Measurements and calculations for NRVUs
ANNEX IXSupplementary provisions
ANNEX IX Measurements and calculations for NRVUs NRVUs shall be tested and calculated using a ‘reference configuration’ of the product. Dual use units shall be tested and calculated in the ventilation mode. 1. THERMAL EFFICIENCY OF A NON-RESIDENTIAL HEAT RECOVERY SYSTEM The thermal efficiency of a non-residential heat recovery system is defined as where: — η t is the thermal efficiency of the HRS [-]; — t 2 ″ is temperature of the supply air leaving the HRS and entering the room [°C]; — t 2 ′ is temperature of the outside air [°C]; — t 1 ′ is temperature of the exhaust air, leaving the room and entering the HRS [°C]. 2. FILTER CORRECTIONS In case one or both filters are missing in comparison to reference configuration, the following filter correction shall be used: From 1 January 2016: F = 0 in case the reference configuration is complete; F = 160 if the medium filter is missing; F = 200 if the fine filter is missing; F = 360 if both the medium and the fine filters are missing. From 1 January 2018 F = 150 if the medium filter is missing; F = 190 if the fine filter is missing; F = 340 if both the medium and the fine filters are missing. ‘fine filter’ means a filter that meets the conditions for filter efficiency in the following test and calculation methods, to be declared by the filter supplier. Fine filters are tested at air flow of 0,944 m 3 /s and filter face 592 × 592 mm (installation frame 610 × 610 mm) (face velocity 2,7 m/s). After proper preparation, calibration and checking the airstream for uniformity, initial filter efficiency and pressure drop of the clean filter are measured. The filter is progressively loaded with appropriate dust up to a final filter pressure drop of 450 Pa. At first 30 g is loaded in the dust generator subsequently there must be at least 4 equidistant dust loading steps before reaching the final pressure. The dust is fed to the filter at a concentration of 70 mg/m 3 . Filter efficiency is measured with droplets in the size range 0,2 to 3 μm of a test aerosol (DEHS DiEthylHexylSebacate) at a rate of about 0,39 dm 3 /s (1,4 m 3 /h), Particles are counted 13 times, successively upstream and downstream of the filter at minimum 20 seconds with an optical particle counter (OPC). Incremental filter efficiency and pressure drop values are established. Average filter efficiency over the test for the various particle size classes is calculated. To qualify as a ‘fine filter’ the average efficiency for particle size 0,4 μm should be more than 80 % and the minimum efficiency should be more than 35 %. The minimum efficiency is the lowest efficiency among the discharged efficiency, initial efficiency and the lowest efficiency throughout the loading procedure of the test. The discharge efficiency test is largely identical to the average efficiency test above, except that the flat sheet of filter media sample is electrostatically discharged with isopropanol (IPA) before testing. ‘medium filter’ means a filter that meets the following conditions for filter efficiency: A ‘medium filter’ is an air filter for a ventilation unit with performance tested and calculated as for the fine filter, but meeting the conditions that the average efficiency for particle size 0,4 μm should be more than 40 %, to be declared by the filter supplier.