ERV vs HRV in Massachusetts: Which One Meets Code?

ERV vs. HRV in Massachusetts: Which Does Your Home Need?

Both an ERV (energy recovery ventilator) and an HRV (heat recovery ventilator) meet the Massachusetts Stretch and Specialized Code, as long as the unit is HVI-listed with a sensible recovery efficiency of at least 65% at 32°F (225 CMR 22 R403.6.1.2). The difference is moisture: an ERV transfers some humidity between the airstreams, an HRV transfers only heat.

Code sections citedChecked October 2026RESNET-certified HERS rater

The Difference

	ERV	HRV
Recovers heat	Yes	Yes
Transfers moisture	Yes, part of it	No
Winter	Keeps some humidity in; less dry air	Exhausts more moisture; helps damp homes
Summer	Limits humid outdoor air coming in	Brings in outdoor humidity
Meets MA code	Yes, if SRE is 65% or more at 32°F	Yes, if SRE is 65% or more at 32°F

How an ERV Works

Diagram of how an energy recovery ventilator (ERV) works: fresh outdoor air and stale indoor air pass through the core without mixing

Two fans run continuously: one brings fresh outdoor air in, the other pulls stale air out of kitchens, baths and laundry.
Both airstreams pass through the core side by side but never mix.
In winter the warm outgoing air pre-warms the cold incoming air, so you get fresh air without a big heating penalty (code requires 65%+ sensible recovery).
In summer an ERV also moves some humidity from the incoming air to the outgoing stream. An HRV recovers heat only.

Choosing between them? See ERV vs. HRV.

Which Fits Your Home

Most tight new Massachusetts homes with normal occupancy: an ERV is a common choice.
Homes with high indoor humidity in winter (many occupants, indoor pool, drying laundry): an HRV removes more moisture.
Either way, size the airflow from the floor area, bedrooms and blower door result, and balance it at final.

Code details: ERV/HRV requirements in Massachusetts.

What Matters More Than the Letter

Correct airflow from the ventilation calculation.
Balanced supply and exhaust (testing and balancing).
Running continuously, with filters kept clean.
Good duct design, short runs, intake away from vents.

FAQ

Does Massachusetts code require an ERV or an HRV?

Either. 225 CMR 22 requires heat or energy recovery; both qualify if the SRE is at least 65% at 32°F.

Is an ERV better for Massachusetts winters?

An ERV keeps some humidity indoors, which helps homes that get too dry. Homes that run humid may do better with an HRV.

Will an ERV dehumidify my house in summer?

No. It limits how much outdoor humidity comes in, but it is not a dehumidifier. Air conditioning or a dehumidifier removes moisture.

How do I know if a unit meets the 65% SRE?

Check its listing in the HVI Certified Product Directory at your design airflow. We check it for you before purchase.

Who verifies the ERV or HRV at final?

A HERS rater, HERS Rating Field Inspector or BPI professional tests the airflow (R403.6.3).

Is there a Mass Save discount on ERVs and HRVs?

Mass Save offers a $500 instant discount on qualified ERVs and HRVs for existing homes (retrofit only, not new construction), applied at participating distributors. New all-electric homes can instead get the <a href="https://homeenergyefficiencyconsultants.com/services/mass-save-new-construction-incentives-massachusetts/">Mass Save new construction incentive</a> through a HERS rater.

Town-by-Town Permit Checklists

Local building department details, checked on each town's own website:

Sources: 225 CMR 22 (Stretch/Specialized residential) · EPA: A Brief Guide to Mold, Moisture and Your Home · Mass Save HRV/ERV instant discount. Code text current as of October 2026; DOER has proposed updates to the Stretch and Specialized codes, so confirm before you file.

Not Sure Which Unit to Choose?

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