Influence of Measurement Uncertainties on the Thermal Environment Assessment

ISO 7726 Standard describes both the measurement techniques and the related metrological performances of instruments required for the assessment of the thermal environment. Unfortunately the calculation of required discomfort and stress indices rarely takes into account the evaluation of single measurement uncertainties and their effect on the thermal environment assessment. To assess the uncertainty in the determination of Predicted Mean Vote (PMV) and the Predicted Percentage of Dissatisfied (PPD) indices, required by ISO 7730 for the verification of the environment conformity, typical uncertainties in the measurement of both physical (the air temperature, the mean radiant temperature, the air velocity and the relative humidity) and subjective parameters are calculated. In order to verify the conformance of comfort indices measured by means of different measurement techniques and devices, some experimental tests in three typical environments have been carried out: i) residential; ii) office; iii) industrial. To highlight both the compatibility of measurement and the suitability the tests were carried out using three special comfort-analysis data-loggers each provided with different sensors characterised by different instrumental uncertainties.