increased floor surface
temperature, so it is far from obvious how much difference an extra 25mm
of insulation will make.

I've never understood the details, but I can see enough to know your
argument has an error.

Dennis is right on this one.
Instead of a temperature difference of say 20 degrees on an outside wall, your talking about a thirty or forty degree difference because its the heat source.

The actual rate of heat transfer varies depending on the nature of the ground and the movement of groundwater.
The best being dry sand gravel, the worst being wet clay.
You get some of any heat lost back but less then 25% usually

Complex topic.
http://www.sciencedirect.com/science...6013239190066K

On 14/06/16 21:06, Tim Lamb wrote:
In message , The Natural Philosopher
writes

So the 4" concrete pad in the middle of the cottage is in close contact
with piping at 55C. The pipe temperature will vary due to thermostat
demands but should settle at something above say 10C for the surrounding
ground. Slow thermal response is not a huge concern for 24 hour
occupation.

Within the site, I assume there will be a thermal gradient between the
concrete and the subsoil. Is this likely to cause significant losses
other than near the edges?


Yes. Due to the fact that its HOT and worst of all, when its coldest
outside is when you want the most heat in that slab, and its hottest,
and loses the most.

Yebbut. We are discussing losses to subsoil which is not intimately
linked to air temperature fluctuations.


Actually they are.

There is just a lot of soil between your floor and the outside air
temperature.

If you study the building regulations the way heatloss is calculated is
the same as through the walls, but a radically different U value is
assigned to a 'slab against the ground', and the form factor of the
house is taken into account.

I.e the 'subsoil' is not an infinite sink. It has thermal capacity and
thermal resistance and its losing heat to the air all the time. In terms
of heatloss calculations the soil looks like a very thick wall.

Of soggy wet clay. Or damp sand. Or rock. Or chalk.

3 meters of rock is about the same insulation value as a standard wall
insulation however, and its not that far from the center of the room to
the outside, on an average hose, let alone the edges.

And the floor area is the same as the roof. By and large.


New work will probably have 4" of insulation under the screed and pipes.

At LEAST.



--
Ideas are more powerful than guns. We would not let our enemies have
guns, why should we let them have ideas?

Josef Stalin

In message , John
Rumm writes
On 14/06/2016 19:54, dennis@home wrote:
On 14/06/2016 18:44, Tim Lamb wrote:


Come on chaps! Keep it clean...

You have no chance TNP has lost it.


So the 4" concrete pad in the middle of the cottage is in close contact
with piping at 55C. The pipe temperature will vary due to thermostat
demands but should settle at something above say 10C for the surrounding
ground. Slow thermal response is not a huge concern for 24 hour
occupation.

What happened to the 25 mm jabalite (expanded poly)?


Cast concrete 100mm + 25 mm expanded poly has a U value of about 0.6 wm2/k

Cast concrete 100mm has a U value of about 1 wm2/k

Cast concrete 100mm with 50 mm expanded poly has a U value of about 0.4
Wm2/k

So the extra 25mm will save you about 0.2 Wm2/k
While the first 25 mm will save you about twice that.


PIR foam is slightly better with the additional 25mm giving a U value of
about 0.33 Wm2/k


Within the site, I assume there will be a thermal gradient between the
concrete and the subsoil. Is this likely to cause significant losses
other than near the edges?


New work will probably have 4" of insulation under the screed and pipes.

PIR foam would give a U value of about 0.16 Wm2/k.
Expanded poly would be about 0.25Wm2/k

Building regs approved doc part L1B (conservation of fuel etc), has the
following to say on floors:

"The cost-effectiveness of floor insulation is complicated by the
impact of the size and shape of the floor (Perimeter/Area ratio). In
many cases existing uninsulated floor U-values are already relatively
low when compared with wall and roof U-values. Where the existing floor
U-value is greater than 0.70W/m2-K, then the addition of insulation is
likely to be cost-effective. Analysis shows that the cost-benefit curve
for the thickness of added insulation is very flat, and so a target
U-value of 0.25W/m2-K is appropriate subject to other technical
constraints (adjoining floor levels, etc.)"

Having UFH pushes the U value threshold down some from the 0.7 mentioned.

I have not tried it, but the following might suit Tim's needs:

http://www.kingspaninsulation.co.uk/...alculator.aspx

I found that. There is no ability to insert less than 60mm of insulation
in the calculation and Kingspan want to e-mail the result.

I guess they might be worth a phone call anyway.


--
Tim Lamb

In message ,
harry writes
On Tuesday, 14 June 2016 11:04:22 UTC+1, Tim Lamb wrote:
Underfloor heating.

Insulation thoughts... the existing ground floor has 25mm Jablite topped
with 22mm chip. Recommendation is to over fit 25mm of pre-grooved
insulation and a further set of flooring: chip + Vinyl or engineered
hardwood.

Downside is loss of height in doorways.

What is the real energy loss in heating a relatively uninsulated floor
slab in a roughly square building? For 24 hour occupation, doesn't it
come down to what is lost at the edges?
--
Tim Lamb

Only a couple of inches makes a big difference in a doorway hieght usagewise.
Is there a damp proof membrane under the floor already?
If not, it needs to be taken up and remedied along with insulation.
Lot of work.

There is an existing membrane.

Simplest is to lay the piping on top of the existing and renew the
floor. This will reduce door openings by 67mm.

--
Tim Lamb

In message ,
harry writes
On Tuesday, 14 June 2016 13:59:25 UTC+1, Tim Watts wrote:
On 14/06/16 13:38, dennis@home wrote:

You really don't understand physics do you!

You might, but you've overlooked one thing - see below:

If you put pipes onto and they are at 55C that will only about double
the heat loss through the floor and that loss is only the 1% so at best
adding another 25 mm will take it to the same level as a normal room
without UFH.

Just for the understanding.. if you double the temperature difference
you double the loss. If you double the insulation you halve the loss.


No - because you've incorrectly assumed the substrate temperature under
the subfloor remains the same (your assumption appearing to be about 0c )


This is true of walls and roofs. But the general mass of earth under the
house will rise in temperature with an increased floor surface
temperature, so it is far from obvious how much difference an extra 25mm
of insulation will make.

I've never understood the details, but I can see enough to know your
argument has an error.

Dennis is right on this one.
Instead of a temperature difference of say 20 degrees on an outside
wall, your talking about a thirty or forty degree difference because
its the heat source.

The actual rate of heat transfer varies depending on the nature of the
ground and the movement of groundwater.
The best being dry sand gravel, the worst being wet clay.
You get some of any heat lost back but less then 25% usually

Complex topic.
http://www.sciencedirect.com/science...6013239190066K

Sadly they want money to read that article. Otherwise looks appropriate.

--
Tim Lamb

In message , Tim Lamb
writes
In message ,
harry writes
On Tuesday, 14 June 2016 11:04:22 UTC+1, Tim Lamb wrote:
Underfloor heating.

Insulation thoughts... the existing ground floor has 25mm Jablite topped
with 22mm chip. Recommendation is to over fit 25mm of pre-grooved
insulation and a further set of flooring: chip + Vinyl or engineered
hardwood.

Downside is loss of height in doorways.

What is the real energy loss in heating a relatively uninsulated floor
slab in a roughly square building? For 24 hour occupation, doesn't it
come down to what is lost at the edges?
--
Tim Lamb

Only a couple of inches makes a big difference in a doorway hieght usagewise.
Is there a damp proof membrane under the floor already?
If not, it needs to be taken up and remedied along with insulation.
Lot of work.

There is an existing membrane.

Simplest is to lay the piping on top of the existing and renew the
floor. This will reduce door openings by 67mm.
Oops! 47mm.


--
Tim Lamb

On 15/06/2016 08:28, Tim Lamb wrote:
In message , John
Rumm writes
On 14/06/2016 19:54, dennis@home wrote:
On 14/06/2016 18:44, Tim Lamb wrote:


Come on chaps! Keep it clean...

You have no chance TNP has lost it.


So the 4" concrete pad in the middle of the cottage is in close contact
with piping at 55C. The pipe temperature will vary due to thermostat
demands but should settle at something above say 10C for the
surrounding
ground. Slow thermal response is not a huge concern for 24 hour
occupation.

What happened to the 25 mm jabalite (expanded poly)?


Cast concrete 100mm + 25 mm expanded poly has a U value of about 0.6
wm2/k

Cast concrete 100mm has a U value of about 1 wm2/k

Cast concrete 100mm with 50 mm expanded poly has a U value of about 0.4
Wm2/k

So the extra 25mm will save you about 0.2 Wm2/k
While the first 25 mm will save you about twice that.


PIR foam is slightly better with the additional 25mm giving a U value of
about 0.33 Wm2/k


Within the site, I assume there will be a thermal gradient between the
concrete and the subsoil. Is this likely to cause significant losses
other than near the edges?


New work will probably have 4" of insulation under the screed and
pipes.

PIR foam would give a U value of about 0.16 Wm2/k.
Expanded poly would be about 0.25Wm2/k

Building regs approved doc part L1B (conservation of fuel etc), has
the following to say on floors:

"The cost-effectiveness of floor insulation is complicated by the
impact of the size and shape of the floor (Perimeter/Area ratio). In
many cases existing uninsulated floor U-values are already relatively
low when compared with wall and roof U-values. Where the existing
floor U-value is greater than 0.70W/m2-K, then the addition of
insulation is likely to be cost-effective. Analysis shows that the
cost-benefit curve for the thickness of added insulation is very flat,
and so a target U-value of 0.25W/m2-K is appropriate subject to other
technical constraints (adjoining floor levels, etc.)"

Having UFH pushes the U value threshold down some from the 0.7 mentioned.

I have not tried it, but the following might suit Tim's needs:

http://www.kingspaninsulation.co.uk/...alculator.aspx

I found that. There is no ability to insert less than 60mm of insulation
in the calculation and Kingspan want to e-mail the result.

I guess they might be worth a phone call anyway.



You can try this one, you can change the resistance to match your
construction by the looks of it (I haven't tried to do it).