Thought it was time for another update on the radiant barrier. The heat I use in our home (1400 SF) is a Monitor Vented Kerosene unit. These are very efficient heaters and I've been using them for about 16 years. I used one in my home in the Charlotte, NC area without radiant barrier before moving to KY. The heated area was about 1000 SF and I usually averaged 125-150 gallons of kerosene use per winter. This winter in a 1400 SF home with colder KY temperatures with the radiant barrier installed on the roof we used 85 gallons of kerosene to heat all winter. I enjoy heating all winter for what my neighbors were paying each month for electric heat. So using an average of 137.5 gallons normally used in our NC home apposed to 85 gallons and heating an extra 400 SF of space at a price of $4. per gallon for kerosene the savings was $210. on heating for the winter. I also suspect the electrical savings for the a/c last summer was $30-$40 per month. We usually use the a/c about 4 months of the year so using an average savings of $35. a month in a/c the cooling savings would be $140. per summer. Last summer our highest electric bill was $112. and that was with several days that month being around 100* with a heat index of 110-120*. Using those figures I figure the payback for the material $345. and an additional $100. in labor added to my metal roof installation for rolling it out and fastening it down the payback is going to be less than 1.5 years. At current heating and cooling cost figuring the material will last at least 20 years installed underneath the metal roof the savings after payback will be $6555., not bad for a $445. investment, much better than putting it in a certificate of deposit at the current rate of about 1% return. I wish I had a way of putting radiant barrier on all the walls underneath the exterior siding for even more savings, but that won't be done unless I eventually have to have the house re-sided. The cost of radiant barrier material at current prices to do the exterior walls would only be about $250. and I'm pretty sure the payback would be a year or less. After seeing the energy savings with radiant barrier on the roof alone if I were building a new house I'd have it on the roof, floor joist, and walls.
In the all metal exterior garage I used R-13 insulation in the walls covered with radiant barrier on the inside and radiant barrier alone on the bottom of the trusses, in the winter it's warm enough to work in the garage without heat and in the summer the temperature is cool enough you can stand to work in it without having a heat stroke. I had the radiant barrier alone in my garage in NC and could work in it late night (1:00-2:00 AM) in the middle of the winter without heat. A few times when I'd first start working in it I'd start a portable 10K BTU kerosene heater to knock off the chill, but would have to turn it off in about 5-10 minutes, because I'd be sweating and would work for several hours without ever starting the heater back up.
In case anyone is interested in buying any radiant barrier here's a link to the cheapest price I could find when I bought mine.
Texas Heat Management Online Store The price has increased since I bought mine, but is still cheaper than most other suppliers were selling it for at the time of my purchase. I had several different companies send me samples and all the materials were the same weight and strength just different brands. When I bought mine the price also included free shipping, I'm not sure whether they still offer that or not.