EN 308 is the European standard that specifies test methods for the determination of heat transfer in heat exchangers, including the air-to-air recovery devices used in HVAC. It is the foundation that lets you trust a manufacturer's effectiveness number.
What it covers
EN 308 describes the laboratory set-up, instrumentation accuracy, and calculation procedure for measuring both sensible and - where applicable - latent (moisture) transfer between the two airstreams under controlled, repeatable inlet conditions.
The core metric: effectiveness
| Term | Meaning |
|---|---|
| Sensible effectiveness | Actual sensible heat transferred / maximum possible |
| Latent effectiveness | Actual moisture transferred / maximum possible |
| Temperature change ratio | Supply temp change / (exhaust - outdoor temp) |
How to read a test report
Always check the inlet temperature and humidity, the airflow rates, and whether the figure is sensible or total. A wheel quoted for total effectiveness is not comparable to a plate quoted for sensible only - EN 308 lets you normalise this.
Common pitfall
Comparing a certified EN 308 value at one airflow against a brochure value at a different airflow. Effectiveness varies with face velocity, so match the duty conditions.
Why it matters to you
Specifying against EN 308-tested values protects you from overstated performance and supports compliance with building energy rules. Pair it with the EN 13053 AHU rating for a complete specification.