a b s t r a c tOccupant behavior is now widely recognized as a major contributing factor to uncertainty of building performance. While a surge of research on the topic has occurred over the past four decades, and particularly the past few years, there are many gaps in knowledge and limitations to current methodologies. This paper outlines the state-of-the-art research, current obstacles and future needs and directions for the following four-step iterative process: (1) occupant monitoring and data collection, (2) model development, (3) model evaluation, and (4) model implementation into building simulation tools. Major themes include the need for greater rigor in experimental methodologies; detailed, honest, and candid reporting of methods and results; and development of an efficient means to implement occupant behavior models and integrate them into building energy modeling programs.
Despite the fact that buildings are designed for occupants in principle, evidence suggests buildings are often uncomfortable compared to the requirements of standards; difficult to control by occupants; and, operated inefficiently with regards to occupants' preferences and presence. Meanwhile, practitioners-architects, engineers, technology companies, building managers and operators, and policymakers-lack the knowledge, tools, and precedent to design and operate buildings optimally considering the complex and diverse nature of occupants. Building on the success of IEA EBC Annex 66 ("Definition and simulation of occupant behavior in buildings"; 2013-2017), a follow-up IEA EBC Annex 79 ("Occupantcentric building design and operation"; 2018-2023) has been developed to address gaps in knowledge, practice, and technology. Annex 79 involves international researchers from diverse disciplines like engineering, architecture, computer science, psychology, and sociology. Annex 79 and this review paper have four main areas of focus: (1) multi-domain environmental exposure, building interfaces, and human behavior; (2) data-driven occupant modeling strategies and digital tools; (3) occupant-centric building design; and (4) occupant-centric building operation. The objective of this paper is to succinctly report on the leading research of the above topics and articulate the most pressing research needs-planned to be addressed by Annex 79 and beyond.
Significant diversity between occupants and their presence and actions results in major uncertainty with regards to predicting building performance. However, current occupant modelling approacheseven stochastic ones-suppress occupant diversity by focusing on developing representative occupants. Accordingly, existing approaches tend to limit the ability of stochastic occupant models to provide probabilistic building performance distributions. Using occupancy data from 16 private offices, this paper evaluated three hypotheses: 1) occupant parameters have a continuous distribution rather than discrete; 2) modelling occupants from aggregated data suppresses diversity; and, 3) randomly selecting occupant traits exaggerates synthetic population diversity. The paper indicates that samples sizes for the studied occupants would have more appropriately been an order of magnitude higher: hundreds. This introductory paper shows that there are many future research needs with regards to modelling occupants.
In light of recent research, it is evident that occupants are playing an increasingly important role in building energy performance. Around the world, a driving factor for how buildings are designed-and operated in some cases-is the local building codes. Yet, occupant-related aspects of building energy codes have traditionally been simple because: 1) occupants are often seen as a source of uncertainty that cannot be reconciled by current code methodologies and language, and 2) the codes have not kept up with the recent surge of interest and importance of occupants. This paper provides a review of 22 international building energy codes and standards by first comparing quantitative aspects and then analyzing rules and approaches mandated by the codes. The review of requirements for prescriptive and performance path requirements revealed a wide range of occupant-related values, approaches, and attitudes. For example, a key value such as occupant density varies by nearly a factor of three between countries' codes, which among other things underlines the need for development of locally tailored occupant behaviour models for future occupant-centric building performance standards and codes. Moreover, occupants are often referred to only implicitly; the level of optimism that occupants make energy-saving actions varies greatly; and, only a few codes address occupant feedback and system usability. Based on the findings, a set of initial recommendations for future building energy codes is made. The focus in this paper is offices, though the general recommendations are applicable to other building types.
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