EVALUATION OF THERMAL ENVIRONMENT IN SHELTERS

Abstract : Various schemes which have been advanced for expressing the significance of a given set of environmental conditions as a single number, or as a semi-quantitative simple phrase, are reviewed. An index of relative strain is developed, similar to that used by Belding and Hatch in their heat stress index, but based on Burton's wet clothes formula for the calculation of actual and relative cooling demands. A chart is developed in which relative strain lines are drawn on a psychrometric chart for standard conditions of activity, clothing, air movement, and radiant heat transfer most likely to be found in shelters. A table is provided for adjusting the reading on the chart for certain non-standard conditions of activity and air movement. The significance of each zone for a standard ''average'' person is expressed in graphic form for such considerations as comfort, discomfort, distress, failure, performance, and tolerance. Further charts indicate the significance of each zone for non- standard states.