Renzo Piano Pavilion, Kimbell Art Museum
Fort Worth, Texas
Architects: Renzo Piano Building Workshop, kendall/heaton associates
Lighting designer: Arup
Louis Kahn’s Kimbell Art Museum building in Fort Worth, Texas, is widely considered to be one of the best spaces in the world for viewing art, largely because of the silvery ambient light that seems almost magically to fill the concrete vaults of its roof. When the museum commissioned Renzo Piano Building Workshop to design an expansion to this lauded facility, it requested a continuation of that light condition. “I think the light in the Kahn building is just about the most ideal light I’ve ever seen for viewing paintings and other art,” said Eric Lee, director of the Kimbell Art Museum. “That’s the gold standard for us.”
Of course, the Kimbell did not want a knock-off. The institution wanted the addition to be very much grounded in the 21st century, and sustainability was central to this goal and a large part of the lighting design.
The new building, known as the Piano Pavilion, bears a close kinship with the architect’s other Texas art spaces—The Menil Collection in Houston and The Nasher Sculpture Center in Dallas—in that it features skylit galleries with sunlight modulating hardware on the roof. While the previous projects feature static shading systems—baffles and perforated screens—the Kimbell addition’s skylights are shaded by a motorized louver system outfitted with photovoltaic arrays. The louvers open to face south, for the PVs, at five-degree increments. Arup provided the museum with a table indicating the number of footcandles of daylight a setting will provide at any time of year, giving curators the flexibility to set the amount of light for an exhibition’s needs. The louvers are also capable of rotating 180 degrees to protect the skylight and the PV arrays from North Texas’ not infrequent hailstorms.
While the louver system opens and closes, it does not react to changes in sunlight throughout the day. “We didn’t want to sanitize the daylight so much,” said Andy Sedgwick, a partner in Arup’s building engineering team, which designed the project’s lighting scheme. “One of the special features of natural light is the fact that it is variable and it changes all the time. If you have a system that is too reactive you can kill that dynamism and you loose some of the special character.” It does however close completely during off hours and opens minutes before the museum begins accepting visitors. This cuts down on heat gain from the sun during the long summer mornings, reducing demand on the HVAC system.
As with the Kahn building, the Piano Pavilion features a mix of daylight and electric light. The tops of the structure’s 100-foot-long, 54-inch-deep, 8-inch-wide, laminated, twinned Douglas fir beams are outfitted with LED strips that project 3000K white light up at the bottom of the fritted, low-iron, UV-filtered IGUs that makeup the skylight. This maintains a gentle glow that shines down into the galleries during cloudy days and in the evening. Fabric scrims span between the beams, further diffusing the light.
The galleries’ art lighting is provided by a set of track-mounted LED fixtures from California company Xicarto. The luminaire provides high color rendering (95 CRI, which is phenomenal for an LED product) and show consistent color from fixture to fixture, even after years of use. “We’ve found it very compelling among museum professionals,” said Sedgwick. “They like it at least as much as tungsten halogen.” These are 3000K, which is apparently Piano’s favorite color temperature. “Everything that Piano does is 3000K,” continued Sedgwick. “We normally don’t have to ask.”
A mororized louver system outfitted with PVs allows curators to dial-in the ideal amount of natural light for any exhibition.