BS EN 13141-8:2014 BSI Standards Publication Ventilation for buildings — Performance testing of components/products for residential ventilation Part 8: Performance testing of unducted mechanical supply and exhaust ventilation units (including heat recovery) for mechanical ventilation systems intended for a single room BS EN 13141-8:2014 BRITISH STANDARD National foreword This British Standard is the UK implementation of EN 13141-8:2014 It supersedes BS EN 13141-8:2006 which is withdrawn The UK participation in its preparation was entrusted to Technical Committee RHE/2, Ventilation for buildings, heating and hot water services A list of organizations represented on this committee can be obtained on request to its secretary This publication does not purport to include all the necessary provisions of a contract Users are responsible for its correct application © The British Standards Institution 2014 Published by BSI Standards Limited 2014 ISBN 978 580 76416 ICS 91.140.30 Compliance with a British Standard cannot confer immunity from legal obligations This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 July 2014 Amendments issued since publication Date Text affected BS EN 13141-8:2014 EN 13141-8 EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM June 2014 ICS 91.140.30 Supersedes EN 13141-8:2006 English Version Ventilation for buildings - Performance testing of components/products for residential ventilation - Part 8: Performance testing of un-ducted mechanical supply and exhaust ventilation units (including heat recovery) for mechanical ventilation systems intended for a single room Ventilation des bâtiments - Essais de performance des composants/produits pour la ventilation des logements Partie : Essais de performance des unités de soufflage et d'extraction (y compris la récupération de chaleur) pour les systèmes de ventilation mécaniques non raccordés prévus pour une pièce Lüftung von Gebäuden - Leistungsprüfung von Bauteilen/Produkten für die Lüftung von Wohnungen - Teil 8: Leistungsprüfung von mechanischen Zuluft- und Ablufteinheiten ohne Luftführung (einschließlich Wärmerückgewinnung) für ventilatorgestützte Lüftungsanlagen von einzelnen Räumen This European Standard was approved by CEN on February 2014 CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member This European Standard exists in three official versions (English, French, German) A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom EUROPEAN COMMITTEE FOR STANDARDIZATION COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels © 2014 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members Ref No EN 13141-8:2014 E BS EN 13141-8:2014 EN 13141-8:2014 (E) Contents Page Foreword Introduction Scope Normative references 3.1 3.2 Terms, definitions and classification Terms and definitions Classification 10 Symbols and abbreviations 10 5.1 5.2 5.2.1 5.2.2 5.2.3 5.2.4 5.2.5 5.3 5.3.1 5.3.2 5.3.3 5.4 5.4.1 5.4.2 5.4.3 5.4.4 5.4.5 5.4.6 5.4.7 5.5 Test methods 12 General 12 Performance testing of aerodynamic characteristics 12 General 12 Internal leakages and mixing 12 Air flow 16 In/out airtightness 17 Filter bypass 17 Specific performance testing of aerodynamic characteristics for alternating ventilation unit including a storage type heat exchangers 17 Reference air flow 17 Leakages 19 In/out airtightness 20 Performance testing of thermal characteristics 20 Temperature and humidity ratios on supply air side (mandatory measurement) 20 Temperature and humidity ratios on exhaust air side (optional measurement) 20 Test requirements 20 Test operating conditions 21 Temperature conditions 21 Test procedure 22 Test model for testing alternating ventilation units 23 Effective power input 25 6.1 6.2 6.3 Classification 25 Leakage classification 25 Airflow sensitivity classification 25 Indoor/outdoor airtightness of the complete unit 26 Requirements 26 8.1 8.2 Calculations 27 General calculations 27 Special calculations for alternating heat exchangers 28 9.1 9.2 9.2.1 9.2.2 9.2.3 9.2.4 9.3 Performance testing of acoustic characteristics 29 General 29 Radiative sound power in the indoor or outdoor space 29 General 29 Reverberant room method 29 Anechoic or semi-anechoic room method 30 Free field method 30 Airborne sound insulation 31 10 10.1 Test results 31 Test report 31 BS EN 13141-8:2014 EN 13141-8:2014 (E) 10.2 10.3 10.4 10.5 10.6 10.7 10.8 Product specifications 32 Additional information related to the performance of the product 32 Leakages 32 Air flow 33 Effective power input 33 Temperature and humidity ratios 33 Acoustic characteristics 34 11 Cleaning and maintenance 35 Annex A (informative) Test layouts 36 Annex B (normative) Pressure leakage test method 38 B.1 External leakage test 38 B.2 Internal leakage test 38 Annex C (normative) Indoor mixing 40 C.1 General 40 C.2 Determination of indoor mixing - First test 40 C.3 Determination of indoor mixing - Second test 40 C.4 Indoor mixing calculation 40 Bibliography 41 BS EN 13141-8:2014 EN 13141-8:2014 (E) Foreword This document (EN 13141-8:2014) has been prepared by Technical Committee CEN/TC 156 “Ventilation for buildings”, the secretariat of which is held by BSI This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by September 2014, and conflicting national standards shall be withdrawn at the latest by September 2014 Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights This document supersedes EN 13141-8:2006 In comparison to EN 13141-8:2006 the following changes have been made: — alternating ventilation units including a storage type heat exchangers have been included; — measurement of the deviation of air flow rate due to faỗade pressures in normal use has been introduced; — temperature conditions have been modified to be the same as in EN 13141-7 that is to say °C / 20 °C EN 13141 consists of the following parts, under the general title Ventilation for buildings ― Performance testing of components/products for residential ventilation: — Part 1: Externally and internally mounted air transfer devices; — Part 2: Exhaust and supply air terminal devices; — Part 3: Range hoods for residential use; — Part 4: Fans used in residential ventilation systems; — Part 5: Cowls and roof outlet terminal devices; — Part 6: Exhaust ventilation system packages used in a single dwelling; — Part 7: Performance testing of a mechanical supply and exhaust ventilation units (including heat recovery) for mechanical ventilation systems intended for single family dwellings; — Part 8: Performance testing of un-ducted mechanical supply and exhaust ventilation units (including heat recovery) for mechanical ventilation systems intended for a single room; — Part 9: Externally mounted humidity controlled air transfer device; — Part 10: Humidity controlled extract air terminal device — Part 11: Positive pressure ventilation systems According to the CEN-CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom BS EN 13141-8:2014 EN 13141-8:2014 (E) Introduction This European Standard specifies methods for the performance testing of components used in residential ventilation systems to establish the performance characteristics as identified in EN 13142 [1] This European Standard incorporates many references to other European and International Standards, especially on characteristics other than the aerodynamic characteristics, for instance on acoustic characteristics In most cases some additional tests or some additional conditions are given for the specific use in residential ventilation systems This European Standard can be used for the following applications: — laboratory testing; — attestation purposes The position of this European Standard in the field of standards for the mechanical building services is shown in Figure BS EN 13141-8:2014 EN 13141-8:2014 (E) Figure — Position of EN 13141-8 in the field of the mechanical building services BS EN 13141-8:2014 EN 13141-8:2014 (E) Scope This European Standard specifies the laboratory test methods and test requirements for the testing of aerodynamic, thermal and acoustic performance, and the electrical power of an un-ducted mechanical supply and exhaust ventilation unit used in a single room The purpose of this European Standard is not to consider the quality of ventilation but to test the performance of the equipment In general, a ventilation unit contains: — supply and exhaust air fans; — air filters; — air to air heat exchanger or air storage mass for exhaust air heat and humidity recovery; — control system; — inlet and outlet grilles Such equipment can be provided in more than one assembly, the separate assemblies of which are designed to be used together Such equipment can contain alternating heat exchangers which provide separate supply and exhaust air flows In certain cases, i.e alternating ventilation unit, the manufacturer may recommend that the equipment can be installed in such a way that it serves more than one room For the purpose of this European Standard, these products are assessed in a single room This European Standard does not deal with ducted units or units with heat pumps Safety requirements are given in EN 60335-2-80:2003 [2] Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application For dated references, only the edition cited applies For undated references, the latest edition of the referenced document (including any amendments) applies EN 306, Heat exchangers - Methods of measuring the parameters necessary for establishing the performance EN 779, Particulate air filters for general ventilation - Determination of the filtration performance EN 12792:2003, Ventilation for buildings - Symbols, terminology and graphical symbols EN 13141-4, Ventilation for buildings - Performance testing of components/products for residential ventilation - Part 4: Fans used in residential ventilation systems EN ISO 717-1, Acoustics - Rating of sound insulation in buildings and of building elements - Part 1: Airborne sound insulation (ISO 717-1) EN ISO 3741, Acoustics - Determination of sound power levels and sound energy levels of noise sources using sound pressure - Precision methods for reverberation test rooms (ISO 3741) EN ISO 3743-1, Acoustics - Determination of sound power levels and sound energy levels of noise sources using sound pressure - Engineering methods for small movable sources in reverberant fields - Part 1: Comparison method for a hard-walled test room (ISO 3743-1) BS EN 13141-8:2014 EN 13141-8:2014 (E) EN ISO 3743-2, Acoustics - Determination of sound power levels of noise sources using sound pressure Engineering methods for small, movable sources in reverberant fields - Part 2: Methods for special reverberation test rooms (ISO 3743-2) EN ISO 3744, Acoustics - Determination of sound power levels and sound energy levels of noise sources using sound pressure - Engineering methods for an essentially free field over a reflecting plane (ISO 3744) EN ISO 3745, Acoustics - Determination of sound power levels and sound energy levels of noise sources using sound pressure - Precision methods for anechoic rooms and hemi-anechoic rooms (ISO 3745) EN ISO 9614-1, Acoustics - Determination of sound power levels of noise sources using sound intensity - Part 1: Measurement at discrete points (ISO 9614-1) EN ISO 9614-2, Acoustics - Determination of sound power levels of noise sources using sound intensity - Part 2: Measurement by scanning (ISO 9614-2) EN ISO 10140-1:2010, Acoustics - Laboratory measurement of sound insulation of building elements - Part 1: Application rules for specific products (ISO 10140-1:2010) EN ISO 10140-2, Acoustics - Laboratory measurement of sound insulation of building elements - Part 2: Measurement of airborne sound insulation (ISO 10140-2) EN ISO 10140-5, Acoustics - Laboratory measurement of sound insulation of building elements - Part 5: Requirements for test facilities and equipment (ISO 10140-5) Terms, definitions and classification For the purpose of this document, the terms and definitions given in EN 12792:2003 and the following apply 3.1 Terms and definitions 3.1.1 external leakage leakage to or from the air flowing inside the casing of the unit to or from the air external to the equipment under test 3.1.2 internal leakage leakage inside the unit between the exhaust and the supply air flows 3.1.3 filter bypass leakage air bypass around filter cells 3.1.4 indoor/outdoor airtightness maximum of air flow at – 20 Pa and + 20 Pa corresponding to the setting when the fans are off 3.1.5 outdoor mixing mixing of the two airflows external to the equipment under test between discharge and intake ports at outdoor terminal points caused by short circuiting 3.1.6 indoor mixing mixing of the two airflows under test between discharge and intake ports at indoor terminal points caused by short circuiting BS EN 13141-8:2014 EN 13141-8:2014 (E) Key reverberant room unit under test Figure — Reverberant room method: test rooms – Cross section 9.2.3 Anechoic or semi-anechoic room method The unit shall be fitted in a sound insulating and absorbing box in order to eliminate the influence of the side (inner or outer) which is not being measured Particular attention should be paid to seal the gaps between the unit under test and the box An example of a test installation for anechoic and semi-anechoic room method is given in Figure a) semi anechoic room method b) anechoic room method Key semi-anechoic room unit under test sound absorbing and insulating box anechoic room unit under test sound absorbing and insulating box Figure — Set-up for anechoic and semi-anechoic room method: cross section 9.2.4 Free field method NOTE The sound power radiated can be extremely low and the conditions for free field conditions can be hardly fulfilled (the measured values can be very close to background noise) The unit shall be mounted over a reflecting plane in a flat outdoor area or in a large room and shall be fitted in a sound insulating and absorbing box in order to eliminate the influence of the side (inner or outer) which is not being measured Particular attention should be paid to seal the gaps between the unit under test and the box An example of a test installation for free field over a reflecting plane is given in Figure 30 BS EN 13141-8:2014 EN 13141-8:2014 (E) Key reflecting plane unit under test sound absorbing and insulating box Figure — Setup for measurement in free field over a reflecting plane: cross section 9.3 Airborne sound insulation Acoustic measurement shall be carried out according to engineering methods described in EN ISO 10140-1:2010, EN ISO 10140-2 and EN ISO 10140-5 The unit shall be installed according to the manufacturer's instructions; if optional components (e.g silencers, extra connection ducts) are included in the test, they shall be mentioned and described in the test report The unit shall be mounted at least at m distance from any intersection of walls or corner of the room, unless it is intended specifically for mounting at surface intersection or in a corner If this is the case, this should be specified by the manufacturer and mentioned and described in the test report Particular attention should be paid to seal the gaps between the unit under test and the test room wall Airflow control devices used by laboratories shall not interfere with acoustic measurements The fans shall be switched off but the dampers, if present, shall be open like in the normal conditions of working of the unit An example of a test installation is given in Figure 10 Key transmitting room unit under test receiving room Figure 10 — Double room set-up: cross section of test rooms 10 Test results 10.1 Test report The test report shall include at least the following information: a) name and address of testing laboratory and location where the test is carried out when different from the address of the testing laboratory; 31 BS EN 13141-8:2014 EN 13141-8:2014 (E) b) unique identification of report (such as serial number) and of each page, and total number of pages of the report; c) name and address of the client; d) description and identification of the test item; e) date of receipt of test item and date(s) of performance of test; f) identification of the test specification or description of the procedure; g) description of the sampling procedure, where relevant; h) any deviations, additions to or exclusions from the test specification, and any other information relevant to a specific test; i) identification of any non-standard test method or procedure utilized; j) measurements, examinations and derived results, supported by tables, graphs, sketches and photographs as appropriate, and any failures identified (see 5.2 to 5.5); k) a statement on measurement uncertainty (where relevant); l) a signature and title or an equivalent marking of person(s) accepting technical responsibility for the test report and date of issue; m) a statement to the effect that the results are only for the items tested; n) a reference to this European standard (i.e EN 13141-8); o) qualitative specification of visual inspection of the filter, if appropriate 10.2 Product specifications The product specification shall be given as follows: — maximum air volume flow: qvmax in m s — filter class according to EN 779 −1 −1 or l.s ; 10.3 Additional information related to the performance of the product The manufacturer should declare which strategy is used to: — control condensation problems during the critic seasons (that could be winter time in northern Europe as summer time in southern Europe with humid climates); — avoid frosting in the SRHR unit NOTE For example it is interesting to know the time of unbalanced conditions when one fan is off The laboratory shall report the part of the strategy that can be checked 10.4 Leakages The equipment leakages established in accordance with 5.2.1 shall be given as follows: — 32 external leakage: qve in m s −1 −1 or l.s ; BS EN 13141-8:2014 EN 13141-8:2014 (E) — external leakage/maximum flow rate: qve/qvd in %; — internal leakage from supply to exhaust flow: qvise in m s — internal leakage from exhaust to supply flow: qvies in m s — internal leakage from exhaust to supply/supply flow rate: qvies/qv in %; — external leakage/maximum flow rate: qvi/qvmax in %; — indoor mixing: qmi in m s — indoor/outdoor airtightness in m /h; — outdoor mixing (calculated): qme in %; — indoor mixing/maximum flow rate: qmi/qvmax in %; — outdoor mixing/maximum flow rate (calculated): qme/qvmax in %; — external leakage/pressure curve; — leakage class −1 −1 or l.s ; −1 −1 or l.s ; −1 −1 or l.s ; 10.5 Air flow The air flow/pressure characteristic established in accordance with 5.2.2 for supply and exhaust air flows, for each voltage and for each setting shall be recorded as follows: −1 or l.s ; −1 −1 or l.s ; — supply air volume flow: qvs in m s — extract air volume flow: qve in m s — reference air volume flow: qvref in m s — airflow sensitivity classification; — corrected air flow according to EN 13142 [1] −1 −1 −1 or l.s ; 10.6 Effective power input For the effective power input the following results shall be reported at each operating point according to 5.2.2 — list of the major electrical components of the unit; — total electric power input PE in active mode at each point according to 5.5 in W; — specific effective power input PE/qvmax at each point (including reference point) according to 5.5 in W/(m s ) or −1 W/(l.s ); — total electric power input PE in fans off mode according to 5.5 in W; — total electric power input PE in manual off mode according to 5.5 in W −1 10.7 Temperature and humidity ratios a) The temperature ratios, according to 5.4, shall be reported including the following values: — temperature θ11, θ22, θ12, θ21; 33 BS EN 13141-8:2014 EN 13141-8:2014 (E) — water content x11, x22, x12, x21; — mass flow qm11, qm22, qm12, qm21; — temperature ratio for supply air without condensation b) The following optional information shall be reported if measured: — temperature ratio for exhaust air without condensation; — temperature ratio for supply air with condensation; — temperature ratio for exhaust air with condensation c) The following additional information for cold climate shall be reported if tested: — temperature ratio for supply air (optional); — temperature ratio for exhaust air (optional); — observations of the influence of freezing and condensation on the operation of the heat recovery unit and the condensation water outlet Temperature ratios shall always be stated together with the leakage class of the unit (see 6.1) Every operating point shall be recorded with all relevant information (airflows, pressure conditions, humidity values, temperature, etc.) 10.8 Acoustic characteristics The test installation and conditions shall be clearly described All the information concerning the measurements shall be recorded according to the specifications of the standard adopted For the assessment of noise radiated toward the inner side and the outer side, in accordance with 9.2, the presentation of the results in the report shall include the following for both the internal and external sides of the unit: — test method and description of set-up; — A-weighted sound power levels (indoor and outdoor), LWA, in dB; — sound power levels (indoor and outdoor), LW in dB, in third octave bands between 125 Hz and 10 000 Hz, or in octave bands between 125 Hz and 000 Hz, according to the standard adopted; — air volume flows at acoustic test conditions: minimum air volume flow, maximum air volume flow (qvmax) and −1 −1 third air volume flow chosen (qv), in m s or l.s For the assessment of airborne sound insulation, in accordance with 9.3, the presentation of the results in the report shall include the following: — test method and description of set-up; — global airborne sound insulation index Dn,e,w (Ctr) in dB calculated according to EN ISO 717-1; — airborne sound insulation Dn,e in third octave bands, in dB, between 125 Hz and 10 000 Hz 34 BS EN 13141-8:2014 EN 13141-8:2014 (E) 11 Cleaning and maintenance The manufacturer should declare how the SRHR should be cleaned NOTE SRHR main problem concerns the fact that it is not easy to reach the external grilles from the room where the SRHR is installed 35 BS EN 13141-8:2014 EN 13141-8:2014 (E) Annex A (informative) Test layouts The test setups to determine the internal leakage using tracer gas method, airflows, and temperature ratios shall be as shown in Figures A.1, A.2 and A.3 Key tracer gas inlet — extract air (11) tracer gas measurement — supply air (22) and exhaust air (12) Figure A.1 — Tracer gas internal leakage measurement a) measuring supply b) measuring extract flow Key auxiliary fan airflow rate measurement device static pressure measurement auxiliary fan airflow rate measurement device static pressure measurement Figure A.2 — Measurement set up using balancing fan 36 BS EN 13141-8:2014 EN 13141-8:2014 (E) Key extract air supply air outdoor air exhaust air Figure A.3 — Temperature measurement layout 37 BS EN 13141-8:2014 EN 13141-8:2014 (E) Annex B (normative) Pressure leakage test method B.1 External leakage test The external leakage test shall be carried out by blanking off and sealing all ducts and connecting a fan to both the supply and the exhaust air sides of the recovery devices as shown in Figure B.1 The static pressure of the casing shall be taken as the mean value at the two sides Thus, static pressure tappings are located on a blanking off plate each side and both taps are connected to the same pressure measuring instrument The external leakage flow rates at over-pressure in the casing and at under-pressure are established with suitable air flow measuring equipment The accuracy of the measured values shall be kept within ± % for the flow rates and ± % for the static pressures of the casing Key adjustable fan air flow measuring equipment exhaust air side supply air side heat recovery device static pressure measuring equipment Figure B.1 — Test setup for leakage For alternating ventilation unit including a storage type heat exchanger, the test setup for leakage is simplified because Key and are combined Measurement devices shall comply with EN 306 B.2 Internal leakage test The internal leakage test shall be carried out by blanking off and sealing all ducts and connecting one supply fan to the exhaust air side and one exhaust fan to the supply air side of the recovery device as shown in Figure B.2 The 38 BS EN 13141-8:2014 EN 13141-8:2014 (E) over-pressure on the exhaust air side is ascertained with the aid of a static pressure tapping in the blanking off plate and the pressure Pa at a corresponding tapping on the supply side The internal leakage flow rate is established with air flow measuring equipment connected to the supply air side The uncertainty of the measured values shall not exceed ± % for the flow rate and ± % for the static pressure difference between the two sides of the recovery device Key adjustable fan air flow measuring equipment exhaust air side supply air side heat recovery device static pressure measuring equipment Figure B.2 — Test setup for internal leakage Measurement devices shall comply with EN 306 39 BS EN 13141-8:2014 EN 13141-8:2014 (E) Annex C (normative) Indoor mixing C.1 General Indoor mixing represents the risk of short-cut between the supply air and the extract air, and therefore is linked directly with the efficiency of the ventilation system Two tests are needed in order to determine the indoor mixing C.2 Determination of indoor mixing - First test Internal leakage on outdoor air shall be measured by means of a tracer gas at Pa and fans at maximum setting according to Figure c) The tracer gas should be introduced into the outdoor inlet duct as close as possible to the grille, if this is not possible, a short length of duct (less than 150 mm) of the same cross section as the grille should be fastened to the grille and the tracer gas introduced into the ductwork The tracer gas concentration should be measured at the line of the outdoor grilles If this is impossible short pieces of ductwork of the same cross section as the grille should be applied and measurement made within the ductwork To measure internal leakage on outdoor air a deflector is introduced between the indoor grilles and sealed to ensure that exhaust gas cannot be mixed back into the intake port The deflector should be applied between the extract and intake ports It should be fixed to the outside of the grille and extend to at least 300 mm in each direction Tracer gas is introduced into the outdoor inlet duct and the concentration is measured in both the extract and supply ports The internal leakage on outdoor air, as a percentage of the supply flow, is then the ratio of the two concentrations, so that: C12 C22 c internal leakage on outdoor air = where term c refer to subfigure c of Figure C.3 Determination of indoor mixing - Second test The second test measures the consequences of both the internal leakages on outdoor air and the indoor mixing, when the deflector is removed according to Figure d) A separate mixing measurement is made at both the indoor and outdoor grille locations, the measurement with the highest percentage figure is used for the calculations C.4 Indoor mixing calculation The indoor mixing is therefore calculated as the difference between the percentages measured during this test and the internal leakage on outdoor air, so that: indoor mixing = C12 C22 d C − 12 C22 c where terms c and d refer to subfigures c and d of Figure NOTE The duration of the test is limited such that any influence of the contamination/saturation of the test room from the gas is minimised 40 BS EN 13141-8:2014 EN 13141-8:2014 (E) Bibliography [1] EN 13142, Ventilation for buildings - Components/products for residential ventilation - Required and optional performance characteristics [2] EN 60335-2-80:2003, Household and similar electrical appliances — Safety — Part 2-80: Particular requirements for fans (IEC 60335-2-80:2002) 41 This page deliberately left blank This page deliberately left blank NO COPYING WITHOUT BSI PERMISSION 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