A comparison of current evaluation methods for thermal environment applied to garage work

Summary

The thermal environment in 42 garages was measured and compared with the results of questionnaires completed by mechanics working in these garages. In the garages studied, the mean air temperature appeared to be rather low. Mean air velocity was moderate (0.17 m/s), with a significant variation among garages (0.07–0.60 m/s). An accurate estimation of the metabolic activity and clothing factor was made. Four current climate standards were selected to evaluate the climate conditions of the investigated garages, i.e. L-index, L-index (comfort), PMV-index and the ASHRAE-index. It appears that the number of garages within the standards acceptable (or recommended) range varies considerably with the standard used. Converting the different standards to the same basis (80% acceptation) does not reduce this variation. These large differences are explained by evaluation of different parameters on which the standards are based. In order to evaluate the thermal environment in garages, Fanger's PMV-index is recommended, as it shows the greatest sensitivity (0.75) combined with a similar positive predictive value (0.65) compared to the other standards. Moreover, this standard incorporates air velocity, which is shown to be crucial in evaluating the thermal environment in garages.