Kyle Konis

Visual Comfort Analysis of Innovative Interior and Exterior Shading Systems for Commercial Buildings using High Resolution Luminance Images

Abstract The objective of this study was to explore how calibrated high dynamic range (HDR) images (luminance maps) acquired in real world daylit environments can be used to characterize, evaluate, and compare visual comfort conditions of innovative facade shading and light-redirecting systems. Detailed (1536 × 1536 pixel) luminance maps were time-lapse acquired from two view positions in an unoccupied full scale testbed facility. These maps were analyzed using existing visual comfort metrics to quantify how innovative interior and exterior shading systems compare to conventional systems under real sun and sky conditions over a solstice-to-solstice test interval. The results provide a case study in the challenges and potential of methods of visualizing, evaluating and summarizing daily and seasonal variation of visual comfort conditions computed from large sets of image data.

Leveraging ubiquitous computing as a platform for collecting real-time occupant feedback in buildings

Building occupants represent a rich source of information for evaluating environmental design practices and building operations. This article presents a scalable diagnostic technology for collecting real-time indoor environmental quality (IEQ) feedback from building occupants: an interactive desktop polling station. The device demonstrates the potential of ubiquitous computing, a model of human–computer interaction in which information processing is integrated into everyday objects, to engage occupants in providing IEQ feedback in real work environments. Example data from a field study of a high-performance office building are presented demonstrating the applicability of multiple devices to acquire detailed feedback over daily and seasonal variations in climatic conditions. Sample results show how polling station data can help identify the frequency and magnitude of discomfort with the spatial and temporal granularity needed to assess, validate, and improve the performance of environmentally responsive building technologies, controls, and design strategies. Analysis of repeated-measures subjective assessments paired with concurrent physical measurements is performed to demonstrate how existing standards and assumptions for occupant comfort could be evaluated and refined using detailed occupant feedback from buildings in use. Results are discussed regarding implications for improving decision-making for the design, certification, and operation of environmentally responsive buildings.

Innovative Daylighting Systems

The building facade and perimeter zone represents a complex design integration challenge due to the diverse array of design and functional requirements paired with the increasing number of energy and environmental objectives set by design teams seeking to achieve a low-energy design concept that simultaneously supports a high level of indoor environmental quality. As designers seek to integrate daylighting within an efficient whole-building energy strategy, it is challenging to manage trade-offs between performance objectives such as envelope thermal performance, lighting and HVAC energy demand with human factors such as visual comfort, daylight availability, visual connection to the outdoors, and personal control. This requires an integrated approach to the application of technology, informed at a fundamental level by empirical knowledge of end-user needs. The following sections define four key areas of advancement for daylighting technologies that have the potential to help enable high-performance daylit buildings with enhanced indoor environmental quality.

The Role of Metrics in Performance-Based Design

To evaluate the performance of buildings in use and to predict performance during design, it is necessary to identify what the appropriate measures of performance should be, when and how measures should be collected, and how results will be interpreted to determine success or failure.

A Performance-Based Design and Delivery Process

The emergence of low energy and Zero Net Energy (ZNE) building performance requirements combined with a growing array of human-factors objectives for light is driving a reversal of the conventional process of design and performance analysis. Rather than using a predetermined design as a starting point for analysis, practitioners and researchers are exploring how performance requirements can be used to identify promising solutions among multiple early-stage design alternatives. In an ideal case, exploration begins in the earliest stages of conceptual design, enabled using iterative, simulation-based analysis and informed by emerging “form-finding” workflows. In a conventional design process, energy/environmental analysis tools are rarely used to inform design decision-making in early stages of design, if at all. Rather, analysis occurs after design development, often for code-compliance purposes or to obtain green building certification. Consequently, feedback from analysis cannot be usefully incorporated into changes to the project that may improve comfort and energy efficiency. Because the largest impacts on project performance are generally established by decisions made in early stages of design, it is critical for performance evaluation to be integrated into the conceptual and schematic phases of design, where significant changes can be made without large impacts on project cost or schedule. Furthermore, decision-making about design doesn’t stop at the construction documentation stage but may continue through ongoing value engineering, construction, outfitting and commissioning of the final building. It may even continue to the stage where new occupants experience the space and learn how it is designed to support their work. These activities can be facilitated by the use of various types and scales of physical mockups, beginning early in design schematics and continuing into the construction phase to fine tune the interactions between a variety of integrated systems, their controls and the building’s occupants. Whole-building performance specifications, building energy benchmarking and disclosure requirements, outcome based codes and energy-performance-based procurement add additional incentive for design teams to seek mechanisms for reliable, performance feedback throughout all stages of design and project delivery. Climate also plays a critical role in the performance-based design process. In addition to the integration of on-site energy harvesting technologies, projects targeting low or ZNE outcomes often implement passive environmental control strategies (e.g. solar control, natural ventilation, thermally charged/discharged mass, daylighting), which must be carefully designed in response to local climate and context. Therefore, simulation tools must be capable of reliably modeling the effects of the local climate and urban context as well as the behavior of passive systems and occupant impacts. Finally, the shift towards environmentally responsive design strategies places a renewed focus on the role of building occupants in project performance, both in terms of long-term acceptance of comfort conditions in more dynamic indoor environments, as well as in terms of occupant interaction with the building energy concept.

The Challenge of Effective Daylighting

Effective use of daylight in buildings is a fundamental consideration for minimizing the carbon impacts of the built environment and for creating indoor environments that support the comfort, performance and well-being of building occupants. Highly glazed, “transparent” facades have become iconic images for buildings promoted as “sustainable,” “green,” or “high-performance,” but these designs often fail to capture the claimed energy savings and may be thermally and visually uncomfortable. Little guidance exists for designers to examine how human-factors objectives such as daylight sufficiency, visual comfort and view should be defined, measured, and evaluated in context with whole-building energy objectives to establish confidence that goals for project performance can be realized after value engineering, construction, commissioning and occupancy. The integration of facade technologies, controls, and other building systems with occupant needs and the reality of building operations is a complex task, which requires a comprehensive and continuous approach. This book argues that effective daylighting requires the development of strategies and methods that acknowledge the needs and behaviors of building occupants as a critical determinant of long-term energy performance. The book defines effective daylighting with specific energy and human-factors performance objectives. It presents a range of promising daylighting design strategies and discusses them in context with simulation-based workflows and project case studies. Finally, the book presents and discusses the ongoing evolution of the glazing, shading and light control technologies and systems that underlie daylight solutions, and the applicability of emerging methodologies for optimizing and validating daylighting performance.

Validating Performance from the Perspective of End Users

Effective daylighting requires rethinking the simplified approach to glazing and facade systems to acknowledge the needs and behaviors of building occupants as a critical determinant of long-term performance. Occupants represent a rich multi-sensory source of information on environmental performance. This chapter argues that a lack of human factors data from buildings in use leads to environmental design that is largely detached from the preferences or needs of building occupants, with cascading implications for occupant comfort and energy use. Emerging methods for collecting human factors data on Indoor Environmental Quality (IEQ) are presented and discussed for integrating detailed occupant-feedback into building evaluation, operation, and the design process. This chapter concludes by proposing an approach to environmental design informed by examination of occupant behavior, personal modifications, and subjective assessments of IEQ and speculates on how this approach may lead to better outcomes for building occupants.