Tightened performance requirements have been enforced through Ecodesign Directive 1253/2014/EG, applicable to all residential and non-residential ventilation units. This legislation pushes building industry specialists (design engineers, consultants & manufacturers) to adapt solutions that favour lower air velocity, lower specific fan power, lower overall energy consumption and improved heat recovery efficiency.


All ventilation units shall be equipped with a multispeed drive (3 or more fixed speed steps), a variable speed drive (frequency inverter) or electronically commutated motor (EC).

The minimal thermal efficiency of a heat recovery system shall be 67% for Tier 1 (2016) and 73% for Tier 2 (2018) which will encourage the use of counter flow and rotary heat exchangers.

The maximum Tier 1 and Tier 2 internal specific fan power requirements will encourage the use of lower face velocities and hence lower pressure drops.

All bidirectional ventilation units to have heat recovery.

The minimum Tier 1 and Tier 2 fan efficiencies will encourage the use of direct driven backward curved centrifugal fans.

All heat recovery systems to include thermal bypass facility.

An increase in investment cost and sufficient floor space can therefore be anticipated at building design stage. The following comparison table clarifies this idea by showing percentage values of size increase across several stages/categories of designing a heat recovery, air handling unit.

ErP Directive Tier 1 (2016) Tier 2 (2018)
Unit cross-section
W x H (mm); 2015 design: 1535mm x 1320mm
1835mm x 1420mm 1835mm x 1860mm
Unit cross-section
Increase of unit cross-section compared to 2015 design (%)
29% 68%
Investment costs
Increase of PHE size (length) compared to 2015 design (%)
28% 57%
Investment costs
Increase in overall unit cost in comparison to 2015 design (%)
15% 33%
Energy consumption
Reduction in fan absorbed power compared to 2015 design (%)
21% 37%


BS EN 13053
Ventilation for buildings. AHUs. Rating and performance for units, components and sections.

BS EN 1886
Ventilation for buildings. AHUs. Mechanical performance (stipulates the casing air tightness).

BS EN 13779
Ventilation for non-residential buildings.

EN 308
Heat exchangers. Test procedures for establishing performance of air to air and flue gas heat recovery devices. (At reference conditions of +5˚C outside, +25˚C inside and dry conditions).

EN ISO 16890
Air filters for general ventilation.

EN 16798-3
Energy performance of buildings; ventilation for buildings.