As I've discussed in earlier blogs, there are six key systems defining a certified GreenBuilt home. In no particular order, these are:
While it is certainly possible to add green features to any home, it is the development of comprehensive high-performance systems which mark a certified home. The certification hierarchy begins with Energy Efficiency, which is rated by third party verifiers conducting a series of tests to determine the Home Energy Rating System (HERS) score.
Currently the HERS benchmark score of 100 is met by a home built to the definitions in the 2006 International Energy Conservation Code. Any home with a HERS rating above 100 is using more energy (is less efficient), while those below 100 use less energy (are more efficient). The basic requirement for an EnergyStar Qualified home is a HERS score of 85. This means that an EnergyStar Qualified home uses only 85 percent (or less) of the energy of one built to the 2006 code. Older homes of typical construction may have HERS ratings of 125 or more; high-performance homes may be under 60.
Other certification systems (National Green Building Standard, LEED) require EnergyStar qualification as a starting point. The remaining five systems all must still reach minimum scores to qualify for various levels of certification (Bronze, Silver, Gold, Emerald).
The chart below illustrates the relationship of the certification systems, HERS ratings, and value to the homeowner.