On the effects of the mean radiant temperature evaluation in the assessment of thermal comfort by dynamic energy simulation tools

Abstract

The European Directive 844/2018, the EN 16798–1 and −2, and the ISO 17772 Standards establish that when designing a new building or energy retrofitting an existing building, the Indoor Environmental Quality must be considered. One aspect of IEQ is thermal comfort, which is affected by the mean radiant temperature, tr. This variable is the only one that an HVAC system cannot control directly. In fact, it depends on the temperatures of the surfaces surrounding the subject which are influenced by the air temperature. It can be calculated using the methods envisaged by the ISO EN 7726 standard or alternative approximate methods.It is therefore important to understand whether the differenttr calculation methods affect the PMV value and, therefore, the classification of the thermal environment according to the EN 16798-1 Standard. For many years, building dynamic energy simulation software tools which integrate energy analyses with the evaluation of thermal comfort have been used for the design and verification of the energy performance of buildings. This paper compares different methods of calculating the mean radiant temperature used by Energy Plus with the Design-Builder interface and analyses the influence of the results on the evaluation of thermal comfort in three buildings.