An ERV or HRV brings filtered fresh air into a tightly sealed home while recovering most of the energy from the stale air it exhausts. An HRV transfers heat only; an ERV transfers heat and moisture, helping balance humidity. In the Bay Area's mild, sometimes-humid coastal climate an ERV is often the better fit — but the right choice depends on your home and how tight it is.
What problem does whole-home ventilation solve?
Older homes "breathe" through countless leaks, so fresh air came whether you wanted it or not. Modern, energy-efficient homes are sealed tight — efficient, but they trap stale air, cooking and cleaning odors, CO₂, and moisture. Mechanical ventilation restores fresh air on purpose, with filtration and energy recovery, instead of relying on leaks or open windows. It's the IAQ lever most homeowners have never heard of (see improving indoor air quality).
How does an ERV or HRV actually work?
A recovery ventilator runs two air streams past each other through a core: outgoing stale indoor air and incoming fresh outdoor air. The core transfers energy between them without mixing the streams, so in winter the outgoing warm air pre-warms the incoming fresh air (and vice versa in summer). The fresh air is filtered on the way in. The result: ventilation that costs a fraction of the energy that simply opening a window would waste.
ERV vs. HRV — which is right here?
| Factor | ERV | HRV |
|---|---|---|
| Recovers heat | Yes | Yes |
| Recovers moisture | Yes | No |
| Helps humidity balance | Yes | Less so |
| Often better for | Mild/variable, humidity-sensitive homes | Cold, dry climates |
The right pick depends on your home's tightness, humidity, and layout — confirmed in person.
When is an ERV/HRV worth it for your home?
- Newer or recently sealed home that feels stuffy or holds odors.
- Smoke-season concerns — filtered fresh air without opening windows (wildfire smoke).
- Humidity swings — an ERV helps moderate them.
- Electrification / deep retrofit — tight homes especially benefit from balanced ventilation.
Ventilation complements filtration — it doesn't replace it. An ERV/HRV brings in fresh, filtered air; your system's MERV filter and any dedicated cleaner handle what's already circulating. The best results pair both — see do I need a whole-home air purifier?
Why trust Air Synergy with ventilation?
A family-owned team with decades of combined technician experience in the Bay Area and a 4.9-star rating across 189 reviews, we size and place ERVs/HRVs for balanced airflow and recommend one only when your home will genuinely benefit — not as a default upsell. Explore indoor air quality services.
Your next step
Stuffy, tight home — or want fresh air on smoke days? Book a free in-home assessment. We'll evaluate your home's tightness and recommend the right ventilation in plain English.
ERV/HRV guidance reflects standard ASHRAE-aligned ventilation practice; the right unit depends on your home. Terms in the glossary. Company facts per Air Synergy.
Common questions
What's the difference between an ERV and an HRV?
Both bring in filtered fresh air while recovering energy from the air they exhaust. An HRV (Heat Recovery Ventilator) transfers heat only; an ERV (Energy Recovery Ventilator) transfers both heat and moisture, helping balance indoor humidity. In the Bay Area's mild, sometimes-humid coastal climate, an ERV is often the better fit, but the right choice depends on your home.
Do I need whole-home ventilation if I have a newer, tight house?
Often yes. Modern, energy-efficient homes are sealed tightly, which is great for efficiency but traps stale air, odors, and moisture. A balanced ERV or HRV gives you continuous filtered fresh air without throwing away the energy you paid to heat or cool — solving the stuffiness without opening windows to smoke or pollen.
Won't opening windows do the same thing for free?
Windows work when the outdoor air is clean and mild, but they waste conditioned air and let in smoke, pollen, and noise. An ERV/HRV gives controlled, filtered fresh air year-round while recovering most of the energy — fresh air on smoke days and cold nights, without the penalty.