1、BSI Standards PublicationBS ISO 16956:2015Thermal performance inthe built environment Determination of air flow ratein building applications by fieldmeasuring methodsBS ISO 16956:2015 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 16956:2015.The UK participati
2、on in its preparation was entrusted to TechnicalCommittee B/540/8, Mirror committee for ISO/TC 163 - ThermalPerformance and Energy use in the built Environment.A list of organizations represented on this committee can beobtained on request to its secretary.This publication does not purport to includ
3、e all the necessaryprovisions of a contract. Users are responsible for its correctapplication. The British Standards Institution 2015. Published by BSI StandardsLimited 2015ISBN 978 0 580 83498 1ICS 91.120.10Compliance with a British Standard cannot confer immunity fromlegal obligations.This British
4、 Standard was published under the authority of theStandards Policy and Strategy Committee on 31 January 2015.Amendments issued since publicationDate Text affectedBS ISO 16956:2015 ISO 2015Thermal performance in the built environment Determination of air flow rate in building applications by field me
5、asuring methodsPerformance thermique des btiments Dtermination du taux de renouvellement dair dans les btiments par des mthodes de mesure sur siteINTERNATIONAL STANDARDISO16956First edition2015-02-01Reference numberISO 16956:2015(E)BS ISO 16956:2015ISO 16956:2015(E)ii ISO 2015 All rights reservedCOP
6、YRIGHT PROTECTED DOCUMENT ISO 2015All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permi
7、ssion. Permission can be requested from either ISO at the address below or ISOs member body in the country of the requester.ISO copyright officeCase postale 56 CH-1211 Geneva 20Tel. + 41 22 749 01 11Fax + 41 22 749 09 47E-mail copyrightiso.orgWeb www.iso.orgPublished in SwitzerlandBS ISO 16956:2015I
8、SO 16956:2015(E)Contents PageForeword v1 Scope . 12 Normative references 13 Terms and definitions . 14 Symbols and abbreviated terms . 25 Types and selection of measurement method . 25.1 Types of measurement methods and their application . 25.2 Selection of measurement method 26 Basic specifications
9、 measuring instruments and utilization methods . 26.1 General . 26.2 Thermal anemometer . 26.3 Pitot tube and manometer 36.4 Vane-type anemometer . 37 Field measuring methods of air flow rate of ventilation and air conditioning systems 37.1 Multipoint air velocity measurement method . 37.1.1 Measure
10、ment in a duct . 47.1.2 Measurement method at duct connection of air-conditioning system . 67.1.3 Selection of measuring instruments . 77.2 Tracer gas measurement method . 77.2.1 Formula 77.2.2 Tracer gas . 87.2.3 Procedures for measuring air flow rate . 87.2.4 Tracer gas injection procedures . 97.2
11、.5 Tracer gas sampling procedures . 107.3 Flow hood method 107.3.1 General. 107.3.2 Equipment composition . 107.3.3 Measurement procedures . 117.4 Pressure compensation measurement method .117.4.1 Equipment composition . 127.4.2 Measurement procedures . 137.4.3 Effective application range . 137.5 Pr
12、essure difference measurement method . 137.5.1 Measuring equipment 137.5.2 Selection of measuring instruments 147.5.3 Measuring procedures .148 Uncertainty 158.1 Uncertainty of each measurement 158.1.1 Multipoint air velocity measurement method 158.1.2 Tracer gas measurement method.158.1.3 Flow hood
13、 method 158.1.4 Pressure-loss compensation measurement method .158.1.5 Pressure difference measurement method 158.2 Analysis of uncertainty . 159 Measurement report .169.1 Information related to measured object 169.2 Items related to measuring method 169.3 Measurement results 16Annex A (normative) P
14、osition for cross-section measurement in a duct using multipoint measurement method 17 ISO 2015 All rights reserved iiiBS ISO 16956:2015ISO 16956:2015(E)Annex B (normative) Accuracy of air velocity measurement instrument 21Annex C (informative) Types of tracer gas .22Bibliography .23iv ISO 2015 All
15、rights reservedBS ISO 16956:2015ISO 16956:2015(E)ForewordISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each m
16、ember body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International
17、Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the different typ
18、es of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be
19、held responsible for identifying any or all such patent rights. Details of any patent rights identified during the development of the document will be in the Introduction and/or on the ISO list of patent declarations received (see www.iso.org/patents).Any trade name used in this document is informat
20、ion given for the convenience of users and does not constitute an endorsement.For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISOs adherence to the WTO principles in the Technical Barriers to Trade (TBT), see the
21、following URL: Foreword Supplementary information .The committee responsible for this document is ISO/TC 163, Thermal performance and energy use in the built environment, Subcommittee SC 1, Test and measurement methods. ISO 2015 All rights reserved vBS ISO 16956:2015BS ISO 16956:2015Thermal performa
22、nce in the built environment Determination of air flow rate in building applications by field measuring methods1 ScopeIn the cooling and heating loads of a building, the air taken in from outside account for a large portion of the entire load; in order to estimate this load, it is necessary to corre
23、ctly grasp the air flow rate of ventilation and air-conditioning systems. This International Standard stipulates the methods for measuring the rate of air flow through the ducts in a steadily operating ventilation and air-conditioning system and in the air control ports including air diffuser, sucti
24、on opening, and exhaust opening.2 Normative referencesThe 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 reference
25、d document (including any amendments) applies.ISO 5168, Measurement of fluid flow Procedures for the evaluation of uncertainties3 Terms and definitionsFor the purposes of this document, the following terms and definitions apply.3.1orifice platethin plate having a hole, or holes, bored through itNote
26、 1 to entry: These are used for measuring the difference in static pressure of the flow before and after the disc and obtaining the air flow rate in the duct by multiplying by a predetermined coefficient.3.2tracer gasgas used to measure its concentration varying in the airNote 1 to entry: This gas i
27、s mixed with a sufficiently small amount of air so as not to affect the flow, and the amount of air is determined by measuring the gas concentration diluted in the air.3.3volumetric concentrationratio of the volume of the specific gas to the unit volume of the mixture of airNote 1 to entry: It is ex
28、pressed in cubic meters per cubic meters or 10-6 vol.3.4mass flowmass of air or tracer gas flowing in unit time Note 1 to entry: It is expressed in mg per second or kg per hour.3.5volumetric flowvolume of air flowing in unit time Note 1 to entry: It is expressed in cubic meters per hour.INTERNATIONA
29、L STANDARD ISO 16956:2015(E) ISO 2015 All rights reserved 1BS ISO 16956:2015ISO 16956:2015(E)4 Symbols and abbreviated termsAmong the symbols used in this International Standard, only those common to all items are shown below. Individual symbols are explained at the relevant sub clauses.Symbol Quant
30、ity UnitAArea of evaluation section of air flow rate. Sectional area of duct and sectional area of air control portm2NNumber of divisions for measurement of evaluation section. The number of lattice-like divisions of rectangular duct section and radial number of divisions in round duct.-VAverage air
31、 velocity of section of measured portion.The section is divided into n and if the time average air velocity at the centre of each is vi, the following formula is applied:vnviin=11m/s5 Types and selection of measurement method5.1 Types of measurement methods and their applicationThe measurement metho
32、ds covered in this International Standard are the multipoint air velocity measurement method, tracer gas measurement method for air flow rate in air duct, flow hood method, pressure compensation measurement method, and pressure difference measurement method between outlet and inlet. The method selec
33、ted should be suitable for the purpose, as well as for the field conditions.5.2 Selection of measurement methodThe measurement method is selected considering the following items specified in Clause 7 and Clause 8:a) ventilation/air-conditioning equipment subject to measurement;b) position for measur
34、ement;c) measurement period;d) accuracy;e) practicability (equipment size and composition simplicity, preparation, ease of data processing, and cost).6 Basic specifications measuring instruments and utilization methods6.1 GeneralThe following describes air velocity measuring instruments common to va
35、rious measurement methods.6.2 Thermal anemometerIn the category of thermal anemometers, there are the hot-wire anemometer and the semiconductor anemometer. The hot-wire anemometer has less resistance against flow and is suitable for multipoint air velocity measurement in air duct when measuring very
36、 low air velocity. Attention should be paid to the directivity of the sensor. The sensor should be calibrated as necessary to avoid errors due to deterioration and adhesion of dust.2 ISO 2015 All rights reservedBS ISO 16956:2015ISO 16956:2015(E)Since the semiconductor anemometer has improved accurac
37、y beyond 1 m/s and the distance between the sensor and transducer can be extended, it is suitable for multipoint air velocity measurement for fixed setting in air duct for permanent installation.6.3 Pitot tube and manometerThe Pitot tube has less resistance to flow and is suitable for multipoint mea
38、surement, but to be accurate, the flow velocity in the straight-pipe section should be 4 m/s or higher. However, when the cross-section of the duct is small, the Pitot tube is not used.When the air velocity is calculated from the dynamic pressure, it is obtained by using the density of measured air
39、depending on air temperature and atmospheric pressure as given in Formula (1):vPv= (/ )2 (1)wherev is the air velocity, in meter per second; is the air density, in kg per cubic meters;Pvis the dynamic pressure, in Pa.The result of Formula (1) is multiplied by the compensation coefficient k of the Pi
40、tot tube, if it is shown. Air density, , is obtained from measured air temperature and atmospheric pressure P, using Formula (2):=+001 293273 15273 15 101325TTPPPatm,(2)where0is the density when dry air temperature is 0,0 C (= 1,293), in kg per cubic meters;T is the thermodynamic temperature of dry
41、air, in K; is the air temperature, in C;T0is the thermodynamic temperature when is 0,0 C (273,15), in K;P is the atmospheric pressure, in Pa;Patm1 atmospheric pressure (101 325); in Pa.6.4 Vane-type anemometerThe vane-type anemometer generally cannot be used for multipoint measurement because the va
42、ne is too large. If it is used, it is advisable to select a mini-vane anemometer with the measured portion made smaller.7 Field measuring methods of air flow rate of ventilation and air conditioning systems7.1 Multipoint air velocity measurement methodThe multipoint air velocity measurement method o
43、btains the air flow rate by measuring the average air velocity in the duct and multiplying it by the sectional area of the duct. For both a round duct and ISO 2015 All rights reserved 3BS ISO 16956:2015ISO 16956:2015(E)rectangular duct, the cross-section is divided into multiple equal areas, the rep
44、resentative air velocity is measured and the average air velocity is calculated. The air flow rate is expressed by Formula (3):QSv=3600 (3)whereQ is the air flow rate in the duct, in cubic meters per hour;S is the duct sectional area of measured portion, in square meters;v is the average air velocit
45、y of cross-section of measured portion, in meter per second.7.1.1 Measurement in a duct7.1.1.1 Position for cross-section measurementThe position for cross-section measurement is selected in accordance with Annex A. Normally, it is a place having a straight section of not less than six times the equ
46、ivalent diameter, De, of the duct on the upstream side in the air flow direction. When precise measurement is required, a straightening or wire grid is provided upstream.In the case of a rectangular duct, the equivalent diameter, De, is calculated by Formula (4):Dababe=+2/() (4)whereDeis the equival
47、ent diameter when a rectangular duct is converted to a round duct, in meter;a is the width of rectangular duct, in meter;b is the height of rectangular duct, in meter.7.1.1.2 Simplified measurement methodWith the simplified measurement method, as shown in A.4, the measured cross-section is divided i
48、nto four equal parts and the four centres and the centre of the whole, five points in total, are selected as the measuring points. The arithmetic average of the five points is used as the average air velocity. If the required conditions are met, including securing the length of the straight-pipe sec
49、tion, the uncertainty can be minimized (approximately 10 %) even with this method. If, however, a sufficient straight-pipe length cannot be secured upstream from the measurement position, the measuring points are increased to a number closer to the precise measurement method.7.1.1.3 Precise measurement methoda) In the case of a rectangular cross-sectionWith the precise measurement method, the rectangular cross-section is divided into multiple equal rectangles in such a way that the length of one side will be about
