This paper introduces the equivalent contact temperature (ECT) model for local thermal comfort assessment in contact areas for non-uniform environmental conditions. It aims to complete the comfort evaluation scheme of the equivalent temperature approach included in ISO 14505-2 by the contact areas back and buttocks that are currently neglected in the standard. For the assessment of local and overall thermal comfort of seated persons, these contact areas are of great importance, especially if exposed to personal comfort systems. Person-oriented climatization systems, such as seat heating and ventilation, are much more energy efficient than conventional HVAC systems and allow to incorporate the human individual into the system's control loop. The ECT-approach is formally defined, analytically as well as mathematically derived and validated by a subject study. The results of the subject study (air temperature of 26 °C and 29 °C) confirm the cooling effect due to the seat ventilation and show fundamental correlations between ECTs and body part specific mean thermal votes for buttocks and back.Practitioner summary:The equivalent contact temperature model for local thermal comfort assessment in contact areas for non-uniform environmental conditions is formally defined, analytically as well as mathematically derived and validated by a subject study. It completes the existing equivalent temperature comfort scheme by both contact areas back a nd buttocks to improve thermal comfort assessment.
Keywords: Equivalent contact temperature; contact areas buttocks and back; equivalent temperature; non-uniform thermal environments; thermal comfort.