Daylighting Design Process: Two Cases

Increasing complexity and demands for high performance within architecture have compelled new ways of confronting traditional design processes. Two recent projects — the design for the upcoming Austin Central Library by the joint venture of Lake|Flato Architects and Shepley Bulfinch, and the McGarrah Jessee office renovation by McKinney York Architects — illustrate how daylighting can act as the primary driver in defining and deploying a strategy for design. While each architect utilized a different approach, both cases highlight smart and meaningful methods for creating compelling daylit spaces.

Lake|Flato-Shepley Bulfinch initiated both learned-instinct and empirically derived design to engage a natural lighting strategy for the Austin Central Library, which broke ground this past May and is expected to be completed in the summer of 2016. As the library will be located in an urban yet relatively exposed downtown site, all facades were specifically tuned to respond to their respective solar orientations. Although this allowed the perimeter spaces controlled access to natural light, the design's stout footprint demanded a more rigorous scheme to drive daylight to the core of the building. Early programming studies and an integrated sustainability charette had created an opportunity for the design team to incorporate a primary rooftop daylighting element with a generous central public atrium, pushing library and administrative functions to the solar-tuned outside edges of the floorplan.

With collaboration from the Integrated Design Lab from the University of Washington in Seattle, standard daylighting assumptions were applied to several preliminary design iterations of the library's central atrium. The culmination of this effort was an arrangement of large north- and south-facing roof monitors bookending a glazed light well. This element was tasked with both collecting direct light to wash interior atrium walls and driving soft ambient daylight deep into the space as general illumination. Informed daylighting principals had guided the design team in the application of a solar-centric building design; however, the plan needed to be proven and tuned quantifiably.

As the effects of light are scalable, a physical model was constructed at a scale appropriate to gathering illuminance data and producing interior false-color luminance maps and daylighting photos. The daylight consultant, lighting and interior designers, and architects assisted in this design scrutiny, utilizing actual outside solar conditions that allowed for immediate analysis and interpretation of design implications. Based on these observations, the atrium’s aperture configuration was modified on the fly, reducing monitor glazing area and changing light well geometry to maximize daylighting performance. Additional confirmation of the design team’s physical model findings was ultimately derived through digital 

model and analysis processes, also completed in partnership with the Integrated Design Lab.

When approaching the rehabilitation of the once-iconic, modernist American National Bank building in downtown Austin in 2010, McKinney York Architects developed straightforward yet elegant procedures to maximize the impact of natural light on the proposed design. At some point, a tinted film had been applied to the fully glazed north facade, significantly reducing interior light levels and casting a queasy shade on an entry atrium and in the second floor perimeter offices. In addition, partitions and private office planning had severely limited access of natural light to a majority of the interior. By relieving the curtain panels of their shaded coatings, introducing more open space planning, and removing dividing panels between offices and the now light-filled atrium, the design team dramatically bolstered natural lighting levels within the building immediately.

The west facade of the original building was composed primarily of brick. It was an intimidating mass lacking any connection between the interior and exterior. Although this design move may have simultaneously served the design directives of modernism and the necessity to shield a potentially harsh western exposure, downtown Austin had grown. The surrounding high-rises now provided shade to this face of the building, giving the design team the freedom to introduce apertures and a much-needed connection on this side. Striking a balance between external shading patterns and interior spatial layouts requiring specific qualities of lighting, window punches were thoughtfully carved into the brick exterior. A larger void spans two stories and creates a balcony, bringing balanced daylight further into the rear of the building. The effect is a strategic increase of natural light in the building and a randomized pattern of apertures along a once-stark brick facade.

McKinney York was able to devise a daylighting strategy that embraced the lighting requirements of the client and leveraged factors typically considered as constraints to achieve a carefully tuned and tactical architectural response. Furthermore, as the project expands from the now-completed second floor renovation to a presently unoccupied third, lessons learned regarding nuanced, owner-driven lighting expectations have begun to inform design in a feedback scenario. The more open-ended daylighting design approach employed by Lake|Flato-Shepley Bulfinch was able to reconcile similar complex and stringent program-driven lighting needs through testing-based iteration. The formulaic procedure of daylighting design deployed in the Austin Central Library has manifested a direct and holistic response to specific solar conditions, while McKinney York’s reactive and in-situ method of evidence-based daylighting strategy has produced a project that is tailored and appropriate, yet relaxed.

This article is expanded content for Texas Architect, July/August 2013.