A LOOK-UP TABLE FOR ET*
Authors: Aynsley, R.M. ; Hope, Peter
New Effective Temperature designated ET* an index for indicating the combined effects of air temperature and
humidity on human thermal response was developed by Gagge et al in 1971. This index is the ASHRAE preferred
index for use in warm humid climates. One reason it is not widely used is the complexity of calculation.
Computation time also becomes a factor in run time of computer software developed to assess energy efficiency of
naturally ventilated buildings in warm humid climates when ET* values are calculated on an hour by hour basis over
The writers have addressed both these problems by precomputing ET* values for the relevant range of air
temperature and relative humidity encountered in warm humid climates and creating a look-up table. The table can
be used with recently published Bin Weather Data. This enables the frequency of occurrence of ET* conditions to
be assessed in terms of hours per year. These tools will help establish quantitative methods for assessing indoor
thermal comfort in buildings with effective natural ventilation during warm humid conditions.