I am currently in the process of having a house built and I am wondering what type of after the fact insulation or ventilation changes would help me with my electricity bills and keeping the entire house cooler. The house I am building has about 1600 sq feet of attic space. I will have a 12 seer 4 ton unit in 2267 total square feet excluding the garage. The attic insulation is r30 blown with exterior wall insulation of r13 batt. I live in San Antonio, Texas where the temp can get to 100 very often in the summer. I did not get the radiant barrier from my builder, because they were going to charge way to much to have it installed. I am considering an after the fact radiant barrier paint or an attic fan. I am not sure if I would use a gable mount or on the roof. The builder does not allow any unauthorized changes during the construction. I looked at the department of the energy website and noticed that with r30 insulation a radiant barrier does not help that much? Is this true. I also have seen that attic fans are not good in some cases, so I am bit confused. This concern comes from the fact that the new homes in this area have a huge temperature difference between the upstairs and the downstairs. I asked the builder if we could put a return duct on both floors and to help out with this, but they said no way. Any help would be greatly appreciated.
In your heat, a radiant barrier is a good idea but must be coupled with good attic ventilation. Be sure the eve vents are not covered with insulation and that there is good ventilation out the peaks of the roof. Radiant barrier can reduce attic heat by 30-40 degrees. Consider solar ventilation fans (Home Depot).
I lived in HOuston and we had reflective film on all windows and wind driven turbines in the attic. We were told by one contractor that he was shying away from the electric fans because of increased risk of attic fires when motors froze plus intense heat from climate. We had a whole house fan in Georgia and it worked O.K., but, it was very noisy and turned the edges of our carpet black as it was so powerful, ****ing dirt up through the flooring (we have three levels, and a really old house). So, we ripped it out. Turbines would really get loud during the hurricanes, but, worked pretty well.