Enhanced effects of footwarmer by wearing sandals in winter office: A Swedish case study

Abstract

Human-centred thermal environment conditioning can guarantee thermal comfort needs of human occupants in their micro-environments by using localized heating/cooling devices. Meanwhile, less intensified thermal conditioning of unoccupied surrounding environments can achieve heating/cooling energy efficiency. The concept was originated from task/ambient conditioning, which was developed for personal comfort systems. Most of the localized heating/cooling devices are workstation based or chair based. Task conditioning would become more closely to targets (human bodies) by using special clothing materials or thermoelectric elements. From thermal physiological viewpoints, thermal stimulus to thermally sensitive body parts may generate better results for not only local thermal comfort but also for whole body thermal comfort. Thermal stimulus to the extremities (feet) has demonstrated good thermal comfort effects. Scandinavians are accustomed to outdoor harsh environments and prefer wearing heavy shoes' outdoors in winter. They have the habit of changing heavy shoes to sandals when entering offices, which give the opportunity to enhance localized heating effects of footwarmers by reducing shoes’ thermal resistance. Climatic chamber tests with 32 Nordic subjects were performed under different indoor ambient heating temperatures with/without the aid of footwarmers. With footwarmers and sandals, indoor heating temperature at 16°C was acceptable, which achieved energy efficient thermal comfort.