U.S. Department of Energy, June 2012:
New Mexico has amended the 2009 IECC to allow a HERS Index Score as an option to the prescriptive compliance path. The state has also adopted an amendment that determines climate zones based on altitude in addition to the the DOE latitude map.
There is growing momentum among building code jurisdictions and regional utilities to adopt a standardized means by which to measure residential dwelling energy consumption (performance, a.k.a. cost of operation). The HERS rating has emerged as that standard providing a stadardized measurment of the overall performance of a building as an integrated system and taking into account a given climate zone.
In the case of New Mexico they took their new process a step further by defining climate zones according to elevations along with geographic latitudes. The climate zone(s) are factored in when measuring for the HERS Index. Because of the changes of elevations within the state of New Mexico they added two additional climate zones. New Mexico went from being climate zones 3-5 to now being climate zones 3-7.
See an in-depth explanation of the HERS index.....HERE.
See the connection to how this may impact new building construction and existing building rennovation.....HERE.
We are going to work our way along as a nation to getting this sustainability thing correct. The U.S. will hopefully become a leader and we will all be the beneficiaries.