SE-2417 -- The Role of Clothing in Meeting FEA Energy Conservation Guidelines

During the summer and winter of 1974, the Federal Energy Administration (FEA) established temperature gUidelines for winter heating and summer cooling by attempting to lower or raise the desired working condition by 6 deg F (or 3 deg C) respectively, about the optimum level 75 F (23.9 C) currently set by ASHRAE STANDARD 55-74. Their gUidelines for winter indoor temperatures were 68 - 70 F (20 - 21.1 C) and for summer 78 - 80 F (25.6 - 26.7 C) or a proposed 80 - 82 F (26.7 - 27.8 C). The summer's settings should be accomplished without humidity control and reheat.

Both the Fanger comfort equation (1) and our earlier model of temperature regulation (2 and 3) can be used to deduce the options available to the heating, ventilating and air-conditioning engineer in m~eting the above FEA guidelines. These options are briefly summarized in Table 1. During the summer, the discomfort caused by a 6 deg F (3 deg C) rise in Ta could be balanced theoretically by a drop to low relative humidity. Radiant cooling is impractical. The same level of comfort could be maintained if the air movement were raised to the 75 fpm (0.4 .m/s) level. Both these solutions may well require extensive electric energy in the form of air-conditioning equipment and fans. The same 6 deg F (3 deg C) rise in Ta could also be balanced theoretically if the normal clothing insulation were reduced to a 0.2 Clo level, which insulation level was actually worn by only 5% of males but by 43% of females during our 1974 'summer survey for FEA in New York#. An intrinsic Clo level of 0.4 was observed to be worn by about 50% of the males and females. During both these surveys people dressed for work according to season rather than for their expectations of the indoor temperature. From the above relationships, as has already been recognized by the FEA,. the most practical first order compromise between a need for energy conservation and maintenance of thermal comfort in the summer is the use of less insulative clothing during office work.