Please register to participate in our discussions with 2 million other members - it's free and quick! Some forums can only be seen by registered members. After you create your account, you'll be able to customize options and access all our 15,000 new posts/day with fewer ads.
Umm, if I scotch tape a single piece of 8 1/2" x 11" white printer paper up on one of the metal garage door panels and compare the difference in temperature (using an infrared temperature gun) of an uncovered darkish (tanish brown) metal garage door panel with the temperature of the white piece of paper, I would have seen a similar difference in temperature just like in the first YouTube video. Space the paper off the tanish brown metal garage door panel a 1/2" or 1" and the temperature drops even further... With the white printer paper - why is the temperature so much less when it has no 'radiant' or insulating qualities? Where did the heat go? Of is the heat really still in the garage!
In the second (Attic Foil) video the man (Adam) said; "the radiant barrier reflects the heat back". Reflects the heat back to where? Back into the garage door panels? Back outside on the exterior side of the garage panels?
Umm, if I scotch tape a single piece of 8 1/2" x 11" white printer paper up on one of the metal garage door panels and compare the difference in temperature (using an infrared temperature gun) of an uncovered darkish (tanish brown) metal garage door panel with the temperature of the white piece of paper, I would have seen a similar difference in temperature just like in the first YouTube video. Space the paper off the tanish brown metal garage door panel a 1/2" or 1" and the temperature drops even further... With the white printer paper - why is the temperature so much less when it has no 'radiant' or insulating qualities? Where did the heat go? Of is the heat really still in the garage!
In the second (Attic Foil) video the man (Adam) said; "the radiant barrier reflects the heat back". Reflects the heat back to where? Back into the garage door panels? Back outside on the exterior side of the garage panels?
I'm waiting on something that makes sense (the truth would be nice) instead of smoke-and-mirror deception. Yes - PURPOSELY DECEPTIVE...
Laser Thermometers - Dark-colored objects give the most accurate temperature reading; shiny (or light colored) objects may reflect infrared light back to the thermometer, which will skew the temperature readings. To get the best temperature reading from shiny (or light colored) objects, a portion of the object should be covered with black tape. The black tape should be allowed to come to the ambient temperature of the object being tested before a reading is taken. Use the black tape as the target for the temperature reading.
Measuring temperature of shiny surfaces:
It has been found that in the case of shiny surfaces, temperature measurement by infrared thermometers is affected by the reflectivity of the surface. Shiny surfaces may range from aluminum and steel to non-stick cook wares. So, for gauging temperature in these kinds of situations, it is very necessary that you provide coating in these surfaces. This may consist of non-stick cooking spray, or masking tape that covers the reflective metal surface.
It is an absolute fact that [when] using an infrared thermometer to measure a shiny surface, such as a so-called heat barrier with aluminum foil, that the temperature reading comparison will be inaccurate (lower) compared to a darker and less reflective surface with a higher blackbody emissivity value. This inaccurate infrared thermometer reading of a shiny surface is used to purposely DECEIVE people.
Last edited by BstYet2Be; 07-31-2012 at 12:42 AM..
Reason: Source of quoted article? Link must be included - copyrights can only quote 2-3 sentences w/link
It is an absolute fact that [when] using an infrared thermometer to measure a shiny surface, such as a so-called heat barrier with aluminum foil, that the temperature reading comparison will be inaccurate (lower) compared to a darker and less reflective surface with a higher blackbody emissivity value. This inaccurate infrared thermometer reading of a shiny surface is used to purposely DECEIVE people.
I didn't use an infrared thermometer. I used a standard, digital thermometer, for several days before I installed the RB, and after. Temps averaged about 10 degrees cooler after installation.
Don't get too caught up in the whole "radiant" aspect of this. That IMO is pretty much inconsequential. For starters, the term "radiant barrier" is somewhat misleading. If you search for that on Home Depot or Lowes website, you'll see that what pulls up is some reflective type of material, very thin, similar to what you see used for a car windshield sun visor. What I'm talking about (and what you see in attics) is actually called "insulated sheathing."
What matters here is that these panels have a R-factor of 2 to 4, depending upon thickness. Here is the exact product I used:
A thin garage door panel, with no insulation whatsoever, obviously won't keep heat out as well as adding this. In my case, with half inch thick sheathing, I lowered temps 10 degrees.
Last edited by BstYet2Be; 07-31-2012 at 12:42 AM..
Reason: updated quoted text
I didn't use an infrared thermometer. I used a standard, digital thermometer, for several days before I installed the RB, and after. Temps averaged about 10 degrees cooler after installation.
Don't get too caught up in the whole "radiant" aspect of this. That IMO is pretty much inconsequential. For starters, the term "radiant barrier" is somewhat misleading. If you search for that on Home Depot or Lowes website, you'll see that what pulls up is some reflective type of material, very thin, similar to what you see used for a car windshield sun visor. What I'm talking about (and what you see in attics) is actually called "insulated sheathing."
What matters here is that these panels have a R-factor of 2 to 4, depending upon thickness. Here is the exact product I used:
A thin garage door panel, with no insulation whatsoever, obviously won't keep heat out as well as adding this. In my case, with half inch thick sheathing, I lowered temps 10 degrees.
Insulation does not stop the transfer of heat into or out of an area, it only slows the heat gain down time-wise based on the insulation's R-Factor. Given enough time (and not much time is needed) the inside of the garage temperature will be the same whether there is insulation or not...and whether there is a so-called radiant heat barrier or not. A garage typically has no heat or cooling (maybe a little bit from an adjoining room that has HVAC, therefore it is like an old tobacco barn or out-house. You can line that tobacco barn or out-house with 1/2" of insulation and given a few minute's time it wouldn't make any difference whether you added insulation or not. Adding 1/2" of insulation on a garage door's metal panels, with or without (radiant heat barrier) foil, is not going to lower the temperature heat gain in a garage beyond a few minute's time.
Insulation does not stop the transfer of heat into or out of an area, it only slows the heat gain down time-wise based on the insulation's R-Factor. Given enough time (and not much time is needed) the inside of the garage temperature will be the same whether there is insulation or not...and whether there is a so-called radiant heat barrier or not. A garage typically has no heat or cooling (maybe a little bit from an adjoining room that has HVAC, therefore it is like an old tobacco barn or out-house. You can line that tobacco barn or out-house with 1/2" of insulation and given a few minute's time it wouldn't make any difference whether you added insulation or not. Adding 1/2" of insulation on a garage door's metal panels, with or without (radiant heat barrier) foil, is not going to lower the temperature heat gain in a garage beyond a few minute's time.
My thermometer disagrees with you. At 6pm after a 100+ day, my garage is 10 degrees cooler. Whether you want to believe the facts or not, that's up to you.
By shielding the garage, you are slowing down the heat transfer from the cooler air of the garage to the outside air, and the effects are felt a lot longer than a few minutes. Conversely, when the temperature drops at night or when a quick storm rolls through, the outside air can cool down much faster than the garage does now.
If you don't believe me, measure the temperature of your garage, before and after. It's not magic, just numbers. R-Max works as intended, only takes a couple hours to cut/install.
My thermometer disagrees with you. At 6pm after a 100+ day, my garage is 10 degrees cooler. Whether you want to believe the facts or not, that's up to you.
By shielding the garage, you are slowing down the heat transfer from the cooler air of the garage to the outside air, and the effects are felt a lot longer than a few minutes. Conversely, when the temperature drops at night or when a quick storm rolls through, the outside air can cool down much faster than the garage does now.
If you don't believe me, measure the temperature of your garage, before and after. It's not magic, just numbers. R-Max works as intended, only takes a couple hours to cut/install.
Let's see now, I assume your garage is not cooled...and any adjoining room that abuts the garage has maximum insulation so-as not to lose any heat/cooling through its wall or walls into the unconditioned garage. Please tell me how your garage is able to be 10 degrees lower than the outside temperature as measured in the shade?
Let's say it's 100 degrees outside in the shade and [say] 125 degrees in the direct sun, maybe more. Let's build a building in the shade and put some window openings in it but do not install windows and just have openings for air flow. Won't the inside of this bulding be the same as the outside temperature as measured in the shade? Let's close up that building with windows or siding and expose one side of it to the sun and you have a much hotter box, right. Can you tell me why your closed up garage is 10 degrees cooler than the outside temperature as measured in the shade? Does your R-Max have some type of tiny little micro A/Cs buillt into it? Or could it be that possibly an adjoining room that is air conditioned is cooling down your garage a bit?
If your house sets under a huge bevy of thick shade trees and you decided to take a two month trip and you turned off the power - do you think the garage's temperature would always be 10 degrees cooler? Or would it maybe lag behind increasing in temperature as the temperature climbed toward 100 degrees, and lag behind in decreasing as the temperature dropped in the evening?
If I built a garage size building with no power in Antarctica where the temperature was a constant -40 degrees with thick cloud cover and insulated it with 10 foot thick insulation - what would the temperature be inside that building? Same question with the building in the shade in Ethiopia with the temperature at 135 degrees in the shade? Could it possibly be that the building in Antarctica would match the outside temperature at some time point? Could it be that the building in Ethiopia would match the outside temperature at some time point? Is insulation somehow related to its measure of thermal resistance over T (time)? Well, dang!
Oh, check your insulation in the wall or walls adjoining your garage - because unless your garage is intentionally cooled with A/C then you are losing some cooling through your home's adjoining wall(s) and that is cooling your garage...because there is no other way (other than T lag) that your garage should be 10 degrees cooler than the outside temperature.
Or would it maybe lag behind increasing in temperature as the temperature climbed toward 100 degrees, and lag behind in decreasing as the temperature dropped in the evening?
I don't know what all that other junk was, but this bit is the only part that matters.
My garage stays about 10 degrees cooler than the outside temp. As the outside temp increases, so does the garage temp. My garage has two walls that adjoin to air conditioned rooms. The ceiling of the garage is also covered by an air conditioned 2nd floor. My previous garage door had no insulation whatsoever. A thermometer placed outside my garage in my driveway showed ambient temps were exactly the same as what they were inside the garage (or very close, I took several measurements over a couple days.) In fact, sometimes the garage would actually be hotter, if I had pulled a hot car into the garage, the heat had nowhere to go.
At 5:30pm or so when I would arrive home from work, temps outside would range from 8 to 10 degrees hotter than in the garage after the install.
As I've already stated, the garage now loses heat more slowly. So when the sun goes down, and it cools down to 75-80 degrees outside at night, the garage retains that warmth longer. But by 3-4am or so, they are probably about the same.
The important piece here is that the garage no longer gets as hot as it does outside, nor will it get as cold. I don't think you understand how insulation works if you are not getting that concept.
Bottom line, if you want a cooler garage, insulate the door. If not, then don't.
Please register to post and access all features of our very popular forum. It is free and quick. Over $68,000 in prizes has already been given out to active posters on our forum. Additional giveaways are planned.
Detailed information about all U.S. cities, counties, and zip codes on our site: City-data.com.
Please register to participate in our discussions with 2 million other members - it's free and quick! Some forums can only be seen by registered members. After you create your account, you'll be able to customize options and access all our 15,000 new posts/day with fewer ads.
