118 replies to this topic

[MarkBC]

There are actually some fabrics out there with a reflective surface meant for many uses, including clothes, but I don't have a clue how cost-effective they are.

I didn't know about these reflective fabrics -- I'd be interested. When I think of reflective fabrics I can only think of a slinky dress on a Hollywood celebrity...or something Elvis used to wear, but I'm sure you're talking about practical fabrics.

Thinking about celebrity-wear, I just had an idea. How about covering the surface of the insulating fabric (whether fleece or arctic pack) with shiny silver sequins! It would still be flexible and yet be reflective. That would be sooo cool!
But that sequin-sewing job would definitely be one you'd want to outsource to cheap labor.

[Lighthawk]

But that sequin-sewing job would definitely be one you'd want to outsource to cheap labor.

Susan says she is definitely not available. You might want check with Ski3pin, Barking Spider and the Lady as to their hourly rates.

Have you found a source for a 12V LED disco light to go with the decor?

[highz]

I didn't know about these reflective fabrics -- I'd be interested. When I think of reflective fabrics I can only think of a slinky dress on a Hollywood celebrity...or something Elvis used to wear, but I'm sure you're talking about practical fabrics.

Thinking about celebrity-wear, I just had an idea. How about covering the surface of the insulating fabric (whether fleece or arctic pack) with shiny silver sequins! It would still be flexible and yet be reflective. That would be sooo cool!
But that sequin-sewing job would definitely be one you'd want to outsource to cheap labor.

Here is one example, but since they don't mention a price, it makes me think it must be expensive.
http://www.afminc.com/thermoflect.asp

and another - again, no price on the page...
http://www.radiantba...om/temptrol.htm

Or, rob a bunch of pizza delivery people, grab those fabric insulating carriers and stitch 'em together

[Lighthawk]

Here is one example, but since they don't mention a price, it makes me think it must be expensive.
http://www.afminc.com/thermoflect.asp

and another - again, no price on the page...
http://www.radiantba...om/temptrol.htm

Or, rob a bunch of pizza delivery people, grab those fabric insulating carriers and stitch 'em together

Nice catch, HighZ. I checked out the site and they do an excellent job of explaining the three modes of heat transfer: CONDUCTION, CONVECTION, and RADIATION
Radiant heat loss is our biggest heat loss and aluminum foil reflects 95%.

[MarkBC]

Radiant heat loss is our biggest heat loss and aluminum foil reflects 95%.

Ummm...this can't be true, or it's misleading in some way. If this were true -- that radiant heat loss is the overwhelmingly major form of heat loss from homes/buildings then nobody would bother to put insulation in the walls of homes and modern walls wouldn't have thicker insulation than a few decades ago. Walls would be very thin -- just thick enough to contain a few layers of foil. Unless all the history of insulation has been a scam.
I think it's important to realize that these "facts" are presented on a website that's selling radiant heat barriers. I never believe someone who's trying to sell me something -- not without unbiased confirmation.

[Lighthawk]

My statement was intended to be about campers, not so much houses. I don't think only a radiant barrier would be sufficient for a house. Reminds me of those emergency space blankets.

We use bulk insulation in houses to reduce heat loss from conduction. I used to do my own calcs for to prove energy efficiency for building permits and the formula went: Square Footage x Temp. Difference x U value (inverse of R value) = BTU's lost per hour. Take a 8' x 10' wall with R20 insulation with 70F inside and 30F outside: 80SF x 40F (70F-30F) x .05 (inverse of 20) = 160 BTU's. Aluminum frame windows are an example where conductive heat loss is fairly severe. Sometimes the frames are so cold, they hit dew point and condense water. FWC uses styrofoam (I believe) in the ceiling as a type of bulk insulation.

Convective heat loss can happen, but you need the air to be mighty still for the air to begin to circulate. I don't think it's that significant, but that's just my opinion. It's " not intended to be a factual statement "

Infiltration can be an issue, but what the hey! I'm cracking my vents when I run my Wave anyhow. And when we open the door, well the interior gets an air change on the spot.

Radiant loss is interesting. Warm bodies emit long-wave infrared radiation that travels in a straight line. Thermal radiation is what we feel from the sun or a woodstove. You can store radiant heat with mass (you wanted a granite countertop in your camper didn't you?? ). Regular low-density insulation (fiberglass batts, blown cellulose,etc.) are very poor at stopping infrared loss. This is where aluminum foil can be very effective as a radiant barrier. The reflectix has this attribute and is also effective as a barrier against conductive heat loss due to it's insulation values from two layers of closed air cells.

For the record: I am not a reflectix dealer

[Overland Hadley]

I checked out the site and they do an excellent job of explaining the three modes of heat transfer: CONDUCTION, CONVECTION, and RADIATION
Radiant heat loss is our biggest heat loss and aluminum foil reflects 95%.

Thanks for the link, I printed it out and read through it a couple times today. Very interesting. I tried the little experiment with holding aluminum foil up to your face, and it was interesting to see how fast I felt the heat, and how warm the heat felt.

So, two things-

a reflectix type arctic pack would be the warmest, correct?

my idea of doing an aluminum interior would be good radiant insulation, correct?

[MarkBC]

My statement was intended to be about campers, not so much houses.

Well....I don't think it [mostly radiant heat-loss] is true for campers, either...but I don't have any facts on this, just gut-feel. And as a recently-retired professional researcher, I'm not a big fan of gut feel or guesses -- even my own -- as a basis for belief.

But -- I have an infrared thermometer, I know how to use it, and I'm the kind of guy who's liable to use it!

...And mine has a hair-trigger.

So, as an alternative to pointless guess-work, I'm going to perform some experiments!
I don't have an exact experimental plan yet, but I think the basis for the analysis will be the temperature of the outside of the soft-side. I think a typical experiment will consist of applying one type of insulation to one soft-side and a different type of insulation to the other soft-side (on the insides). Then, after a period of time to allow the external surface temperatures to reach a steady state, I'll measure the temperatures of the outside of each soft-side.

I'm thinking of testing/comparing these "insulating" materials:

• Closed-cell polyethylene foam
• Reflectix
• Aluminum foil (household)
• Fleece

- Mark
"Will research for food"

[Overland Hadley]

Ummm...this can't be true, or it's misleading in some way. If this were true -- that radiant heat loss is the overwhelmingly major form of heat loss from homes/buildings then nobody would bother to put insulation in the walls of homes and modern walls wouldn't have thicker insulation than a few decades ago. Walls would be very thin -- just thick enough to contain a few layers of foil. Unless all the history of insulation has been a scam.

We (the home builder I work for) are using a form of insulated aluminum foil in the house we are currently building. Although we are only using it under the heated floor, not in the walls or the ceiling.

[Overland Hadley]

I'm going to perform some experiments!

Excellant!

Will this be completed tonight? Tomorrow? I am very interested in your findings.