Massachusetts recently joined the ranks of states and municipal code jurisdictions that have incorporated the Energy Rating Index as a compliance option to their residential energy building codes.
Section 407.6.1.3 of the Massachusetts Energy Efficiency portion of the state's building code addresses the Energy Rating Index option:
C407.6.1.3 Energy rating index. The Energy Rating Index (ERI) shall be a numerical integer value that is based on a linear scale constructed such that the ERI reference design has an Index value of 100 and a residential building that uses no net purchased energy has an Index value of zero (0). Each integer value on the scale shall represent a one (1) percent change in the total energy use of the rated design relative to the total energy use of the ERI reference design. The ERI shall consider all energy used in the residential building. The RESNET Home Energy Rating System (HERS) index is the approved ERI approach in Massachusetts.
C407.6.1.4 ERI-based compliance. Compliance based on an ERI analysis requires that the rated design be shown to have an ERI less than, or equal to, the appropriate value listed in Table C407.6.1.4, when compared to the ERI reference design prior to issuance of any credit for onsite renewable electric generation.
C407.6.1.4.1 Trade-off for onsite renewable energy systems. New construction following C407.6.1.3, and existing buildings and additions following C501.4 may use any combination of the following renewable trade-offs to increase the maximum allowable HERS rating for each unit separately served by any combination of the following:
1. Solar photovoltaic array, rated at 2.5kW or higher, shall offset 5 HERS points;
2. Clean Biomass Heating System, solar thermal array, or geothermal heat pump, or a combination of these systems, operating as the primary heating system shall offset 5 HERS points; and
3. Solar thermal array for primary domestic hot water heating or Clean Biomass Stove shall offset 2 HERS points. Note: a Clean Biomass Stove offset may not be combined with a primary heating system offset.
The State of Massachusetts also adopted a RESNET Home Energy Rating System (HERS) as an Approved Alternative Energy Performance Method. The section reads:
For residential units within a building up to 5 stories above grade plane, and with independent unit-level heating and cooling systems, a HERS rater verified index of 55 or less for the finished units together with a completed and HERS rater verified ENERGY STAR Thermal Enclosure Checklist
To view the new Massachusetts provisions go to Massachusetts ERI.