The European test standard EN 13141 provides specifications for testing the tightness, ventilation technology, energy efficiency and acoustic properties of domestic ventilation units, including various classifications. Based on this, the German Institute for Building Technology (DIBt) has published an updated test specification, LÜ-A 21.
Which key figures are determined according to EN 13141 / DIBt LÜ-A 21?
Device tightness
In EN 13141 and LÜ-A 21, devices are classified according to their external and internal tightness. According to LÜ-A 21, leakage is calculated as a percentage of the maximum volume flow of the appliance. For tests in accordance with EN 13141, the reference volume flow of the appliance is used as the basis.
Tightness classes
For recuperative heat exchangers, which are tested using the pressure test method, there are the tightness classes A1-A3. LÜ-A 21 restricts this classification to A1 and A2. Regenerative heat exchangers are tested using the tracer gas method. Classes B1-B3, which are only defined in EN 13141, apply to tracer gas measurements in the chamber. For regenerative heat exchangers, there are classes C1-C3 for measurements in the air duct in combination with pressure tests for external leakage. Devices whose leakage exceeds the specified limit values are not classified.
Air volume flows and heat recovery
Based on the operating range of the ventilation unit in m³/h, three test points are determined for carrying out the unit tests.
Checkpoints
EN 13141 defines three air volume flows as test points for the thermodynamic measurement of domestic ventilation units:
qvd = maximum air volume flow of the device defined by the manufacturer
qvn = nominal air volume flow, calculated using the formula: qvn = 0.7 * qvd
qvmin = minimum air volume flow rate of the device search defined by the manufacturer
While the air volume flow in LÜ-A 21 is specified inm3/h, EN 13141 uses l/s as the unit.
The conversion formula is: 1m3/h= 3.6 l/s
EN 13141 specifies three measuring points for testing domestic ventilation units with heat exchangers. Only the dry measuring point is mandatory. Measuring point 2 with condensation is only mandatory for devices with regenerative heat exchangers in order to be able to measure the moisture recovery of the device. Extreme condensation conditions are optionally indicated by measuring point 3. Notwithstanding this, measuring points 1 and 2 are mandatory for every test in accordance with LÜ-A 21.
Temperature ratio ηΘ,su, ηΘ,ex
The supply air-side temperature ratio η Θ,su must be specified for each measured point in accordance with EN 13141, and the exhaust air-side temperature ratio η Θ,ex is also optional. LÜ-A 21 of the DIBt only considers the supply air-side temperature ratio. To determine the ηWRG, the measured values of the supply air-side temperature ratio η Θ,su are averaged at the test point qvn. Values that have already been corrected by the DIBt in the general technical approval are provided with a corresponding footnote.
Humidity ratio ηx, su, ηx, ex
The humidity ratio is shown separately in EN 13141 and LÜ-A 21 to enable an assessment of the humidity recovery of residential ventilation units. This value is important for enthalpic and regenerative heat exchangers. The supply air humidity ratio ηx , su indicates the percentage of water content that is recovered from the extract air for the supply air. EN 13141 also specifies the humidity ratio ηx , ex on the exhaust air side.
Specific electrical power consumption W/(m3/h)
The specific electrical power consumption is measured during the thermodynamic measurement at the reference point qvn is determined.
Acoustic properties
According to EN 13141, a performance test of the acoustic properties of the domestic ventilation unit must be carried out. The A-weighted sound power level of the housing LWA and each air duct (outside, supply, extract and exhaust air) is shown in dB(A) in the device list in the TZWL e-bulletin.