Volume 5, Issue 9 (October 2008)
Comparison of Parallel and Serial Methods for Determining Clothing Insulation
This paper examines the fundamental differences between the parallel and serial methods for the calculation of clothing insulation using a thermal manikin and demonstrates the differences in the insulation values calculated using these two methods. The parallel method is based on the condition that manikin surface temperatures remain uniform (UST), while the serial method is based on the condition that manikin heat fluxes remain uniform (UHF). Eleven clothing ensembles were evaluated on manikins in UST mode. Three of them were also evaluated on manikins in UHF mode. Insulation values were then calculated using both the serial and parallel methods. Results from UST mode showed that the parallel insulation values ranged from 1.24 to 5.79 clo, while the serial insulation values ranged from 1.43 to 7.98 clo. Differences in the parallel and serial insulations increased as the insulation increased, and the serial insulations were approximately 14–38 % higher than the parallel insulations. Results from UHF mode showed that the parallel insulations were 1.30 clo to 5.89 clo and close to the serial insulations of 1.34 clo to 5.99 clo. In conclusion, the methods of insulation calculation should be determined by the operating mode of the manikin. Only the parallel method should be used when manikins are operated in UST mode and only the serial method should be used when manikins are operated in UHF mode. Insulation values calculated using the incorrect method will be misleading.