1、BS 8206-2:2008Lighting for buildings Part 2: Code of practice for daylightingICS 91.060.50; 91.160.10NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBRITISH STANDARDPublishing and copyright informationThe BSI copyright notice displayed in this document indicates when the docume
2、nt was last issued. BSI 2008ISBN 978 0 580 57793 2The following BSI references relate to the work on this standard:Committee reference CPL/34/10Draft for comment 07/30157086 DCPublication historyFirst published June 1992Second edition, September 2008Amendments issued since publicationAmd. no. Date T
3、ext affectedBS 8206-2:2008 BSI 2008 iBS 8206-2:2008ContentsForeword iiiSection 1: General 11 Scope 12 Terms and definitions 1Section 2: Aims and criteria for design 43 The contribution of daylight 44 Windows and view 55 Daylight and room brightness 86 Daylight for task lighting 11Section 3: Further
4、design issues 147 Electric lighting used in conjunction with daylight 148 Sunlight shading 169 Energy efficiency 1810 Conservation of materials inside buildings 2011 Statutory and legal requirements affecting the provision of daylight 21Section 4: Methods of calculation 2312 Sunlight 2313 Calculatio
5、n of average daylight factor 2914 Calculation of daylight illuminance 3115 Examples of the calculation of window transmittance 32AnnexesAnnex A (informative) Data for daylight and sunlight calculations 33Annex B (informative) Climate-based daylight modelling 40Bibliography 44List of figuresFigure 1
6、Solar altitude and solar azimuth 3Figure 2 Views from windows of different shapes and sizes 7Figure 3 Window reveal drawn on a sunpath diagram for London 26Figure 4 Obstructing building superimposed on the sunpath diagram 27Figure 5 Use of sunlight probability diagram to determine sunlight reaching
7、window reference point 27Figure 6 Angle of visible sky used in calculating average daylight factor 30Figure 7 Limiting depth of a side-lit room 31Figure A.1 Sunpath diagram for London (latitude 51 N) 36Figure A.2 Sunpath diagram for Edinburgh (latitude 56 N) 37Figure A.3 Sunlight probability diagram
8、 38Figure A.4 Diffuse illuminance (Eh) availability for London 39Figure A.5 Diffuse illuminance (Eh) availability for Edinburgh 39Figure A.6 Mean horizontal diffuse illuminances at London (Kew) 40List of tablesTable 1 Minimum glazed areas for view when windows are restricted to one wall 6Table 2 Min
9、imum average daylight factor 10Table A.1 Approximate values of the reflectance of light 33Table A.2 Mean light transmittance of glazing materials 34BS 8206-2:2008ii BSI 2008Table A.3 Percentage losses of light in particular types of buildings 35Table A.4 Exposure multiplying factors 35Table A.5 Spec
10、ial exposure multiplying factors 35Table A.6 Correction factors for frames and glazing bars 36Table A.7 Diffuse orientation factors for an 09.00 to 17.00 working day 38Summary of pagesThis document comprises a front cover, an inside front cover, pages i to iv, pages 1 to 48, an inside back cover and
11、 a back cover. BSI 2008 iiiBS 8206-2:2008ForewordPublishing informationThis part of BS 8206 is published by BSI and came into effect on 30 September 2008. It was prepared by Subcommittee CPL/34/10, Light and lighting, under the authority of Technical Committee CPL/34, Lamps and related equipment. A
12、list of organizations represented on this committee can be obtained on request to its secretary.SupersessionThis part of BS 8206 supersedes BS 8206-2:1992, which is withdrawn.Information about this documentThis part of BS 8206 represents a full revision of the standard. This revision has been prepar
13、ed to take account of the publication of BS EN 12464-1 and BS EN 15193. In particular, some of the manual calculations that appeared in the 1992 edition have been omitted and a new annex on climate-based daylight modelling has been added. There is also a new clause on daylighting and health.Annex B
14、in the 1992 edition gave what was termed “service illuminances” for tasks. Task lighting is now specified in BS EN 12464-1 and this annex, therefore, has been deleted.The standard describes good practice in daylighting design and presents criteria intended to enhance the well-being and satisfaction
15、of people in buildings, recognizing that the aims of good lighting go beyond achieving minimum illumination for task performance. Simple graphical and numerical methods are given for testing whether the criteria are satisfied, but these are not exclusive and computer methods may be used in practice.
16、 Sunlight and skylight data are given. The aim of the standard is to give guidance to architects, engineers, builders and others who carry out lighting design. It is recognized that lighting is only one of many matters that influence fenestration. These include other aspects of environmental perform
17、ance (such as noise, thermal equilibrium and the control of energy use) fire hazards, constructional requirements, the external appearance and the surroundings of the site. The best design for a building does not necessarily incorporate the ideal solution for any individual function. For this reason
18、, careful judgement needs to be exercised when using the criteria given in the standard for other purposes, particularly town planning control.NOTE Figure 2 in this standard is reproduced from the CIBSE Lighting Guide LG10 Daylighting and window design 1 by permission of the Chartered Institution of
19、 Building Services Engineers.BS 8206-2:2008iv BSI 2008Use of this documentAs a code of practice, this part of BS 8206 takes the form of guidance and recommendations. It should not be quoted as if it were a specification and particular care should be taken to ensure that claims of compliance are not
20、misleading.Any user claiming compliance with this part of BS 8206 is expected to be able to justify any course of action that deviates from its recommendations.Presentational conventionsThe provisions in this standard are presented in roman (i.e. upright) type. Its recommendations are expressed in s
21、entences in which the principal auxiliary verb is “should”.Commentary, explanation and general informative material is presented in smaller italic type, and does not constitute a normative element.Contractual and legal considerationsThis publication does not purport to include all the necessary prov
22、isions of a contract. Users are responsible for its correct application.Compliance with a British Standard cannot confer immunity from legal obligations. BSI 2008 1BS 8206-2:2008Section 1: General1 ScopeThis part of BS 8206 gives recommendations regarding design for daylight in buildings. It include
23、s recommendations on the design of electric lighting when used in conjunction with daylight.NOTE Data for daylight and sunlight calculations are given in Annex A.2 Terms and definitionsFor the purposes of this part of BS 8206, the following terms and definitions apply. 2.1 daylightvisible part of gl
24、obal solar radiation BS EN 12665:2002NOTE Daylight consists of a combination of sunlight (see 2.10.1) and skylight (see 2.11.1).2.2 windowconstruction for closing a vertical or near-vertical opening in a wall or pitched roof, which will admit light and may provide ventilation BS 6100-1:2004, 5.3.5 2
25、.3 rooflightconstruction for closing an opening in a flat roof or low pitched roof, intended primarily for lighting and consisting of a frame and glazing BS 6100-1:2004, 5.3.132.4 transomhorizontal member dividing an opening or frame of a window or door BS 6100-1:2004, 5.3.242.5 obstructionanything
26、outside a building which prevents a direct view of the sky from a given reference point2.6 no-sky lineoutline on a given surface of the area from which no sky can be seen2.7 working planehorizontal, vertical or inclined plane in which a visual task lies BS 6100-7:2008, 52002NOTE If no information is
27、 available, considered to be horizontal and 0.7 m above the floor for offices; horizontal and 0.85 m above the floor for industry and in dwellings.2.8 window reference pointpoint in the centre of a window or rooflight opening on the plane of the inside surface of the window wall or roof NOTE This is
28、 used in determining sunlight penetration and average daylight factor.2.9 supplementary electric lightingelectric lighting used continuously in combination with daylightingBS 8206-2:20082 BSI 20082.10 sunlight2.10.1 sunlightthat part of the light from the sun that reaches the earths surface as paral
29、lel rays after selective attenuation by the atmosphere 2.10.2 probable sunlight hourslong-term average of the total number of hours during the year in which direct sunlight reaches the unobstructed groundNOTE A period of “probable sunlight hours” is the mean total time of sunlight when cloud is take
30、n into account.2.10.3 solar altitudeangle between a line passing through the centre of the solar disc and a horizontal plane on the earths surface BS 6100-7:2008, 59006NOTE This is illustrated in Figure 1.2.10.4 solar azimuthhorizontal angle between a vertical plane passing through the centre of the
31、 solar disc and a vertical northsouth planeNOTE 1 Solar azimuth is measured clockwise from due north.NOTE 2 This is illustrated in Figure 1.2.11 skylight2.11.1 skylightthat part of the light from the sun that reaches the earths surface as a result of scattering in the atmosphere 2.11.2 standard over
32、cast sky completely overcast sky for which the luminance Lat an angle of elevation above the horizon is expressed as a function of the luminance Lzat the zenith by the formula:NOTE This formula for overcast sky luminance distribution is presented as an alternative formula in BS ISO 15469:2004, Claus
33、e 6. BS ISO 15469:2004 also contains fifteen other formulae for different types of sky.2.11.3 daylight factorratio of illuminance at a point on a given plane due to light received from a sky of known or assumed luminance distribution, to illuminance on a horizontal plane due to an unobstructed hemis
34、phere of this sky BS 6100-7:2008, 59011NOTE 1 For the purposes of the calculation of daylight factor in this standard, it is assumed that the sky has the luminance distribution of the standard overcast sky.NOTE 2 Direct and reflected sunlight are excluded from all values of illuminance.NOTE 3 The po
35、int in an interior for which the daylight factor is calculated is known as the “room reference point”.LLz12 sin + ()3-= BSI 2008 3BS 8206-2:20082.11.4 average daylight factorratio of total daylight flux incident on a reference area to total area of reference area, expressed as a percentage of outdoo
36、r illuminance on a horizontal plane due to an unobstructed hemisphere of sky of assumed or known luminance distribution BS 6100-7:2008, 59012NOTE 1 For the purposes of this standard, it is assumed that the average daylight factor is the mean daylight factor over a horizontal working plane, unless st
37、ated otherwise.NOTE 2 Direct and reflected sunlight are excluded from all values of illuminance.2.11.5 vertical sky componentratio, expressed as a percentage, of that part of illuminance, at a point on a given vertical plane, that is received directly from a standard overcast sky (see 2.11.2), to il
38、luminance on a horizontal plane due to an unobstructed hemisphere of this skyFigure 1 Solar altitude and solar azimuthKeyZagZenithSolar altitudeSolar azimuthZSWEagNBS 8206-2:20084 BSI 2008Section 2: Aims and criteria for design3 The contribution of daylight3.1 GeneralDaylighting gives to a building
39、a unique variety and interest. An interior which looks gloomy, or which does not have a view to the outside when this could reasonably be expected, will be considered unsatisfactory by its users. The recommendations of this part of BS 8206 recognize that a principal aim of the designer is to produce
40、 interiors which are comfortable and give pleasure to their occupants.Recommendations are made in this section about three separate uses of windows, which are:a) for view;b) to enhance the overall appearance of interiors, using sunlight (the direct beam) and skylight (diffuse daylight);c) for lighti
41、ng of visual tasks.It is important to consider the primary function to be served by each window or rooflight in a building, because the criteria differ. Two of the functions, the overall illumination of the interior and the task lighting, may be fulfilled also by electric lighting, which has differe
42、nt qualities. For many buildings, the best design uses daylighting and electric lighting together, with appropriate lighting control, during daytime hours.3.2 Daylight and health3.2.1 Regulation of the circadian systemThe role of the circadian system (which controls daily and seasonal body rhythms)
43、is to link the functions of the body (e.g. the sleep/wake cycle, and changes in core body temperature and in hormone secretion) with the external day/night cycle. Disruption to this system from lack of light can cause problems such as depression and poor sleep quality which could lead to more seriou
44、s problems. Therefore, it is important that occupants of buildings, particularly those of limited mobility in, for example, hospitals and nursing homes, and people who might be unable to go outside much, are given access to high levels of daylight, particularly in the mornings, to assist the entrain
45、ment of circadian rhythms. Therefore, buildings used by such people should have spaces with high levels of daylight, such as conservatories, which are readily accessible to them.3.2.2 MoodMood can be modified by lighting. Daylighting is dynamic and variable and is strongly favoured by building occup
46、ants. Adequate access to daylight can have a positive impact on mood especially in situations where people are static for long periods of time, for example, in a hospital ward. BSI 2008 5BS 8206-2:20083.2.3 Seasonal affective disorder (SAD)A small percentage of people suffer a seasonal mood disorder
47、 known as seasonal affective disorder (SAD) with a further number suffering a mild form known as sub-syndromal SAD (S-SAD). Symptoms include depression, lack of energy, increased need for sleep and increased appetite and weight gain, occurring in the winter when there is little daylight. Such sympto
48、ms can be reduced by exposure to daylight.3.2.4 Ultraviolet (UV) radiationThe ultraviolet (UV) radiation in sunlight can be damaging to the skin. However, with people spending many daylight hours behind glass in buildings, there is the danger of insufficient exposure to UV radiation to maintain heal
49、thy levels of vitamin D. A vitamin D deficiency leads to rickets in children and softening of the bones in adults.Exposure to sunlight, even through glass, can kill many types of viruses and bacteria and so can be of great value in winter when there is a high incidence of respiratory infections.4 Windows and view4.1 PrincipleUnless an activity requires the exclusion of daylight, a view out-of-doors should
