"Nasal insulation"

[isolde]

Lambda is a measure of thermal conductivity, and infrared radiation, as the name itself suggests, is precisely thermal radiation, so lambda 0.021 W/mK for PU is perhaps half the truth.

Heat conduction is not the same as thermal radiation. Two completely different mechanisms for energy transfer. In homogeneous materials, there is no transfer of heat via radiation. It is thus not possible to reflect this.

I'm not claiming that conductivity and radiation are the same thing either. Saying that thermal radiation doesn't occur through walls is saying too much. It may be negligible to someone interpreting physics strictly. In any case, there are several products that refer to all three ways to insulate against heat losses. Another example: ThermoReflekt http://www.wiedland.se/thr/

Emergency blankets made of aluminum foil are another, where the heat source, i.e., the human body, is covered by a layer of clothing, so according to your definition, radiation shouldn't be able to occur.

 

[Krawk]

I am also not claiming that conductivity and radiation are the same thing.

Ok, I read too quickly. However, the product's fact sheet shows no improvement due to the radiation reflector. The U-value for the constructions matches that of equivalent ones without foil.

It's too much to say that thermal radiation does not occur through walls.

I am also not claiming that thermal radiation is not significant for heat transfer through walls. Unless the wall is made of, for example, solid concrete.

It may be negligible for someone who strictly interprets physics.

What?

In any case, several products rely on all three methods to insulate against heat loss. Another example: ThermoReflekt [link]

However, that product has free air in front in all installation instructions. It then manages to reflect thermal radiation. However, it insulates only by reflecting radiation. It does not stop conduction and convection to any significant extent. Foam plastic boards, on the other hand, work solely by preventing convection with minimal conduction, just like regular insulation, but a little better.

Rescue blankets made of aluminum foil are another example, where the heat source, i.e., the human body, is covered by a layer of clothing, so radiation, according to your definition, should not be able to occur.

You don't have the blanket snug against the body/clothing. Except at a few points, there is air in between. The blanket also prevents moisture from escaping, reducing losses.

---

Reflective insulation works. However, it's not as effective as traditional insulation with the same construction thickness. Simply slapping on an aluminum foil or similar onto an insulation board and then using it as usual, flush against other materials, does not yield any effect. Vacuum insulation also works, very well in fact. The biggest problem here is the cost and mechanical sensitivity. It's a hassle to get a puncture in the wall.

 

[-MH-]

You don't have the blanket tight against your body/clothes. Except at a few points, there is air in between.
The blanket also prevents moisture from escaping, which reduces losses.
.

And it also keeps the wind out.

 

[isolde]

That product, however, has free air in front in all installation instructions. It can then reflect thermal radiation. However, it only insulates by reflecting radiation. It does not significantly prevent conduction and convection. The foam boards work solely to prevent convection with minimal conduction. Just like regular insulation, but a little better.

No, floor heating embedded in a concrete slab has no "free air in front." The same goes for pipe insulation. ThermoReflekt's thermal conduction can be reduced by increasing the thickness of the construction, even though ThermoReflekt clearly states:

"to achieve R-19 with fiberglass, about 15 cm thickness is needed, while R-19 with bricks is achieved only at about 100 cm, and with ThermoReflekt Polynum Big, R-19 is achieved with a thickness of 0.8 cm."

Those are somewhat impressive figures, unless they were measured under very special conditions.

You don't have the blanket lying flat against the body/clothes. Except in a few points, there is air in between.

It was a brave attempt to illustrate radiation effect. I could just as well exemplify an outer wall covered with aluminum foil, which also doesn't lie flat against the wall but is glued to a thin insulation board. What's in the insulation board? Mostly air. The radiation effect decreases with increased thickness. Therefore, there's no point in gluing aluminum foil on thick foam boards, just as you mentioned.

 

[Krawk]

No, underfloor heating embedded in a concrete slab has no "free air in front." The same with pipe insulation.

If you pour concrete directly on the foil, it doesn't work. The fact that they write something different on their website doesn't change the laws of physics.

ThermoReflekt's heat conduction can be reduced by increasing the thickness of the construction, although ThermoReflekt clearly claims that:

"to achieve R-19 with fiberglass, about 15 cm thickness is needed, while R-19 with bricks is achieved first at about 100 cm, and with ThermoReflekt Polynum Big, you achieve R-19 with a thickness of 0.8 cm."

Those are somewhat impressive figures if they haven't been measured under very special conditions.

They again fail to mention that there must be an air gap in front of the foil for it to function. That is, the thickness of a construction with conventional insulation and radiant reflective becomes the same.

It was a valiant attempt to illustrate the effect of radiation. I could just as easily exemplify an outer wall covered with aluminum foil, which also doesn’t lie flat against the wall but is glued to a thin insulation board. What's in the insulation board? Mostly air.
The effect of radiation decreases with increased thickness. Therefore, there's no point in gluing aluminum foil on thick foam boards, just as you mean.

Unfortunately, the radiation doesn't travel very far in the insulation board before it collides with a fiber. It's probably an average of a few millimeters. But sure. A slight improvement in insulating ability is possible.
However, it only works under the condition that you have an adhesive that doesn’t block the reflection.

 

[L-Bror]

I have ThermoReflekt in the attic. It is convenient to work with anyway. I have the 8mm model. I can provide more information on how it works as the winter progresses.

 

[isolde]

Unfortunately, the radiation doesn't get very far in the insulation board before it collides with a fiber. It's probably about an average of a few millimeters.

Oh yes, thermal radiation does pass through thicker layers of mineral wool than a measly millimeter. I definitely don't believe that an inch-thick board/wall between a wood stove and a person insulates the radiant heat. I don't think we'll get any further than that. Thank you.

 

[KnockOnWood]

To provide a popular science explanation as to why this works in space but not on Earth:

This has probably been explained here on the forum before (though I don't remember by whom).

Heat is transferred through radiation (infrared (=heat) radiation, or through conduction (called convection).

Convection requires a medium: air, wood, concrete, steel, or something else. Depending on the material's thermal conductivity (is that the right word?), the insulation effect varies.

If there is no medium, as in space where it is vacuum, no convection occurs. It is like in a thermos, where the air is removed. All heat loss occurs through radiation, and that loss is minimized by providing the surfaces with a reflective coating, often silvering.

That is why NASA materials work in space, where it is vacuum. No convection occurs, and radiation losses are prevented with a reflective surface.

But down here on Earth, the insulating material is filled with air, convection carries the heat away, while the reflective coating has relatively little effect.

So if you want to build with NASA material, move to the moon!

Physics scientists: You are welcome to correct my misperceptions!

//KoW

 

[hakaner]

There is vacuum insulation that has also started to enter the construction industry, an example is Vacupor from Porextherm. It can be described as having placed the insulation in a vacuum chamber and then enclosed it with an aluminum foil-like material. This results in panels with almost a vacuum inside (less than 5mBars pressure), which provides a very good insulation value: 0.005 W/mK. Compare that to regular wool insulation or foam plastic, which is between 0.036-0.040 W/mK. That is about 8 times better... These panels are quite sensitive in handling, but they can be an alternative for example in renovation with underfloor heating on a poorly insulated floor with low ceiling height, 10mm = 80mm foam plastic. However, they do not lose all their insulating ability if punctured and have 0.019 W/mK, still 2 times better than "regular" insulation. -If you want the best, you have to pay... ~800:-/m^2 is what I've been told for 10mm, but for the renovation of individual rooms it may be an option if you have limited ceiling height, for example. They are available in thicknesses of 10-30mm and as panels from 300x250mm up to 1200x1000mm.

 

[KnockOnWood]

Vacupor has apparently gone through some approval process in Germany
"Vacupor® is classified as non-combustible and is approved as a building material according to German standards (Z-23.11-1662)."

However, its ability to withstand puncturing is contradicted on the agent's website
"The laminated aluminum foil of the Vacupor® NT must not be damaged by drilling, cutting, milling, nailing or the like, since the interior pressure of the panel will rise and the special properties of the panel, in particular its excellent insulation characteristics, will be lost."
Sounds quite sensitive.

Prefer to wait for Swedish approval. Isn't a "treudd" required?
Otherwise, the building committees and insurance companies won't be too happy.

However, it would be interesting to see practical tests carried out.
Of insulation materials, windows, heating systems, passive house concepts, and the like.
Build a standardized friggebod, insulate with the revolutionary material, and measure. Shouldn't be difficult or expensive.

//KoW

 

[Alfhem]

I can finally bring joy to all insulation enthusiasts with the following excerpt from Ulf Nordvall's (et al.) study (Umeå housing company):
"Four identical sheds, Sorsele cabin, were purchased and first insulated to a common base level. Three of these sheds were then additionally insulated as below while one shed was used as a reference.
FB1: Additional insulation: Termoreflekt, R-19
FB2: Additional insulation: 90 mm mineral wool (Isover)
FB3: Base implementation
FB4: Additional insulation: Ecoprim, Varmvägg 200, 68 mm

The obtained results clearly show that of the studied alternatives for additional insulation, the best results were achieved (in descending order), as follows

1. 90 mm mineral wool (Isover)
2. Ecoprim Varmvägg 200, 68 mm
3. Termoreflekt R-19

The obtained results for the two best alternatives are in accordance with the specified thermal performance of the materials used. For this application of insulation material, i.e., additional insulation on the inside, we did not achieve the insulating effect advertised for Termoreflekt. In the advertisement for Termoreflekt, R-19 it is claimed that the material should correspond to 15 cm rock wool or 21 cm fiberglass wool. The obtained result is in accordance with the conclusions presented by Dr Mohammad S. Al-Homoud in: Performance characteristics and practical applications of common building thermal insulation materials, Building and Environment 40 (2005); 353-366
The author states that The best use of reflective insulation is in warm climates, just below the roof. It is also beneficial in walls exposed to direct solar radiation. It is least useful on surfaces that are heavily shaded and/or well insulated."

Thank you all for your valuable comments and opinions. There will be no additional insulation with space materials here with us.......We'll see how it goes in winter with trad. 9 cm fiberglass..........

 

[Mikael_L]

Just a small factual error ...

Heat is conducted through radiation (infrared (=heat) radiation, or through conduction (called convention).

Heat is transferred through radiation, conduction, or convection. (Or of course a combination)
We have covered radiation; what you are referring to as convection here is conduction.
Convection requires a moving medium, such as air or water that moves along the warm surface.
So in concrete or metal, it can never be a matter of convection; it is almost 100% conduction there.
But otherwise, I think you've got it absolutely right.

http://sv.wikipedia.org/wiki/Konvektion