HRV vs ERV Whole House Ventilation Guide
Fresh air feels great for a minute, then your comfort drops as heat and moisture rush in. That is why balanced ventilation has become the standard for tight homes. Heat recovery ventilators and energy recovery ventilators bring in filtered outdoor air while sending stale air out through a heat exchange core. You get cleaner air with far less energy waste. This guide explains HRV vs ERV technology, shows which one fits your climate and home, covers sizing, retrofit or new build strategies, costs, upkeep, and how to choose a model with confidence.
Why balanced ventilation matters
Balanced ventilation supplies outdoor air in a controlled way while exhausting pollutants at the same time. Each airstream gets filtered. The core transfers energy between the two flows so the incoming air arrives tempered for comfort. Berkeley Lab describes how balanced systems cut indoor pollutant levels compared with exhaust only strategies that pull makeup air from random leaks and garages. You get steady dilution of carbon dioxide, odors, and VOCs without the comfort penalty of cracked windows. See the balanced ventilation primer from Lawrence Berkeley National Laboratory for a clear overview at svach.lbl.gov.
Central Texas homes face humidity swings for much of the year. Infiltration brings moist air that burdens your cooling system. Controlled outside air through an ERV helps keep that extra moisture out. If you want a refresher on how excess humidity hurts comfort and indoor air quality, read our guide on humidity risks.
Tightening the envelope with air sealing often comes first in energy upgrades. Less leakage cuts bills yet it also reduces incidental fresh air from cracks. That raises the value of a dedicated fresh air system. If you are planning envelope work, bookmark our field guide to sealing air leaks.
What is an HRV and an ERV
Both devices are balanced ventilation systems. Each pulls stale air out while bringing outdoor air in. The two airstreams pass through a core that recovers energy you would otherwise throw away.
A heat recovery ventilator moves heat between the outgoing and incoming air. It does not move moisture by design. An energy recovery ventilator moves both heat and moisture using an enthalpy core or wheel. These working definitions come from the ENERGY STAR HRV and ERV specification page hosted by Natural Resources Canada. See the formal descriptions at natural-resources.canada.ca.
How the cores transfer heat and moisture
Think of the core as a highly specialized radiator. In an HRV, the surfaces conduct thermal energy from the warm airstream to the cooler one. The two airstreams never mix. In winter, outgoing warm air preheats the incoming cold air. In summer, outgoing cooler indoor air precools the incoming hot air. That is heat recovery.
In an ERV, the core also allows a portion of water vapor to move across a membrane. During a humid summer, an ERV passes some moisture back to the outgoing airstream so the air entering your home carries less water. During a dry winter, it can hold on to some indoor moisture so indoor relative humidity does not crash. The key nuance from Berkeley Lab is simple. An ERV does not dehumidify the house. It only reduces the amount of moisture the ventilation air brings in or takes away. See that clarification at svach.lbl.gov.
What HVI ratings mean
Comparing models by brochure buzzwords falls short. Use the standardized ratings from the Home Ventilating Institute. The HVI Consumer Guide explains the metrics in plain language and links to an online directory for side by side comparisons at hvi.org.
Key terms you will see:
- SRE or Sensible Recovery Efficiency. This shows how much sensible heat the unit recovers after accounting for case losses, airflow imbalance, leakage, defrost, and actual fan power. Use this for heating season comparisons.
- TRE or Total Recovery Efficiency. This adds latent energy to the picture. It is most helpful for cooling season performance and ERV comparisons.
- ASRE and ATRE. These are adjusted metrics that remove fan energy. They support whole home energy modeling and fair apples to apples checks.
Why this matters. Older ASE or ASEF values can hide high fan watt draw or leakage. Fantech summarizes this pitfall and why SRE or TRE tell a more honest story. Their short explainer is at fantech.net.
HRV vs ERV by climate
Climate drives the choice more than brand or gadget features. In hot humid regions such as Austin, Houston, or Atlanta, an ERV shines. The enthalpy core reduces the added moisture load that would otherwise ride in with your fresh air. A peer reviewed modeling study found ERVs cut total HVAC energy compared with HRVs by roughly ten to seventeen percent in Miami, Houston, and Atlanta. The study also showed gains in Baltimore and Los Angeles, though recovery did not beat no recovery in Los Angeles due to mild conditions. You can read the open access paper at pmc.ncbi.nlm.nih.gov.
In cold or cold dry climates, many homes still favor an ERV because it helps keep indoor relative humidity from plunging in winter. Wood floors, trim, and musical instruments hold up better with stable humidity. Family comfort improves when winter air does not feel parched. That said, some tight small homes with high occupant density may need an HRV in winter to keep indoor humidity in check. Energy Vanguard explains this nuance well at energyvanguard.com.
In the mild Pacific Northwest, many projects use HRVs due to modest temperatures and fewer high humidity events. The better answer is still project by project. Think about occupant loads, cooking or shower habits, pets, and allergy concerns. Match the device to the moisture profile you expect. A good designer will review both SRE and latent effectiveness for the target airflow.
One more reminder. An ERV limits how much moisture the ventilation air adds or removes. It does not replace a whole home dehumidifier in a hot humid climate with long wet seasons. Berkeley Lab makes this point directly in the balanced ventilation primer linked above.
How to size ventilation
Sizing starts with the ASHRAE 62 point 2 whole building rate. The simple formula used in many U S codes is about one cfm per one hundred square feet of conditioned floor area plus seven point five cfm times the number of bedrooms plus one. Energy Code Ace shows the calculation with examples and a small table at energycodeace.com.
Quick example for context. A one thousand eight hundred square foot home with three bedrooms lands near forty eight cfm for continuous ventilation. That is a starting point. Some projects select a unit with higher maximum airflow for boost mode during parties or large gatherings. Some regions permit intermittent operation with higher cfm and shorter run time. Your local code and comfort goals set the final target.
Remember filters. If you want MERV thirteen intake filtration for allergy control, account for the added pressure drop. A larger unit can run at a lower fan speed to stay quiet and efficient.
If allergies flare up each spring, you will find practical tips in our guide to improve indoor air quality. Better filters in your HRV or ERV are a strong start.
Retrofit vs new build
New construction offers a clean slate. You can route short, straight ducts to bedrooms and living areas for supply air, then pull exhaust from baths, laundry, and near the kitchen. Retrofits require creativity. Finished ceilings and tight chases push design toward compact units, decentralized strategies, or careful integration with existing ductwork. Good outcomes come from simple airflow paths, low fan watts per cfm, quiet operation, and clear service access for filters and core cleaning.
Fully ducted best practice
A dedicated supply to the main living spaces gives you fresh air where people spend time. Dedicated exhaust from baths and laundry removes moisture at the source. Place a pickup near the kitchen rather than over the range. A range hood still handles cooking peaks. Keep duct runs short for lower static pressure. Choose ECM motors with low watts per cfm. Pick a unit rated for quiet operation in bedrooms. Fine Homebuilding summarizes this strategy and warns against using a central furnace blower to move ventilation air due to the energy hit from continuous fan operation. Read their overview at finehomebuilding.com.
Integrate with existing ducts
Many retrofits tie a supply from the HRV or ERV into the return trunk of a furnace or air handler. That can work if designed correctly with interlocks. It can also short circuit if both intake and exhaust tie to the return, which just recirculates air without delivering outdoor air to rooms. The Building America Solution Center flags this risk and offers guides to avoid it at basc.pnnl.gov.
In hot humid regions, field pros often avoid dumping outdoor air into a return unless the plan is engineered in detail. Poor design can create condensation in ducts, wet insulation, mold, and comfort complaints. HVAC School has a clear warning on return tie pitfalls plus better options at hvacrschool.com.
Integrations must prevent the air handler from running full time just to distribute ventilation air. Separate controls or a smart relay help. The goal is tempered outdoor air delivered efficiently without an energy penalty.
Spot ERVs for tight spaces
Some homes cannot fit new ductwork without major drywall work. A small spot or decentralized ERV can meet the ventilation requirement in a compact package. Panasonic WhisperComfort models sit in a ceiling bay or wall, run at modest cfm, and use small diameter ducts with a single wall cap. They are popular for apartments or targeted rooms. See the 60 cfm model overview at na.panasonic.com and the product page at iaq.na.panasonic.com.
Cold weather operation
When outdoor air drops below freezing, moisture can condense and freeze inside a core. HRVs and some ERVs use frost control strategies to protect the core. Methods include a preheat coil upstream of the intake, periodic defrost cycles, or a temporary supply and exhaust imbalance that warms the core. The right method depends on your unit and climate. RenewAire outlines frost control approaches at supporthub.jswmi.com. Zehnder has a concise cold weather FAQ at zehnderamerica.com.
Cold climate owners sometimes worry that ERVs cannot handle deep winter. Modern ERVs with proper frost control operate well. They also help keep indoor air from becoming desert dry. In certain small and very tight homes, a winter HRV core may better manage moisture. Some multifamily Passive House projects even swap cores seasonally. Steven Winter Associates compares winter HRV and summer ERV strategies in multifamily at swinter.com.
Costs and what drives price
Installed cost spans a wide range because every home is different. Many contractor quotes fall in the two thousand five hundred to five thousand five hundred dollar range for a conventional HRV or ERV with moderate new ductwork. Examples include a Midwest contractor page at womackheatingandcooling.com and a Southeast contractor page at arrowhvacsc.com. Cost calculators sometimes cite eight hundred to twelve hundred dollars for install labor if ducts already exist or a lower add when paired with new HVAC. Treat those as low end. Inch Calculator provides context at inchcalculator.com.
On the other end, premium European systems with fully ducted layouts and high grade filtration can reach five figures in large homes. Market anecdotes often cluster between four thousand five hundred and six thousand one hundred dollars for mid range jobs, with top tier packages running fifteen to twenty thousand in single family homes. Treat forum posts as stories rather than quotes. The point is to set expectations about spread. A typical thread with user reports lives at reddit.com.
What moves price up or down in real projects:
- Whether new ducts must be added or existing ducts can be tapped without short circuiting
- One story versus two story routing with long vertical chases
- Target filtration such as MERV thirteen or HEPA cabinets
- Noise goals for bedrooms that push toward larger, slower fans
- ECM motors and smart controls with boost timers and humidity limits
- Commissioning, balancing, and post install airflow verification
A site visit gives the only reliable quote. We measure actual static pressure paths, check attic and crawlspace access, evaluate exterior termination locations, and confirm make up air paths in closed door scenarios.
Maintenance checklist
HRVs and ERVs last a long time with simple care. Set reminders for filter checks and a yearly core inspection. A little attention protects airflow, efficiency, and clean air delivery.
Use this quick list as a guide. Always follow your specific manual.
- Filters. Inspect every two to three months. Clean or replace every six to twelve months or sooner in dusty seasons. Many units accept MERV eight to MERV thirteen. Venmar offers a clear maintenance outline at venmar.ca.
- Core service. HRV cores can be washed gently with mild soap in warm weather so they dry completely before reassembly. ERV paper type enthalpy cores should not be washed. Vacuum dust off the surface only.
- Exterior hoods. Keep intake and exhaust at least ten feet apart. Clear leaves, lint, and nests seasonally. Verify screens are free of debris.
- Condensate. Check drains for clear flow in humid months or during defrost cycles.
- Balance. Recheck and adjust flows after any filter or core work. Consider a yearly professional balance and a tune up. Book HVAC preventative maintenance to keep ventilation performance on track.
What to look for in a model
Two units can look similar yet perform very differently once installed. Focus on ratings, fan energy, sound, and service. Your future self will thank you.
Use this buyer checklist when comparing options:
- HVI certified SRE and TRE at the airflow you plan to use. Also check ASRE or ATRE if you need modeling inputs. Then verify fan watts per cfm at that same point. The HVI directory is at hvi.org.
- Latent effectiveness for ERVs in humid climates. Better latent transfer reduces the moisture you bring in during sticky months.
- Noise rating in sones or decibels. Bedrooms demand quiet. A larger unit running slower can help.
- Filter options. Can the intake side take MERV thirteen without a large pressure drop. Is there room for a deeper filter to extend life.
- Frost strategy for cold regions. Check if the unit uses preheat, recirculation, or duty cycle defrost and whether your climate calls for one method or another.
- Service access. Filters should slide out without special tools. The core should be reachable without removing the entire unit.
When comparing literature, rely on SRE and TRE rather than older ASE numbers. As Fantech notes, high ASEF can hide high fan watt draw. Better to choose a unit with honest recovery numbers at low watts per cfm, especially for continuous operation.
FAQs
Do I need an ERV or an HRV in Austin TX
Most homes in Austin benefit from an ERV. The ERV reduces the extra moisture carried by your fresh air during long humid seasons. A peer reviewed study showed ERVs beat HRVs on total energy in hot humid cities. See the study at pmc.ncbi.nlm.nih.gov. Pair the ERV with good dehumidification if indoor humidity still rises above comfort targets. The Berkeley Lab primer also explains why the ERV helps by limiting moisture transfer, not by drying the house. See svach.lbl.gov.
Will an ERV control indoor humidity by itself
No. An ERV does not dehumidify a home. It simply reduces how much water vapor the ventilation air adds or removes. In hot humid regions, plan on an ERV plus sensible cooling that runs long enough to pull latent load, or a dedicated whole home dehumidifier when needed.
Can ERVs be used in cold climates
Yes. Modern ERVs operate in cold climates with proper frost control. They help prevent the house from feeling bone dry. Follow the manufacturer guidance for defrost. RenewAire and Zehnder offer good references at supporthub.jswmi.com and zehnderamerica.com.
Can I connect an ERV to my furnace return
Tread carefully. A simple dump of fresh air into the return can short circuit or cause condensation issues in humid climates. At least one side should be separately ducted. Proper controls must prevent unnecessary blower energy. The Building America Solution Center and Fine Homebuilding both warn about this path and show better options at basc.pnnl.gov and finehomebuilding.com.
How loud are HRVs and ERVs
Quieter models publish lower sone or dB values. Real world noise also comes from duct design. Short, smooth, well insulated ducts reduce blower noise. Bedrooms call for low fan speed or remote units. This is one reason fully ducted systems often cost more yet deliver a better daily experience.
What is better for small tight apartments in winter
It depends on occupant density and moisture sources. A small tight apartment with frequent showers and cooking may push winter humidity too high. An HRV can help dry the space. Some designers swap an HRV core for winter and use an ERV core for summer in larger projects. Steven Winter Associates discusses this seasonal approach for multifamily Passive House at swinter.com. For tight retrofits where ducting is tough, a spot ERV can meet code rates without major work.
Safety and installation notes
Keep outdoor intake and exhaust terminations separated to avoid cross contamination. Ten feet is a common minimum in manufacturer manuals. Do not pull air from garages, attics, or crawlspaces. Seal and insulate ducts per ACCA Manual D and the unit manual. The Building America Solution Center offers practical installation tips at basc.pnnl.gov.
A quick way to move forward
Start with a short assessment. We measure your current airflows, check rooms that need supply or exhaust, look at filter goals for allergies, verify access for a serviceable installation, and match a model to the airflow you need. Balanced ventilation supplies filtered outdoor air while exhausting stale air, which reduces pollutants compared with exhaust only approaches. Berkeley Lab makes that case clearly in their primer at svach.lbl.gov.
If you live in a hot humid climate like Central Texas, an ERV is often the smarter choice for comfort and energy. If your project is a cold climate new build, an ERV with frost control often keeps winter comfort steadier. Tight homes need fresh air by design after envelope work, so coordinating sealing air leaks with a fresh air plan pays off. Schedule a ventilation assessment or ask about pairing ERV with whole home dehumidification. If your system is already in place, book HVAC preventative maintenance so filters, cores, and flows stay in top shape.