# Uncertainty Analysis of Thermal Comfort Parameters

## Abstract

International Standard ISO 7730:2005 defines thermal comfort as that condition of mind that expresses the degree of satisfaction with the thermal environment. Although this definition is inevitably subjective, the Standard gives formulae for two thermal comfort indices, predicted mean vote (*PMV*) and predicted percentage dissatisfied (*PPD*). The *PMV* formula is based on principles of heat balance and experimental data collected in a controlled climate chamber under steady-state conditions. The *PPD* formula depends only on *PMV*. Although these formulae are widely recognized and adopted, little has been done to establish measurement uncertainties associated with their use, bearing in mind that the formulae depend on measured values and tabulated values given to limited numerical accuracy. Knowledge of these uncertainties are invaluable when values provided by the formulae are used in making decisions in various health and civil engineering situations. This paper examines these formulae, giving a general mechanism for evaluating the uncertainties associated with values of the quantities on which the formulae depend. Further, consideration is given to the propagation of these uncertainties through the formulae to provide uncertainties associated with the values obtained for the indices. Current international guidance on uncertainty evaluation is utilized.

## Keywords

Thermal comfort Uncertainty evaluation GUM GUM supplement 1 Monte Carlo method## Notes

### Acknowledgments

The National Measurement Office, an Executive Agency of the UK Department for Business, Innovation and Skills, supported the work of the NPL authors through the Mathematics and Modelling for Metrology programme. Financial support of FCT (Portuguese Foundation for Science and Technology) in the context of Project Ref. Pest OE/MAT/UI0219/2014, and Project VALIMED, under the Madeira Regional Programme “Intervir+”, is grateful acknowledged.

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