Energy Efficiency: Building Envelope
The foundation wall area from the exterior grade to the sill plate is the most critical to insulate.
Use light-colored roofing and siding to stop heat gain from entering the structure.
Corner and partition construction should minimize air pockets and allow for full insulation.
When insulating the basement or crawl space do not forget to insulate the box sill.
When using steel framing you must install R-6 insulation foam board to the exterior wall to overcome the thermal bridging which causes heat loss.
Caulking and sealing of the exterior wall and its components is very important to the overall efficiency of the home.
8 inches of concrete has the same R-value as a single pane of glass
Any concrete floor less than 2 feet below ground (including walk-out basements) should have the perimeter insulated to R-10 minimum.
With the low R-value of concrete, the basement may be the single largest heating load.