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Continuing
Education
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Use
the following learning objectives to focus your study while reading
this month’s ARCHITECTURAL RECORD / AIA Continuing Education article.
Learning
Objective:
After
reading this article, you will be able to:
1.
Explain how a mining site was reconstructed to become a village
center and training academy.
2.
Describe how natural resources
are conserved in the Mont-Cenis Academy complex.
3.
Describe the advantages of the
greenhouse environment over the natural environment.
4. Describe
how photovoltaics are incorporated into the project..
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The Mont-Cenis
Academy complex is proof that daring design can be generated by
ecological solutions-solutions that, despite their technological
sophistication, do not make the resulting space feel driven by
machinery and computer calculations. The villagelike grouping
of buildings that compose the civil service training academy and
community center, built on abandoned coal fields in the town of
Sodingen (since joined with the adjacent town of Herne), take
a holistic approach to energy-conscious architecture. From its
transparent facades to the tall pine logs that serve as columns,
this boxy, overarching greenhouse structure and the buildings
inside seem simple at first view. But Mont-Cenis is a complex
project that carries a complex message with implications for the
future of the region and of building design in general: architecture
in the next millennium will take place not in new construction
on virgin land, but in renovating existing buildings or erecting
new structures on sullied sites.
The academy
is in the Ruhrgebiet, a once mighty industrial region north of
the Ruhr River in Germany and home to towns like Duisburg, Essen,
and Dortmund. It was Europe's largest industrial region, but economic
factors, including a recession in the 1980s, closed its coal mines,
steel works, and coke processing plants. The economic devastation
was significant, but the pollution was even more destructive to
the region. During the processing plants' peak production, acid
rain dumped several million tons of sulfur dioxide each year on
the soil, some of which was already contaminated by coal sludge
and other industrial waste.
The mine
at Sodingen, which served as the economic and physical center
of town, closed in 1978 and was later razed. In its place, Mont-Cenis,
with its surrounding town park, was conceived as a new center
that would contain the area's social security offices and a multifunction
hall, along with the training academy. The public is free to enter
the building, eat in the cafeteria, or use the library. If rooms
are available, they can stay the night in the academy hotel.
The portion
of the Ruhrgebiet where Mont-Cenis is located was bucolically
rebaptized as Emscher Park about 10 years ago. The region includes
17 cities with a combined population of 2 million people, many
of whom are set on forgetting the area's sooty past by investing
in a "green" future. With so many old factory sites to be saved,
converted, or destroyed, and with a new building program to be
defined, the regional government established the International
Building Exhibition Emscher Park (IBA) in 1989. Not an exhibition
per se, IBA is a land development program like the one formed
to organize the reconstruction of Berlin (though Berlin's building
program focused on new buildings while the IBA worked predominately
with existing structures). The IBA established development guidelines
emphasizing the use of ecological approaches and new technology
in building projects. The thrust of its mission was to renaturalize
the landscape, renovate housing sites, clean up polluted rivers
and land, and transform major industrial sites into recreational
or cultural venues.
The changes
in the region within the past 10 years are dramatic. The cities
within Emscher Park are now linked by a chain of parks that runs
along the Emscher River which, like the Ruhr, was cleaned and
stocked with wildlife. Old factories are now galleries and concert
halls. The artist Christo recently installed 13,000 painted steel
drums inside the empty, 330-foot-high gas storage tank at Oberhausen,
west of Herne-Sodingen.
Perhaps the
most impressive industrial renovation is the site of a former
factory at Zollverein, also to the west. A temple of brick architecture,
the central factory building was turned into an industrial design
museum by British architect Lord Norman Foster, Hon. faia. Here,
the latest and slickest industrial products contrast with massive
rusted valves and ovens, all still in place. Outside, the public
is attracted to the area by exhibition spaces, cafes, and restaurants
located among the acres of outbuildings, mine shafts, and pipes
that surround the factory.
At a recent
gala at Mont-Cenis, the IBA celebrated the conclusion of its 10-year
program. Altogether 120 projects were realized, representing an
investment of 5 billion DM (about $118 million), two-thirds of
this from public money and one-third from private funding. The
Mont-Cenis Academy, completed last summer, is the organization's
major accomplishment.
"This wasn't
an experimental building," says project architect Françoise-Hélène
Jourda. "There is no possibility of risk in architecture." Perhaps
the risk lay with the IBA, whose challenge was to take a site
scarred with mining shafts that once released toxic gases into
the air and convert it into a place that gives back resources
and provides spaces in which to live and learn.
The glass
envelope
The Mont-Cenis
project began with a 1991 competition, won by French architects
Jourda & Perraudin (Gilles Perraudin was Jourda's partner). In
1992, the pair joined with German architects Hegger Hegger Schleiff
(HHS). Jourda, now with her own Paris firm, describes the combination
of talents as a true collaboration: she took the lead on the conceptual
design, and Manfred Hegger contributed ideas and knowledge of
the region. HHS, a firm that specializes in environmental design,
also worked on other Emscher Park projects and oversaw construction
on Mont-Cenis.
From the
first, Jourda was set on using a glass envelope to create a microclimate
for the buildings within, a concept she has used on a smaller
scale in other projects. But Mont-Cenis marks the first time such
an approach has been so thoroughly and so successfully applied
in the region, and perhaps internationally.
The architects,
working with the University of Dortmund, Germany, spent a year
using computer and physical models to analyze airflow, heat exchange,
lighting, and ventilation. The result is a 123,200-square-foot
clear-glass greenhouse with a climate that's more in line with
the south of France than northern Germany. As a result, the interior
buildings were designed without the heavy insulation, HVAC equipment,
and other elements used in cold-climate construction.
The buildings
are arranged in two rows along a central street and canal. Paths
crisscross the landscape of concrete, gravel, and exotic plants.
The influence of the industrial machine is clear; the truncated
library recalls a smokestack, while the multipurpose hall is contained
in a windowless rectangular box. But the factory metaphor blurs
when the architectural details and materials are examined. The
buildings are clad in rough, bleached-wood siding, while portals
are found in some of the building's doors. Continuous wooden decks
run outside the buildings. Without its protective glass envelope,
this is an architecture that would be unthinkable in a northern
climate.
The hangar-like
greenhouse is at once simple and sophisticated. In the winter,
it works in tandem with the concrete and gravel floors to collect
solar energy, while acting as a thermal buffer. In the summer,
doors are left open to allow the breezes to enter. Louvered openings
in the lower quadrants of the glass structure bring in cool air,
while warm air is exhausted through roof vents. The stack effect
is enhanced with internal shades near the ceiling that trap solar
heat and induce airflow. Potted tropical plants and a central
pool contribute their own cooling effects.
These seemingly
basic operations are controlled by a highly specialized computer
system that adjusts the size and number of openings in the envelope
on an hourly basis. Sensors within the building and outdoors monitor
internal and external temperature differentials, wind direction,
the angle of the sun, building humidity, lighting, and other factors.
This information is fed to the computer system, which adjusts
the building's mechanical systems accordingly.
Concrete-lined
tunnels, or "earth ducts," almost 10 feet below ground, conduct
fresh air from their intakes, located 164 feet from the center
of the envelope, to the building. The air, driven through the
6 1/2-by-6 1/2-foot tunnels with fans, is naturally cooled or
heated during very hot or very cold periods respectively, thanks
to consistent below-grade temperatures.
The buildings
within the envelope were positioned to maximize airflow. Each
has windows that open to the hall, bringing in the naturally conditioned
air. Heat-recovery units pull the warmth from exhaust air and
minimize the demand for heating energy. There is no artificial
cooling in the complex.
Air is not
the only natural element circulated through the project. Rainwater
is collected from the roof by a syphon system using four-inch-diameter
pipes that run down the facade behind the vertical columns. The
water, collected and filtered in an underground cistern, is used
to clean the roof, flush the toilets, and water the lawns.
Over the
mines
The site
conditions were, in many respects, the major constraint of the
project. Mine shafts lie all around the site. One reaches a depth
of 4,268 feet-the deepest in the Ruhr region. The barren site
of a former coke furnace, with soil so polluted that vegetation
will not grow, lies 650 feet north. The former pit head of the
mines lies directly beneath the building. In fact, the site stands
several yards above street level, thanks to the 20-foot-high pile
of tailings, gravel, and waste material taken from the shafts.
"The original
competition brief spoke of finding a context for the structure
from the nearby town," Jourda says. "But we were, instead, worried
about the land beneath us." Rather than engage the site, she floated
the project on concrete piles.
The envelope
is a three-part structure. Its primary support system, a grid
of tree trunks 18 inches in diameter and 50 feet tall, supports
the laminated roof trusses. The forest of rough-hewn fir columns
is both rustic and refined. "Wood is the ultimate ecological material,"
Jourda says. "It is renewable and can be used with little waste."
The pines, selected from nearby forests, were cut more than a
year before they were installed, leaving them time to dry naturally.
Even so they are scored along their entire length to allow shrinkage
without cracking. The trunks are anchored to the concrete foundation
with custom-made cast-iron feet designed by the architects and
the engineers. The connections allow for movement in the logs,
which sway as the building moves.
The primary
support system is capped by a secondary structure of wood beams
and wall trusses. The function of this is to support the tertiary
structure. This consists of structural-glass facades and an aluminum
frame that holds the laminated-glass roof.
Rooftop
power plant
It is no wonder
that the architects refer to the roof as a power-generating station.
Photovoltaic (PV) cells are embedded in an ultraviolet-resistant
resin between the layers of glass on the roof and also on the
south and west facades. These produce two and a half times the
energy that the complex needs, about 750,000 KW/year. The power
generation is monitored by a computer system that directs any
surplus into Herne-Sodingen's electric grid. At night and during
periods of low light, the complex pulls energy back from the electrical
grid or draws from methane-powered cogeneration plants on the
site. The rooftop PV array covers 83,700 square feet, while the
facades support a 7,000-square-foot array. The solar energy is
converted to usable power with 600 modular inverters. Altogether
Mont-Cenis represents the largest use of PVs in Germany, Hegger
says.
The original
competition brief didn't call for the use of PVs. But when the
architects showed the clients how much energy the space could
produce, the installation of the PVs became a priority. In fact,
it was the power company that funded half of the 15 million DM
(about $28 million) budget for the PV system, an investment that
is paid back daily in additional energy resources.
The roof
has a 4 percent southfacing incline to optimize solar gain. Originally,
the solar cells were evenly distributed across the roof. But computer
modeling demonstrated that the building interior would be darkened
by the density of cells. So Dr. Helmut Muller, a professor at
the University of Dortmund who led the solar design research,
concentrated the cells over the internal buildings and left clear
glass between the buildings and over the central thoroughfare.
Also, the cells within the panels are arranged in varying densities-from
86 percent directly over the buildings to 58 percent in transitional
zones. The dappling of the cells, along with the shifting daylight,
creates ever-changing cloud patterns.
"The PV panels
also satisfy the need for shade and enclosure," Hegger adds. To
avoid overheating the building, 65 to 80 percent of the roof area
and 25 to 40 percent of the south and west facades are shaded.
Trees around the envelope and ivy planted along the walls also
help.
The PV system,
along with the other energy-saving aspects of the building, are
manageable and intelligent choices that architects can use to
help overcome the odds at a site like Mont-Cenis. "With the end
of heavy industry in Germany, we have learned that knowledge is
the best protection," Hegger says. "We have seen a lot of fashions
in architecture. But real change comes from economic or political
forces. We are entering a phase when these economic questions
need to be solved and architecture will need to find solutions."
Jourda agrees: "Most ecological architecture is just good sense."
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The
sum of its parts
The
minimalist buildings beneath the glass envelope are arranged
in slightly offset rows to create an urban perspective.
The buildings are intentionally simple; the architects intended
for occupants to spend most of their time in the vast, light-filled
atrium.
Limiting
the structures to three main building materials-wood, glass,
and concrete-maximized the use of pre-fabricated components.
Working with a limited palette and designing buildings on
a grid, with no irregular shapes and corners (aside from
the conical library), minimized waste. In addition, the
concrete acts as a heat sink, contributing heat-storage
capacity.
The
buildings used most frequently by the public are the 2,600-square-foot
cone-shaped library and the 5,500-square-foot. civic administration
offices. They are just inside the front entrance of the
complex.
The
library serves as an information center, with books, maps,
and other materials on Mont-Cenis and the surrounding region.
The wood-framed structure is capped by a skylight that's
covered with white-light holograms. These direct the sunlight
entering the space to the ground floor.
The
blocky, three-story civic administration building, next
door to the library, is used by residents seeking social
security; unemployment remains high in the region.
The
22,000-square-foot classroom building, which, like the envelope,
is mostly glass, is accessed from a door on the east side
of the complex. It contains another cone-shaped structure
which serves as the lobby. Holograms on the skylight over
this cone create a kaleidoscope of color on the floor. In
the classrooms, floor-to-ceiling windows, spanned by light-shelves,
maximize light and air circulation.
Other
structures include a three-story hotel with continuous wood
balconies around each level; a multiuse hall; and a restaurant,
open to the public, with seating inside and out in the atrium.
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On-site
power plants
Almost
all coal mines emit some gas and the shafts surrounding
the Mont-Cenis Academy are no exception. The mines vent
approximately 36 million cubic feet of methane, as well
as other toxic gases, each year. Before Mont-Cenis was built,
this gas was simply vented into the atmosphere. But Jourda
and Hegger, working with the University of Dortmund and
the local utility, Stadtwerke Herne AG, conceived of two
cogeneration plant modules at Mont-Cenis that would use
the gas to create electricity and heat.
Located
at the eastern edge of the park, the mine-gas-driven cogeneration
plants supply 235 KW/year of electricity and 378 KW/year
of heat. The electricity supplements that produced by the
photovoltaic array atop the building envelope. The heat
is used to warm the complex. Oddly, more gas rises in overcast
weather conditions than when the sky is clear, making the
cogeneration facilities a perfect compliment to the photovoltaic
system.
Some
of the energy that isn't used is stored in a 2.2 MWh battery
storage plant, also on the property. That energy is used
to reduce peak demand loads, to compensate for perturbances
in the solar supply system, and to supply emergency power
to the complex. Any remaining supply is fed back to the
utility grid. The plants are likely to pay for themselves
within their first year of operation. That's because the
amount of power they're giving back to the grid is enough
to prevent the local utility from having to build a new
power-generating station. These savings are being passed
on to Mont-Cenis.
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Continuing Education