BS-7643-2-1993 ISO-6242-2-1992.pdf

BRITISH STANDARD BS 7643-2: 1993 ISO 6242-2: 1992 Building construction Expression of users requirements Part 2: Air purity requirements UDC 69.004.2:697:644.1 Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 10:32:10 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7643-2:1993 This British Standard, having been prepared under the direction of the Technical Sector Board for Building and Civil Engineering, was published under the authority of the Standards Board and comes into effect on 15 March 1993 © BSI 07-1999 The following BSI references relate to the work on this standard: Committee reference B/500 Draft for comment 89/16305 DC ISBN 0 580 21644 6 Committees responsible for this British Standard The preparation of this British Standard was entrusted by the Technical Sector Board for Building and Civil Engineering (B/-) to Technical Committee B/500, upon which the following bodies were represented: Building Employers Confederation Consumer Policy Committee of BSI Convention of Scottish Local Authorities Department of Education and Science Department of the Environment Department of the Environment (Building Research Establishment) Incorporated Association of Architects and Surveyors Meteorological Office National Building Specification Ltd. National Council of Building-Material Producers National House-Building Council Royal Institute of British Architects Society of Chief Architects of Local Authorities Amendments issued since publication Amd. No.DateComments Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 10:32:10 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7643-2:1993 © BSI 07-1999i Contents Page Committees responsibleInside front cover National forewordii Introduction1 1Scope1 2Users objectives1 3Parameters for expressing users requirements1 4Factors affecting the choice of criteria1 Annex A (informative) BibliographyInside back cover Table 1 Parameters2 Table 2 Factors affecting criteria2 Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 10:32:10 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 7643-2:1993 ii © BSI 07-1999 National foreword This Part of BS 7643 has been prepared under the direction of Technical Committee B/500, Basic data, and is identical with ISO 6242-2:1992 Building construction Expression of users requirements Part 2: Air purity requirements, published by the International Organization for Standardization (ISO). ISO 6242-2 was prepared by Subcommittee 3, Functional/user requirements and performance in building construction, with the active participation and approval of the United Kingdom. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 and 2, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 10:32:10 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ISO 6242-2:1992(E) © BSI 07-19991 Introduction This part of ISO 6242 is one of a set dealing with the expression of environmental requirements for buildings, in terms suitable for use in regulations and briefs for building projects. The parameters defined can be used for routine verification of the performance of buildings, either by calculation (for example at the design stage) or measurement (for example of spaces or whole buildings), and are meant to provide readily understood information on users requirements throughout the building process. This set of International Standards is not intended to represent the complete state of knowledge about these aspects of environmental science, some of which are the concern of other ISO Technical Committees. 1 Scope This part of ISO 6242 defines how the air purity requirements of building users can be identified, expressed and quantified. It describes users objectives and the parameters used to express them. For each parameter, it specifies units of measurement, preferred increments for values and means of evaluation. It also lists the environmental and human factors affecting the choice of a value (criterion) for each parameter. It is intended for use a) in preparing briefs for building projects; b) in formulating building laws and regulations; c) in drafting standards and other normative documents; and d) more generally when specifying the required performance of buildings in terms of users requirements. Some of the parameters given in this part of ISO 6242 apply only to certain types of building. Compliance with this part of ISO 6242 does not therefore depend on implementing the whole of its contents in every case. 2 Users objectives 2.1 Control of air purity within buildings shall fulfil the following objectives: a) to limit the ingress and/or accumulation in indoor air of contaminants (for example gases, particles, microbes, aerosols) injurious to health, the fabric of the building or its contents, or equipment or processes; b) to prevent the accumulation in indoor air of contaminants detrimental to comfort; c) to provide an adequate supply of oxygen for occupants and combustion appliances; d) to control nuisance due to odours; and e) to control relative humidity. 2.2 Criteria meeting these objectives shall reflect the following: a) activities to be accommodated; b) age and health of the occupants; c) proportion of likely occupants it is intended to satisfy; d) character and location of combustion appliances dependent on indoor air; e) time during which the requirements must be satisfied (taking account of climatic extremes and intermittency); and f) any facility for local control of the air purity by the occupants. 3 Parameters for expressing users requirements The purity of air depends on a) for health, the maximum content of noxious substances; b) for comfort, the maximum concentration of CO2, SO2, CH4 and other gases. These may be interpreted in terms of air supply rate, such as air changes per hour; air supply per person; air supply per square metre of floor area; air supply per combustion appliance. 3.1 Location, uniformity and tolerance for air purity parameters In all but large spaces, it is normal to assume that the mixing of fresh air with contaminated air will be sufficient to achieve uniform dilution of contaminants, but this depends on the correct design and functioning of the air supply and exhaust system. Exceptionally, in certain processes, mixing may not be acceptable and laminar flow systems may be required. The requirements for air change rates shall be regarded as minima, with no tolerance allowed. 3.2 Expression of air purity parameters Details of means of expression, together with associated information, are given in Table 1. 4 Factors affecting the choice of criteria Details of factors likely to affect the choice of criteria for particular applications, together with associated information, are given in Table 2. Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 10:32:10 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ISO 6242-2:1992(E) 2 © BSI 07-1999 Table 1 Parameters Table 2 Factors affecting criteria ParameterDefinition Means of expression: units; preferred increments Nature of criterion Means of evaluation Rate of supply of fresh air for occupants Alternatives: 1) Average number of air changes per hour Air changes/h; chosen from the series: MinimumCalculation: in accordance with national standards or codes of practice in tenths from 0,1 to 0,9; in fifths from 1 upwards Measurement: tracer gas techniques 2) Average of volume of air supplied to each occupant l/s per person; chosen from the series: Minimum in units from 1 to 10; then increments of 2 3) Average volume of air supplied per square metre of floor area l/(s·m2); units Minimum Rate of supply of fresh air to combustion appliances without independent air supply Average volume of air supplied per unit of rated energy input to the combustion appliance l/s per kW of rated input; units NOTEDifferent fuels may require different rates of air supply per kW. MinimumCalculation: in accordance with national standards or codes of practice Measurement: tracer gas techniques Factor Examples of classes/categories Means of expression Sources of information Activities and tasks for which ventilation is provided Reclining Sedentary Standing Light activity Medium activity Heavy activity Appropriate rate of fresh air supply, taking into account density of occupation and the amount of smoke or fumes generated National standards or codes of practice Density of occupation 2 m2/person 5 m2/person 10 m2/person The higher the density of occupation, the greater the air supply needed per person for odour removal National standards or codes of practice Time during which requirements must be satisfied 80 % 90 % 95 % Where fresh air is supplied solely by natural ventilation, its rate will depend on wind speed and on internal/external temperature difference. The frequency of these factors will need to be checked from local meteorological records National standards or codes of practice Fuel typeGas Oil Coal/peat Wood Sufficient air must be available to meet the full rated input of a combustion appliance at all times, even though it may operate at a lower rate for part of the time National standards or codes of practice Licensed Copy: London South Bank University, London South Bank University, Fri Dec 08 10:32:10 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ISO 6242-2:1992(E) © BSI 07-1999 Annex A (informative) Bibliography 1 ISO 4225:1980, Air quality General aspects Vocabulary. 2 ISO 4226:1980, Air quality General aspects Units of measurement. 3 ISO 6240:1980, Performance standards in building Contents and presentation. 4 ISO 6241:1984, Performance standards in building Principles for their preparation and factors to be considered. 5 ISO 7162:1992, Performance standards in building Contents and format of standards for evaluation of performance. 6 ISO 7164-1:, Performance standards in building Part 1: Definitions and means of expression for the performance of a whole building1). 7 International Energy Agency: AIC Technical Note 18 : A subject analysis of the AICs bibliographic database AIRBASE (4th edition, January 1986)2). 1) To be published. 2) Air Infiltration Centre, Bracknell, RG12 4AH, United Kingdom. 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