Do I need a COMcheck for a multifamily building in Massachusetts?

Often, yes. Multifamily buildings of four or more stories fall under 225 CMR 23, the commercial and multi-family energy code. Dwelling units can comply through the HERS or Passive House pathway, but mixed-use buildings show compliance by use type, so retail, office, amenity, and other non-HERS portions still need their own documentation, typically COMcheck certificates.

What COMcheck certificates does Massachusetts require at permit?

Under the 225 CMR 23 amendments, buildings up to 20,000 sf submit COMcheck Envelope, Lighting, and Mechanical Compliance Certificates with a Plan Review Inspection Checklist. Buildings over 20,000 sf submit COMcheck Lighting and Mechanical Compliance Certificates with the checklist, and document the envelope through backstop and thermal bridge derating calculations. Confirm the edition in force at your permit address.

What is the difference between a lighting COMcheck and a mechanical COMcheck?

They are two certificates from the same project file. The lighting certificate checks interior lighting power space by space, lighting controls, and exterior lighting. The mechanical certificate checks equipment efficiencies, controls, ventilation, energy recovery where required, insulation, and economizer requirements for the systems serving nonresidential and common spaces.

Does a HERS path building in Massachusetts still need COMcheck?

For the parts that are not dwelling units, usually yes. The HERS and Passive House pathways follow their own reporting rules, but on a building over 20,000 sf that uses those pathways for only part of the building, that exception does not cover the rest. On ECC's 112-unit Revere study, the dwelling units stayed on a Stretch HERS path and the study still called for a COMcheck report for all common and support areas.

How is this page different from ECC's Texas COMcheck page?

The Texas page covers a statewide commercial code floor where mid-rise and mixed-use filings are typically documented on ASHRAE 90.1 or COMcheck instead of a HERS-first path. This page covers Massachusetts, where 225 CMR 23 lets dwelling units use HERS or Passive House while non-residential and common portions show their own compliance, with a 20,000 sf split on the COMcheck submittal. Use a free feasibility study to map the split on your drawings.

COMcheck Massachusetts: Mixed-Use Multifamily Certificates and When to Study First

COMcheck in Massachusetts for mixed-use and 4+ story multifamily: which lighting, mechanical, and envelope certificates 225 CMR 23 asks for, and when to study first.

October 08, 2026

On a Massachusetts mixed-use or mid-rise apartment building, the HERS rating is only part of the permit set. The retail bay, the lobby, the corridors, the garage, and the mechanical rooms still have to show commercial energy code compliance, and in Massachusetts that usually means COMcheck certificates. Teams get caught when they assume the dwelling-unit path covers the whole building, or when they order a COMcheck before anyone has decided which compliance path each part of the building is on.

This page is the Massachusetts COMcheck door for multifamily developers. For the statewide code picture, see energy code compliance Massachusetts. For Stretch versus Specialized, see Specialized Stretch Code for multifamily. For the dwelling-unit side, see HERS rater Massachusetts and, inside the city, HERS rater Boston. The Texas commercial path is a different story, covered in ASHRAE COMcheck Texas multifamily.

Who Needs a COMcheck in Massachusetts

In Massachusetts, multifamily buildings of four or more stories, and all commercial construction, are governed by 225 CMR 23, the commercial and multi-family energy code (with the Stretch and Specialized provisions). Buildings of three stories or fewer fall under 225 CMR 22, the residential code.

Inside 225 CMR 23, a mixed-use building does not pick one path for the whole structure. The code says that where different use types require different compliance pathways, each use type shows compliance separately. In practice:

Dwelling units on a mid-rise can comply through the HERS pathway (for Group R buildings with multiple dwelling units) or a Passive House pathway
Retail, office, amenity, and other nonresidential portions comply on their own pathway
Common areas such as corridors, lobbies, stairs, and support spaces still need lighting and mechanical documentation
Parking garages that are part of a larger building may follow the prescriptive path even where they exceed 20,000 square feet (a code exception)

So a building can be fully on a HERS path for its apartments and still owe COMcheck certificates for everything that is not an apartment.

What 225 CMR 23 Asks For at Permit

The Massachusetts amendments split the COMcheck submittal at 20,000 square feet:

Buildings up to 20,000 sf. The permit set is accompanied by completed COMcheck Envelope, Lighting, and Mechanical Compliance Certificates, plus a Plan Review Inspection Checklist.

Buildings over 20,000 sf. The permit set is accompanied by COMcheck Lighting and Mechanical Compliance Certificates and a Plan Review Inspection Checklist. The envelope is shown instead through backstop and thermal bridge derating calculations under the state's Stretch Energy Code Technical Guidance. Buildings over 20,000 sf on a modeled performance pathway also submit the simulation calculations that pathway requires.

HERS and Passive House buildings. Buildings documenting compliance on the certified performance pathways (HERS or Passive House) follow the reporting rules for those pathways. The catch for mixed-use: on a building over 20,000 sf that uses HERS or Passive House for only part of the building, that exception does not cover the rest. The retail floor and other non-HERS portions still owe their own documentation.

The code text has been amended since its first adoption, including amendments effective in 2025. Confirm the edition and any local Specialized Opt-In adoption at your permit address before anyone builds a model.

Lighting COMcheck vs Mechanical COMcheck

People search for these as if they were separate products. They are two certificates from the same project file.

Lighting COMcheck. Interior lighting power is checked space by space against the code allowance, along with lighting controls and exterior lighting. On a 112-unit Revere, MA study (CS57), the common-area lighting plan was 100% LED with space-by-space interior lighting power of about 0.41 W/sf in corridors, 0.90 in the lobby, 0.49 in stairways, 0.18 in the parking garage, and 0.42 in storage and mechanical rooms. On a 30-unit Boston study (CS82), the ground-floor retail sales space carried an allowed lighting power of 1.05 W/sf. Your allowances depend on your space types and the edition in force.

Mechanical COMcheck. Equipment efficiencies, controls, ventilation, energy recovery where required, duct and pipe insulation, and economizer requirements are checked for the systems serving nonresidential and common spaces. On the Boston retail space in CS82, the basis for not providing an economizer was recorded on the COMcheck mechanical certificate.

Envelope COMcheck. Only part of the story on larger buildings. Under the 20,000 sf split above, buildings over that size document the envelope through the backstop and thermal bridge derating calculations instead.

Prescriptive vs Performance for the Non-Residential Portions

The Massachusetts amendments limit the prescriptive path. Prescriptive compliance may only be used for nonresidential buildings, or portions of mixed-use buildings, up to 20,000 sf. Larger nonresidential portions go to a modeled performance pathway. For residential buildings or portions over 12,000 sf, the code directs the targeted performance pathway unless the building uses the HERS or Passive House pathway.

That is why the size of the retail podium, the garage, and the amenity floor matters before design is locked. A ground-floor retail bay under 20,000 sf can usually stay prescriptive with COMcheck. A large commercial component can push the project into whole-building modeling.

What It Looks Like in ECC Studies

ECC studies already published on the site show how the split works on real Massachusetts buildings:

112-unit Revere, MA (CS57). A seven-story mixed-use building, 79,464 sf, concrete podium over garage with six stories of wood-framed residential, on a Stretch Code HERS path with ENERGY STAR MFNC. The dwelling units stayed on HERS, and the study still called for a COMcheck report for all common and support areas, ASHRAE 62.1 ventilation rate calculations, and interior and exterior lighting power density calculations. The recommended ductless all-electric path landed at about $42.52/sf net.
30-unit Boston, MA (CS82). A six-story mixed-use building plus a one-story retail building, 21,626 sf conditioned, under the Specialized Opt-In code with HERS ≤ 45 and ENERGY STAR MFNC. The paperwork scope paired HERS/ERI models and certificates for the units with COMcheck documentation for the common areas and retail. The current all-electric design modeled at about $58.11/sf net, with $52,500 to $97,500 in modeled Mass Save incentives.
92-unit Newburyport, MA (CS71). Two buildings, 100,930 sf conditioned, under the Specialized code: a residential building on Phius CORE 2024 and a separate single-story commercial building that complies prescriptively with COMcheck envelope, lighting, and mechanical certificates, the plan review checklist, and mandatory air-leakage testing. The recommended residential wall path came in at about $37.32/sf net.

These are Massachusetts outcomes. We cite them as proof of method, not as a price for your building.

Common COMcheck Mistakes on Massachusetts Multifamily

Assuming the HERS path covers the whole building. It covers the dwelling units. Retail, amenity, and other non-HERS portions still show their own compliance.
Running an envelope COMcheck on a building over 20,000 sf when the permit set needs backstop and thermal bridge derating calculations instead.
Forgetting the garage and support spaces. They carry lighting, ventilation, and controls requirements even when they are unconditioned.
Ordering COMcheck before the path is locked. If the retail portion is near 20,000 sf, or the residential portion is near 12,000 sf, the pathway choice changes what gets documented.
Letting the certificate drift from the drawings. The Plan Review Inspection Checklist and field inspections check what was actually installed against the certificates.

When to Study First

Settle the path before anyone buys COMcheck or modeling hours:

Confirm the code at the permit address: 225 CMR 23 Stretch, or the Specialized Opt-In code, and the edition in force
Split the building by use type: dwelling units, common areas, retail or office, garage
Check each portion against the 20,000 sf and 12,000 sf thresholds
Pick the dwelling-unit pathway (HERS or Passive House) and the pathway for each non-residential portion
Model the envelope and mechanical packages side by side and compare net cost after incentives, including Mass Save multifamily incentives and ENERGY STAR MFNC where they apply
Then produce the COMcheck certificates, HERS models, and checklists against that locked plan

That comparison is what a free feasibility study produces. For the Massachusetts study method, see energy code feasibility study Massachusetts. If the path is already chosen and you need COMchecks, HERS modeling, inspections, or testing, see ECC services. For HERS rating fees, see HERS rating cost Massachusetts.

Bottom Line

A Massachusetts mixed-use or mid-rise multifamily building usually needs two kinds of paperwork: a dwelling-unit path such as HERS or Passive House, and COMcheck certificates for everything that is not an apartment. Under 225 CMR 23, buildings up to 20,000 sf submit envelope, lighting, and mechanical certificates, while larger buildings submit lighting and mechanical certificates and document the envelope through backstop and thermal bridge calculations. Split the building by use, lock each path, then produce the certificates that match the plan.