Behind the Facade: Evaluating the Effect of Facade Design on Daylight Admittance and Perceptual Assessments

Abstract

Creating and evaluating architectural spaces is a mixture of art, science and engineering, but our understanding of the qualitative aspects of space, and the relationship between subjective reactions (sensory/perceptual experience) and physical stimuli remain incomplete. There is a disconnect between environmental values measured through simulation and users’ sensory and perceptual experiences. Designers and architects have historically relied on performance criteria, such as light levels or energy demand, to assess a design’s performance. However, the proliferation of digital tools for architecture has changed the traditional design/build process, creating new opportunities to optimize design and integrate complexity in response to simulated performance. Building facades are one of the most challenging architectural elements to design, requiring aesthetic, performance and functionality concerns to be integrated. A successful building interior depends heavily on the facade’s design, and on a juxtaposition of different spatial volumes and light conditions. Natural light is one of the critical aspects of architectural spaces; it influences ambiance, overall atmosphere, and occupants’ perceptions, whether positively or negatively. However, many lighting metrics focus on quantifying light on horizontal work surfaces, thus overlooking the importance of daylight perception, ambiance, and the dynamic nature of natural light, as affected by facade design. This dissertation focuses on the design of building facades: their pattern, complexity, and effect on daylight distribution and occupants’ visual impressions. The objective of the studies described is to enhance occupants’ experience of built environments through the integration of building science, technology and design. It employs an approach new to architectural research—Conceptual Content Cognitive Mapping—to identify attributes that might provide better insight into questions of light quality. The method was used to survey the concepts people find relevant to their experience of daylight in an office environment. A simulation method developed to understand the effect of facades’ design geometry on daylight ingress and distribution is introduced. It calculates the spatial illuminance and luminance distribution through building facades, providing hourly light values for a full year. Iteration allows simulation data to be traced back to the building facade, allowing further improvement of its design. This novel method promotes the integration of formal building design with sustainable practices. An experimental study using 360° HDR renderings of office environments in virtual reality (VR) was conducted to gain insight into the effect of facade design and light distribution on participants’ subjective impressions of a space. The results indicate that both color and furniture have statistically significant effects on attributes of the interior, and on participants’ perceptions of brightness. Users’ overall preference for a space relates less to actual measured lighting values and more to the overall design of the environment. The results highlight the importance of occupants’ visual perception alongside energy use considerations. The need to bring natural light into spaces is not merely to support tasks; it is also essential to human comfort and environmental sustainability. This research contributes a new method to create and evaluate building facades that allows designers to understand the effect of facade design on natural light propagation; its iterative nature allows designs to be adjusted for improved performance. This research also pushes boundaries and engages in dynamic new debates regarding qualitative assessment of architectural environments in VR by using three-dimensional scenes rendered in VR for user preference studies.