MLS PIN #s HERS Ratings and Net Zero Homes

In 2015 MLS PIN, the largest multiple listing service in the state of MA, updated their green data fields. Data base fields in the MLS are the central nervous system of the real estate transaction. The fields are used by consumers searching for specific features different homes offer, and by appraisers searching for accurate sold comps to establish valuation. Accuracy of the fields is essential for a healthy marketplace.

In April, 2015 MLS PIN added the last field of the 16 upgrades to their green data list: the HERS Index Score. A HERS rating is a rigorous third party verified evaluation of the home's energy efficiency. The U.S. Dept. of Energy estimates a typical existing home to have a HERS score of 130-140. New construction homes modeled from the IECC 2006 building code rates at 100 (like your golf score the lower the better with your HERS score). In order for new construction in MA stretch code communities, a home must reach HERS scores between 65-70 depending on the gross living area of the home. LEED Platinum homes many times reach HERS scores in the 30's - and, the holy grail of building science is a HERS score of 0. Net zero homes include some source of energy production on the end user side of the meter (in MA solar PV is the typical choice). The energy production coupled with an extremely efficient design produces homes that produce as much energy as the use on an annual basis, hence the term net zero.

Reviewing the 2016 numbers to date in MLS PIN: 305 single family homes were listed with a HERS Index Score field entered. Of these 55 single family homes indicated the home had a HERS Score of 0 - the holy grail of building science.

In order for a home to reach net zero it must be utilizing some type energy production on site. Of the 55 homes that said their homes had a HERS Index Score of 0 only two had any evidence of solar PV in the pictures or remarks and one indicated the home had geothermal (this home also was marketed with rigorous R-45 wall and R-65 ceiling insulation).

Of the 55 homes listed with a HERS Index Score 40 were built in 2015-16. 18 were marketed as Energy Star Certified, 2 as LEED certified and 1 was NGBS certified.

I also did a key word search of "net zero" and 11 additional properties were marketed using the term, none of which used the HERS Index Score data field in MLS PIN. Ten of these properties were built in 2015-16, and nine of the properties indicated they were "net zero ready" if the buyer purchased a solar package with the new construction.


1) It is clear that many listing brokers are confused about what a HERS Index Score is, and what the score means.

2) The misinformation could lead to significant distortion of the high performance home market as appraisers look for accurate comps.

3) Agents using inappropriate HERS Index Scores could be accused of greenwashing.

4) More real estate industry education on this subject is needed.