British Standards Document
BS EN 13141-8
Ventilation for buildings. Performance testing of components/products for residential ventilation. Performance testing of non-ducted mechanical supply and exhaust ventilation units (including heat recovery)

https://doi.org/10.3403/30376483U

BS EN 13141-8 is maintained by RHE/2. The current release of this standard is:

BS EN 13141-8:2022 Ventilation for buildings. Performance testing of components/products for residential ventilation. Performance testing of non-ducted mechanical supply and exhaust ventilation units (including heat recovery)

https://doi.org/10.3403/30376483 (published 31/10/2022)

This standard is available from the following sources:

Other historical versions of this standard document also exist:

BS EN 13141-8:2014 [current until 10/10/2022]
BS EN 13141-8:2006 [current until 31/07/2014]