I am one of those people involved with ‘a’ radiant barrier product, just one. Over the years I have tested ours vs a few dozen of our competitors.
There are different types of radiant barrier materials out there. Ours is a radiant barrier coating, an ENERGY STAR ‘Cool Roof’ coating. I wish someone in charge of these would create a seperate classification just for the coatings.
I hate it when the coating classification gets lumped in with the aluminum foil types and the others. If you staple up aluminum foil to the attic rafters or floor, how do they prevent convected heat transfer? Aluminum foil is great for protecting the tender skin of a Thanksgiving turkey from getting burnt, but it still turns brown and crispy. Am I wrong??
A reputable radiant barrier coating will form and maintain what the industry refers to as “An intimate bond”. The bonding ability should be questioned and considered just as importance as the coating’s Reflectivity and Emissivity.
Many radiant barrier coatings do NOT maintain an intimate bond, they just sit on top of whatever they are applied to.
Some should not be applied where it gets too cold, some should not be applied where it gets too hot. Why? THEY LOSE THEIR ABILITY TO MAINTAIN ANY BONDING, thus the roofing industry has temperature zones now that one must assume is because of that very reason. Almost none of those coatings can be applied to a vertical surface or ceiling because they fall off!.
I cannot speak of the other coatings out there on this matter, RETAINING HEAT. We have applied our coating to the outside of boilers, steam pipes, incinerators, industrial air pollution control equipment, exhaust piping, etc. and had great results. We have had surface temperature reductions from 75 degrees all the way up to 330 degrees.
As with any other types of products, there are good ones and bad ones. Some coatings are exceptionally good. Some should be considered criminally bad, at least in my opinion. Our industry gets enough black eyes from the lousy coatings out there without being compared to the tin foil types claiming one thing and then performing differently.
It’s just not fair to lump them all together.
I have just posted three videos to youtube, very large files.
I hope you find them useful and informative as to what a 'Good' coating can do.
http://www.youtube.com/watch?v=GGaKytKT8XQ 1988. This URL is the video from our testing at an ice cream plant in Fresno, Cal. Tested on mineral capsheet and galvanized walls. Energy calcs and company statement attached.
http://www.youtube.com/watch?v=v-7Vv6x_bpE 1989. This is the video URL for the Anheuser - Busch Nevada distributorship test. I tested Cerama-Tech on mineral capsheet, metal roof, large roll up metal doors, AC units and several smaller applications. We had the energy calcs performed by SDG&E engineers, also attached.
http://www.youtube.com/watch?v=M1Vq74oMoQY This is the video of some homeowners in Mariposa Calif. They did their own real life test of Cerama-Tech on their own mobile home. It does not look real impressive but the temperature readings are a great demonstration of Cerama-Tech vs standard white paint.
These VHS videos were thought to be lost for almost 20 years.
Someone found one in a box in their storage building and sent it to me. I had them put to digital format. The video quality of the ice cream plant video is not great, it had degraded a little over those years.
We have been producing results of 50%+ reductions in BTU’s and heat transfer for well over 20 years. For more recent results, check our websites.
Just added all 3 of these to our website
Yesterday I attended a Home Show. Three exhibitors offered Free Energy Audits. Two were selling radiant barriers, one of which was selling roofing, gutters and other products he called "green". The third offers decent audits and sells HVAC and water heaters.
I got into a discussion with the radiant barrier sales people and they were, frankly, clueless about moisture issues and pressures in homes.
I'm less concerned about what this type of mis-representation will do to our legitimate auditing business, and more concerned about what their lack of knowledge is doing to houses. Not to mention the waste of money their customers are subjected. to.
I guess our coating industry isnt the only one getting black eyes from these types. You have found out that seldom do the 'Trade show salespeople' EVER have a good working knowledge of the product/s they are selling.
Here is one gimmick that several companies in our industry use to try and fool someone into cutting a check.
They will show you beautiful fliers with before, during and after pictures of a black roof being coated with a white roof coating. It will show a 'Before' temperature reading of the surface temperature of the black roof. The flier might show a picture of them spraying on the white coating. Then they will show someone holding a different but similar looking heat measuring device about 4 feet above the roof with a much cooler reading then the 'Before' reading.
You dont have to have a college degree to figure out you are looking at apples and oranges here. If your 'Before' reading is from the surface temperature of a hot black roof, the 'After' reading should ALSO be of the suface temperature of the same roof. The air temperature reading afterwards will be a few degrees above ambient air temperaure and WAY less than the 'Before' reading. And, if you think I am exaggerating here, go to the Emergy Star website and look under 'Cool Roofs'. You will see a company and product showing to be what looks exactly what I have just described.
You might also be surprised when they representative says "What's that?", when you ask to see an MSDS or a copy of their 'Energy Star' lab certification. If they have one available, then ask them if that laboratory is actually owned by the company that makes the coating they are selling.
Ask the sales rep to explain exactly "What does Reflectivity and Emissivity actually mean". They will probably stutter and stammer and start sweating bullets.
Just a few suggestions for you to have some fun with these folks and their radiant barrier stuff. I get an occasional call from someone going to one of these shows and I go with them to pick the other companies stuff to pieces.
I love going to those kind of trade shows and picking their literature to pieces.
First off, a reputable radiant barrier dealer / installer should never claim that a radiant barrier will address anything but "radiant heat gain". It is asinine to assume that it would or should have any affect on conduction or convection. It's not made to, hence the reason why Energy Star and other organizations don't assign it any 'R' value.....you need thermal mass to achieve any kind of 'R' value as we all know.
Second, even though it is a very thin sheet of reflective material, it is very effective at reflecting radiant heat gain -but in order for it to work, it needs an air space or vacuum. Just look at the physics of the thermos. It works on the exact same principles. Please explain to me how a coating application can work when there is no air space or void for it do it's thing?
I'm not trying to discredit you or your product, but I just honestly want to know how it's possible that a fully adhered coating to wood framing members or sheathing / roof deck can work when the air space / void is what makes it work.
It's funny to me that we all know about the 3 ways that heat is transferred, yet home builders only address 2 of them......leaving heat gain / loss via radiation the odd man out. Why is that when the majority of the heat gain in our homes in the summer months comes directly from the radiant heat of the sun beating down? We can address convective and conductive heat loss / gain by making sure the building envelope is properly air sealed and by installing traditional insulation. What can we do to combat radiant heat loss / gain? Install a radiant barrier.
I've had people tell me that it's more cost effective for customers to just add more cellulose or some other kind of traditional insulation instead of wasting $ on radiant barrier, to which I say - why? Why would you keep addressing only 2 out of the 3 methods of heat transfer when that third one being ignored will make the biggest difference? Traditional insulation only slows down heat that is being transferred via conduction and convection, it doesn't even stop it completely (I think we all know this as fact) Radiant barriers on the other hand, if installed properly can block up to 90% of the radiant heat gain by reflecting it back to its source.
With that being said, I ALWAYS let my customers, friends or family know if their attics are "under-insulated" as far as traditional insulation goes and will ALWAYS recommend bringing their 'R' value up to where it needs to be for their climate zone FIRST, and then will educate them on the benefits of installing a radiant barrier to supplement that.
When you address all three, and do it correctly - it creates a synergistic effect and does makes a difference.
Hi Hal, Tamasin, and Joshua, I'm far from ready for this discussion, but I can pose an application for consideration and see if survives the critique and yes it uses a radiant barrier. Since I didn't want to steal Hal's thread I will link to my new one: http://homeenergypros.lbl.gov/forum/topics/using-the-sciences-to-ou...
For this thread, I agree that better information is needed about this important part of our business, radiant heat transfer, both barriers and utilization of the process.
"you need thermal mass to achieve any kind of 'R' value"
Thermal mass and R-value are two entirely distinct properties. Thermal insulations are merely materials, usually very low-mass materials, that trap dead air.
Radiant roofing materials work because the air gap is the atmosphere, but they don't work that much better than a white roof, and roof venting also reduces solar heat gain into the conditioned space.
A radiant barrier, such as builders foil, can also be a convection barrier in the right location as long as all seams and edges are sealed.
HELP! I've been hijacked! HAHAHA hijack away!
Hal Skinner - Cerama-Tech Distributor
To get back to your topic, the adhesion of a roofing material is important as a weather barrier, but irrelevant as a radiant barrier.
Anytime you are considering a roofing material, you are considering a new roof or a new roofing system. Any new roof must have good bonding. I use the word bonding because it becomes a part of the roof. To adhere to a roof means that it sits on top and kind of sticks to it.
Now, I will have to speek specifically about roof coatings. A roof coating's ability to bond will differ depending on the type of material it is being applied to. I will use, for example, residential asphalt shingles and commercial rooled roofing. Some roof coatings will adhere, as you say sit on top and stick to the ceramic particals. Depending on the age of the shingles those particles may not be bonding very well to the felt underneath. There is a bonding test that is used for this specific application, I believe
Sorry Robert, something came up and had to leave the computer and had to start a new reply.
In the case of our coating it took 450-500 lbs pull to seperate the rooled roofing (TAMCO). Our coating penitrated into the first layer of felt, the seperation was between the first and second layer of felt. Our coating becomes a part of the roof, it doesn't just sit on top. This also means, in the case of asphalt or comp shingles on a house, that same amount of force will be required to seperate to the overlaping shingle on top from the shingle underneath. This is a HUGE selling point in area's of the country that experience high winds. We have even had cases in Texas and Oklahoma where the Cerama Tech roof was undamaged and everyone elses in the general area was stripped off by a tornado.
As far as waterproofing a roof goes, that goes without saying that it must be an ability of what type of a roof is being installed.
The roof coating must also have anti-fungul properties.
Longevity and warrenty are also an issue especially in roof coatings.
The material's solar reflectivity, thermal emissivity and energy savings is only 1 aspect of a roof coating. There are many other aspects that must be considered and included in any proposal to a prospective customer.
Reduced load on the cooling system will not only reduce the energy bill but will extend the life of the unit itself, another HUGE selling point as an example.
Your residently customers are going to want to hear everything and how it will benifit them, and for how long. They are making a big investment and the more information you can present to them to make it a SMART investment and show them how they are going to save money in many different ways, open their eyes to savings they would have never considered will make them much more willing to sign the dotted line. If your only presentation to them is on simple energy savings you will have a rough time making that sale.
If you can give them a deminstration of how the coating can also retain heat, a deminstration they can feel themselves at the time and demonstrate year-round energy savings, so much the better.
That's it for now.
This was supposed to be a thread on "Different classifications of radiant barrier materials" but you have turned it into a sales pitch for your product.
You specifically mention roof products. I am only an expert on my own product, I do not speak about other peoples product.
What I gave you was a partial check list for ANY roof coating being considered. I did mention the name of the product that I have worked with for 26 years. I have gone up against dozens of "competitive" coatings, side-side, in those years.
I was hoping you or someone else would fill in a few more of the blanks that I did not. For example: it should have good elastimeric properties.
There are two people that are qualified to certify applicators of our product for warrentee applications; the inventor of the product and myself. Sorry, sometimes it hard for me to get out of the teaching mode. I'll try not to be so offensive the next time.
Then why did you misleadingly title this thread "Different classifications of radiant barrier materials"?
An "expert" on only one product is no expert at all, but merely a salesman.