Opportunities and challenges of using thermal comfort models for building design and operation for the elderly: A literature review

In a progressively ageing society, providing thermally comfortable environments for the elderly has received attention from academics and practitioners. Thermal comfort models lay the foundation to promote the health and well-being of occupants of all ages and to achieve sustainable community goals. However, most existing models are developed for healthy adults and thermal comfort specifically for the elderly lacks understanding, which can result in mismatches between the elderly's thermal requirements and supply. Therefore, this literature study aims to comprehensively analyse the existing research on this topic and identify deficiencies in knowledge. The literature analysis confirms that the commonly used Predicted Mean Vote and Predicted Percentage Dissatisfied (PMV-PPD) index and multi-node thermoregulation models contain limitations in their application for the elderly. The latter models were established based on existing thermoregulation models for young adults by integrating age-related physiological changes and thus have improved their predictive accuracy but this requires further research. Moreover, the thermal sensation and adaptation measures of the elderly have unique characteristics. The effects of thermal adaptation are mainly reflected in the clothing regulating behaviour, physiological skin temperature changes, and the psychological effects of economic factors. This literature review highlights that there is an urgent need to develop elderly-based thermal comfort models considering ageing-related factors, including adaptation approaches. The prospected research direction attempts to fill the existing gaps and contributes to the body of knowledge about the elderly's thermal comfort whilst laying the foundation for indoor environmental design and operation to support the elderly's health and well-being.