The 2006 International Energy Conservation Code (IECC) envelope requirements are not coupled to the home''s glazing area percentage. A home with modest glazing area, say 13% of
floor area, will likely require a more efficient envelope for 2006 IECC compliance. Conversely, a home with larger glazing area, say 20% of floor area, may achieve 2006 IECC compliance with less insulation.

The 2006 IECC also implemented a new climate zone system. The system introduced more homogeneity across climates, resulting in less variation in the envelope requirements from location to location. Therefore, some locations have slightly different (higher or lower) efficiency requirements under the 2006 IECC than under the previous codes.