“Effectiveness” is the number every code and rating system quotes, but the value only means something if the test method is stated. This article maps the main heat recovery effectiveness test standards and how they define the metric.
Definitions
- Sensible effectiveness ηs = (Tsupply − Toutdoor) / (Textract − Toutdoor).
- Enthalpy (total) effectiveness ηt = (hsupply − houtdoor) / (hextract − houtdoor), using moist-air enthalpy.
- Latent effectiveness uses humidity ratio in place of enthalpy.
The Standards
| Standard | Scope |
|---|---|
| EN 308 | Test procedures for air-to-air and flue-gas heat recovery devices (sensible and latent). |
| EN 13053 | Rating and performance of air-handling units, including heat recovery sections and pressure drop. |
| EN 13141-7 | Performance testing of residential mechanical supply/exhaust ventilation units. |
| AHRI 1060 / 1061 | Energy recovery ventilators — the method ASHRAE 90.1 references for its 50% minimum. |
Why the Method Matters
- Test conditions differ: Ecodesign measures ηt at −10 °C, 0 °C, and +10 °C outdoor; ASHRAE uses design heating and cooling conditions.
- A wheel rated 75% by AHRI 1060 may read differently under EN 308 because of how leakage and frost are handled.
- Pressure drop is part of the story — a more effective core that needs a bigger fan can erase the saving, which is why Ecodesign SFP limits bind efficiency and fan power together.
Picking a Device Against the Numbers
Use the measured ηt from the relevant standard when checking code floors. For non-rotating critical ventilation, compare a membrane core against a wheel on the same test basis, and fold the pressure drop into the AHU selection calculation.
Frequently Asked Questions
What is sensible effectiveness?
The ratio of temperature change delivered to the supply air versus the temperature difference between extract and outdoor air.
What is enthalpy effectiveness?
The same ratio using moist-air enthalpy, capturing both temperature and humidity recovery.
Which standards govern recovery testing?
EN 308, EN 13053, and EN 13141-7 in Europe, and AHRI 1060 and 1061 referenced by ASHRAE 90.1.
Why does the test method matter?
Different standards use different conditions and treat leakage and frost differently, so the same device can read differently, and pressure drop must also be considered.
Frequently Asked Questions
What is sensible effectiveness?
The ratio of temperature change delivered to the supply air versus the temperature difference between extract and outdoor air.
What is enthalpy effectiveness?
The same ratio using moist-air enthalpy, capturing both temperature and humidity recovery.
Which standards govern recovery testing?
EN 308, EN 13053, and EN 13141-7 in Europe, and AHRI 1060 and 1061 referenced by ASHRAE 90.1.
Why does the test method matter?
Different standards use different conditions and treat leakage and frost differently, so the same device can read differently, and pressure drop must also be considered.
Specify the right heat exchanger
Our engineers size the core to your airflow, temperature and pressure-drop budget, and select plate, rotary or heat-pipe recovery by application. Read the heat exchanger guide or contact us for a specification.
Related products
Plate, wheel or pipe recovery for HVAC and ventilation.
Stationary, high-surface-area cores for air and liquid.
High-effectiveness energy recovery for large airflows.
Passive, fully separated streams for clean applications.