Technology
Architects Ramping Up the Design Power of Photovoltaics
Solar
power is on the rise, and designers are using it to make a
statement
(archrecord.construction.com - 03/19/04)
By Peter
Fairley
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| Gregory
Kiss and Nicholas Goldsmith, FAIA, designed structures
using PV panels for Under the Sun, an exhibition about
solar power mounted at the Cooper-Hewitt, National Design
Museum in 1998. Since that time, solar power’s popularity
has increased, thanks to rising demand for green-building
techniques.
Photography: Courtesy Cooper-Hewitt, National Design Museum. |
Solar power got a shot in the arm last
year when an off-the-grid housing complex in Santa Monica
won a merit award from the AIA Los Angeles chapter. Berlin
architect and jury member Matthias Sauerbruch said that Colorado
Court, by Pugh + Scarpa, was the first architectural application
of photovoltaic (PV) panels that actually looked good. A national
architectural jury agreed with him. Colorado Court went on
to garner a 2003 AIA Honor Award [RECORD, May 2003, page 135],
and soon the design world buzzed with admiration for its five-story-high
walls of brilliant blue PV panels.
Ever since its nascent years, solar
power has gotten a bad rap. In the 1970s and 1980s, clunky-looking
(and often poor-performing) panels were tacked onto buildings
as little more than an afterthought. The design-conscious
railed against them; manufacturers responded by developing
building-integrated PV products, which sought to disguise
solar-powered materials in facades or roofs. But projects
like Colorado Court and The Solaire, a new high-rise in Manhattan’s
Battery Park City, do just the opposite: They embrace, even
celebrate, the look of conventional PV technology. In the
process, they’re defining a new aesthetic for green buildings—one
that’s well-established in Europe but still struggling
for life in the U.S.
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Gaining ground and making a statement
The use of solar power is growing rapidly. PV installations
in the U.S. jumped 53 percent in 2002 and rose another 30
to 40 percent last year, according to the Solar Energy Industries
Association. Not surprisingly, economics is driving demand.
States like California are offering tax rebates and other
incentives for using solar power. When combined with high
energy prices, the payback period for investment in PV can
be as little as four years.
PV use seems set to keep growing, with
the increasing popularity of building green fostered by the
U.S. Green Building Council and their LEED rating system.
Solar power is worth one LEED credit toward certification—but
perhaps more critically, PVs are among the most observable
environmental amenities that can be designed into a building.
For architects, making PV technology stand out puts their
projects on the map with the public. Rafael Pelli, AIA, partner
with New York–based Cesar Pelli and Associates, says
this was one reason he highlighted the solar-power system
in designing The Solaire’s facade. “We were actively
seeking some expression in the building that spoke about its
intent,” says Pelli. “The photovoltaics were visible
and immediately identifiable as something different.”
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Photography:
Courtesy The Colt Group
Recent office buildings in Germany (left and opposite,
bottom left) demonstrate a PV aesthetic that’s just
beginning to emerge in the U.S. At The Solaire in Manhattan’s
Battery Park City (below), solar panels are built into
the facade above the entrance, the most visible of the
project’s environmental features. Visitors to the
Domaine Carneros Winery in Napa Valley can glimpse its
rooftop PV array from surrounding hills (opposite, top
left). |
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| Photography:
Courtesy The Solaire |
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| Photography:
Courtesy Powerlight |
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| Photography:
Courtesy The Colt Group National Renewable Energy Laboratory
(right two) |
Solar panels adorn the upper reaches
of The Solaire, like Manhattan’s first solar high-rise
at 4 Times Square [RECORD, March 2000, page 90]. But The Solaire
also features a 28-foot-wide column of PV panels, starting
above the southwest-facing front entrance and rising 13 floors.
This feature screams “renewable power,” whereas
4 Times Square’s thin-film panels are indistinguishable
from tinted glass. Pelli says the panels expand the design
to “argue for a different kind of building expression”
while also meeting the strict guidelines for Battery Park
City, which specify glass and brick construction. The key,
he says, is the pieced-together appearance of the cells. “They
have a visual quality all their own, and yet they are very
sympathetic, with the fine-grained texture of a brick wall.
The monocrystalline cells break down into a series of pieces,
so they feel like very modular units making up this larger
field,” he says.
Like The Solaire, Colorado Court is
anything but shy about its photovoltaics. Pugh + Scarpa partner
Lawrence Scarpa, AIA, says that his firm views sustainability
as a design tool. At Colorado Court, power production was,
in a sense, only part of the justification for using PVs on
the building. “I thought it was crucial to making the
building look good, and the only way we could sell that was
if it had a function,” says Scarpa.
PV is making a mark on infrastructure
projects, too. A 1-megawatt installation for a car-park canopy
at Naval Base Coronado in San Diego employs 3,000 blue crystalline
PV panels, bathing the vehicles below in a mix of shade and
light. The structure was installed by Berkeley, California–based
PowerLight. Tom Dinwoodie, the engineer-turned-architect who
founded PowerLight, says the company aimed to match the airy
feel of European train stations, hoping that visitors will
step out of their cars and enjoy the view. As with Colorado
Court’s solar walls and awnings, natural light filters
around the PV cells, providing enough illumination underneath
to read by while protecting commuters and cars from blazing
sunlight. “It’s a fabulous effect,” says Dinwoodie.
San Francisco–based 450 Architects
brought this shadow-and-light effect indoors when they designed
the Argonne Child Development Center in San Francisco. The
firm used 17 semitransparent solar panels to build three south-facing
skylights in the school’s north-facing roof. Last year,
the school was honored as one of AIA’s Top Ten Green
projects [RECORD, May 2003, page 54].
| PV technology: The rigid
and the flexible
Photovoltaic cells are composed
of semiconducting material, usually silicon, which makes
them capable of producing electricity from sunlight.
Two technologies for making cells offer different looks
and applications as they vie for space on rooftops,
facades, and shading structures.
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Photography: Courtesy National Renewable Energy
Laboratory |
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Wafer (or cell) technology Crystalline
cells, the most widely used technology on the market,
are grown in long cylinders and sliced into wafers.
Polycrystalline cells are either drawn in sheets or
made into ingots and then cut into squares. They’re
cheaper but produce less power than crystalline cells.
Thin-film technology
Thin-film cells are made by depositing layers of semiconductive
material onto a glass, metal, or plastic surface. They’re
less rigid than crystalline cells and even cheaper than
polycrystalline, but less efficient than either.
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Even for installations on commercial
roofs, where aesthetics are a secondary concern, PV is considered
a huge improvement on what came beforehand. Solar panels backed
by insulation are sprouting up atop big-box retail stores,
manufacturing plants, and office buildings in California.
A visual makeover is the inevitable by-product of this trend,
Dinwoodie says. “We tile roofs with these blue sparkling
[PV] tiles. What was there before? Usually a gravel or a bituminous
roof with puddles of mud.” Though many rooftop systems
are invisible to all but air travelers, some are distinctly
high-profile. In San Francisco, a 675-kW system atop the Moscone
Convention Center is a magnificent blue field visible from
downtown high-rises. Then there’s the shimmering solar
rooftop of Napa Valley winery Domaine Carneros, which visitors
can admire from the surrounding vine-covered hills. “It’s
like the sea on this rooftop, and then you have the green
from the hills. The rows of solar arrays bleed into the rows
of the vineyard,” says Dinwoodie.
It’s tough being beautiful
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Images:
Courtesy: Pugh + Scarpa
Light and shadow are filtered through PV cells on the
facade of a municipal building in Winterthur, Switzerland
(below). An array of sparkling blue tiles tops the Toyota
Motor Sales building in California (far below). The PV
cells for Pugh + Scarpa’s Solar Umbrella (below)
will provide form and shading, and meet all its energy
needs. |
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| Images:
Courtesy The Colt Group powerlight (bottom right) |
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| Images:
Powerlight |
For architects who want to use PV as
a visual element, finding the right material for each project
can be challenging—especially when government funds or
grants require projects to use locally sourced materials.
Pelli’s firm originally designed The Solaire with a black
stripe of PVs, but had to purchase the panels within 500 miles
of Manhattan to qualify for New York State’s green building
tax credit. As a result, blue panels were used instead of
black ones. (Pelli says he has no regrets: “I think they’re
more beautiful, more visually interesting as a material.”)
Pugh + Scarpa had to make last-minute adjustments to the design
of Colorado Court when PV panel manufacturer BP Solar, a subsidiary
of the oil and gas giant, bought out their supplier. Scarpa
says they convinced BP Solar to custom-manufacture panels
with a clear backing to let the light shine through, but the
design still had to accommodate BP’s panel size. Public
funds used for the project made it impossible for Scarpa to
turn to Japanese or European suppliers, which make a wider
range of panel sizes, he says. In theory, as more states and
owners in the U.S. adopt PV technology, local manufacturers
will offer more choices in the coming years.
Another challenge in making PV installations
look right is educating contractors. Scarpa wasn’t fully
satisfied with the installation at Colorado Court, noting
that the electrical, plumbing, and structural subcontractors—who’d
never put in a solar system before—didn’t understand
that the panels were part of the visual aesthetic of the building.
As a result, he says, the placement of equipment such as electrical
conduits and plumbing lines was not carefully considered.
Scarpa recommends that architects require detailed engineering
drawings of installation locations and procedures as part
of the bid package, as well as preconstruction meetings with
contractors to review the system and answer questions.
The disappearing act
The ultimate challenge to integrating
PV technology is accommodating those customers, or neighbors,
who are holdouts against the renewable-power look. Solar-power
NIMBYs are often particularly vocal in residential areas.
In California, the state’s legislative assembly saw fit
to expand the state’s Solar Rights Act last year, seeking
to quash antisolar building codes and bylaws across the state
that were largely put in place because of aesthetic concerns.
Even in San Francisco, a city that has embraced solar power,
residential architects must proceed with caution to avoid
costly, time-consuming disputes with neighbors. Richard Parker,
AIA, a partner at 450 Architects, says 90 percent of his firm’s
projects last year included PV, but not all are visible from
the street. For example, he designed a parapet to hide a solar
installation atop a home in Noe Valley that is surrounded
by Arts-and-Crafts-style houses. “We’re going to
be generating a ton of power, and you’re not even going
to be able to see it,” says Parker.
Another solution is to switch to products
that incorporate PVs within building materials. This is where
thin-film products come in. When viewed from outside, thin
films have a uniform color, usually black or gray; they can
also be produced on flexible substrates like
plastic, making them easier to apply
to metal roofing and fiberglass-reinforced tiles. Architects
agree that opaque, thin-film PV panels have a role to play
in some buildings. “Where you have an all-glass building
and you’re paying for the glass already, I think there’s
a logic to [using] it,” says Pelli.
What thin films offer in stealth is
offset, unfortunately, in efficiency. They produce as little
as one-third the power as conventional crystalline PV cells—a
serious liability given that their installed costs are only
marginally lower than that of crystalline cells. Still, especially
for large roof systems, their economics can make sense.
A leading proponent of using thin-film
technology atop buildings is Southern California Roofing,
the nation’s fifth-largest roofer. In 2003, two of the
firm’s principals established a separate start-up company
called Solar Integrated Technologies in Los Angeles, to bond
charcoal-colored thin-film PV to metal and membrane roofing.
The new product is both a roof and a power-generating system.
“We turn a liability into a producing asset,” says
Richard Schoen, FAIA, executive vice president for both firms
who teaches sustainable architecture and community planning
at UCLA. “We aren’t on the roof,” says Schoen,
“we are the roof.”
Schoen has seen a rise in interest in
thin-film technology from architects, and says his firm has
had inquiries about designs ranging from solar sails to tensile
structures. In other words, thin films, like their crystalline
predecessors, are themselves begetting exciting and highly
visible solar structures, as Scarpa and fellow Pugh + Scarpa
partner Angela Brooks are realizing in a transformation of
the Venice, California, bungalow they share. A solar canopy
comprised of thin-film panels will wrap a 1,200-square-foot
extension of their 700-square-foot home. They call the addition
the Solar Umbrella, recalling Paul Rudolph’s Umbrella
House and Heyward Apartments of 1953. The panels of amorphous
silicon will meet all of the Solar Umbrella’s electrical
demand, while screening the house from intense southern sunlight.
“Solar panels, conventionally relegated to a one-dimensional
utilitarian application, define envelope, provide shelter,
and establish a distinctive architectural expression,”
the partners write in a summary of the project.
The panels look like tinted black glass
from the outside, but from below, says Scarpa, incident light
is filtered as through a prism, resulting in rainbows of illumination
that “enliven the more permanent and fixed elements of
the design,” say the designers.
That’s certainly a far cry from
tacking solar panels to the roof.
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