I have been a builder for nearly 20 years, and have been a foam insulation contractor for 8. I learned at the beginning form Energy Wise Structures. I can assure you that their sizing of A/C equipment is going to be better than most A/C contractors. They have thousands of home under meter contols. They know what is going on. Do NOt be afraid to use their recommendations. As a builder I have proven them. Usually the tonnage is about 40-50 percent less than what you would normally come up with. We usually use them when we are working with a new A/C contractor to make them feel safer. It does work. WE usually use their recommendation and 2 stage equipment. For instance, a 3100 sq foot house might normally come out to 6-7 tons regularly, we might put in a 4 ton two stage, and that means the house will be colled on 2 tons about 90-95% of the time. IT really works! The customers will call back and say they have never lived in a house that comfortable, even in the 110-115 degress we had last year,...No Complaints! Ou A/C guys need to stop fighting it nd just join the wave. It will make your job easier and your customers happier.