Quick answer
Read in 4 minAn ERV (Energy Recovery Ventilator) or HRV (Heat Recovery Ventilator) is a small piece of equipment that brings outdoor fresh air into your house and exhausts indoor stale air, while transferring heat (and in the ERV's case, humidity) between the two streams so you don't waste the energy you spent conditioning the indoor air. Old leaky houses ventilated themselves — every door open, every can light, every gap was an unintentional fresh-air strategy. New tight builds (anything code-built after about 2010 in Indiana) often have so little natural air exchange that CO2, VOCs, and moisture accumulate. ASHRAE Standard 62.2 sets a residential ventilation target — roughly 7.5 CFM per occupant plus 3 CFM per 100 sq ft — and most modern Newburgh and Evansville builds need mechanical help to hit it. ERV is the right call for our humid summers; HRV is fine for cold dry climates but rarely the right pick here.
- 01 ASHRAE 62.2: about 7.5 CFM/person + 3 CFM/100 sq ft of continuous fresh-air ventilation.
- 02 ERV (Energy Recovery): transfers heat AND humidity — right for SW Indiana's humid summers.
- 03 HRV (Heat Recovery): transfers heat only — better for dry cold climates, less common here.
- 04 Recovery efficiency: 60-85% for heat, 50-75% for moisture on quality units.
- 05 Cost installed: $1,500-3,500 depending on layout and ducting.
Section 02
When ventilation goes from optional to required
If your house was built before 2000 with standard fiberglass batts, average windows, and no air sealing, it probably leaks enough to ventilate naturally. If your house was built after 2010 to current Indiana energy code — better windows, spray foam, sealed sheathing — it might be tight enough that natural infiltration is a fraction of what ASHRAE 62.2 requires. The simplest field test is a blower-door test, which tells you literal air changes per hour at 50 pascals. Below about 3 ACH50, you're likely in mechanical-ventilation territory. Above 5 ACH50, you're probably fine without it.
Section 03
What we see in SW Indiana new construction
Most of the new builds in Newburgh, McCutchanville, and the Evansville eastside that we commission are testing in the 2-4 ACH50 range — tight enough that CO2 in closed bedrooms climbs into the 1,500-2,500 ppm range by morning. Homeowners describe waking up unrested, headachy, with the faintest "stuffy" smell. Adding an ERV at 60-100 CFM continuous solves it completely. The homeowner's sleep changes within a week. This is one of the upgrades we recommend most often for newer construction and the one most often missed by the original builder.
Section 04
When the bath fan is doing what an ERV should
Some homeowners rely on bath fans as their ventilation strategy. The problem is bath fans only run when someone hits the switch, they exhaust without making up the air (which then sneaks in through whatever gap it can find — often the chimney or dryer vent backward), and they're not balanced. A real ventilation system runs continuously at low CFM, balanced supply and exhaust, with energy recovery between them. Bath fans are for moisture control during showers, not whole-house ventilation.
Section 05
When ventilation interacts with humidity
In a humid SW Indiana summer, dumping 80 CFM of 76°F dew-point air into your house all day would absolutely make your humidity problem worse — unless the ventilation system has energy recovery. An ERV core transfers moisture between exhaust and supply, so it removes 50-75% of the latent load before the fresh air ever hits your AC. That is why ERV is the right pick in our climate, not HRV. We have seen homeowners install HRVs (recommended online by people in dry climates) and end up with high indoor humidity from the unrecovered moisture load.
How it works
The mechanism, explained.
The basic principle — balanced exchange
A ventilation unit has two fans: one pulls fresh outdoor air in, one pushes stale indoor air out. The two streams pass through a heat exchanger core where they exchange thermal energy (and in an ERV, moisture too) without mixing. In winter, exhaust air at 70°F preheats fresh air coming in at 20°F to maybe 60°F before it enters the house — recovering about 75% of the heat. In summer, the reverse: cool exhaust air pre-cools incoming hot air. That recovery is the whole point — you get fresh air at near-neutral energy cost.
ERV vs HRV — the moisture difference
An HRV transfers heat only. The core is impermeable to water vapor. Good for cold dry climates (Minnesota, North Dakota) where indoor moisture from cooking and showering is what you actually want to exhaust. An ERV transfers heat AND water vapor through a permeable membrane core. In summer, it sends some of the incoming humid air's moisture back outside on the exhaust stream. In winter, it sends some of the outgoing dry exhaust's moisture back into the supply, keeping indoor RH from collapsing. In SW Indiana with our humid summers and moderate winters, ERV wins almost every time.
How it integrates with the HVAC system
Most residential ERVs tie into the return-duct of the air handler so the existing blower distributes the fresh air through the house. Some installations are fully ducted independently, which is better but more expensive. The unit itself usually sits in a mechanical closet, basement, or attic and runs continuously at low speed — maybe 60-100 CFM for a 2,000 sq ft house — with a boost mode for high-occupancy times. Modern units have controls that vary speed based on CO2, RH, or VOC measurements.
Why "just opening a window" doesn't substitute
Windows ventilate randomly. They depend on wind, indoor/outdoor temperature differential, and human attention. In a Southwest Indiana July, opening a window dumps 76°F dew-point air into the house and ruins your AC's day. In a January cold snap, opening a window for ten minutes drops indoor temp 5°F and the heat works hard to recover. A mechanical ERV exchanges 60-100 CFM continuously at near-neutral energy cost. Same fresh air, dramatically lower bill, much more reliable.
Key terms in context
Vocabulary you'll see on a real estimate.
This guide is written for indoor air & comfort decisions in Southwest Indiana. It uses the same terminology you'll hear from techs, inspectors, and the permit office.
Failure mode 01
Living in a tight house with no ventilation
The path most new-build homeowners are on by default: a 2-3 ACH50 tight envelope, no mechanical ventilation, bath fans used only after showers. CO2 climbs in closed bedrooms, VOCs from flooring and furniture don't clear, indoor humidity drifts up in summer, and "the new house smell" never quite leaves. The homeowner adapts to it slowly and doesn't realize they're chronically under-ventilated. The first time we install an ERV on one of these houses the homeowner's feedback is usually about sleep quality, not air quality — they didn't know they weren't sleeping well.
Failure mode 02
Installing the wrong unit for the climate
We have walked into Evansville homes with HRVs installed by someone who got the recommendation from a forum thread written by someone in Wisconsin. In our climate, an HRV passes humid summer air through with no moisture recovery and the homeowner gets high indoor RH from the fresh-air stream. The right answer for SW Indiana is almost always ERV, and the right answer might also include a dedicated dehumidifier in series for very humid weeks. The honest math is climate-specific — read the regional installer's recommendation, not the national forum's.
Proof, process & local validation
- 01 Perfect Climate sizes ventilation to ASHRAE 62.2 and verifies with a balometer reading at the supply and exhaust grilles.
- 02 We blower-door test new builds before recommending mechanical ventilation — sometimes the house already leaks enough.
- 03 ERV installs across SW Indiana, all climate-appropriate for our humid summers.
How we build this guidance
- Perfect Climate installs Broan, Honeywell, Lifebreath, and Lennox ventilation systems based on house tightness.
- We perform blower-door testing on suspected tight builds to confirm whether mechanical ventilation is needed.
- Pat trained the team on ASHRAE 62.2 sizing — we don't pull CFM out of a hat.
Methodology · Perfect Climate validates ventilation needs with blower-door testing and ASHRAE 62.2 calculations, then verifies airflow at the grilles after installation — measured, not estimated.
Last updated 2026-06-24
Ready for the next step?
When you're ready, get a measured estimate with no commission script.
Continue exploring
Related reading + your next step.
Common questions
Questions, answered.
01 Do I really need mechanical ventilation in an older house?
Probably not. Most pre-2000 builds in SW Indiana leak enough that natural infiltration meets ASHRAE 62.2 requirements without any help. The honest test is a blower-door measurement. If you're above 5 ACH50 you're almost certainly fine. If your house was tightened during a renovation (spray foam, new windows, sealed sheathing), it's worth re-testing because tightening up can put you into ventilation-required territory.
02 How much does an ERV cost installed?
$1,500-3,500 for a typical residential ERV installed, depending on the unit and the ducting complexity. A simple tie-in to existing HVAC ductwork is at the low end; a fully ducted independent supply and exhaust grille set is at the high end. Operating cost is small — under $10/month in electricity for continuous low-speed operation — because energy recovery offsets most of the conditioning load.
03 Will an ERV solve my humidity problem?
It will help, but it's not a primary humidity-control device. An ERV recovers about 50-75% of the latent load from incoming fresh air, which is why it's preferred over HRV in our climate. But it doesn't actively remove moisture the way a dedicated dehumidifier does. For homes with persistent high humidity, the answer is usually a dehumidifier first, then the ERV adds fresh air without making humidity worse.
04 Can I just run the bath fans more?
It's a partial solution but inefficient and unbalanced. Bath fans exhaust without controlled makeup air, so the house pulls makeup through the chimney, dryer vent, or wherever else it can find. That can backdraft combustion appliances (dangerous) and pulls humid attic or crawlspace air down. A balanced ERV is dramatically better — same fresh air, none of the backdraft risk, and energy recovery on top.
05 How often does an ERV need service?
Annually. The filters at the supply and exhaust intakes need cleaning or replacing, the core itself benefits from a vacuum and inspection, and the controls need a quick check. It's a 30-minute job we do as part of an annual maintenance visit. Skip the service and the unit clogs up, airflow drops, and the recovery efficiency falls off — at which point you're paying to ventilate but not getting the recovery benefit.
