Do Mass Save multifamily incentives require a HERS rater?

For performance-based Mass Save new-construction pathways, yes in practice. The program relies on modeled and tested ratings (and ENERGY STAR MFNC documentation when you enroll at that tier). A RESNET-recognized HERS rater produces the model, inspections, tests, and certificates Mass Save reviewers expect, while the same ratings support Stretch Code CO.

What should I look for when hiring Mass Save HERS raters for multifamily?

Prioritize multifamily sampling experience, Massachusetts Stretch Code work, and a track record filing Mass Save and ENERGY STAR MFNC paperwork on similar unit counts. Ask how they group unit types, when they inspect before drywall, and how they keep compliance certificates aligned with incentive files. A single-family-only book of work is a red flag on apartment projects.

How much do Mass Save-related HERS rating services cost per unit?

Typical multifamily HERS rating services (modeling, inspections, and testing) run about $150 to $400 per unit. Unit-type count, building count, sampling scope, and retests move the number. That fee is separate from Mass Save incentive dollars, which on larger ECC Massachusetts studies have modeled from the mid-six figures into about $1.1M when ENERGY STAR MFNC paperwork is included.

Should I hire a HERS rater before or after a feasibility study?

Run the feasibility study first. It chooses the Stretch Code path, fuel type, envelope and HVAC package, and whether Mass Save plus ENERGY STAR MFNC is worth enrolling. The HERS rater then models and tests that path. Hiring the rater first can lock a more expensive build or miss enrollment windows. ECC offers feasibility studies at no cost.

Mass Save HERS Raters: Multifamily Ratings, Incentives, and Who to Hire

Need Mass Save HERS raters for Massachusetts multifamily? How HERS ratings unlock Mass Save and ENERGY STAR incentives, what raters actually do, typical cost, and why a free feasibility study comes first.

September 11, 2026

If you are enrolling a Massachusetts multifamily project in Mass Save, the HERS rater is not a side vendor you hire after drywall. Mass Save new-construction incentives and ENERGY STAR Multifamily New Construction (MFNC) paperwork both lean on the same energy model, field inspections, and tested ratings. The right multifamily HERS rater / provider stack is how enrollment, Stretch Code compliance, and incentive documentation stay on one schedule.

This page is about that hire-and-enrollment path. For a general Massachusetts rater overview, see HERS rater Massachusetts. For rebate tiers and application timing, see Mass Save incentives for multifamily. For how ratings work on apartment buildings nationwide, see HERS rating multifamily.

Why Mass Save Enrollment Runs Through HERS

Mass Save's multifamily new-construction path is performance-based. Your modeled and tested HERS scores (plus ENERGY STAR MFNC when you chase that tier) are what prove you cleared the program's thresholds. A RESNET-recognized HERS rater builds those models, inspects insulation and mechanical rough-in, runs blower door and duct leakage tests on the sampled units, and produces the certificates and files Mass Save and ENERGY STAR reviewers expect.

Skip early rater involvement and three things usually break:

Enrollment happens after design is frozen, so the incentive tier no longer matches the mechanical or envelope package you can actually build
Sampling and unit-type grouping do not match how the buildings will be constructed, which triggers extra tests and CO risk
ENERGY STAR MFNC paperwork trails the Mass Save file, so voluntary certification money that was already in the design never gets claimed

The rating still has to clear Stretch Code or Specialized Code for Certificate of Occupancy. Mass Save is the incentive layer on top of that compliance path, not a replacement for it.

What Multifamily Mass Save HERS Raters Actually Do

On a Mass Save-bound multifamily job, the rater (and the provider organization behind them) typically:

Confirm the Stretch Code or Specialized Code target that sets the HERS ceiling for CO
Align the energy model with Mass Save and ENERGY STAR MFNC program rules so one model feeds compliance and incentives
Group unit types, orientations, and buildings so sampling stays legal and efficient
Inspect air barriers, insulation, and mechanical rough-in before drywall
Test sampled units and expand sampling if a unit fails
Package HERS certificates plus the supporting files Mass Save and ENERGY STAR need at mid-construction and completion

A single-family-heavy rater can miss corridor modeling, shared walls, and multifamily sampling. Those misses show up as failed tests, delayed COs, and incentive files that do not match the as-built project. Hire for multifamily Mass Save experience, not only a RESNET credential on paper.

Typical Cost and What Moves the Number

For modeling, inspections, and testing on typical multifamily scopes, HERS rating services usually land around $150 to $400 per unit. Repeated unit types and clean sampling pull the per-unit number down. Extra buildings, odd unit mixes, and retests push it up.

That rating fee is not the incentive. On ECC feasibility models, Mass Save (often with ENERGY STAR MFNC paperwork) has modeled in the mid-six to low-seven figures on larger Massachusetts jobs when enrollment and testing line up. Cutting the rater early to save a few dollars per unit is how those stacks get missed.

Proof From ECC Massachusetts Studies

Use real project math before you pick a rater stack.

On our 296-unit Amesbury study (CS81), Stretch Code HERS paths sat at HERS ≤ 48 with the carbon-credit insulation path versus HERS ≤ 45 without it. The recommended all-electric path came in around $45.50/sf net, with modeled Mass Save incentives in the $686,000 to $1,130,000 range when ENERGY STAR MFNC paperwork was included. CO still rested on tested HERS ratings, with sampling allowed.

On a 320-unit Northbridge project (CS78), Stretch Code with HERS ≤ 45 and ENERGY STAR MFNC modeled at about $39.49/sf net on the recommended all-electric path, with incentives in the $640,000 to $1,120,000 range. On a 105-unit Northbridge job (CS76), the recommended all-electric HERS path landed near $31.70/sf net. A 250-unit Shrewsbury study (CS67) ran Stretch Code at HERS ≤ 45 with ENERGY STAR MFNC at about $41.70/sf net on the recommended path.

Those figures come from ECC's own feasibility models. The pattern is the same: choose the Mass Save and code path first, then hire the multifamily HERS rater to execute that path.

Who to Hire (and in What Order)

1. Feasibility before the rater contract. Lock fuel type, envelope package, HVAC, Stretch Code target, and whether ENERGY STAR MFNC is worth the paperwork. That study sets the HERS ceiling and the incentive tier the rater must hit.

2. A multifamily-capable HERS rater / provider. Ask how they handle sampling on your building count, whether they have run Mass Save and ENERGY STAR MFNC files on similar Massachusetts jobs, and how they sequence rough-in inspections with your GC schedule.

3. One documentation trail. Compliance certificates, Mass Save enrollment, and ENERGY STAR MFNC should not live in three disconnected folders. The model and field tests should feed all three.

If you are early in design, start with a free feasibility study. If the path is already chosen and you need modeling, inspections, testing, or certification paperwork, see ECC services for HERS/ERI, ENERGY STAR, and related scopes.

Bottom Line

Mass Save HERS raters are the field team that turns a Massachusetts multifamily enrollment into tested scores, CO-ready certificates, and incentive files that match ENERGY STAR MFNC when you chase that tier. Budget roughly $150 to $400 per unit for rating services, involve the rater before drywall, and run a feasibility comparison before you freeze mechanical and envelope decisions. That order protects the CO date and the Mass Save stack.