HERS Raters Massachusetts

HERS raters in Massachusetts, as well as other states, work with the residential builder/developer/design team, and should be included in the team from the outset.

HERS raters are typically experienced building professionals, who in addition, take a week or two week long intensive training course in residential energy efficiency. After completing the training, learning how to use HERS rating software, and passing a comprehensive test. New raters must also complete at least 5 home energy rating ratings with an experienced HERS rater before being able to independently award ratings. In addition to this initial training and certification, HERS raters must be affiliated with a certified HERS provider which is responsible for ongoing code education and quality assurance oversight of the HERS rater’s work.

HERS ratings require testing of the air leakage rate of residential units. A blower door test will test the house itself for air leaks. In addition, for homes that have forced air heating and central air conditioning systems that have ductwork running outside of the heated portion of a house, duct testing or a duct leakage test is needed. These tests help calculate how much energy is needed to heat and cool a home, and help builders to identify possible problems before a home is completed, when there is still time to fix them cost-effectively.

HERS Index For Home Energy Rating

HERS stands for ‘Home Energy Rating System,’ and is a national standard that uses information on the design of the energy systems in a home to calculate, via computer modeling, the average energy needs of that home and give it a rating score. The HERS Index was developed by the non-profit Residential Energy Services Network (RESNET) for the mortgage industry, and is utilized by the Federal Internal Revenue Service (IRS) and the LEED for Homes program.


On the HERS 2013 index scale smaller numbers are better, with 0 representing a net zero energy home, and 100 represents a home built according to meet the national model energy code in 2006 (the IECC 2004 with 2005 amendments) . A HERS rating of 65 means that the home uses about 35% less energy than the same size home built to the 2004/2005 IECC code requirements. The Residential Stretch code is based on the nationally successful ‘Energy Star for Homes’ program requirements, which utilize HERS ratings.

Residential buildings meeting the stretch code through a HERS rating and thermal bypass checklist require independent certification by a HERS rater. Their work will produce a report detailing the energy systems in the building and will provide a HERS index score, together with proof of whether the home qualifies for the federal $2,000 tax credit. Submission of a copy of the
HERS report, together with a completed Energy Star Thermal Bypass checklist, and posting the relevant energy data on the electrical panel in the home are the steps required to demonstrate compliance with the energy portions of the code, and must be submitted to the local building inspector prior to receiving a certificate of occupancy.

For new residential homes including multi-family homes of 3 stories or less, builders essentially follow the Energy Star for Homes program requirement in Massachusetts, and are required to show that each unit meets or is below a maximum HERS index score. For new homes greater than 3,000 square feet in size the maximum HERS score is 65 (Energy Star tier 2), for smaller homes less than 3,000 square feet in size the maximum HERS score is 70. In addition to the HERS score the homes must be inspected using the Energy Star ‘thermal bypass checklist’ and similar to the new base code may require duct testing. These inspections ensure that the home is well air sealed, while the HERS rating ensures that the home is designed to be well insulated with efficient heating and cooling and lighting – all measures that save energy and reduce utility bills.

New homes built under the stretch code will have to get a HERS rating. Renovations and additions to homes have the option of the HERS rating or a ‘prescriptive’ approach, whereby specific efficiency measures are required, but no computer modeling is done. The HERS performance-based approach provides a very good way to ensure that homes are not only well designed but also well built. As part of the HERS rating the home will be tested for air leakage, and under both the base and the stretch code homes with heating and cooling ducts may also have those tested for leakage. Combined with the thermal bypass checklist the HERS rater, builder and building inspector can have confidence that the completed homes really are energy efficient.