Right-Sizing Ventilation
Finished attics sit at the top of the stack and can accumulate heat, humidity, and CO₂ faster than lower floors. A window plus a bath exhaust may meet minimums, but it rarely delivers consistent indoor air quality year-round. An energy recovery ventilator (ERV) supplies filtered outdoor air while exhausting stale air, exchanging heat and moisture to keep comfort steady without energy penalties.
When an ERV Makes Sense
Choose an ERV if the attic is a bedroom, studio, or primary suite; if windows are closed much of the year; or if the roof assembly is very tight (blower-door results show low ACH). Pair the ERV with a quiet, code-sized bath fan ducted outdoors to control peak humidity after showers.
Design & Commissioning
Size for low, continuous airflow (e.g., 30–60 CFM), route short, insulated ducts, and provide easy filter access. Balance the ERV so supply equals exhaust, and keep relative humidity near 40–50% through NYC’s seasons.
See a step-by-step setup in our NYC attic ventilation and air quality guide.