Museum design teams juggle the
sometimes-competing demands for preservation of collections, human
comfort, and energy conservation
A Museum is inherently an energy hog. Prolonging the life of artwork
and cultural artifacts requires a consistent interior
environment–generally one maintained at 70 degrees Fahrenheit with 50
percent relative humidity–regardless of the season or weather. These
requirements result in large energy loads, especially for humidifying
and dehumidifying outdoor air.
Designing
a high-performing museum requires state-of-the-art HVAC equipment, to
be sure, but passive strategies such as building orientation and a
thermally efficient envelope, detailed and well-executed, are at least
as important. "It isn't about configuring the right mechanical
system, but about designing the right building," says Adam
Trojanowski, principal at Altieri Sebor Wieber. Trojanowski's firm is
mechanical engineer to Tod Williams Billie Tsien Architects for the
Barnes Collection–the museum set to open in downtown Philadelphia in
May that will house the highly regarded collection of Impressionist
and early-Modern paintings amassed by the late Dr. Albert C. Barnes.
Until last summer, the collection had been on display on the Barnes
estate in Merion, a Philadelphia suburb.
The
new 93,000-square-foot Barnes includes a shoebox-shaped permanent
exhibition pavilion, as well as an L-shaped wing for conservation
labs, offices, and visitor amenities like a gift shop and café.
Together, the two volumes define an interior court, topped with an
etched-glass canopy, or "lightbox," that allows controlled and diffuse
daylight into adjacent spaces.
On
track for LEED-Platinum certification, the museum is designed to
exceed the performance of the 2007 version of the energy standard
ASHRAE 90.1 by an impressive 43 percent. Some of the strategies that
contribute to these savings include ventilation-air heat recovery,
demand-control ventilation, and rooftop photovoltaic panels that are
expected to supply more than 7 percent of the building's electricity.
But more than half of the anticipated energy savings can be attributed
to the thermal properties of the envelope, along with the inclusion
of overhangs and other shading devices that help control heat gain,
says Trojanowski. At the Barnes, the galleries' exterior walls have a
limestone rainscreen-skin with bronze fins and stainless-steel
reveals, rigid insulation with an adhered air-and-vapor barrier, and a
grout-filled block wall. The whole assembly, including a plywood and
sheetrock interior stud wall, is as thick as 40 inches in some
locations. The windows are set back from the limestone skin–a detail
that helps limit direct-sunlight penetration and emphasizes the
facade's "beefiness" and "heft," giving the building a sense of
permanence, says Williams/Tsien senior associate Philip Ryan. But the
assembly's depth and composition also provide sound thermal
performance, with an R-value of 15. (The R-value is a measure of a
material's ability to retard or resist heat transfer.)
Lightbox: At the new Philadelphia home for the
Barnes Collection, a court (bottom) covered with an etched-glass canopy
is defined by a shoeboxlike gallery pavilion and an L-shaped wing
(top). The configuration allows designers to take advantage of indirect
daylight for gallery illumination