Radiation from Concrete

Hi all.
If this is not the best forum to raise this issue, then I apologise and perhaps someone could steer me to somewhere more suitable.
I would like to conduct an evaluation of the effectiveness of the 'ceramic bead' type of isulation that is used by adding to paint and applying to a surface such as that supplied by http://www.hytechsales.com/ ..
Apparently, this type of insulation reduces heat loss through radiation, rather than heat loss through conduction as per the 'standard' types of insulation materials normally used.
Does anyone know how much energy is radiated from concrete, or where I might find such information? I presume it would be related to temperature.
Take care.
Mike

AC Me wrote:

Hi all.
If this is not the best forum to raise this issue, then I apologise and perhaps someone could steer me to somewhere more suitable.
I would like to conduct an evaluation of the effectiveness of the 'ceramic bead' type of isulation that is used by adding to paint and applying to a surface such as that supplied by http://www.hytechsales.com/

there's no way this stuff insulates against anything.

AC Me wrote:

Hi all.
If this is not the best forum to raise this issue, then I apologise and perhaps someone could steer me to somewhere more suitable.
I would like to conduct an evaluation of the effectiveness of the 'ceramic bead' type of isulation that is used by adding to paint and applying to a surface such as that supplied by http://www.hytechsales.com/ .
Apparently, this type of insulation reduces heat loss through radiation, rather than heat loss through conduction as per the 'standard' types of insulation materials normally used.
Does anyone know how much energy is radiated from concrete, or where I might find such information? I presume it would be related to temperature.
Take care.
Mike

Radiated energy from a surface is proportional to the emissivity of the surface and the fourth power of the *absolute* temperature. The most emissive surface is a black body. You can find the theory in any physics textbook.
You can reduce the emissivity to about 10% or so by painting the surface white, and to about 1% by applying a mirror finish.
Radiation is a surface effect. Adding stuff inside a material that is in conductive contact with the bulk of it will have no effect at all on radiation. Glass beaded paint is certainly highly reflective, and I believe the idea of the ceramic beads is that they have low emissivity / high reflectivity in the near infra-red where most of this radiation occurs. So the theory is good but the practice is dubious. The amount of heat loss through radiation with only a few degrees of differential at normal temperatures is small.
However radiation is a two way street. Whatever you do to reduce heat loss through radiation also proportionately reduces the heat absorption from the sun or anything else hot, as emissivity is the inverse of reflectivity. As the sun's photosphere is some 20 times the absolute temperature of your house, you are generally onto a loser unless your objective is to keep your house cool in a hot climate, or you are in a very cold and sunless place.
The majority of heat loss through a wall is through conduction and convection, and evaporation in wet weather (a.k.a. wind-chill).
If you really want to check, I have developed an instrument for directly measuring the heat flow though walls, doors, ceilings etc. I note from this that the flow though my single glazed windows reverses when they are exposed to the weakest sunshine, and even in hazy bright conditions.
Tim Jackson

On Wed, 26 Nov 2008 22:15:22 +0000, Tim Jackson wrote:

Radiated energy from a surface is proportional to the emissivity of the surface and the fourth power of the *absolute* temperature. The most emissive surface is a black body. You can find the theory in any physics textbook.
You can reduce the emissivity to about 10% or so by painting the surface white, and to about 1% by applying a mirror finish.

According to the emissivity table that came with my Wahl instrument, gloss paint is below 1%, depending on pigment (color doesn't matter much) and mirror surfaces such as glass and chrome are in the 0.01 to 0.001 range.

Radiation is a surface effect. Adding stuff inside a material that is in conductive contact with the bulk of it will have no effect at all on radiation. Glass beaded paint is certainly highly reflective, and I believe the idea of the ceramic beads is that they have low emissivity / high reflectivity in the near infra-red where most of this radiation occurs. So the theory is good but the practice is dubious. The amount of heat loss through radiation with only a few degrees of differential at normal temperatures is small.

Not really. Radiation emission certainly is NOT a surface effect. Glass hot enough to glow is a simple illustration that one can easily visualize. The paint very well may be transparent or partially so to the wavelength involved.
If these ceramic pellets/discs are hollow, radiation certainly takes place at the surface/space interface.
Does this product work? No idea? Could it work in theory? Absolutely. A couple of quick questions you can ask them are a) what is the NASA patent number b) what is the NASA technology transfer contract number. c) who is the NASA contract administrator and d) what is the article number (normally a NASA tech briefs article) for the substance. All this information is easily and readily available if they really are NASA technology partners, as NASA refers to companies who license their technology.
At the second stage of evaluation, ask for independent lab test results. I'm not sure but I believe that NASA requires such testing before a product can be tagged with the NASA logo and the "technology partner" moniker applied.
I CAN tell you that ceramic coatings CAN do wonders. A common use is on racing engine exhaust headers. A few micron coating turns the headers from an engine compartment scorching heater to something that you can touch for short periods. There is almost no radiant OR conducted heat.

However radiation is a two way street. Whatever you do to reduce heat loss through radiation also proportionately reduces the heat absorption from the sun or anything else hot, as emissivity is the inverse of reflectivity.

Absolutely false. Asymetrical emissivity/absorptive materials have been commercially available for decades. Most common use I know of is on thermal solar collectors. Even some finishes are asymetrical. black chrome comes to mind. Omega engineering has this info conveniently tabulated for your handy reference.

The majority of heat loss through a wall is through conduction and convection, and evaporation in wet weather (a.k.a. wind-chill).

May or may not be true but with a concrete wall, if it's cold, it doesn't matter how warm the room is, one can still be uncomfortable because of radiative losses from the body to the walls. Most anyone who's been in a concrete block building in the winter recognizes the effect, if not the cause.

If you really want to check, I have developed an instrument for directly measuring the heat flow though walls, doors, ceilings etc. I note from this that the flow though my single glazed windows reverses when they are exposed to the weakest sunshine, and even in hazy bright conditions.

Since this instrument has been an off-the-shelf item for decades, I can just imagine what kind of crap you've "improved on".
Back to the OP: It looks like enough of this stuff to treat a gallon of paint is about $10. I suggest getting some, painting a square of surface in a room and then compare it on a cold or very hot day. Simply standing in front of the painted square vs another area will let you feel the difference. Cheap enough experiment.
BTW, glass microspheres are widely used to reduce the weight of composite resins. I cant get to the site right now for some reason but AirCraft Spruce sells the beads in gallon buckets for very little money. You might buy some of them and give them a test alongside this magic stuff.
John

-- John De Armond See my website for my current email address http://www.neon-john.com http://www.johndearmond.com <-- best little blog on the net! Tellico Plains, Occupied TN The profligate use of energy is the sign of a healthy, expanding civilization. Conservation is a leap backward toward the caves.

On Nov 27, 9:39�am, Tim Jackson wrote:

Neon John wrote: On Wed, 26 Nov 2008 22:15:22 +0000, Tim Jackson wrote:
Radiated energy from a surface is proportional to the emissivity of the surface and the fourth power of the *absolute* temperature. �The most emissive surface is a black body. �You can find the theory in any physics textbook.
You can reduce the emissivity to about 10% or so by painting the surface white, and to about 1% by applying a mirror finish.
According to the emissivity table that came with my Wahl instrument, gloss paint is below 1%, depending on pigment (color doesn't matter much) and mirror surfaces such as glass and chrome are in the 0.01 to 0.001 range.
Oh true, I can read test books too. �But *exterior* surfaces won't stay that way for long in practice. �I'm talking about actual building surfaces and worst case after a few years of weathering and bird shit. I'd refer you to,www.omega.com/literature/transactions/volume1/emissivity..html which would correct me the other way if anything.
Radiation is a surface effect. �Adding stuff inside a material that is in conductive contact with the bulk of it will have no effect at all on radiation.
Not really. �Radiation emission certainly is NOT a surface effect. �Glass hot enough to glow is a simple illustration that one can easily visualize. �The paint very well may be transparent or partially so to the wavelength involved.
I admit I did mean opaque materials. �Paints and walls are generally designed to be opaque, otherwise they are called varnishes and windows. � I know we can create exotic materials and situations in the lab that don't fit my simple model.
However radiation is a two way street. Whatever you do to reduce heat loss through radiation also proportionately reduces the heat absorption from the sun or anything else hot, as emissivity is the inverse of reflectivity.
Absolutely false. �Asymetrical emissivity/absorptive materials have been commercially available for decades. �Most common use I know of is on thermal solar collectors. �Even some finishes are asymetrical. �black chrome comes to mind. �Omega engineering has this info conveniently tabulated for your handy reference.
On CONCRETE? We are losing the plot a bit here aren't we? If you paint concrete white you lose heat absorption during the day. Are you disputing that? �Few building materials are seriously asymmetric.
What is important is that in daytime we are talking about incoming radiation in the near infrared and emission in the far infrared. Many materials have emissivity which varies with wavelength.
But this is not really the question here. �We are talking about heat radiated from the surface of the wall, heat received by the surface of the wall from the ambient environment, and heat received from the sun.
The first two will be in balance if the surface of the wall is at ambient temperature and the sky is opaque. �In practice, conducted heat losses through the wall will elevate it slightly above ambient. �In still air a solid wall without cavity may be losing say 50W/m� which will warm the outside surface by no more than 3�C in absence of differential radiation. The differential radiation on a cloudy day will be under 20W/m� (the remainder being convection) and lower it by about 1�C. Making the emissivity *zero* would therefore reduce the losses by about 5%, which is about the same as adding a layer of embossed wallpaper inside.
In foul weather, forced convection and evaporation will reduce the differential and the benefit will be less.
On a clear night however you lose a lot more, your roof could lose 400W/m�. Of course it gets most of that back by conduction and condensation from the air, but it means the surface can get several degrees colder than ambient (hence dews and ground frosts). �By applying a low emissivity coating you may raise the surface temperature by a degree or two, and so reduce the conductive losses through the wall by up to 10%. On the other hand, I severely doubt that the paint coating will not also increase the reflection of sunlight which at 1000W/m� times the sine of the sun's elevation, is likely to be more.
My conclusion is that whatever you save (if anything) by applying a coating, it is always a percentage of what you are losing by conduction through the wall, so the better insulator the wall, the less advantage. And almost always it will be cheaper and easier to improve the wall's insulation.
The majority of heat loss through a wall is through conduction and convection, and evaporation in wet weather (a.k.a. wind-chill).
May or may not be true but with a concrete wall, if it's cold, it doesn't matter how warm the room is, one can still be uncomfortable because of radiative losses from the body to the walls. �Most anyone who's been in a concrete block building in the winter recognizes the effect, if not the cause.
� The radiated heat from the body is around 100W according to Wikipedia. The corresponding received radiation from an environment at freezing would be about 60W. �This is independent of the air temperature.
On the other hand, if you are in a room with walls at 0�C filled with warm air, there will be a considerable convection current off the walls which is what will make it feel uncomfortable. �(If the air is cold, you get the same convection off your body.) Also I've noticed that it is almost always colder inside an unheated bare concrete structure (specifically a football stadium stand) than outside, because of thermal inertia.
If you really want to check, I have developed an instrument for directly measuring the heat flow though walls, doors, ceilings etc. �
Since this instrument has been an off-the-shelf item for decades, I can just imagine what kind of crap you've "improved on".
I didn't say I'd improved on anything. I didn't say it was a product. I built and calibrated my own instrument for my own use because I couldn't find one on the market here that would do what I wanted, such as take a reading on the underside of a 3m high ceiling without damaging the decoration. �It was made from spares from thermal instruments (eg bed-quilt conductivity test) that I do build and sell commercially to industry. �I'd be interested in any references you have though, if my experience of industrial instrument is anything to go by, my device is probably an order of magnitude cheaper.
Tim Jackson

Thanks for all the info so far guys.
I guess I should clarify. I am currently constructing my own home. I have decided that I want the energy usage of the structure to be better than required by the construction codes. Here in Ireland the codes, or building regulations, require certain maximum 'u' values for each part of the building fabric, or a maximum overall 'u' value. I have decided that those parts of the structure that cannot easily be improved afterwards should have the best insulation I can manage right now. This means the floor in particular. So I am putting in three layers of under-floor insulation. The first layer will be about 1" thick. On top of this will be a layer about 2 and 3/8" thick through which will be running ducting for domestic hot and cold water and also the boiler return pipes which will allow the possible future installation of boilers behind open fires or with certain stoves. Then there will be a 2" layer on insulation on top of which will be underfloor heating pipes. A 1" or 2" strip of insulation will also be around the periphery of each room. However, as the periphery insulation is only 1" to 2" thick, this creates a 'cold bridge' that would result in an energy loss that would be higher than I would like. One possible solution might be to make use of the aforementioned 'insulating paint', applying this to the peripheral insulation. Another possible use in my situation would be to paint the copper boiler return pipes as there will be only a couple of inches of insulation, at best, between these and the sub-floor and these would be expected to have an operating temperature of 70 C (158 F) or higher. And perhaps to the ducts or the insulation surface underneath the ducts. This might help keep the domestic hot water in the pipes warmer for longer and could have an effect on serial usage (e.g. in the morning as everyone gets ready for work and school).
As an aside, I also intend to 'bury' temperature sensors in the building fabric during construction so that the 'performance' of the building can be monitored afterwards.
Thanks, all, for your comments and suggestions. I do appreciate it.
Take care.
Mike

Neon John wrote:

On Wed, 26 Nov 2008 22:15:22 +0000, Tim Jackson wrote:
Radiated energy from a surface is proportional to the emissivity of the surface and the fourth power of the *absolute* temperature. The most emissive surface is a black body. You can find the theory in any physics textbook.
You can reduce the emissivity to about 10% or so by painting the surface white, and to about 1% by applying a mirror finish.
According to the emissivity table that came with my Wahl instrument, gloss paint is below 1%, depending on pigment (color doesn't matter much) and mirror surfaces such as glass and chrome are in the 0.01 to 0.001 range.
Oh true, I can read test books too. But *exterior* surfaces won't stay

that way for long in practice. I'm talking about actual building surfaces and worst case after a few years of weathering and bird shit. I'd refer you to, www.omega.com/literature/transactions/volume1/emissivity.html which would correct me the other way if anything.

Radiation is a surface effect. Adding stuff inside a material that is in conductive contact with the bulk of it will have no effect at all on radiation.
Not really. Radiation emission certainly is NOT a surface effect. Glass hot enough to glow is a simple illustration that one can easily visualize. The paint very well may be transparent or partially so to the wavelength involved.
I admit I did mean opaque materials. Paints and walls are generally

designed to be opaque, otherwise they are called varnishes and windows. I know we can create exotic materials and situations in the lab that don't fit my simple model.

However radiation is a two way street. Whatever you do to reduce heat loss through radiation also proportionately reduces the heat absorption from the sun or anything else hot, as emissivity is the inverse of reflectivity.
Absolutely false. Asymetrical emissivity/absorptive materials have been commercially available for decades. Most common use I know of is on thermal solar collectors. Even some finishes are asymetrical. black chrome comes to mind. Omega engineering has this info conveniently tabulated for your handy reference.
On CONCRETE? We are losing the plot a bit here aren't we?

If you paint concrete white you lose heat absorption during the day. Are you disputing that? Few building materials are seriously asymmetric.
What is important is that in daytime we are talking about incoming radiation in the near infrared and emission in the far infrared. Many materials have emissivity which varies with wavelength.
But this is not really the question here. We are talking about heat radiated from the surface of the wall, heat received by the surface of the wall from the ambient environment, and heat received from the sun.
The first two will be in balance if the surface of the wall is at ambient temperature and the sky is opaque. In practice, conducted heat losses through the wall will elevate it slightly above ambient. In still air a solid wall without cavity may be losing say 50W/m� which will warm the outside surface by no more than 3�C in absence of differential radiation. The differential radiation on a cloudy day will be under 20W/m� (the remainder being convection) and lower it by about 1�C. Making the emissivity *zero* would therefore reduce the losses by about 5%, which is about the same as adding a layer of embossed wallpaper inside.
In foul weather, forced convection and evaporation will reduce the differential and the benefit will be less.
On a clear night however you lose a lot more, your roof could lose 400W/m�. Of course it gets most of that back by conduction and condensation from the air, but it means the surface can get several degrees colder than ambient (hence dews and ground frosts). By applying a low emissivity coating you may raise the surface temperature by a degree or two, and so reduce the conductive losses through the wall by up to 10%. On the other hand, I severely doubt that the paint coating will not also increase the reflection of sunlight which at 1000W/m� times the sine of the sun's elevation, is likely to be more.
My conclusion is that whatever you save (if anything) by applying a coating, it is always a percentage of what you are losing by conduction through the wall, so the better insulator the wall, the less advantage. And almost always it will be cheaper and easier to improve the wall's insulation.

The majority of heat loss through a wall is through conduction and convection, and evaporation in wet weather (a.k.a. wind-chill).
May or may not be true but with a concrete wall, if it's cold, it doesn't matter how warm the room is, one can still be uncomfortable because of radiative losses from the body to the walls. Most anyone who's been in a concrete block building in the winter recognizes the effect, if not the cause.
The radiated heat from the body is around 100W according to Wikipedia.

The corresponding received radiation from an environment at freezing would be about 60W. This is independent of the air temperature.
On the other hand, if you are in a room with walls at 0�C filled with warm air, there will be a considerable convection current off the walls which is what will make it feel uncomfortable. (If the air is cold, you get the same convection off your body.) Also I've noticed that it is almost always colder inside an unheated bare concrete structure (specifically a football stadium stand) than outside, because of thermal inertia.

If you really want to check, I have developed an instrument for directly measuring the heat flow though walls, doors, ceilings etc.
Since this instrument has been an off-the-shelf item for decades, I can just imagine what kind of crap you've "improved on".

I didn't say I'd improved on anything. I didn't say it was a product. I built and calibrated my own instrument for my own use because I couldn't find one on the market here that would do what I wanted, such as take a reading on the underside of a 3m high ceiling without damaging the decoration. It was made from spares from thermal instruments (eg bed-quilt conductivity test) that I do build and sell commercially to industry. I'd be interested in any references you have though, if my experience of industrial instrument is anything to go by, my device is probably an order of magnitude cheaper.
Tim Jackson

On Nov 27, 6:01�pm, Tim Jackson wrote:

AC Me wrote: Thanks for all the info so far guys.
I guess I should clarify. I am currently constructing my own home. I have decided that I want the energy usage of the structure to be better than required by the construction codes. Here in Ireland the codes, or building regulations, require certain maximum 'u' values for each part of the building fabric, or a maximum overall 'u' value. I have decided that those parts of the structure that cannot easily be improved afterwards should have the best insulation I can manage right now. This means the floor in particular. So I am putting in three layers of under-floor insulation. The first layer will be about 1" thick. On top of this will be a layer about 2 and 3/8" thick through which will be running ducting for domestic hot and cold water and also the boiler return pipes which will allow the possible future installation of boilers behind open fires or with certain stoves. Then there will be a 2" layer on insulation on top of which will be underfloor heating pipes. A 1" or 2" strip of insulation will also be around the periphery of each room. However, as the periphery insulation is only 1" to 2" thick, this creates a 'cold bridge' that would result in an energy loss that would be higher than I would like. One possible solution might be to make use of the aforementioned 'insulating paint', applying this to the peripheral insulation. Another possible use in my situation would be to paint the copper boiler return pipes as there will be only a couple of inches of insulation, at best, between these and the sub-floor and these would be expected to have an operating temperature of 70 C (158 F) or higher. And perhaps to the ducts or the insulation surface underneath the ducts. This might help keep the domestic hot water in the pipes warmer for longer and could have an effect on serial usage (e.g. in the morning as everyone gets ready for work and school).
As an aside, I also intend to 'bury' temperature sensors in the building fabric during construction so that the 'performance' of the building can be monitored afterwards.
Thanks, all, for your comments and suggestions. I do appreciate it.
Take care.
Mike
I am pretty sure this paint will do no better than metallised plastic or even tinfoil when used internally. �There is no sunlight, night, or weathering to consider. �A reflector under your boiler pipes might possibly be useful. �But 70�C return is a bit hot isn't it? �I don't even run my boiler as high as 70�C. �A condensing boiler won't work very well up there. Can't you reduce the pumping or specify bigger radiators to lower the return temperature and improve the boiler efficiency? It'll gain you more than any reflectors.
Tim

Hi Tim.
The 70 C figure is based on measurements from existing systems, rather than expectations for mine. I have found that before a 'system' has 'warmed-up' the return flow temperature is low (and rising) but when the 'system' has 'warmed-up' the return temperature can approach that of the boiler outlet temperature. Condensing boilers are a rarity here in Ireland. Standard oil-fired boilers usually operate in the region of 90 C, or even above. The pipes in question are to make provision for the potential later installation of 'open fires' (fireplaces) or possible installation of stoves all of which will use solid fuel. These allow a certain level of fuel independence. It is rather difficult to control the water temperature from the boilers of solid fuel burning devices. My 'radiators' will be the floor as I am, or will be, installing an under-floor heating system.
I'll try to acquire a small quantity of this 'ceramic-bead insulation additive', do a simple test and will post the results back here. If I can get the material, I propose to do the following: 1. Measure the diameter of a section of outlet pipe of an oil-fired boiler. 2. Paint a portion of the outlet pipe of this oil-fired boiler. 3. Measure the diameter of the outlet pipe in the same location as before and at the same temperature conditions as the first diameter measurement when the paint has dried. 4. Measure the temperature of the pipe either side of the painted section. 5. Measure the temperature of the painted section. 6. Post the results here.
Caveats A. The relative diameters will be an approximation as it would be difficult to guarantee the pipe is measured in exactly the same location and it cannot be assumed that the layer of paint is the same thickness all around the pipe. The temperature can be measured in approximately the same location as the diameter is measured to reduce the possibilities of error. B. The boiler being used for this test may not be the most suiatble as it is distinctly underpowered for the location installed - it struggles to bring the area to any basic level of comfort. C. I cannot guarantee the accuracy of either measuring device (a digital thermometer and a digital vernier calipers) but it will be the differential measurements that will be of interest.
Take care.
Mike

AC Me wrote:

Thanks for all the info so far guys.
I guess I should clarify. I am currently constructing my own home. I have decided that I want the energy usage of the structure to be better than required by the construction codes. Here in Ireland the codes, or building regulations, require certain maximum 'u' values for each part of the building fabric, or a maximum overall 'u' value. I have decided that those parts of the structure that cannot easily be improved afterwards should have the best insulation I can manage right now. This means the floor in particular. So I am putting in three layers of under-floor insulation. The first layer will be about 1" thick. On top of this will be a layer about 2 and 3/8" thick through which will be running ducting for domestic hot and cold water and also the boiler return pipes which will allow the possible future installation of boilers behind open fires or with certain stoves. Then there will be a 2" layer on insulation on top of which will be underfloor heating pipes. A 1" or 2" strip of insulation will also be around the periphery of each room. However, as the periphery insulation is only 1" to 2" thick, this creates a 'cold bridge' that would result in an energy loss that would be higher than I would like. One possible solution might be to make use of the aforementioned 'insulating paint', applying this to the peripheral insulation. Another possible use in my situation would be to paint the copper boiler return pipes as there will be only a couple of inches of insulation, at best, between these and the sub-floor and these would be expected to have an operating temperature of 70 C (158 F) or higher. And perhaps to the ducts or the insulation surface underneath the ducts. This might help keep the domestic hot water in the pipes warmer for longer and could have an effect on serial usage (e.g. in the morning as everyone gets ready for work and school).
As an aside, I also intend to 'bury' temperature sensors in the building fabric during construction so that the 'performance' of the building can be monitored afterwards.
Thanks, all, for your comments and suggestions. I do appreciate it.
Take care.
Mike

I am pretty sure this paint will do no better than metallised plastic or even tinfoil when used internally. There is no sunlight, night, or weathering to consider. A reflector under your boiler pipes might possibly be useful. But 70�C return is a bit hot isn't it? I don't even run my boiler as high as 70�C. A condensing boiler won't work very well up there. Can't you reduce the pumping or specify bigger radiators to lower the return temperature and improve the boiler efficiency? It'll gain you more than any reflectors.
Tim

On Thu, 27 Nov 2008 09:39:53 +0000, Tim Jackson wrote:

Oh true, I can read test books too. But *exterior* surfaces won't stay that way for long in practice. I'm talking about actual building surfaces and worst case after a few years of weathering and bird shit. I'd refer you to, www.omega.com/literature/transactions/volume1/emissivity.html which would correct me the other way if anything.

That's nice, Tim. I'm glad you can read "test books". Now if you only had some field experience. I do. In the past I did full scale energy audits and not just the electrical ones I do now. I have 4 or 5 (I'll be glad to provide an inventory for you if it would be a teaching moment) professional IR pyrometers (not the dime store optic-less, fixed emissivity stuff like HF sells) including one with a chilled mirror cassegranian telescope that lets me look at individual splices and connections on transmission lines. It looks like a large barrel rifle and has gotten the attention of the cops more than once. I no longer own an IR pyro camera (too much money tied up in not enough business but now that the price has dropped to the low 4 digit range, I may get another.
One thing you quickly learn is that emissivity guides are just that - guides. I calibrate my instruments by placing a foil thermocouple on the surface to be measured and set the emissivity until the pyrometer agrees or the camera profile agrees.
Your BS about outdoors is just that since this kind of coating is used indoors. It would be idiotic to place the stuff on an outer surface where pollution and chalking would defeat it in months. Well, considering with whom I'm debating...

Radiation is a surface effect. Adding stuff inside a material that is in conductive contact with the bulk of it will have no effect at all on radiation.
Not really. Radiation emission certainly is NOT a surface effect. Glass hot enough to glow is a simple illustration that one can easily visualize. The paint very well may be transparent or partially so to the wavelength involved.
I admit I did mean opaque materials. Paints and walls are generally designed to be opaque, otherwise they are called varnishes and windows. I know we can create exotic materials and situations in the lab that don't fit my simple model.

They are opaque to visible spectrum but not to IR. Do a little research on how places like the Smithsonian use IR to detect painting on the same canvas underneath the obvious visible painting. MANY paints are perfectly transparent to IR. Again, you'd know that if you'd either done your homework or had some experience.
With my vintage early 90s B&W IR camera, I could see right through the paint on a customer's oil painting. I detected more than one forgery by seeing the underlying image where the forger had re-used the canvas so as to have period-correct canvas. The forger could scrape off the old paint but not enough that it would not show up under IR.

However radiation is a two way street. Whatever you do to reduce heat loss through radiation also proportionately reduces the heat absorption from the sun or anything else hot, as emissivity is the inverse of reflectivity.
Absolutely false. Asymetrical emissivity/absorptive materials have been commercially available for decades. Most common use I know of is on thermal solar collectors. Even some finishes are asymetrical. black chrome comes to mind. Omega engineering has this info conveniently tabulated for your handy reference.
On CONCRETE? We are losing the plot a bit here aren't we? If you paint concrete white you lose heat absorption during the day. Are you disputing that? Few building materials are seriously asymmetric.

But we're talking about coatings to minimize the radiation of concrete, aren't we?

What is important is that in daytime we are talking about incoming radiation in the near infrared and emission in the far infrared. Many materials have emissivity which varies with wavelength.
But this is not really the question here. We are talking about heat radiated from the surface of the wall, heat received by the surface of the wall from the ambient environment, and heat received from the sun.

No we're not. We're talking about keeping it out of the conditioned spaces. It matters little if the blocks get hot if the radiative and conductive processes are stopped at the last millimeter by wall treatment.

My conclusion is that whatever you save (if anything) by applying a coating, it is always a percentage of what you are losing by conduction through the wall, so the better insulator the wall, the less advantage. And almost always it will be cheaper and easier to improve the wall's insulation.

That's probably true as far as it goes. Going farther, one can use multiple barriers - insulation, an aluminum radiation barrier, perhaps sheet rock and (if it proves out) a ceramic or microsphere coating. One would want to do a cost-analysis, something that would not be simple. there is software to automate the process.

The radiated heat from the body is around 100W according to Wikipedia. The corresponding received radiation from an environment at freezing would be about 60W. This is independent of the air temperature.

If that's what Wikipedia says then it is wrong as usual. The ASHRAE handbook's standard human, used for sizing HVAC and modeling same, sets the total emission, including nonsensible (latent) heat in exhaled and sweat evaporated moisture at 100 watts. the distribution of the heat doesn't matter much for HVAC purposes because it all has to be eliminated to maintain comfort. It DOES matter when discussing radiant heat transfer. Still puzzling why you drew this into the conversation other than for obfuscation.
John -- John De Armond See my website for my current email address http://www.neon-john.com http://www.johndearmond.com <-- best little blog on the net! Tellico Plains, Occupied TN Better to pass boldly into that other world in the full glory of some passion than fade and wither dismally with age. -Joyce

On Thu, 27 Nov 2008 06:04:06 -0800 (PST), AC Me wrote:
<please edit your replies. Thank you.>

Thanks for all the info so far guys.

Jackson's developed a well-deserved rep for bullsh*tting in areas where he knows little. Take what he says with a grain of salt.

I guess I should clarify. I am currently constructing my own home. I have decided that I want the energy usage of the structure to be better than required by the construction codes. Here in Ireland the codes, or building regulations, require certain maximum 'u' values for each part of the building fabric, or a maximum overall 'u' value. I have decided that those parts of the structure that cannot easily be improved afterwards should have the best insulation I can manage right now. This means the floor in particular.

I know I'm taking a big risk of tromping on my dick trying to advise about another country's standards so.. What is "u" value. It is like our "R" value? How is it measured/calculated.

So I am putting in three layers of under-floor insulation. The first layer will be about 1" thick. On top of this will be a layer about 2 and 3/8" thick through which will be running ducting for domestic hot and cold water and also the boiler return pipes which will allow the possible future installation of boilers behind open fires or with certain stoves. Then there will be a 2" layer on insulation on top of which will be underfloor heating pipes. A 1" or 2" strip of insulation will also be around the periphery of each room.

OK, let me make sure I understand this. You're going to have a slab of concrete on top of a vapor barrier. On top of that will be 1" of something (specify please). then a 2+" air space. Then 2" of more insulation (again, please specify) and then some kind of flooring with hydronic radiant floor heating.
Several questions.
- what will the flooring be? - I don't see a radiation barrier in there (presumably why you asked about the paint. - What constitutes the walls of the air/utility space?
I've never been there, but from friends who live in Ireland, I'm told that air conditioning is rarely needed. True? If so then we need to concentrate on heating.
I don't agree with this layout. Any heat loss from the utility space, if directed properly upward, contributes to room comfort and therefore is not wasted. NO need for any insulation above the utility spaces.
You must concentrate on stopping the heat from flowing down. MY first layer of insulation next to the utility space would be an infrared barrier - plain old paper-backed aluminum foil or whatever equivalent is available over there. Aluminum is about the 3rd best reflector of long wavelength IR behind gold and copper. If you can afford copper foil, go for it :-)
Under the foil you require a conduction barrier. Fiberglass batting, styrofoam, rigid foam and similar products all do that. If the materials are in contact, there won't be any convection. Since this is a floor and you don't want to raise it too far above the ground, I'd go with the highest "R" (or "u") value per unit thickness I could find. Probably rigid foam. At the same time, make sure it's a product with a life rating similar to that of your house. It'd be a bitch to have to rip up the floor to replace foam that is undergoing "reversion" or return to the monomer state (translate: gooey mess.
Under THAT I'd place another radiant barrier and perhaps a second vapor barrier, for in the event the first one gets punctured. Another thin layer of insulation and the vapor barrier that is against the soil (preferably on a layer of sand to be gentle to the plastic vapor barrier) and you're done.
This is overkill but that's what you asked for. Very little heat is lost downward through the floor even when the floor is a concrete slab resting on a vapor barrier and then just dirt and embedded with hydronic heating tubes.
I have a friend whom I helped install a radiant slab system in his shop. A second friend pretty much copied the first setup except that he put a layer of styrofoam under the slab as recommended. Both have the same wood burning water boiler.
I've measured and calculated the energy usage and am amazed that they are essentially the same, within the limits of measuring noise. I sat and thought and calculated a bit and now I think that I understand.
Dry earth is a good insulator. Not great but good. In the installation with the slab against the dirt, the dirt is quickly dried by the 180 deg water flowing through the pipes. The pipes are about 1/3 the slab thickness from the bottom so the bottom gets much hotter than the top. Once the soil dries out, its insulating qualities aren't that much different than a similar thickness of fiberglass batting. In both cases, fairly conductive material (clay in one case and glass in the other) entrap air in little pockets. The air does the insulating. The pockets are too small for convection to set up so it's only the thermal conduction that matters. The actual volume of solids (clay or glass) in either case is small.
I'd go with a layer of insulation, a radiant barrier and be done with the floor. The ceiling is where you need to spend all your effort and dollars.
Something else you might want to consider is embedding small water tubing in the walls. I was once at a DuPont facility on other work and was shown an experimental room. All surfaces including the ceiling had electrical elements embedded in the sheet rock. That was the most comfortable room I think that I have ever been in. Absolutely no drafts, no chills and no hot spots.
They were experimenting with the concept with an eye toward developing polymer sheeting that could be placed between layers of sheet rock and carry the water. It never came to market, probably because of cost but it damn sure worked.
The engineers explained that the wall radiation was primarily to stop convection drafts by maintaining the same temperature floor to ceiling. The floor elements supplied the bulk of the heat while the ceiling elements prevented head chills, especially on bald guys :-) I forget the number but some ungodly amount of body heat, >50%, is lost through an exposed scalp so that was an important element.
Years ago when electricity was practically free (too cheap to meter :-) there was a product called Ceil Heat. In this product, resistance wires were run in parallel rows about an inch apart on special ceiling sheet rock. Then a thin layer of sheet rock was placed over it. The surface got barely warm to the touch but it was quite comfortable heat.
It failed when electrical prices ran up in the 70s because, given the almost free nature of electricity, they had neglected a radiant heat barrier between the sheet rock and the ceiling joists. Lots of heat got conducted into the attic.
My grandmother owned a Ceil-heated house and I've owned one. Her's was in the cheap days and it was wonderful. Mine hit me with an August electric bill of over $100 in 1976! and that just to take the chill off. Of course, I found that the contractor hadn't installed any insulation in the house. (government built for the poor that I bought on repo.)
I would love to explore that kind of heat, perhaps using water instead of electricity, again, using proper insulation.

As an aside, I also intend to 'bury' temperature sensors in the building fabric during construction so that the 'performance' of the building can be monitored afterwards.

Good idea. Suggest welded bare Type T (copper constantine) because both metals are corrosion-resistant. Dipped in RTV and then embedded in the concrete or whatever, they'll last a lifetime. Type T also generates a decent voltage, in case you want to build your own readout or data acq.
Stay away from thermistors. They drift over time. Platinum RTDs are the Cadillac (Rolls?) of temperature sensors but unless you go with a very high dollar unit, the bonding between the platinum and the base metal wire will likely fail in a few years. We had a rash of failures in nuclear plant (non-safety areas - the Class 1A stuff was the highest of zoot :-) sensors a couple of decades ago.
Copper RTDs have kinda fallen out of favor for some reason but they work, are durable and are even something you could build at home. I'd still stick with Type T bare thermocouples though.
John
-- John De Armond See my website for my current email address http://www.neon-john.com http://www.johndearmond.com <-- best little blog on the net! Tellico Plains, Occupied TN I like you ... you remind me of me when I was young and stupid.

On Nov 28, 1:08�am, Neon John wrote:

On Thu, 27 Nov 2008 06:04:06 -0800 (PST), AC Me <mmal...@gofree.indigo.ie wrote:
please edit your replies. �Thank you.

Thanks for all the info so far guys.
Jackson's developed a well-deserved rep for bullsh*tting in areas where he knows little. �Take what he says with a grain of salt.

I guess I should clarify. I am currently constructing my own home. I have decided that I want the energy usage of the structure to be better than required by the construction codes. Here in Ireland the codes, or building regulations, require certain maximum 'u' values for each part of the building fabric, or a maximum overall 'u' value. I have decided that those parts of the structure that cannot easily be improved afterwards should have the best insulation I can manage right now. This means the floor in particular.
I know I'm taking a big risk of tromping on my dick trying to advise about another country's standards so.. �What is "u" value. �It is like our "R" value? �How is it measured/calculated.

Oh dear! I've gone an' done what I try hard not to do - make assumptions. The u value is the inverse of the thermal resistance of a material, known as the R value. It is a measure of the rate of heat loss through a meterial or through a series of materials combined, such as would occur in a wall or floor. It is measured in Watt per meter squared Kelvin or W/m^2K, where 1K (one Kelvin) is equivalent to 1 degree Celcius (or Centigrade) and is the difference in temperature between either side of the material. In other words, if the external wall of a house had a u value of 0.2 and the internal temperature was 20 degrees Celcius and the external temperarure was 5 degrees Celcius then the heat loss would be 0.2*15 W/ m^2 or 3 Watts per meter squared. If the house had an external wall surface area of 40m^2 then the heat loss through the walls would be 120W. I not good at explanations, and I've just done this off- the-cuff, so I hope this is correct.

So I am putting in three layers of under-floor insulation. The first layer will be about 1" thick. On top of this will be a layer about 2 and 3/8" thick through which will be running ducting for domestic hot and cold water and also the boiler return pipes which will allow the possible future installation of boilers behind open fires or with certain stoves. Then there will be a 2" layer on insulation on top of which will be underfloor heating pipes. A 1" or 2" strip of insulation will also be around the periphery of each room.
OK, let me make sure I understand this. �You're going to have a slab of concrete on top of a vapor barrier. �On top of that will be 1" of something (specify please). �then a 2+" air space. �Then 2" of more insulation (again, please specify) and then some kind of flooring with hydronic radiant floor heating.
Several questions. � Oh dear, I think I may have done it again!.Another assumption.

I think (?) you may be thinking of a house with a basement (?) construction. There are several different types of floor construction used here but a 'typical' floor, if there is ever such a thing, might consist of the following. From the foundations bring the walls, concrete block, up a certain height (normally around 18"). Within these walls is place a certain amount of hardcore (stones), perhaps a depth of 9" leaving a further depth of 9" to be filled. A thin sand screed is placed on top of the hardcore. Upon this is placed a plastic sheeting that acts as a damp-proof and radon-proof membrane. On top of this membrane, place the insulation, typically 60mm of polyurethane or polyisocyanureate boards (usually 1.2m * 2.4m). On top of this place the concrete floor - usually a 6", or 150mm, floor slab is specified. Some insulation is usually 'turned-up' around what will be the edges of the floor slab before the slab is poured to reduce cold bridging (the almost direct contact of the edge of the floor slab to the walls connected to the foundation. The insulation boards usually have a foil finish on both sides. It is not uncommon to place another, thin, sheet of polythene on top of the insulation before the concrete floor is poured to act as a 'slip- sheet' and prevent damage to the foil surface by the concrete as it moves.

- what will the flooring be? - I don't see a radiation barrier in there (presumably why you asked about the paint. - What constitutes the walls of the air/utility space? Air/Utility space - perhaps a basement area in North America?

My floor construction is as follows: Hardcore Sand 'blinding' 4" (100mm) Concrete sub-floor Sand 'blinding' Membrane (damp & radon) 5 and 3/8" (135mm) insulation (polyisocyanureate) 3 and 1/2" (90mm) concrete floor, in whcih the under-floor heating pipes will be buried. The 135 mm of underfloor insulation is make up of three layers - a 25mm layer, a 60mm layer and a final 50mm layer. The underfloor heating pipes are fixed on top of the final 50mm layer. Ducting for domestic hot and cold water pipes will be run through the middle, 60mm, layer. Also through this layer will be the 1" copper pipes that will act as the return to any future boilers fitted to either open fires or solid fuel buring stoves.

I've never been there, but from friends who live in Ireland, I'm told that air conditioning is rarely needed. �True? �If so then we need to concentrate on heating.

Correct

I don't agree with this layout. �Any heat loss from the utility space, if directed properly upward, contributes to room comfort and therefore is not wasted. �NO need for any insulation above the utility spaces.

By utility spaces are you referring to basements? Basements are a rareiity here in Ireland and there is no basement in my construction.

You must concentrate on stopping the heat from flowing down. �MY first layer of insulation next to the utility space would be an infrared barrier - plain old paper-backed aluminum foil or whatever equivalent is available over there. Aluminum is about the 3rd best reflector of long wavelength IR behind gold and copper. �If you can afford copper foil, go for it :-)
Under the foil you require a conduction barrier. �Fiberglass batting, styrofoam, rigid foam and similar products all do that. �If the materials are in contact, there won't be any convection. � Since this is a floor and you don't want to raise it too far above the ground, I'd go with the highest "R" (or "u") value per unit thickness I could find. �Probably rigid foam. �At the same time, make sure it's a product with a life rating similar to that of your house. �It'd be a bitch to have to rip up the floor to replace foam that is undergoing "reversion" or return to the monomer state (translate: gooey mess.
Under THAT I'd place another radiant barrier and perhaps a second vapor barrier, for in the event the first one gets punctured. �Another thin layer of insulation and the vapor barrier that is against the soil (preferably on a layer of sand to be gentle to the plastic vapor barrier) and you're done.
This is overkill but that's what you asked for. �Very little heat is lost downward through the floor even when the floor is a concrete slab resting on a vapor barrier and then just dirt and embedded with hydronic heating tubes..
I have a friend whom I helped install a radiant slab system in his shop. �A second friend pretty much copied the first setup except that he put a layer of styrofoam under the slab as recommended. �Both have the same wood burning water boiler.
I've measured and calculated the energy usage and am amazed that they are essentially the same, within the limits of measuring noise. �I sat and thought and calculated a bit and now I think that I understand.
Dry earth is a good insulator. �Not great but good. �In the installation with the slab against the dirt, the dirt is quickly dried by the 180 deg water flowing through the pipes. �The pipes are about 1/3 the slab thickness from the bottom so the bottom gets much hotter than the top. �Once the soil dries out, its insulating qualities aren't that much different than a similar thickness of fiberglass batting. �In both cases, fairly conductive material (clay in one case and glass in the other) entrap air in little pockets. �The air does the insulating. �The pockets are too small for convection to set up so it's only the thermal conduction that matters. �The actual volume of solids (clay or glass) in either case is small.

Ah, but the biggest problem here, the one that pretty much all the building regs are designed to overcome (with the solutions to all other problems bolted-on) is .....WATER.....WATER and more WATER. It sometimes seems as if it never stops raining (there's the old joke - it only rained twice last week, once for three days and once for four days :)). It's wet, wet, wet. Our soil might get dry, or dryish, sometimes (god, I hope it's sometime soon :)).

I'd go with a layer of insulation, a radiant barrier and be done with the floor. �The ceiling is where you need to spend all your effort and dollars.
Something else you might want to consider is embedding small water tubing in the walls. �I was once at a DuPont facility on other work and was shown an experimental room. �All surfaces including the ceiling had electrical elements embedded in the sheet rock. �That was the most comfortable room I think that I have ever been in. �Absolutely no drafts, no chills and no hot spots.
They were experimenting with the concept with an eye toward developing polymer sheeting that could be placed between layers of sheet rock and carry the water. �It never came to market, probably because of cost but it damn sure worked.
The engineers explained that the wall radiation was primarily to stop convection drafts by maintaining the same temperature floor to ceiling. �The floor elements supplied the bulk of the heat while the ceiling elements prevented head chills, especially on bald guys :-) �I forget the number but some ungodly amount of body heat, >50%, is lost through an exposed scalp so that was an important element.
Years ago when electricity was practically free (too cheap to meter :-) there was a product called Ceil Heat. �In this product, resistance wires were run in parallel rows about an inch apart on special ceiling sheet rock. � Then a thin layer of sheet rock was placed over it. �The surface got barely warm to the touch but it was quite comfortable heat.
It failed when electrical prices ran up in the 70s because, given the almost free nature of electricity, they had neglected a radiant heat barrier between the sheet rock and the ceiling joists. �Lots of heat got conducted into the attic.
My grandmother owned a Ceil-heated house and I've owned one. �Her's was in the cheap days and it was wonderful. �Mine hit me with an August electric bill of over $100 in 1976! and that just to take the chill off. �Of course, I found that the contractor hadn't installed any insulation in the house. �(government built for the poor that I bought on repo.)
I would love to explore that kind of heat, perhaps using water instead of electricity, again, using proper insulation.
As an aside, I also intend to 'bury' temperature sensors in the building fabric during construction so that the 'performance' of the building can be monitored afterwards.
Good idea. �Suggest welded bare Type T (copper constantine) because both metals are corrosion-resistant. �Dipped in RTV and then embedded in the concrete or whatever, they'll last a lifetime. �Type T also generates a decent voltage, in case you want to build your own readout or data acq. �
Stay away from thermistors. �They drift over time. �Platinum RTDs are the Cadillac (Rolls?) of temperature sensors but unless you go with a very high dollar unit, the bonding between the platinum and the base metal wire will likely fail in a few years. �We had a rash of failures in nuclear plant (non-safety areas - the Class 1A stuff was the highest of zoot :-) sensors a couple of decades ago.
Copper RTDs have kinda fallen out of favor for some reason but they work, are durable and are even something you could build at home. �I'd still stick with Type T bare thermocouples though.
John
-- John De Armond See my website for my current email addresshttp://www.neon-john.comhttp://www.johndearmond.com<-- best little blog on the net! Tellico Plains, Occupied TN I like you ... you remind me of me when I was young and stupid.

Ah, shucks! Thanks!
Mike

Neon John wrote:

On Thu, 27 Nov 2008 09:39:53 +0000, Tim Jackson wrote:
Oh true, I can read test books too. But *exterior* surfaces won't stay that way for long in practice. I'm talking about actual building surfaces and worst case after a few years of weathering and bird shit. I'd refer you to, www.omega.com/literature/transactions/volume1/emissivity.html which would correct me the other way if anything.
That's nice, Tim. I'm glad you can read "test books". Now if you only had some field experience.

Sorry about the typo, they do happen occasionally. I was busy rushing out to do some field work and failed to proof read.

Your BS about outdoors is just that since this kind of coating is used indoors. It would be idiotic to place the stuff on an outer surface where pollution and chalking would defeat it in months. Well, considering with whom I'm debating...

Let's keep it polite. Your language does not enhance your argument.
According to the manufacturers website it is suitable for either interior or exterior use. I doubt if anyone would choose painted concrete as their interior decor, so it begs the question of where the poster did intend to put the paint. I admit that until his second post I assumed this was retro-fit, not new build, so he does have the opportunity to put the coating on an intermediate layer, not just a choice of inside or out.
A reflective coating will not do anything if it is covered by something opaque, it only works in the presence of a transparent insulating barrier, eg an air gap.

Radiation is a surface effect. Adding stuff inside a material that is in conductive contact with the bulk of it will have no effect at all on radiation. Not really. Radiation emission certainly is NOT a surface effect. Glass hot enough to glow is a simple illustration that one can easily visualize. The paint very well may be transparent or partially so to the wavelength involved.
I admit I did mean opaque materials. Paints and walls are generally designed to be opaque, otherwise they are called varnishes and windows. I know we can create exotic materials and situations in the lab that don't fit my simple model.
They are opaque to visible spectrum but not to IR. Do a little research on how places like the Smithsonian use IR to detect painting on the same canvas underneath the obvious visible painting. MANY paints are perfectly transparent to IR. Again, you'd know that if you'd either done your homework or had some experience.
I do know that and know that it is irrelevant. We are talking about

concrete, and a paint designed to reflect infra-red. Both are quite opaque to infra-red.

However radiation is a two way street. Whatever you do to reduce heat loss through radiation also proportionately reduces the heat absorption from the sun or anything else hot, as emissivity is the inverse of reflectivity. Absolutely false. Asymetrical emissivity/absorptive materials have been commercially available for decades. Most common use I know of is on thermal solar collectors. Even some finishes are asymetrical. black chrome comes to mind. Omega engineering has this info conveniently tabulated for your handy reference.
OK lets get this straight. It is fundamental thermodynamics that any

object in equilibrium with its surroundings is at the same temperature as its surroundings. Show me something otherwise and I will show you a perpetual motion machine. Thus the radiative heat-flows in and out of such an object must be equal. Therefore the radiation and absorption *at any given temperature* must be equal. Regardless of the emissive properties of the object.
So called asymmetric materials actually have an emissivity which varies with temperature, typically for solar applications a high emissivity in the wavelengths associated with sunlight, and a low one in wavelengths associated with its own temperature, so that re-radiation of received energy is minimised.
There is no such thing as room-temperature asymmetry. For two objects at say 273�K and 293�K (0�C and 20�C) the black-body spectra overlap by around 98% so no amount of wavelength-dependency will make a significant difference. So where we are talking about wall to room or wall to ground or even heating-pipe to ground temperature differences, there is no asymmetry. In the home-power arena "asymmetry" is only relevant to sunlight.

The radiated heat from the body is around 100W according to Wikipedia. The corresponding received radiation from an environment at freezing would be about 60W. This is independent of the air temperature.
Still puzzling why you drew this into the conversation other than for obfuscation.

It was you who mentioned body radiation, so any obfuscation is at your door. My point being that you get most of the radiated heat back, it doesn't matter what the absolute numbers are. There is nothing to stop the outward radiation and the total losses being about the same. The total loss only includes NET radiation loss, the received radiation has to be deducted, in this example it would be about 40W net loss.
I'm still hoping you will point me, and the group, at a source for heat flow meters. I am keen on enabling domestic users to make realistic return-on-investment calculations for energy-saving investments, and so combat some of the excesses of cowboy salesmen presenting themselves as "energy auditors". I am fed up with adverts like "We guarantee you will save up to 30% of your heating bills", which is no claim at all.
Tim

On Wed, 26 Nov 2008 10:29:33 -0800 (PST), AC Me wrote:

Hi all.
If this is not the best forum to raise this issue, then I apologise and perhaps someone could steer me to somewhere more suitable.
I would like to conduct an evaluation of the effectiveness of the 'ceramic bead' type of isulation that is used by adding to paint and applying to a surface such as that supplied by http://www.hytechsales.com/ .
Apparently, this type of insulation reduces heat loss through radiation, rather than heat loss through conduction as per the 'standard' types of insulation materials normally used.
Does anyone know how much energy is radiated from concrete, or where I might find such information? I presume it would be related to temperature.

It's snake oil. Just like tri-iso-9 and all other "thin" insulation. Useful in space, completely useless on earth.
--

On Nov 26, 12:29�pm, AC Me wrote:

Hi all.
If this is not the best forum to raise this issue, then I apologise and perhaps someone could steer me to somewhere more suitable.
I would like to conduct an evaluation of the effectiveness of the 'ceramic bead' type of isulation that is used by adding to paint and applying to a surface such as that supplied byhttp://www.hytechsales.com/ .
Apparently, this type of insulation reduces heat loss through radiation, rather than heat loss through conduction as per the 'standard' types of insulation materials normally used.
Does anyone know how much energy is radiated from concrete, or where I might find such information? I presume it would be related to temperature.
Take care.
Mike

I used it and measured no difference on heat ducts with an IR thermometer. Its been out for maybe 25 years, and the only people pushing it are salesman. Insulate the way that works, foamboard, fiberglass etc. You want to evaluate it, you dont have a lab or the knowledge to test it. Its been tested by pro labs. It may help a bit but not as advertised.

Neon John wrote:

Jackson's developed a well-deserved rep for bullsh*tting in areas where he knows little. Take what he says with a grain of salt.
Take everything you read on Usenet with a large pinch of salt. I've got

an international reputation for bullsh*tting where I know a lot, so lets not worry about that.
This is not a place for ex-cathedra pronouncements but a place to discuss things. We all want to achieve the same ends, so let's work together to add our own knowledge rather than denigrate others'. None of us has the whole answer.
My customers think I know a lot about temperature sensing, heat flow and that sort of thing. They pay my wages, John doesn't. I'm still surviving, enough said. As far as I know he's basing his opinion on a handful of Usenet discussion posts.

I know I'm taking a big risk of tromping on my dick trying to advise about another country's standards so.. What is "u" value. It is like our "R" value? How is it measured/calculated.

U-value is thermal conductance in ISO units, ie W/m�/�C. R-value (in Europe) is the reciprocal of that, sometimes called insulance, unpronounceably written �C.m�/W. It is related to the more familiar (to Europeans) Tog value used for specifying bed-quilts, the Tog value is 10 times the metric R-value.

So I am putting in three layers of under-floor insulation. The first layer will be about 1" thick. On top of this will be a layer about 2 and 3/8" thick through which will be running ducting for domestic hot and cold water and also the boiler return pipes which will allow the possible future installation of boilers behind open fires or with certain stoves. Then there will be a 2" layer on insulation on top of which will be underfloor heating pipes. A 1" or 2" strip of insulation will also be around the periphery of each room.
OK, let me make sure I understand this. You're going to have a slab of concrete on top of a vapor barrier. On top of that will be 1" of something (specify please). then a 2+" air space. Then 2" of more insulation (again, please specify) and then some kind of flooring with hydronic radiant floor heating.
Several questions.
- what will the flooring be? - I don't see a radiation barrier in there (presumably why you asked about the paint. - What constitutes the walls of the air/utility space?
I've never been there, but from friends who live in Ireland, I'm told that air conditioning is rarely needed. True? If so then we need to concentrate on heating.
I don't agree with this layout. Any heat loss from the utility space, if directed properly upward, contributes to room comfort and therefore is not wasted. NO need for any insulation above the utility spaces.
Sounds to me like a solid floor with phenolic-foam insulation layers. No

mention of a suspended floor.

This is overkill but that's what you asked for. Very little heat is lost downward through the floor even when the floor is a concrete slab resting on a vapor barrier and then just dirt and embedded with hydronic heating tubes.

I'd agree with that. It varies a lot with circumstances and building regs. have to cover the worst case. I personally find that my measured losses downward are negligible without insulation, as long as I am maintaining a constant temperature. This is probably because in my case the path lengths to exposed surface are rather long. I find the underfloor area tends to simply act as a heat store. My situation is of a 7' high utility space / boiler room under the main floor, with a solid stone-paved floor just above the water table. Vapour barrier? It's hard enough to keep the liquid stuff out, but the ventilated space serves well. The path to surface is typically at least 5m.
If you only heat the building for a small part of the time, then the answers would be very different.

The engineers explained that the wall radiation was primarily to stop convection drafts by maintaining the same temperature floor to ceiling. The floor elements supplied the bulk of the heat while the ceiling elements prevented head chills, especially on bald guys :-) I forget the number but some ungodly amount of body heat, >50%, is lost through an exposed scalp so that was an important element.
I'll agree with that too. It's also a good reason for running minimum

water temperature in radiators. Small hot radiators make big convection currents, and so you need higher average temperatures to feel comfortable. Plus your ceiling is exposed to the hottest air layer so maximises losses.
That's another thing my home heat-flow meter usefully does, it indicates the difference between ceiling and floor air layer temperatures. A large number here is indicative of inefficient heating and/or insulation. It is especially reactive to draughts which are otherwise hard to detect.

As an aside, I also intend to 'bury' temperature sensors in the building fabric during construction so that the 'performance' of the building can be monitored afterwards.
Platinum RTDs are the Cadillac (Rolls?) of temperature sensors but unless you go with a very high dollar unit, the bonding between the platinum and the base metal wire will likely fail in a few years. We had a rash of failures in nuclear plant (non-safety areas - the Class 1A stuff was the highest of zoot :-) sensors a couple of decades ago.
I use mini (2x2.3mm) surface mount, flat-film, class B, Pt100 RTD

sensors on a small piece of PCB for my industrial stuff. These are much cheaper than the old wire-wound units, have excellent performance and I haven't had any failures yet (since 2005). You can apply military grade lacquer over the pcb for environmental protection. The PCB provides a built-in copper foil for thermal contact and electrical screening purposes.
Specifically, Labfacility type DM301 at �2.85 each. www.labfacility.co.uk
Tim