I moved to Texas from Indiana in 1980. The first time I went into an attic in Texas in the summer, I could not believe how hot it was. I noticed that the ductwork and the air handlers for the HVAC system are all located in the attics. I asked why and I was told that we do not build basements (or many crawl spaces) in Dallas, so this is where we put the air ducts... Over the years I came to understand that builders are installing the HVAC ducts in an attic that gets to temperatures around 150 degrees and also the average duct leakage in older home was around 30%. A lot of the cool air is either heated in the ducts as it travels through the hot attic, and/or it is lost due to duct leakage. This does not make sense.

I think designing and building attics in homes in the DFW area that are non vented, insulated, semi-conditioned attics is good move. You vent a roof to let moisture out (not in). This idea was developed in Minnesota, which has a dry (and much cooler) climate. Houston has a humid climate and gets very hot, so  you do not vent a roof in Houston, because you let moisture into the attic. The Dallas Ft. Worth area is a "mixed-humid" climate. It seems like our summers get more humid every year. Most attics in the DFW area are vented, non conditioned, attics and they are really hot in the summer. A lot of builders are still building this way. Yes, radiant barriers does help to cool the attic a little, but that is not the total solution.

Our company has been designing and building our homes with fully encapsulated, semi-conditioned attics for some time now and this system is working. To accomplish this, we removed all of the vents in the attic and we have moved the insulation from the floor of the attic to the underside of the roof deck. We use spray foam insulation for this purpose. Spray foam ( if installed correctly) seals all of the air leaks in the attic. Our attics stay around 75 to 85 degrees year around. Our AC ducts (and air handlers) are now installed in semi-conditioned area which is much, much more efficient than the old way. My HVAC Contractor says that his equipment will now have a much longer life span since it is now not having to operate in very hot attics. Also, think about the items that we all store in the attic. Now they are being stored in a semi-conditioned area. This "new and improved" way of designing and building our attics in the DFW area seems like a good idea to me!