By C.C. Sullivan, Contributing Editor | DAYLIGHTING TECHNIQUES |

SUN, SKY BRIGHTNESS, AND GLOW: MAKING THE MOST OF DAYLIGHT

LEARNING OBJECTIVES After reading this article, you should be able to:

+ DISCUSS the bene ts and ideal kinds of daylighting illumination desired for such interiors as workplaces, libraries, and museums. + DESCRIBE the types of enclo- sure technologies and whole- building design approaches for maximizing bene cial

JEFF GOLDBERG/ESTO, COURTESY CARRIER JOHNSON+CULTURE CARRIER COURTESY GOLDBERG/ESTO, JEFF daylighting. + LIST techniques for improving daylighting performance. + COMPARE the methods or materials commonly used in daylighting applications.

The Tidewater Joint-Use Library, Virginia Beach, Va., has an angled “day- light harvester” that runs its length to maximize available sunlight.

o some project teams, “daylighting” and material degradation caused by ultraviolet means using glass area to admit direct (UV) light. sunlight, period. Yet there are better Building occupants and owners want useful, approaches to illuminating building uniform light, not high-contrast or high-heat interiors. Often, the sun’s direct rays sources, according to surveys like the semi- are the last thing you need for effective nal study led by the University of Washington daylighting. Sunlight comes with high (https://tinyurl.com/zhpx7h3). That’s why solar heat gain—measured as solar controlled and redirected sunlight almost heat gain coeffi cient (SHGC) for various always provides the best approach, while direct types of glazing and translucent materials—and rays may be counted among the least desirable canT lead to glare, occupant thermal discomfort, techniques. Building surfaces and enclosures

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that maximizes the smart use of daylight has a multitude of benefi ts. Energy savings and health ‘THE BEST APPROACH FOR DAYLIGHTING IS TO benefi ts are both achievable.” Natural light, with the full visible light spectrum, has been DELIVER GENTLE, EVEN ILLUMINATION THROUGH- shown to increase alertness and productivity, says Pew. Views to the outdoors also improve OUT A SPACE. THIS DIFFUSED, COMFORTABLE mood and possibly health. Seminal research by DAYLIGHT IS THE BEST FOR VISUAL NEEDS AND Roger Ulrich at Texas A&M University reported an 8.5% advantage in recovery for patients in FOR MINIMIZING ENERGY USE.’ rooms with windows. — LAYNG PEW, AIA, WXY ARCHITECTURE + URBAN DESIGN Daylight is essential to sustainable design ratings as well as health certifi cations, notably the WELL Building Standard. Light helps “mini- receiving direct sunlight need solar control mize disruption to the body’s circadian rhythm,” systems, including shading devices such as says the International Well Building Institute, overhangs and fi ns that may be opaque or which spells out requirements for window per- translucent, solid or louvered, according to formance and design, light output and lighting the Best Practices Manual published by the controls, and task-appropriate illumination lev- Collaborative for High Performance Schools. els to improve energy, mood, and productivity. Canopies, window fi lms, and insulated glazing The effectiveness of daylighting strategies units (IGUs) with internal louvers may also be should be evaluated on the basis of human required. Façades and areas facing north, on usefulness, energy effi ciency, and other factors, the other hand, need ways to maximize daylight says Christopher Alt, RA, Principal and Techni- To renovate a 1990 commercial building in harvest. cal Leader with architecture fi rm Studio Ma, Boston for Columbia “The best approach for daylighting is to Phoenix. Alt’s team uses daylight simulation in Property Trust, design deliver gentle, even illumination throughout a design-phase project modeling in order to as- fi rm Dyer Brown opened up the northwest-facing space. This diffused, comfortable daylight is the sess spatial illuminance qualities, visibility and lobby with a fl oor-to- best for visual needs and for minimizing energy glare, thermal considerations, and the protec- ceiling, point-supported use,” says Layng Pew, AIA, a Principal with WXY tion of building contents. “The 3D simulations glazing system and high- refl ectance, specular wall Architecture + Urban Design, New York. “Design and analyses are especially important in our fi nishes. many museum and cultural building projects, in- cluding some in desert climates, where artifact protection is of paramount concern,” says Alt. Underlying photometrics and daylight modeling are highly effective in the early design phases

DARRIN HUNTER DARRIN to assess a range of project goals, including: n Uniform light distribution n Low glare n Reduction of energy costs n Overall cost effectiveness n Safety and security issues n Maintenance requirements Controlled daylighting is historically elemental to the design of museums, yet recently some cultural institutions have erred on the side of using more artifi cial illumination, including halo- gen and LED sources, and less natural light.

SPECIAL CASES FOR DAYLIGHTING Experts in museum design from Cooper Rob- ertson encourage expanded use of controlled daylight for gallery spaces through careful analy- sis and the application of novel building tech-

48 | BUILDING DESIGN+CONSTRUCTION | March 2017 nologies that “preserve safe light levels and environmental conditions for the art,” says NIC LEHOUX, COURTESY COOPER ROBERTSON Scott Newman, FAIA, a Partner. “Daylighting reduces the need for artificial illumination, allows works to be shown in the full light spectrum for which they were conceived, and accentu- ates the three-dimensionality of sculpture,” he adds. Newman describes the design of the new Whitney Museum of American Art, in Manhattan. For its extensive use of solar illumination, Cooper Robertson and design architect Renzo Piano Build- ing Workshop used fritted glass edges, interior and institutional designs,” says Moss. “For the shades activated by photosensors, and insulat- renovation of the Yuma Heritage Library, we To daylight the new ing glass units with a polyvinyl butyral (PVB) added four double-height structures to serve as Whitney Museum of interlayer. The façade designs respond to the light monitors for the one-story Carnegie town American Art, Cooper Robertson used fritted building’s position or solar orientation. The de- library, a daylighting strategy that transformed glass edges, inte- sign also admits light to wash interior walls and the scale and quality of the user experience.” rior shades activated by illuminate display areas. Other products and assemblies used to admit photosensors, and IGUs with PVB interlayers to At the Florence (S.C.) County Museum, con- tempered, useful solar illumination for daylight- illuminate display areas. trolled natural light illuminates the second-floor ing include view windows, high sidelights with galleries through filtered clerestories and light light shelves, wall-wash toplighting, central and scoops, says Newman. patterned toplighting, linear toplighting, and Whether for museums or any other use, po- tubular skylights. sitioning of openings is critical to the effective- Skylights, roof windows, and other forms ness of daylighting, according to Gregg D. Ander, of toplighting are highly effective for internal FAIA, of Southern California Edison. “The higher light propagation, but they raise similar ques- the window head height, the deeper into the tions about undesirable hotspots, glare, and space the daylight can penetrate,” writes Ander interior wear, says Kevin Krumdieck, AIA, LEED in the Whole Building Design Guide. AP, Principal with Carrier Johnson + Culture. “To Openings “should ideally be composed of two prevent unwanted heating or over-illumination, discrete components: a daylight window and a we assess the skylight orientation (north is view window,” Ander writes. In a typical space, preferred), the roof slope, and the skylight size the daylight window’s sill should be 7½ feet and spacing to distribute the daylight well, while above the finished floor, with a high visible light controlling heat gain and glare,” says Krum- transmission (VLT) of 50–75%. The windows dieck. In some projects, the firm uses solar for occupant view should be located below the panels integrated with sunshade elements to daylight openings, with a lower VLT. mitigate heat from high-angle sun. For some building types, the view windows For office buildings and workplace interiors, often are beside the point. That’s one reason north light is a valuable asset, says Brent D. Zei- Studio Ma Principal Christiana Moss, AIA, often gler, AIA, IIDA, President and Director of Design advocates for clerestory windows and other with Dyer Brown Architects, Boston. “Sunlight fenestration concepts with high sill heights coming from the west, and the setting sun, can ideal for lighting museums and libraries. “For be tough on open workspaces. It can be hot, both qualitative and quantitative reasons, we with long shadows and too much glare on moni- keep going back to clerestory in our cultural tors,” he says. “Morning light from the southeast

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can have a wonderful through lower-height window areas causing visual quality, and in glare, or areas closer to the ceiling plane that the winter months this create excessive brightness during the day. low-angled sunlight Another tool is called dynamic tinting, an appli- helps warm spaces.” cation of smart controls that tracks the sun to Building Teams allow for customized light-zoning strategies. should begin work- The recent addition to Colorado State Univer-

BILL TIMMERMAN, COURTESY STUDIO MA place design analysis sity’s 1964 Morgan Library, in Fort Collins, was by quantifying solar conceived to add seating, computing resources, availability and com- and study space. The school’s administrators paring it with interior wanted a modern glass cube to express their daylight effectiveness safe, open campus while also showcasing sus- and need. For the tainability and effi ciency. “In Colorado, the west- Boston offi ce interiors ern sun is extremely harsh late in the day, mak- of global engineering ing the glare and heat gain on the west façade fi rm Arup, Dyer Brown very hard to mitigate,” says Matt Edmonds, determined that it Project Manager with the facility’s architect, Stu- should locate most diotrope. After considering shades, louvers, and open workspaces on a temperature-based thermochromic glazing, the north side of the the project team selected electronically tint- space, so that those able dynamic glass that can be darkened either areas would receive ample diffused lighting. manually or automatically. Studio Ma added The design team positioned a key shared The electrochomic active glass covers the double-height structures, called space—Arup’s new large, collaborative pan- Morgan Library addition’s two-story western “light monitors,” to try—at the building’s eastern perimeter, where curtain wall, including on operable and egress enhance daylighting it takes advantage of morning light and receives sections. The system is zoned for the upper in the Yuma (Ariz.) Heritage Library. more brightness throughout the day. and lower fl oors, allowing for separate control of each area, as well as activation by exterior TRY ADDING TRANSLUCENCY, photosensors, with a manual override. ACTIVE GLAZING TO THE MIX Other approaches to daylighting glass are Daylight tuning is also accomplished through the also possible. For its Scottsdale Museum of use of varied fenestration materials, including the West, the project team employed a 1.5-inch- glass, polycarbonate, composites and “sand- thick IGU with spectrally selective, low-emis- wich” products, and advanced active glazings. sivity (low-e) coatings and a solar-absorbing Active products include electrochromic glaz- polyvinyl butyral interlayer. PVB is an effective ing, although the term "active" may also be solar-control layer for laminated glass that used to describe sensor-controlled shades and allows high visible light transmission—up to automatic dimming sensors. 75%—while also affording structural integrity, Active approaches tend to make buildings sound abatement, and weather protection to more adaptable to variable sky conditions, sea- the glazing assemblies, says Studio Ma’s Alt. sonal weather changes, and occupant needs, It also reduced energy use 38% compared to says Josh Battles, Manager of Architectural national averages of energy use index. (EUI is Solutions with manufacturer SageGlass. “Elec- the ratio of energy consumed, in Btu, within a trochromic technology means the glass is able building divided by its total square footage.) to tint in accordance with the sun’s position The team for several Connecticut elementary and intensity to control sunlight, heat gain, and schools selected glass enclosure systems to glare,” he says. “By letting sunlight in on cool allow for double-height zones clad in glass for days and blocking it on hot days, the technol- lobbies and libraries, as well as daylight open- ogy reduces energy demand, while increasing ings to ease navigation and inspire learning. occupant comfort and well-being.” At the Columbus Family Academy in New Ha- New applications of electrochromic glazing ven, windows at the ends of each hallway allow include glass panels with multiple tint zones, for easy orientation in the space, according to says Battles, to help reduce transmission architect Svigals + Partners. Every classroom

50 | BUILDING DESIGN+CONSTRUCTION | March 2017 | DAYLIGHTING TECHNIQUES |

It is especially valuable in sunny, hot climates, but can be effective in all climate zones. For example, translucent fenestration made with fi berglass, fi ber-reinforced polymer (FRP) or poly- carbonate facers, and leading-edge translucent aerogel insulation have measured a U-value of 0.05 and insulating effi cacy of up to R-20. As for the daylighting, the illumination is diffused, glare-free, and softened, with VLTs from 5% up to 50%, depending on the insulation selected. In other cases, insulation such as fi berglass batts or an air gap, or both, can be used in place of aerogels. DATTNER ARCHITECTS AND WXY ARCHITECTURE + URBAN DESIGN; INSET: WADE ZIMMERMAN For an adaptive reuse of a commercial box building into the high-end, natural wood-paneled interiors of 1060 Redwood Offi ce Building has windows to the outside and in Mill Valley, Calif., the project team led by many have clerestory windows to Studio VARA and Van Acker Construction used maximize daylight penetration. natural daylighting and ventilation to enhance Similar ideas inform the new its bullpen-style layout and meeting areas. To Sandy Hook School in Newtown, complement the existing building’s industrial Conn., with its large windows and aesthetic, large skylights of translucent panels soaring central lobby of colored glass panels defi ne activity hot spots in the open plan while and metal tree shapes. “To make the concept providing diffused, glare-free daylight, according The design for a sanita- tion garage in Manhattan work best, we designed the building and site to the project team. Faced in polycarbonate, the employed 2,600 custom for optimal daylighting in the fall, winter, and insulated skylights require no shading or other perforated metal vertical spring,” says Julia McFadden, AIA, Project solar protections. On the perimeter, shadow- sunshades to mitigate so- lar heat gain and glare and Architect and Associate Principal with Svigals boxed window openings and black metal panels block vehicle headlights. + Partners. The fi rm specifi ed IGUs and fram- punctuate its façade of corrugated steel panels ing designs to minimize thermal bridging and raised above a dark stucco base. reduce unwanted solar heat gain. Two kinds of The glow of the sky brightness has a powerful glass coatings—one for north-facing windows effect on the mood and performance of offi ce and another for east, west, and south orien- workers, according to studies such as one by tations—provide a neutral appearance and neuroscientists at Northwestern University low refl ectivity, but with high VLT to increase (https://tinyurl.com/jakunkr). daylighting effi cacy. “For the classroom wings, Regardless of the fenestration systems used, colorful vertical fi ns help block direct sun,” says a few factors about daylighting remain constant McFadden. and essential. First, daylighting calculations For school projects like these, daylighting depend on the location’s sky luminance distribu- and outdoor views are central to creating a tion, which allows for “modeling skies under a supportive, inspiring educational experience, wide range of occurrences,” from overcast sky says McFadden, helping students become more (reduced sunlight) to cloudless situations (with aware of their connection to nature and their sunlight), according to Richard Kittler, a physi- surroundings. “The use of glass helps students cist with the Slovak Academy of Sciences. Avail- +EDITOR’S NOTE connect to the natural beauty of the site, and able daylight in a room is linked closely to sky also allows lots of sunlight and views that help brightness, which describes how the sky refl ects This completes the make schools more nurturing and healthy,” she and radiates light, by means of scattering that reading for this course. says. “Colored daylight splashing across the occurs in direct sunlight but also indirectly, as To earn 1.0 AIA CES lobby adds a warm and inspiring touch.” observed with twilight after sunset. This indirect HSW learning units, study the article and scattering creates a very bright light even on take the exam at GLOW AND LUMINANCE overcast and cloudy days. www.BDCnetwork.com/ Translucency is another critical ally in daylight- With these variables in mind, the project DaylightingTech ing applications, one that may be underutilized. team led by Dyer Brown and construction

52 | BUILDING DESIGN+CONSTRUCTION | March 2017 manager Shawmut Design and Construc- ply architectural sun-control strategies, tion executed a $10 million retrofit of a project teams like the one behind a new 1990 commercial building in Boston to addition to the Phoenix Art Museum open up its northwest-facing lobby with show how daylight modeling again can LOOKING FOR A WAY a floor-to-ceiling, point-supported glazing lead to useful design choices. Studio Ma system. Conceived by owner Columbia architects Alt and Moss determined the TO EARN AIA CREDIT? Property Trust, the renovation also ad- optimal overhang depth for a community dresses the building’s sidewalk arcade room overlook, a large window in a space and dark original materials to further otherwise illuminated by clerestories. Check out the brighten up the tenant experience. Dyer Using the modeling program Rhinoceros Brown’s design team added light gray and the daylight tool DIVA, the team newly redesigned pavers under the arcade. In the lobby, studied the room areas with glare and they bumped up surface reflectance those underlit. BD+C university. with the addition of light gray stone and With glare at the overlook window, mica-flecked wall plaster. This improved Studio Ma considered a roof extension illumination in the entry by bouncing or canopy element to protect from over- specular daylight and incidental rays illumination. The question was: How deep into the space. “With elements deep would the overhang need to be to like the frameless glass façade at the optimally address glare without overly entrance, the redesign delivers on the penalizing with loss of daylight? promise of raising the property’s prestige Using the modeling tools, the team and, ultimately, its value,” says the firm’s iteratively tested roof extensions of two Deniz Ferendici. feet and up to 16 feet. They determined The use of glass façades and active the optimal length to be an eight-foot shading mechanisms can allow for even projection from the wall and window.  Online access to continuing greater areas of glass with carefully The Phoenix Art Museum case offers education courses tuned daylight entry. a basic approach to daylighting analy- For a new sanitation garage in New sis for any building. First, identify the  Courses provided to you free York City, a double-skin façade wraps sustainable design principles to test. of charge its acoustical curtain wall with 2,600 Second, isolate and test specific vari- custom-perforated metal fins to vertically ables needed assess those principles.  Credits reported to AIA articulate the massing and mitigate solar Third, record and catalog the test data on your behalf heat gain and glare, says WXY’s Pew. for analysis by the project team. Designed by Dattner Architects in Last, for LEED certification, keep in  Courses in many subject association with WXY, the 425,000-sf mind the basic requirements for daylight- areas – learn about topics municipal building also uses the solar ing in the early design phase, says Coo- you care about control strategy to block views to the per Robertson’s Newman. These include:  Explore case studies, videos, mechanical louvers and garbage trucks n 75% or more of regularly occupied and more from industry experts inside—and to block headlights aiming spaces must be “functionally daylit.” outside—both critical benefits to neigh- This means the area must receive 10 to bors in the trendy downtown district. 500 footcandles, as measured on the They may look like fins, but the equinox at 9 am and 3 pm. 30-inch-wide vertical silver elements are n An extra LEED point is available if Sign up for your free account actually powder-coated aluminum shades 95% of regularly occupied spaces are and start taking courses today! mounted on the entire curtain wall with functionally daylit. a custom bracket system detailed by For green rating programs, the daylight- BDCuniverity.com the architects with manufacturer CS Sun ing analysis points used for an Illumination Controls. A benchmark project for the lo- Engineering Society–based computerized cal government’s Active Design program, simulation must be located 30 inches the garage earned LEED Gold certifica- above the finished floor—a reminder that tion and a commendation for improving natural illumination is needed most at the employee wellness. work plane, on wall areas where paintings In order to properly select and ap- hang, and on students' desktops.+