Comfortable floor temperatures for radiant floor heating in Southern China

Yuxin Wu, Hong Liu*, Baizhan Li, Xingyu Lu, Lu Chen, Risto Kosonen

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

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Abstract

The use of floor radiant heating systems is increasing every day in Southern China. However, designers and users are constantly trying to find how to choose a suitable floor temperature range based on human comfort. This study summarized and analyzed the comfortable floor temperature range of radiant floor heating systems from three aspects: Standard interpretation, literature research, and human experiments. The thermal comfort standards, including GB/T 50785-2012, ASHRAE 55-2020, ISO 7730:2005, ISO/TS 13732-2-2001, and ISO 13732-1:2006, were reviewed. An acceptable range of 19-29℃ (PD<10%) was recommended as the optimal floor temperature in these standards. In addition, building design codes EN 1264-2:2008 and EN 15377-1:2008, GB 50019-2015, GB 50736-2012, and JGJ 142-2012 were reviewed. The acceptable radiation floor temperature range for European building design codes was also specified as 19-29℃, whereas for Chinese design codes range of 24 (or 25)-26 (or 27)℃ with an upper threshold of 28 (or 29)℃ was recommended. However, a literature review of experiments and field studies showed that East Asia preferred higher floor temperatures than the recommended ranges in these standards, for example, 27-33℃ in Korea and 26-30℃ in Japan according to climate chamber studies, and could be as high as 33.6-38.8℃ in a field study. Human experiments were conducted in a typical room with a radiant floor heating system located in a residential building in Chongqing. A total of 45 subjects were recruited to experience the heating system with six different floor temperatures: 25, 27, 29, 31, 33, and 35℃. The subjects were seated with bare feet to evaluate the perceptions related to floor temperatures as follows: Thermal sensation vote (TSV) of feet, thermal expectation of floor temperature, and thermal comfort of feet. The results of the experiments also revealed that the local people in the hot summer and cold winter (HSCW) climate zone of China preferred higher floor temperatures than that recommended in standards or neutral conditions. For long-term occupancy (30-120 min), the neutral floor temperature was approximately 28℃ with an upper threshold of 32.5℃ (i.e., TSV=+0.5), the comfort temperature range was approximately 29-32℃, and the preferred temperature was about 32℃ for most subjects. For shortterm occupancy (1 min), thermal comfort and preference were affected by various factors, and their values were different for subjects of different ages. For subjects aged 16-27 and 30-47, the preferred floor temperatures were 33 and 35℃ for short-term occupancy, respectively, but the difference was reduced with time for long-time occupancy. Considering the fact that the acceptable floor temperatures could be affected by various factors such as floor materials, thermal history, activity levels, and skin conditions of occupants, conservation values from this study were recommended. Therefore, for an average person in normal conditions, the suitable floor temperature range in the HSCW climate zone of China is recommended to be 25-29℃ with an upper threshold of 32℃ for long-term occupancy and 34℃ for short-term occupancy.

Translated title of the contributionComfortable floor temperatures for radiant floor heating in Southern China
Original languageSimplified Chinese
Pages (from-to)2476-2485
Number of pages10
JournalKexue Tongbao/Chinese Science Bulletin
Volume66
Issue number19
DOIs
Publication statusPublished - 18 Jan 2021
MoE publication typeA1 Journal article-refereed

Keywords

  • Floor temperature
  • Hot summer and cold winter climate zone
  • Radiant floor heating
  • Thermal comfort
  • Winter

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