Browsing Department of Mechanical Engineering & the Built Environment by Subjects
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The Accuracy of Thermal Comfort Zone, ASHRAE Standard 55-2013. CIBSE Technical Symposium 2016This study examined the accuracy of thermal comfort zone (ASHRAE Standard 55-2013) in four offices in Norway and the UK. Thermal environment of the workplace is arranged according to this standard, which predicts to satisfy over 80% of occupants. However, users report dissatisfaction regarding the thermal environment. This study investigated the application of the most widely used thermal comfort standard in practice. Field studies of thermal comfort with recordings of the thermal environment, survey questionnaires and interviews were applied. The results did not agree with the PMV and adaptive prediction models by the ASHRAE Standard 55-2013. The follow up interviews revealed the significance of individual differences in perceiving the thermal environment and the impact of the availability of thermal control on user satisfaction.
Building Related Symptoms, Energ, and Thermal Comfort in the Workplace: Personal and Open Plan OfficesThis 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.
Energy Efficiency and User Comfort in the Workplace: Norwegian Cellular vs. British Open Plan WorkplacesTwo office layouts with high and low levels of thermal control were compared, respectively Norwegian cellular and British open plan offices. The Norwegian practice provided every user with control over a window, blinds, door, and the ability to adjust heating and cooling. Occupants were expected to control their thermal environment to find their own comfort, while air conditioning was operatingin the background to ensure the indoor air quality. In contrast, in the British office, limited thermal control was provided through openable windows and blinds only for occupants seated around the perimeter of the building. Centrally operated displacement ventilation was the main thermal control system. Users’ perception of thermal environment was recorded through survey questionnaires, empirical building performance through environmental measurements and thermal control through semi-structured interviews. The Norwegian office had35% higher user satisfaction and 20% higher user comfort compared to the British open plan office. However, the energy consumption in the British practice was within the benchmark and much lower than the Norwegian office. Overall, a balance between thermal comfort and energy efficiency is required, as either extreme poses difficulties for the other.