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A systematic investigation of thermal comfort compliance criteria

University of British Columbia

Thermal comfort impacts occupant health and productivity and is responsible for a significant portion of the total building energy consumption. However, the compliance criteria in current standards to assess thermal comfort in a building’s operation phase are mostly based on a theoretical thermal comfort model (predicted mean vote—PMV) derived from laboratory studies and lack validation from data in real buildings. The research objective is to use field-based data to systematically investigate whether current point-in-time and long-term compliance criteria can reliably predict subjective evaluations of thermal environments. First, an extensive bibliometric analysis of 146 post-occupancy evaluation (POE) projects introduces the state-of-the-art and state-of-the-practice of approaches for field data collection. Then, an analysis of ASHRAE Global Thermal Comfort Database II demonstrates that tiered PMV classes are not appropriate for thermal comfort assessment at a point of time, and we proposed a new approach to derive acceptable temperature ranges as the point-in-time compliance criteria. The derived acceptable temperature ranges in real buildings using this new method are wider than the current standards mandate. Last, using continuous thermal measurements and occupant feedback in four air-conditioned office buildings in Sydney, an assessment of 23 existing and 36 new long-term thermal comfort indices (as the long-term compliance criteria) and their correlation with the occupants’ long-term thermal satisfaction found that the majority of existing indices, especially those based on PMV index, had a weak correlation with thermal satisfaction. The percentage of time outside specified temperature ranges was the best-performing index from the standards (r=-0.63). The newly proposed index based on the percentage of time that daily temperature range is greater than a threshold reported the strongest correlation (r=-0.8) with thermal satisfaction for the used dataset. The results suggest that occupants in real buildings can accept a wider temperature range at a point of time than expected, and their long-term thermal satisfaction with a space is dominated by the frequency and severity of temperature excursions outside an acceptable range and beyond a daily variability threshold. This research informs future amendments of the point-in-time and long-term compliance criteria in international standards to reduce energy consumption in building operations.

Text

2020-03-02

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/73645

Civil Engineering

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/