ERV Air Exchange Systems
in Sanford, Maine

An energy recovery ventilator pairs naturally with a heat pump system: it brings in continuous fresh, filtered outdoor air while recovering up to about 80% of the heating or cooling energy that would otherwise be lost by just cracking a window or running a bath fan. That matters more in some Sanford homes than others — the roughly two-thirds of the city's housing built since 1960, and especially anything built or substantially renovated more recently, tends to be tighter and better air-sealed than the mill-era housing near downtown, which means it needs a deliberate source of fresh air rather than relying on natural leakage the way an old drafty farmhouse does.

Maine's building code — the Uniform Building and Energy Code, adopted through the 2021 IECC and IMC along with 2019 ASHRAE ventilation standards — caps whole-building air leakage at 3 air changes per hour at 50 pascals for new construction statewide, a threshold tight enough that mechanical ventilation, not just natural infiltration, is generally required to meet code-required fresh-air rates. Any new Sanford home built to that standard, or an older home renovated aggressively enough to trigger it, is a strong candidate for an ERV rather than a retrofit afterthought.

Converted mill-era apartments in downtown Sanford present an interesting version of this same question: a unit that's been gutted and rebuilt with modern insulation and tight windows can end up just as sealed as new construction, even though the building itself dates to the Goodall Mills era, which means the ventilation need doesn't track neatly with a building's age on paper. We evaluate air-tightness on its own terms rather than assuming an older building automatically breathes enough on its own.

Installing an ERV means running a dedicated electrical circuit for the unit, which requires the same electrical permit as any other permanently wired mechanical equipment — in Sanford, that goes through the city's own Electrical Inspector at the Code Enforcement Office rather than a state inspector's schedule. We size and duct an ERV to actually reach the rooms that need fresh air, not just the mechanical room it sits in, and we pair the installation with whatever heat pump work a homeowner is already planning so the two systems are commissioned together rather than as separate afterthoughts. Learn more on our ERV and air exchange systems page.