780 CMR, CHAPTER 51, ch. 4, R406, R406.5 - ERI-based compliance.

Revise and Replace section R406.5 and Table T406.5 as follows:

Compliance based on an ERI analysis requires that the rated proposed design and confirmed built dwelling be shown to have an HERS index rating less than or equal to the appropriate value indicated in Table R406.5 when compared to the HERS index reference design for each dwelling unit prior to credit for onsite renewable electric generation.

TABLE R406.5 MAXIMUM ENERGY RATING INDEX

On-site Renewable Energy Application	Maximum HERS Index scorea, b
	New construction	Whole house renovations; additions
None	52	65
Solar Electric Generation	55	70
Clean Space Heating	55	70
Solar Electric & Clean Space Heating	58	75

^a Maximum HERS rating prior to onsite renewable electric generation in accordance with Section R406.5

^b Where on-site renewable energy is included for compliance using the ERI analysis of Section R406.4, the building shall meet the mandatory requirements of SectionR406.2, and the building thermalenvelope shall be greater than or equal to the levels of efficiency and SHGC in Table R402.1.2 or Table R402.1.4 of the 2021 International Energy Conservation Code.

Add subsection R406.5.1 as follows:

R406.5.1 Trade-off for onsite renewable energy systems. New construction following R406.3 or existing buildings and additions following IECC chapter 5[RE] may use renewable energy trade-offs to increase the maximum allowable HERS rating for each unit separately served by any combination of the following:

1. Solar Electric Generation: Solar photovoltaic array rated at 4kW or higher shall offset 3 HERS points for new construction, or 5 HERS points for renovations and fully attached additions.

2. Clean Space Heating: Clean Biomass Heating System, solar thermal array, cold climate air source heat pump having rated coefficient of performance (COP) of at least 1.75 at 5 degrees Fahrenheit, or geothermal heat pump, or a combination of these systems, operating as the primary heating system shall offset 3 HERS points for new construction, or 5 HERS points for renovations and fully attached additions.

Notes

780 CMR, CHAPTER 51, ch. 4, R406, R406.5

Amended by Mass Register Issue 1532, eff. 10/11/2024.