The lighting of buildings / by the Lighting Committee of the Building Research Board of the Department of Scientific & Industrial Research.
- Great Britain. Building Research Board
- Date:
- 1944
Licence: Public Domain Mark
Credit: The lighting of buildings / by the Lighting Committee of the Building Research Board of the Department of Scientific & Industrial Research. Source: Wellcome Collection.
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![ee ay Vat] FO . a or >. DE NE en) ae a THE LIGHTING OF BUILDINGS 17. In artificial lighting systems totally indirect systems were thought at one time to have great advantages for illumination. Reference was made to the ex- cellent distribution of light and its shadowless quality. In time, however, it was found that people did not always like unrelieved indirect light; it seemed _ uninteresting ” for shapes were poorly defined; and sometimes it was termed ‘soporific.” It was often expensive. Usually it cuts across a basic principle of illumination, for the ceiling rather than the object of attention is likely to be the brightest thing i in view. Wholly direct lighting, too, may have disadvantages. ‘The poor illumination of the ceiling can create a ‘“‘gloomy’’ impression to occupants, and give rise also to unpleasant contrasts between the ceiling surface and the lights themselves. Many examples of this can be found in industrial buildings, public halls, and so on, and it is likely to be the case with lay lights. Direct lighting from too few sources gives rise to harsh shadows. A combination of direct and indirect lighting should generally be the aim; 1.e. there should be a component of direct light to give interest and clarity of shape to objects and people in the room, and some indirect light to ensure that over-strong contrasts are avoided and that the full effect of the decoration is obtained. This is sometimes done very well in restaurants, where each table has a table lamp and the room has some general light as well. Similar conditions are found in libraries; the British Standard study lamp (Plate 5) can be recommended as a good example of a light fitting based upon these principles. 18. Such examples as we have quoted might be continued almost indefinitely, but our purpose will have been served if we have succeeded in establishing some alance between this part of the Report, which deals mainly with quality, and the sections which follow where the quantitative factors necessarily acquire some prominence. What we hope mainly from the discussion so far, is that in all fields of building practice designers will have an increased appreciation of the relation- ship between the physiological behaviour of the eye and the nature of their designs. PART Il. METHODS OF MEASUREMENT AND PRINCIPLES OF DESIGN METHODS OF MEASUREMENT AND PRINCIPLES OF DESIGN FOR DAYLIGHT THE SKY AS A SOURCE OF LIGHT 19. For the purpose of daylight design, the sky is usually assumed to be a hemi- sphere equally bright in all parts. In practice this is never exactly true, but it is nearest to being true on those days when it matters most, namely, when the sky is overcast and the general illumination is low. Even under these conditions in this country the south sky is probably twice as bright as the north? and the zenith lighter than the horizon, but the assumption provides a satisfactory and workable basis for design. THE MEASUREMENT OF DAYLIGHT 20. ‘The daylight at a point indoors is usually measured, as in fact it is appraised by the observer, as a percentage of the total light available outdoors under the unobstructed sky, the unit being the daylight factor, abbreviated d.f. Absolute units such as foot-candles are impractical for daylight design because of the con- | stant variation of the actual intensities of daylight. A daylight factor of 1 per cent 1 Tllumination Research Technical Paper No. He ‘Seasonal Variations of Daylight Illumina- tion (H.M. Stationery Office). I2](https://iiif.wellcomecollection.org/image/b3217164x_0014.jp2/full/800%2C/0/default.jpg)
