I run across customers who want energy efficiency but they think that it is all about the insulation. Most building scientists will tell you it is about more than just insulation. In new construction, maximum energy efficiency comes from many considerations. Here are some things to consider. Make sure you get a variable speed dual stage HVAC system. These systems are highly energy efficient and because they have two compressors they ensure not only energy efficiency but comfort level. The windows that you choose are also important. Windows also a great deal of heat that has to be offset by running the HVAC. The key indicator in the south is the Heat Gain Coefficient. This number is on each window and lower is better. The goal is be close to 20 although anything 28 and lower is good. Ideally, the windows, spray foam insulation, and the HVAC system will be designed to work together to maximize their impact and reduce energy costs.