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HRV/ERV Efficiency Calculator

Sensible effectiveness and recovered kW of a heat-recovery ventilator from three temperatures.

0
Sensible effectiveness (%)
0
Heat recovered (kW)

An HRV makes ventilation ~75% 'free'. ERVs also swap moisture โ€” better for humid summers and dry winters alike. Imbalanced flows fake high effectiveness; measure both streams.

Formula

ฮต = (T_supply โˆ’ T_out)/(T_in โˆ’ T_out)
References: CSA C439 / Passive House component criteria

HRV/ERV Efficiency Calculator is a free hrv efficiency for HVAC designers, technicians and energy auditors โ€” instant, accurate and 100% client-side, with the governing formula and reference shown next to the result so the number can be defended, not just quoted.

About HRV/ERV Efficiency Calculator

Sensible effectiveness and recovered kW of a heat-recovery ventilator from three temperatures. The calculation implements ฮต = (T_supply โˆ’ T_out)/(T_in โˆ’ T_out) (CSA C439 / Passive House component criteria). An HRV makes ventilation ~75% 'free'. ERVs also swap moisture โ€” better for humid summers and dry winters alike. Imbalanced flows fake high effectiveness; measure both streams.

How to use HRV/ERV Efficiency Calculator

  1. 1Enter Outdoor air in in ยฐC.
  2. 2Enter Supply air to rooms (after core) in ยฐC.
  3. 3Enter Indoor (extract) air in ยฐC.
  4. 4Enter Ventilation airflow in L/s.
  5. 5Read Sensible effectiveness, Heat recovered instantly โ€” no submit button needed.
  6. 6Need US units? Flip the SI/Imperial toggle and every field converts.

Why use HRV/ERV Efficiency Calculator?

  • โœ“Implements the standard formula โ€” ฮต = (T_supply โˆ’ T_out)/(T_in โˆ’ T_out)
  • โœ“Reference cited on-page: CSA C439 / Passive House component criteria
  • โœ“One-click SI โ‡„ Imperial toggle โ€” values convert in place, physics stays in SI
  • โœ“Live worked example: the substitution recomputes from your numbers
  • โœ“Built-in engineering verdict flags out-of-range results instantly
  • โœ“Runs entirely in your browser โ€” nothing uploaded, free forever

Frequently asked questions

What formula does the HRV/ERV Efficiency Calculator use?+

It computes ฮต = (T_supply โˆ’ T_out)/(T_in โˆ’ T_out), per CSA C439 / Passive House component criteria. The formula is displayed under the result along with a worked example substituted with your own inputs.

What should I keep in mind when using this calculator?+

An HRV makes ventilation ~75% 'free'. ERVs also swap moisture โ€” better for humid summers and dry winters alike. Imbalanced flows fake high effectiveness; measure both streams.

Is this based on ASHRAE methods?+

The calculations follow the standard ASHRAE/ISHRAE formulations cited under the result, simplified where industry practice does the same. For permit-grade design, confirm with the full code procedure.

Is the HRV/ERV Efficiency Calculator free to use?+

Yes โ€” completely free, no sign-up, no limits. It runs client-side in your browser, so inputs stay private and results are instant even on slow connections.

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