Balancing Health and Performance Benefits through Natural Lighting

Understanding how to specify glazing systems that balance access to natural light with thermal performance and building code requirements
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Sponsored by Oldcastle BuildingEnvelope®
By Juliet Grable
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Applications for Glass

There are many potential applications for glass beyond windows and doors. These include skylights and skylight systems, storefronts, window walls, curtain walls, and interior glass partitions. In many cases, these solutions can be used in place of opaque or non-glass systems to optimize daylighting.

Skylight Systems

When it comes to design options for skylights, it’s safe to say that the sky’s the limit. Skylight systems can be designed in almost every conceivable architectural shape. Many manufacturers will work with architects to design and fabricate custom solutions. Skylights range from single units and tubular skylights to canopies and walkway covers to systems that essentially replace all or part of a conventional roof. Such systems can take the shape of a pyramid, hipped ridge, barrel vault, or single slope. Because these systems are structural, they typically include light but strong tubular metal framing. The framing is coated with a protective layer of paint that protects the system from corrosion and weathering. Glass for skylight systems is almost always laminated. Low-e coatings can be specified for thermal performance.


A storefront is a non-load-bearing assembly that forms the entry system and windows of a commercial space. This may include sliding or thermal flush glaze options. Storefronts are generally less expensive than other glazing solutions. “Mall sliders” are economical and convenient sliding glass systems designed for storefronts in malls.

Storefronts must be able to withstand heavy traffic, exposure to the street, and possible vandalism or attempted break-ins. The storefront also provides customers with a valuable first impression.

Storefronts range up to 10 feet high and span a single floor. Storefronts are usually found only on the ground floor, though storefront systems can be used on higher floors if they meet code requirements.

A sleek glass structural glass finwall system in the front complements the functional storefront system on the side of this modern Jaguar Land Rover Dealership in Grand Rapids, Michigan.

Window Walls

As the name suggests, a window wall is wall of glazing that visually connects occupants to the outdoors. Doors may be incorporated into window walls, and the walls can be customized for nearly any desirable configuration. Though they resemble curtain walls, window walls are installed between concrete floor slabs and are significantly less expensive than curtain walls. They do not require fire stopping and can also help attenuate sound.

Window walls are prefabricated in a controlled factory environment and pretested and certified by the manufacturer, which can save time and costs. Often, narrow aluminum frames are used in tandem with glazing to create a clean, contemporary aesthetic. The frames can be thermally broken to improve energy performance. While the daylighting advantages of window walls are obvious, attention must be paid to the increased window-to-wall ratio and appropriate solar control designed in. Window walls can incorporate both vision and spandrel glass to achieve the desired aesthetic. However, architects must incorporate the visible concrete slab of each floor into the exterior building design.

The Cooper Union building in New York City illustrates an original and dynamic strategy for balancing daylighting and energy control using window walls and an exterior treatment of punched stainless steel. The perforated sheets wrap the entire facade, working in tandem with energy-efficient glazing system to control sunlight penetration.

The Cooper Union Academic Building in New York City combines 37,000 square feet of window wall and 18,000 square feet of curtain wall in a sleek, undulating facade.

Curtain Walls

Curtain walls are metal-framed expanses of glazing that are anchored to the concrete slabs of multistory buildings. While glazing is typically installed on-site, some manufacturers offer prefabricated systems. Curtain walls are more expensive than window walls, but they may offer improved resistance to wind and seismic hazards and can accommodate larger spans of glazing. Because they “hang” from the outside of the building, curtain walls enable a continuous expanse of glass and striking aesthetic possibilities. The framing can be thermally broken for enhanced energy performance. Curtain walls require fire stopping to fill the voids between floors.


Architects and designers have the opportunity to improve the health and well-being of occupants by ensuring access to natural light. They can consider a range of glazing systems, from interior glass partitions and window walls to soaring skylights and canopies, in lieu of conventional wall and roofing systems. They can also select glazing to meet the specific aesthetic goals and climate conditions. Designers must carefully balance daylighting goals with building code requirements, energy performance goals, and glare control. An integrated design approach that considers daylighting in tandem with energy performance and other project goals can help ensure a successful outcome. Designers can work with glazing systems manufacturers to select the type of glazing, strength, and aesthetic attributes of the glazing system.

Juliet Grable is an independent writer and editor focused on building science, resilient design, and environmental sustainability. She contributes to continuing education courses and publications through Confluence Communications.

End Notes

1Joseph, Anjali. “Impact of Light on Outcomes in Healthcare Settings.” The Center for Health Design. Aug. 2006. Web. 2 May 2019.

2Mirrahimi, Seyedehzahra et al. “Effect of daylighting on student health and performance.” Computational Methods in Science and Engineering. 2013. Web. 2 May 2019.

3The Economics of Biophilia: Why Designing with Nature in Mind Makes Financial Sense.” Terrapin Bright Green. 2012. Web. 2 May 2019.

4Ulrich, Roger S. “View through a window may influence recovery from surgery.” Science. 27 April 1984. Web. 2 May 2019.

5Joseph, Anjali. “Impact of Light on Outcomes in Healthcare Settings.” The Center for Health Design. August 2006. Web. 2 May 2019.

6Plympton, Patricia et al. “Daylighting in Schools: Improving Student Performance and Health at a Price Schools Can Afford.” National Renewable Energy Laboratory (NREL). August 2000. Web. 2 May 2019.

7The Economics of Biophilia: Why Designing with Nature in Mind Makes Financial Sense.” Terrapin Bright Green. 2012. Web. 2 May 2019.

8Plympton, Patricia et al. “Daylighting in Schools: Improving Student Performance and Health at a Price Schools Can Afford.” National Renewable Energy Laboratory (NREL). August 2000. Web. 2 May 2019.

9Kahn Jr., Peter H. et al. “A plasma display window?—The shifting baseline problem in a technologically mediated natural world.” Journal of Environmental Psychology. 8 May 2008. Web. 2 May 2019.

10Thayer, Julian F. et al. “Effects of the physical work environment on physiological measures of stress.” Lippincott Williams & Wilkins. The European Society of Cardiology. 2010. Web. 2 May 2019.

11Boyce, Peter et al. “The Benefits of Daylight through Windows.” California Energy Commission. January 2003. Web. 2 May 2019.

12Heschong, Lisa et al. “Windows and Offices: A Study of Office Worker Performance and the Indoor Environment.” California Energy Commission. 2003. Web. 2 May 2019.

13Romm, Joseph J. and William D. Browning. “Greening the Building and Bottom Line.” Rocky Mountain Institute. December 1994. Web. 2 May 2019.

14Ander, Gregg D. “Daylighting.” Whole Building Design Guide. 15 September 2016. Web. 2 May 2019.

15Windows for high-performance commercial buildings.” Efficient Windows Collaborative. Web. 2 May 2019.

16Piotrowska, Ewa and Borchert, Adam. “Energy consumption of buildings depends on the daylight.” E3S Web of Conferences 14, 01029. 2017. Web. 2 May 2019.

17Reinhart, Christoph F. “Effects of Interior Design on the Daylight Availability in Open Plan Offices.” Proceedings from ACEEE Summer Studies on Energy Efficiency in Buildings. 2002. Web. 2 May 2019.

18Daylight Dividends: Daylight Resources—Energy Issues.” Lighting Research Center. Web. 2 May 2019.

19Ander, Gregg D. “Daylighting.” Whole Building Design Guide. 15 September 2016. Web. 2 May 2019.

20Moeck, M. et al. “How Much Energy Do Sidelighting Strategies Save?” Lighting Research Center. 2019. Web. 2 May 2019.

21Schneider, Jay W. “Daylighting Guidelines.” Building Design + Construction. 7 January 2011. Web. 2 May 2019.


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Originally published in Architectural Record
Originally published in June 2019