Given the specific character of the brief and the unique requirements of a center for environmental studies, McDonough was faced with some interesting challenges. Programmatically, the Center was simple enough, but the cold, wet climate and the desire for direct connections of interior and exterior spaces were in conflict. Resolving issues like the use of extensive glass areas to break down indoor-to-outdoor separations would be difficult.
Collaboration and division of responsibilities also posed a challenge. When a multidisciplinary project team is melded together to achieve an integrated design, the chain of decision making and assignment of specialty tasks is muddled. The only one who can clearly be responsible for the coherence of the project is the architect. Although McDonough + Partners worked with a distinguished and like-minded group of professionals on this project, it is worth noting that the extra burden of integration was the architect’s — and the technologies of the Oberlin Center were not trifles.
Appropriate Systems
One of the historical examples of designing and programmatically integrating technical systems for their pedagogical value is the Florida A&M College of Architecture. This college building has three wings. Each has a vented-skin thermal chimney covering the south side of the building wall and roof up to an oversized ridge vent. All interior systems are exposed and color coded for identification: Air handlers, dampers, ducts, and structure are laid out like laboratory lessons.
|
Figure 11.31 Site plan of the Oberlin CES. |
The long axis of the main building faces south, as does the glazed facade of the Living Machine. There is an unobstructed view to the south and ample solar access across the Solar Plaza sundial and Elm Street. Views to the east
encompass the Music Conservatory across Professor Street and part of the nearby 1887 Baldwin Cottage. The auditorium wing acts as a large shading fin to protect east-facing glass from early morning sun in summer months. Native hardwood trees are planted along these elevations facing the street. At the north side of the building earth is bermed up to the second-floor level, and an orchard is planted on the raised ground between the main building and the auditorium. The placement of CES in this particular setting has strategic value: Its atrium straddles a primary walkway between the campus library and student center to the north, and a large block of dormitories to the south.
All storm water on the site and nearby ground drains to a pond at the southeast junction of the main building and the Living Machine. The pond acts as a miniature wetlands ecosystem to filter and purify the water naturally, imitating the large wetlands that used to cover this entire region. This condition is greatly facilitated by the absence of on-site parking area accumulations of motor oil and gasoline that would have to be separated before reaching the pond. The flat roof areas above north facing rooms on the second floor are sod covered to slow runoff to the wetlands pond.
Vertical support is framed in 70 tons of steel with recycled content. This support is supplemented by load-bearing concrete block walls on the north and west ends of the main building and all of the auditorium except where it faces the Living Machine.
The roof of the two-story gathering space is spanned by laminated Douglas fir arched beams and decked in fir. All wood materials in the building come from sustainably harvested timber. Intermediate flooring is concrete on metal deck over bar joists.
The roof of the CES is clad in seamed panels of recycled aluminum. The roof of the main building is then covered with photovoltaic panels that clip to the aluminum seams. North-facing rooms on the second floor have a grass-sod – covered flat roof that provides additional shade and insulation and slow storm water runoff to the wetlands pond below.
Daylighting requirements and a desire for contact with outdoor areas dictated a high ratio of glazing. This is satisfied in the atrium by two full-height walls of triplelayer glass units filled with argon gas. The R-value is an impressive 8.3. At half-height of the atrium’s south wall, a trellis of deciduous vines provides solar protection in summer. A roof overhang protects the upper half of the atrium glazing. East-facing glass is protected from low summer sun by the tall mass of the auditorium building. Clear insulated glass with an R-value of 3.4 is used around the Living Machine and in other window areas. A continuous 4 ft high clerestory window separates the north wall from the arching roof, allowing glare-free indirect light to filter down into the main building.
The glazing system also permits natural ventilation. There are operable windows in every space and motorized openers for the north clerestory glazing. Breezes come predominantly from the southwest and are inlet at the atrium floor level and exhausted at a high level through the north clerestory. Computational fluid dynamics modeling was used to study the aerodynamic form of the roof and optimize the system of air pressures around the building that drive the natural airflow.
A tan-colored brick veneer exterior covers the structural concrete block walls. The cavity between the two masonry constructions is filled with insulation, yielding an assembly rating of R-21.
Each space in the CES is served by an individual heat pump for heating and cooling. Having multiple units usually creates a disadvantage because it increases the total system installed capacity in tons of cooling and Btu’s of heating— each zone’s heat pump unit must be sized to that room’s peak load, and capacity cannot be shifted from space to space as it is with a central plant system. The advantages in this case outweigh the increased capacity problem because individual units allow for better control; a unit is used only when the room is occupied. The heat pumps used are water-to-air configurations. In the cooling mode they absorb heat from room air at the evaporator coil and reject it to the condensing coil by the standard vapor-compres – sion freon refrigerant cycle. In the heating mode the freon flow is reversed so that the heat pumps absorb heat from a water stream and reject the same heat to room air.
Aside from efficiency and localized control, there are a few additional advantages to this system. First, the heat pumps can be piped, in parallel, to the same water loop. This connection allows one heat pump in the cooling mode to add heat to the water loop while another heat pump on the opposite side of the building takes heat back out of the same water. Strategically, heat is thus shared between the two heat pump zones with great efficiency. A second major benefit is realized by coupling the heat pumps to geothermal energy for harvesting the immense heat storage capacity and stable temperatures 100 ft below grade. This geothermal connection is made by circulating the heat pump water loop piping through a series of small borings into the earth. Other benefits include the total absence of cluttered outdoor mechanical equipment, independence of each zone for servicing, and avoidance of potential problems related to direct combustion heating with natural gas, such as toxic air quality resulting from broken heat exchangers. A small electric boiler backs up the water loop for extreme periods of cold weather. Because the building produces its own electricity, there is no pollution debt at a remote generating plant of unseen environmental circumstances.
Ventilation air is provided by two larger heat pumps operating at 100 percent outside air. These units take room air and exhaust it through air-to-air heat exchangers in order to preheat the incoming ventilation air. The atrium has its own separate heating system with circulating hot water pipes embedded in the exposed floor slab.
Photovoltaic (PV) collectors on the roof currently provide most of the CES electrical needs. Advancements in PV system efficiency are expected to make the building a net energy exporter within five years. The existing 3,700 ft2 (344 m2) of panels are arrayed across the south sloping section of the roof, an exposure that had to be interfaced with the building’s aerodynamic profile required to promote natural ventilation. Steven Winter Associates, energy consultants to the project, estimate that a typical new classroom building in this climate would use 75,000 Btu/ft2 each year. They project the energy use at CES to be only 23,000 Btu/ft2/yr, a 73 percent savings. Presently, the PV system provides about 13,000 Btu/ft2/yr.
Artificial lighting in the Center is held to a power density of 0.9 W/ft2, less than half of what most new classroom buildings use. The lighting is controlled by occupancy sensors. Along with the high levels of daylight in the building and its daytime-dominated occupancy, the low power density makes the task of providing all of the building’s own energy more viable. In many buildings lighting accounts for half of the total energy used, and frequently about half of that is wasted by poor lighting design and lack of controls. The CES succeeds first in reducing the amount of supplemental artificial light needed, then makes certain it is used only as needed. This illustrates the green building principles of first using natural energy to replace nonrenewable energy and then using intelligence to replace resources.
Although the Living Machine does not literally form the entrance to the building, components of it do occupy the auditorium entryway, also called the Living Machine Atrium. As much as 2000 gallons per day of wastewater is first carried to an anaerobic digester tank and then to a closed aerobic digester where the water is cleansed of wastes by bacteria. Both of these closed digester tanks are buried outside the building. In the building and exposed to view, open aerobic digesters cleanse the water stream further with nitrate-absorbing plants and then deliver it to a clarifying tank. From there, the relatively pure water is polished in a constructed wetlands biofilter of plants and snails that surrounds the base of the open aerobic digesters. Then, the water is stored in a holding tank where it is ready for reuse as flush water.
Linking all of the systems together in this advanced – technology building required an integrated control system. Constant performance monitoring and adjustments to provide optimal control and interaction of its various mechanisms could probably not be done without automation. Integrated controls also include alarm functions that alert users if failures occur or are even anticipated. The digital control system designed for CES combines controls for mechanical, security, fire, and the Living Machine systems into one package. Interestingly, the constant monitoring also empowers learning through a continually updated exhibit located in the atrium. It displays data on energy use, photovoltaic power production, water consumption, and other measures of environmental performance.
Wood from sustainably managed forests was used for the roof beams and roof deck and left exposed for its natural warmth. Maple wood trim was selected according to the same criteria. Flooring is either finished concrete or interchangeable carpet squares, which are essentially leased from the manufacturer, rearranged for uniform wear, and exchanged with the manufacturer for recycling at the end of their useful life.
Technical Integration Highlights
• The raised floor contains electrical, plumbing, and heat pump systems.
• Leased carpet squares incorporate a maintenance program.
• The attachment detail of PV collectors facilitates replacement for technology upgrading.
• Exposed systems and metered performance features mesh with the CES teaching mission.
• The roof deck is exposed as an interior finish
• The location of CES on the north-south axis of the campus between the library/university center to the north and the largest compound of dormitories to the south ensures foot traffic through building.
^ Efficient building design promotes downsizing of alternative energy systems, thus making both the
basic design improvements and the photovoltaic system cost-effective.
• PV panels shade the roof and are cooled in turn by air circulating between them and the aluminum roof deck.
Meta-design, to put William McDonough’s approach in the context of Gregory Bateson’s steps to an Ecology of Mind (1972), can be thought of as “the redesign of design.” This means that the ideals of ecological design have to be taken to a logical extreme, through thinking that is considerably different from that by which we got into our current predicaments.
Arup & Partner’s Alistair McGregor has stated (personal communication, 2001), “If the ideas of efficiency and alternative solutions are pushed far enough, then conventional systems are greatly diminished or disappear completely.” Suddenly, very different kinds of cost-effectiveness can evolve as compared with conventional economic scenarios based solely on long-term energy savings. At Oberlin, for example, the photovoltaic system is feasible because the rest of the building pushes efficiency to the extreme. This principle was demonstrated in a conventional sense many years ago when winning examples of energy-efficient building competitions were analyzed on a first-cost basis. It turned out that the additional costs of increased insulation and higher-quality construction were totally offset by the reduced costs of smaller air-conditioning systems. More insulation means smaller systems and less space to put them in, equals reduced first cost and increased efficiency. What McGregor suggests is the same thing McDonough contends: We should add a design intelligence factor to that equation, finding radical ways to get rid of some conventional systems entirely or replace them with something that does the same thing in a radically different way.
How widespread are programs like the Oberlin Center for Environmental Studies? Judging solely by Internet Web sites in early 2001, there were more than 65 university – based programs in Environmental Studies in the United States, at least 7 in Canada, and more than a few in the United Kingdom. Counted along with education programs in sustainable design in architecture and other colleges, the intellectual momentum is growing. Like green parkland patches on a city map, the greening of universities can be plotted beside the green parkways, the green corporations, and the growing number of green buildings. As they multiply, their footprints spread and touch—small green patches sewn together into a larger and larger quilt.