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Use an ERV (energy recovery ventilator) in commercial buildings and an HRV (heat recovery ventilator) in residential ones — an ERV transfers both sensible and latent heat (temperature and moisture) between exhaust and supply air, while an HRV transfers only sensible heat (temperature). If your project has any cooling load in a warm or humid climate, an HRV will leave you with latent load that the air-conditioning system still has to remove, so the ERV is the correct choice.

ERV vs HRV: side-by-side comparison

ERV vs HRV comparison for commercial and residential applications

Why the difference matters in a commercial building

The distinction between ERV and HRV is not a naming convention — it changes what the equipment can actually do for your building. Both devices sit in the ventilation path and take heat from the exhaust air and transfer it to the incoming outdoor air. The difference is which heat they transfer.

An HRV transfers sensible heat only: the temperature of the incoming air is raised or lowered toward indoor temperature, but its moisture content is unchanged. That is exactly right for a home in a cool climate, where the heating load is the dominant energy cost and the air is not very humid to begin with. The unit is simple, cheap and has almost nothing to fail beyond the filters.

An ERV also transfers latent heat — the moisture in the exhaust air. This matters enormously in a commercial building for one reason: air conditioning load is driven by both temperature and moisture, and in most commercial climates moisture is the more expensive half to remove. Bringing in outdoor air at 28°C and 80% RH and cooling it to 20°C and 50% RH means condensing a large quantity of water out of the supply air. Every kilogram of that water is latent load on the chiller.

ROTER's own documented case illustrates this with numbers. In a 200 m² room in Beijing, a total heat recovery system pre-conditioned the incoming air to about 28°C when the outdoor temperature was 33°C — compared with roughly 7°C for plain ventilation, which would have required far more downstream cooling. The measured result was approximately 1,112 kWh saved in winter and about 1,427 kWh in summer, an annual saving of roughly 42.3% at ¥0.48/kWh.

ERV or HRV: a short decision path

Is the project residential? If yes, and the climate is cool and dry, an HRV is the appropriate and more economical choice. ROTER's single-flow fresh air systems cover this segment at 200–1,000 m³/h.

Is there a significant cooling load? If yes, in any climate that is warm or humid, choose an ERV. The latent recovery is what makes the difference.

Does the air need to be kept dry? If the process or building requires low humidity — pharmaceutical production, battery dry rooms, food processing, electronics — an ERV is necessary, and for very low dew points it should be paired with a rotary desiccant dehumidifier.

Which recuperator type? Plate exchangers (cross-flow, counter-flow and cross counter-flow) give zero cross-contamination and no moving parts. Rotary exchangers (ROT-HRW wheel) handle larger pressure differences and can be specified with high-temperature rotors for industrial exhausts up to 300°C.

Plate, rotary or heat pipe: choosing the ERV core

Once an ERV is confirmed, the core type is the next decision. All three recover heat without mixing the two air streams, but they differ in pressure handling, footprint and cost.

Plate vs rotary vs heat pipe heat exchanger

Frequently asked questions

What is the difference between an ERV and an HRV?

An ERV (energy recovery ventilator) recovers both sensible heat (temperature) and latent heat (moisture) from exhaust air. An HRV (heat recovery ventilator) recovers sensible heat only. In practice an ERV is used for commercial buildings with air-conditioning loads, and an HRV for residential buildings in cooler climates where heating is the dominant load and dehumidification is not required.

Is an ERV more efficient than an HRV?

Not directly comparable — they are measured on different heat transfer. An ERV is usually quoted on total heat recovery efficiency (typically 68–76% across ROTER's CXH series) and an HRV on sensible heat efficiency (typically 70–85%). The meaningful comparison is operating cost: in a commercial building with a cooling load, an ERV typically pays back in 1–3 years because it removes latent load as well as sensible load, which an HRV does not.

Can an ERV be used in a residential house?

Technically yes, but it would be over-specified and more expensive to run than needed. A residential installation in a cool climate is usually better served by an HRV with a plate core, which is simpler and has no rotor to maintain. ROTER's single-flow fresh air systems (RS-20-A02 to RS-100-A02, 200–1,000 m³/h) are built for that scale.

Does a plate heat exchanger allow cross-contamination between the air streams?

No. The supply and exhaust air streams are completely separated by the plates, which prevents cross-contamination and keeps the incoming fresh air clean. In the total heat exchange core, the paper is made of specialty fibres with gaps so small that only small-diameter water vapour molecules can pass through — larger harmful gases and odour molecules cannot. The sensible heat exchange core uses hydrophilic aluminium foil of 0.1–0.2 mm thickness, with epoxy-coated foil available for corrosion resistance.

What fresh air volume does a commercial ERV need?

The fresh air volume should be the larger of the minimum per-person rate and the air-change requirement. Reference figures from the ROTER product manual: general office 30 m³/h per person; high-grade office 30–50 m³/h per person; shopping mall 15–25 m³/h per person. For air-change rate: general rooms 1–2 ACH; computer rooms 2–4 ACH; smoking-intensive meeting rooms 3–8 ACH. Large shopping malls can alternatively set fresh air volume at 30% of the central air-conditioning total supply air volume.

How much energy can a total heat recovery ERV save?

In a documented 200 m² room in Beijing, ROTER measured approximately 1,112 kWh saved in winter and about 1,427 kWh in summer — an annual saving of roughly 42.3%, calculated at ¥0.48/kWh. The key figure is that supply air arrived at about 28°C when outdoor temperature was 33°C, versus about 7°C with plain ventilation, which would have required substantially more downstream cooling.

Which ERV is right for a hospital or data centre?

For hospitals and data centres the requirement is normally a combination of temperature control, low humidity and strict cross-contamination control, which points to a plate total heat exchanger combined with dedicated dehumidification where the dew point must be held low. For data centres, the combined rotary AHU and commercial air conditioning unit series are the relevant ranges. For project references with real quantities and configurations, see ROTER project case studies.

How do I get a quotation for an ERV?

Send the room volume, occupancy, design outdoor conditions and the supply air set point. ROTER sizes the unit and returns a specification with the recovery efficiency calculated at your actual conditions within 24 hours. Full specification tables and published performance data are on the site, and you can submit an inquiry directly.