View and environmental quality in buildings

Humans spend a significant portion of their lives indoors, and the hours spent inside buildings can affect occupant health and well-being and the environment. Maintaining a comfortable indoor environment usually requires systems to condition the space, and this is responsible for roughly one-third of global primary energy use. To address this conflict, researchers and designers have long focused on developing strategies that simultaneously achieve high levels of indoor environmental quality (IEQ) and energy efficiency in buildings. This dissertation focuses on the building envelope, specifically windows, as an essential component affecting both dimensions. Window design and operation can impact multiple environmental factors, such as view, daylighting, thermal profile, acoustical comfort and air quality, which can affect both occupant and energy use. In order to promote healthier and more sustainable buildings, it is essential to understand the integrated IEQ effect of building envelope design and provide tools that can support designers to consider these effects in the design process. As such, this dissertation addresses the following questions and related areas: 1) How can multiple IEQ factors be considered and assessed simultaneously in the design process? Is there a visualization method capable of simultaneously comparing the effects of the building envelope on IEQ factors? 2) How can a window view be evaluated? In what way and how much does a window view affect people? Advanced simulations and visualizations, a literature review, controlled laboratory and virtual reality studies with participants, and statistical analysis were used to explore these topics. I conducted the studies as part of a research team. We developed and evaluated an integrated workflow of ventilation, thermal, and luminous analyses which introduces a potential way of incorporating these three metrics into the design process. The concept of environmental autonomy, that is, a building’s ability to maintain a comfortable environment independently, is central to the workflow. Relatedly, we established the new metric of ventilation autonomy, and assessed the advantages and limitations of applying the three autonomy metrics with building performance simulations. We created a novel visualization to display the hourly and yearly environmental autonomy values, which categorizes nine combinations of thermal and visual comfort values with ventilation autonomy to illustrate the trade-offs between these performance metrics. Of the performance metrics of the building envelope, this dissertation focuses on view as it is a relatively under-studied area. We proposed a framework for the assessment of view quality based on three primary variables (i.e., content, access, and clarity) derived from a review of design standards and certification systems. The key characteristics of each variable were described, and we proposed a conceptual index to evaluate the quality of a view. While discussing the index, we summarized design recommendations for integrating these variables into the building process and identified knowledge gaps for future research. We quantified the effect of having a window view on thermal comfort, emotion, and cognitive performance using a randomized crossover laboratory experiment with 86 participants in spaces with and without windows. We conducted the experiments in the climatic chamber at slightly warm conditions. The findings were that 1) people close to a window may be more forgiving of small deviations in thermal comfort which could lead to energy savings through setpoint adjustments; 2) having a window improves psychological well-being by enhancing positive emotions and reducing negative ones; and 3) providing a visual connection to the outdoors supports working memory and concentration that may be directly related to a person’s work performance. We developed a view access index to consider occupant satisfaction with the extent of the view. Participants evaluated building designs in a virtual reality environment, and, based on the results, we assessed the effects of a window view’s geometric variables on satisfaction in the workplace. We found that the WWR and percentage of the visual field occupied by window view are the primary variables on occupants’ satisfaction with the amount of window view. Based on the data, we developed a view access index while discussing the effectiveness of the index and further studies need to build a more holistic understanding of the complexity of view access in the physical environment. This dissertation contributes to the building industry and the scientific research community by providing empirical evidence from studies of human subjects and developing a set of tools or guidelines which will ensure high-quality indoor environments and views which, in turn, will lead to the design, construction, and operation of buildings that enhance the physiological and psychological well-being of their occupants while minimizing energy use.

Advisor: Schiavon, Stefano SS