Ventilation and heating, lighting and seeing / issued by the Industrial Health Research Board of the Medical Research Council.

Date:
[1943]
Catalogue details

Licence: Public Domain Mark

Credit: Ventilation and heating, lighting and seeing / issued by the Industrial Health Research Board of the Medical Research Council. Source: Wellcome Collection.

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    < temperatures above 68° are undesirable in cool weather, for higher temperatures tend to cause inefficiency as well as discomfort. People who are doing active physical work require lower environ- mental temperatures than sedentary workers. For active yet light work, the temperature should be about 60° to 65° F., and for some of the more strenuous work done in factories, a temperature of between 55° and 60° F. is generally found satisfactory. In hot weather it will usually be impossible to keep factory tempera- tures down to the maximum values suggested above for winter, but such temperatures are not really desirable in very warm weather. During the summer we become acclimatised to higher temperatures, and we commonly wear lighter clothing, so that warmer indoor tem- peratures are tolerable. With good ventilation it will generally be possible to maintain an indoor temperature in summer that is only slightly above the outside temperature. Where air conditioning plant is available, the temperature indoors should not generally be more than 10° F. below that prevailing outside. (b) Radiant Heat. In winter, the internal surfaces of the walls and roofs of lightly constructed buildings may be several degrees cooler than the general air of the shop. Owing to the radiation of heat from their bodies to these cold surfaces, persons working near such walls may need some extra radiant heat, or a rather higher air temperature than would otherwise be necessary. In other cases, where considerable radiant heat is given off from heating apparatus or manufacturing plant, it may be desirable to compensate for this by some reduction in the air temperature, or by increasing the rate of air movement. (c) Air Movement. During the winter months the average speed of air movement in the ordinary factory is usually greater than 20 feet per minute, and it generally averages about 30 feet per minute. In summer, more rapid movement is highly desirable. Out of doors in warm weather we find a breeze very refreshing. Indoors, too, a good rate of air movement is invigorating, while a stagnant atmosphere is oppressive and causes feelings of stuffiness. Even at comfortable temperatures in winter, the air movement should not be much below 20 feet per minute, and, in summer, or in hot factories, air movement becomes much more important. In summer, especially, full use should be made of whatever arrangements for ventilation are provided, so that a refreshing atmosphere can be ensured. The provision of adequate air movement is of great importance, but at the same time objectionable draughts should be avoided. Our sen- sitivity to draughts increases rapidly as the temperature of the air falls, so that an air current which would be quite pleasant in a warm room would be liable to provoke complaints if the temperature were lowered by several degrees. People vary greatly in their sensitivity to draughts. Ventilation Arrangements We speak of natural ventilation and of mechanical ventilation. The latter term is used when mechanical power operates fans, which
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