This is a repository copy of A review on recent developments of thermoelectric materials for room-temperature applications.

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The aim of this research is to investigate the application and performance of an advanced personal comfort system, a thermal chair, using Computational Fluid Dynamics (CFD), Building Energy Simulation (BES) and field test analysis. The thermal chair permits individual control over their immediate thermal environment without affecting the thermal environment and comfort of other occupants. A comprehensive review on the existing research on the design and performance of various personalised thermal control systems was carried out. A prototype of a thermal chair was designed for the study and tested in an open plan office during the heating season in Leeds, UK. 45 individuals used the chair in their everyday context of work and a survey questionnaire was applied to record their views of the thermal environment before and after using the chair. The performance of the chair was investigated through CFD simulations (ANSYS Fluent) providing a detailed analysis of the thermal distribution around a thermal chair with a manikin. Furthermore, a model of a three-story office building with thermal chairs were created and simulated in the commercial BES software, IES Virtual Environment. The benchmark model of the building was validated with previous work and good agreement was observed. The results showed that user thermal comfort can be enhanced by improving the local thermal comfort of the occupant. The additional plug-load energy from the thermal chair was significantly less as compared to the heating energy saved by adjusting the heating set point by 2ºC during the heating season. Monthly heating energy demand was reduced by 27% on January and 25.4% on February. Furthermore, the results of the field study revealed 20% higher comfort and 35% higher satisfaction level, due to the use of thermal chair.

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The neutral thermal sensation (neither cold, nor hot) is widely used through the application of the ASHRAE seven-point thermal sensation scale to assess thermal comfort. This study investigated the application of the neutral thermal sensation and it questions the reliability of any study that solely relies on neutral thermal sensation. Although thermal-neutrality has already been questioned, still most thermal comfort studies only use this measure to assess thermal comfort of the occupants. In this study, the connection of the occupant’s thermal comfort with thermal-neutrality was investigated in two separate contexts of Norwegian and British offices. Overall, the thermal environment of four office buildings was evaluated and 313 responses (three times a day) to thermal sensation, thermal preference, comfort, and satisfaction were recorded. The results suggested that 36% of the occupants did not want to feel neutral and they considered thermal sensations other than neutral as their comfort condition. Also, in order to feel comfortable, respondents reported wanting to feel different thermal sensations at different times of the day suggesting that occupant desire for thermal comfort conditions may not be as steady as anticipated. This study recommends that other measures are required to assess human thermal comfort, such as thermal preference. Practical application: This study questions the application of neutral thermal sensation as the measure of thermal comfort. The findings indicate that occupant may consider other sensations than neutral as comfortable. This finding directly questions the standard comfort zone (e.g. ASHRAE Standard 55) as well as the optimum temperature, as many occupants required different thermal sensations at different times of the day to feel comfortable. These findings suggest that a steady indoor thermal environment does not guarantee thermal comfort and variations in the room temperature, which can be controlled by the occupant, need to be considered as part of the building design.

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Abstract:This study compared building-related symptoms in personal and open plan offices, where high and low levels of control over the thermal environment were provided, respectively. The individualized approach in Norway provided every user with a personal office, where they had control over an openable window, door, blinds, and thermostat. In contrast, the open plan case studies in the United Kingdom provided control over openable windows and blinds only for limited occupants seated around the perimeter of the building, with users seated away from the windows having no means of environmental control. Air conditioning was deployed in the Norwegian case study buildings, while displacement ventilation and natural ventilation were utilized in the British examples. Field studies of thermal comfort were applied with questionnaires, environmental measurements, and interviews. Users' health was better in the Norwegian model (28%), while the British model was much more energy efficient (up to 10 times). The follow-up interviews confirmed the effect of lack of thermal control on users' health. A balanced appraisal was made of energy performance and users' health between the two buildings.