Book - School of Science and Technology

Thermal indices 11Wet bulb temperature °C30282624222018161412Summer comfort zoneWinter comfort zoneEffective temperature °C12 14 16 18 20 22 24 26 2870605040302010Relative humidity %10Average for summer8642Air speedApprox. 0.1 m/sAverage for winter012 14 16 18 20 22 24 26 28 30 32 34Dry bulb temperature °CFigure 1.1 Effective temperature chart. This chart is postulated from a variety of sources as beingapplicable to the British Isles only. It provides a range of conditions for winter and summer withinwhich most people would feel comfortable, provided that they were not transientbe affected by other factors such as the visual environment and perhaps the occupants'lack of control over the environmental conditions.Subjective temperatureThis is an approach not dissimilar to that proposed by Fanger but simpler and morerealistic to apply since account is taken of fewer variables.Dry resultant temperatureThis is the comfort index adopted in the Guide Section Al, to take account of the effects oftemperature, radiation and air movement. The full expression for evaluation of thistemperature is:t res ˆ [t ri ‡ t ai (10v) 0:5 ]/[1 ‡ (10v) 0:5 ]