Choosing the Right ERV Location in High-Performance Homes
Field‑Tested Guidance for Massachusetts Homes
Energy Recovery Ventilators (ERVs) are no longer optional add‑ons in high‑performance homes—they are a core system for meeting Massachusetts energy code requirements, improving indoor air quality, and maintaining comfort in increasingly airtight buildings.
Yet one of the most common issues we see during inspections, testing, and follow‑up service has nothing to do with ERV brand, airflow rating, or control strategy.
It comes down to location.
After working on ERV installations across Massachusetts homes—new construction, additions, and major renovations—one pattern is clear: where an ERV is installed has a direct impact on whether it performs as intended over the life of the home.
Why ERV Location Matters More Than You Think
On paper, many ERV installations technically comply with manufacturer requirements. In practice, however, performance and long‑term success depend on access, serviceability, and environmental conditions.
In Massachusetts’ cold‑climate housing stock, ERVs are commonly installed in:
Attics
Basements
Mechanical rooms
Closets or utility spaces within conditioned living areas
Each option has implications—not just for installation, but for maintenance, durability, and real‑world air quality outcomes.
The Biggest Real‑World Issue: Maintenance Access
ERVs are not “install and forget” systems.
They require:
Regular filter changes
Periodic core inspection and cleaning
Occasional balancing and diagnostics
In practice, ERVs installed in hard‑to‑reach attic locations are rarely maintained unless access is simple, safe, and intentional.
We routinely see:
Filters that haven’t been changed in years
Units buried behind insulation or framing
Access panels that technically exist but are impractical to use
When maintenance doesn’t happen, airflow drops, efficiency declines, and indoor air quality suffers—regardless of how well the system was designed.
ERVs in Attics: Common Practice, With Important Considerations
Attic installations are popular because they keep equipment out of sight and preserve interior space. However, in Massachusetts homes, this location can creates long‑term challenges.
Key concerns with attic ERV installations:
Poor accessibility for homeowners and service technicians
Cold‑weather exposure, increasing condensation and frost risk
Greater likelihood of disconnected or damaged ductwork
Maintenance deferred or ignored entirely
If an ERV is installed in an attic, access must be deliberate—not an afterthought.
At a minimum, attic ERVs should have:
≥ R-6 insulation on all supply and exhaust ductwork
In unconditioned or semi-conditioned attic spaces, ERV ductwork is exposed to large temperature swings. Adequate insulation helps prevent condensation risk, reduces thermal losses, and ensures delivered air temperatures remain stable. Poorly insulated ERV ducts can undermine comfort, reduce efficiency, and introduce moisture issues over time.Adequate lightingA full‑size, code‑compliant access hatch or door
Solid flooring to the unit
Clear service clearance around the unit
Adequate lighting
Without these details, long‑term performance is compromised—even in otherwise high‑quality homes.
Best‑Practice Location: Within the Conditioned Space
From a performance and serviceability standpoint, the best location for an ERV is within the conditioned envelope of the home. This includes mechanical rooms, basements, utility spaces, and conditioned attics, which is where ERVs are most commonly installed in new construction.
Locating the ERV inside conditioned space improves efficiency, reduces condensation risk, and simplifies duct insulation requirements. Just as importantly, it ensures the unit remains accessible for filter changes, balancing, and future service— something that is often overlooked during design but becomes critical over the life of the home.
If an ERV is difficult to access, it will not be maintained properly — regardless of how well it was designed.
Across the homes we test and inspect, ERVs located within the conditioned envelope consistently perform better over time. Common examples include:
Mechanical rooms
Attics and basements within the thermal boundary
Utility closets
Why conditioned‑space installations work better:
Filters are easy to access, so maintenance actually happens
Units operate in stable temperatures, improving reliability
Condensation and frost risk is reduced
Service and balancing can be performed without disruption
In Massachusetts homes built to the Stretch Code or higher, this approach aligns best with both energy performance goals and homeowner behavior.
Code Compliance vs. Performance Reality
Massachusetts energy codes focus on ventilation rates, system type, and testing—but they don’t fully account for whether a system will be maintained ten years later.
From a HERS rating and field verification perspective, we’ve found that:
Systems located in conditioned space are more likely to remain balanced
Homeowners are more aware of their ventilation system
Future service does not require invasive access or safety concerns
Simply put, a serviceable ERV is a functional ERV.
Planning ERV Location Early Matters
ERV location should be addressed during design and framing, not after insulation or drywall.
Early planning allows for:
Shorter, more efficient duct runs
Proper condensate routing (if applicable)
Clear service access built into the home
Better coordination with HVAC and electrical systems
When ERV placement is deferred, compromises follow—and those compromises often show up during midpoint inspections, blower door testing, or years later when filters are never changed.
Final Takeaway
For Massachusetts homes, the question isn’t just whether an ERV is installed—it’s where it’s installed.
Based on field experience, inspections, and long‑term performance:
Attic installations should only be used when access is intentional and robust
ERVs located within conditioned space are easier to maintain and more reliable
Maintenance access is just as important as airflow design
A well‑located ERV supports better indoor air quality, stronger blower door results, and fewer problems down the road.
If you’re planning a new build, addition, or major renovation and want to confirm ERV placement before inspections or testing, working through these decisions early makes all the difference.
Spectrum Energy provides HERS ratings, ventilation verification, building performance testing and commercial and residential solar installations throughout Eastern Massachusetts. Our recommendations are based on what we see in the field—not just what works on paper.
