I saw the product, Aeroseal, demonstrated on the TV show, This Old House. It purportedly improved the temperature differential between upstairs and downstairs rooms and reduced dust by plugging holes in the supply and return air ducts. As soon as I saw the product demonstrated on This Old House, I knew I wanted to try it in my house. My house was built in 1925 and is a 1-1/2 story residence. I've always had problems cooling the upstairs, even with central air conditioning. In the summer, it is unbearably hot upstairs, even with the a/c cranked up. In the winter, it is coolish upstairs, but certainly livable (heat rises). My house has old style vents on the first floor - large square supply vents (5) and two in-floor rectangular return vents. Upstairs, there are only two supply vents and the return air vent is really the stairway down to the first floor. The Aeroseal product addresses the excessive duct leakage that exists in any home. Even if you manually seal by tape the ductwork in your house, there is still quite a bit of leakage. I did a lot of research before getting this product installed, and case studies show that this product consistently reduces leakage by more than 90%. Our heating and cooling appliances are now pretty energy efficient, but the duct work in a building is still a source of a lot of heat/cooling loss. According to the manufacturer, here's some of the technology: 1. Research for Aeroseal was partially funded the US Dept of Energy 2. Aeroseal is the only duct sealant technology that is applied from the inside of the duct system. It is delivered as a non-toxic aerosol mist that seeks out and plugs leaks. 3. Aeroseal has proven to be 95% effective at sealing air duct leaks. 4. The Dept of Energy proclaimed aeroseal technology to be one of the top 23 most important energy conservation technologys for consumer sto come out since the dept was first established. 5. The product was developed at Lawrence Berkeley National Laboratory in 1994. 6. Aeroseal has won several prestigious awards, including DOE energy 100 Award, Popular Science -Best of What's New, This Old House - new technologies and 2012 EBie award for use on an existing building retrofit project. I recommend going to the manufacturer website to get more information and view a video of how the installation works. Also, check out the This Old House segment online when they featured this product. When I looked for an Aeroseal service provider in the Twin Cities, Northern One Hour Heating & Air Conditioning was the only provider. In fact, I contacted them only about a month after they started providing this product. They had a service technician trained by the manufacturer to install the product, and they had done several new house installations. Mine would be the first "old house" in which they would install the product. (Therefore I did get a very nice price discount.) The company sent two technicians to install the product. They arrived on time. The set-up definitely takes the most time- it took a couple hours for my house. They have to seal all the vents tightly and tape up larger gaps in the duct work before starting the actual sealing process. They do a computer analysis before and after the sealing process so that actual results can be measured. (One of the technicians still said that my old house duct work was tighter than new house construction to begin with.) While installing, there was a fine mist that developed in the air. The company has a fan/vacuum that collects a lot of it. Also, they opened a lot of windows to help dissipate the mist. They provided masks for us to wear - I actually didn't wear it though. Breathing the substance created a little stickiness in my nose, but eventually it went away. The mist dissipates quickly. It is supposed to be non-toxic. The sealing itself took about 15 minutes for the supply side, and 25 minutes for the return side. The supply/return sealing can be performed dually, but this company does each side separately. My results are as follows: Supply ducts - original leakage was equivalent to a 25 square inch hole. After finishing the Aeroseal, leakage was equivalent to a 1 square inch hole, corresponding to a 95% reduction in duct leakage. Return ducts - original leakage was equivalent to a 43 square inch hole. After finishing the Aeroseal, leakage was equivalent to a 5 square inch hole, corresponding to a 89% reduction in duct leakage. Clean-up was quick. They left my house in tip-top shape. I also received a printed Certificate of Completion that outlines the overall sealing results for both the supply and return sides. I am really pleased with the results, and I can say that the product really works. For the first time, I can cool my upstairs without the use of a window air conditioner upstairs. I can cool it to be about 2 degrees difference from the first floor. I set the thermostat to 74 degrees and close all the supply vents on the first floor except one. Upstairs, the temperature is about 76 degrees. I am anxious to see what happens in the winter, although summer cooling was the more problematic issue for me. I can also report a HUGE reduction of the dust in my house. Before, I used to see the dust pile up just a few days after dusting. Now, it is over 2 weeks since my last dusting and I still don't see the dust pile up on the furniture or window sills. I highly recommend this product to any homeowner. It saves energy, is good for the environment, and most importantly - improves indoor comfort and reduces dust in your own home. I commend Northern One Hour Heating & Air Conditioning for being the first service provider in the Twin Cities for this product. I hope they get a lot of business installing this product. They did a great job and I couldn't be happier.