Sustainability: From the pages of Building Design and Construction magazine, this article outlines the design of a university building that is aiming to produce more energy than it consumes.
By David Barista, Associate Editor, Building Design and Construction magazine
Imagine a building that produces more energy than it needs to operate, that recycles its own water. A building that breathes and changes with the seasons like a tree. That was the goal for the building team that designed and built the Adam Joseph Lewis Center for Environmental Studies at Oberlin College, a 2,600-student liberal arts university located not far from Cleveland in Oberlin, Ohio.
Spearheaded by David Orr, professor of environmental studies at Oberlin, and funded with contributions from its namesake environmental philanthropist, the 13,600-sq.-ft., $6.61 million building was completed in January 2000. It was designed by a renowned practitioner of sustainable architecture, William McDonough + Partners of Charlottesville, Va.
Beauty through simplicity
The Lewis Center consists of two structures: a two-story main building that houses classrooms, faculty offices and a two-story atrium; and a connected structure that hosts a 100-seat auditorium and a solarium.
Its brick exterior makes reference to the campus's turn-of-the-century building style, while its use of glass curtain wall and its curved roofs add a touch of modernism.
Dominating the interior is an exposed curved ceiling, which is supported by 13 arched glulam wood beams and sheathed with white fir plywood panels. Interior walls do not extend to the ceiling, creating open space throughout the upper portions of the building for light to pass and to further expose the timber ceiling.
'Everyone who visits the building looks up and comments on the exposed beams and roof deck,' adds Orr.
All wood used throughout the center from the beams and ceiling panels to the trim and auditorium seat armrests was harvested from forests managed according to sustainable practices. Other ecologically sensitive materials include low-VOC paints, adhesives and carpet, and materials with recycled content such as structural steel, brick, aluminum curtain-wall frame, ceramic tile in the restrooms and even the toilet partitions. The materials were also selected for their durability and low maintenance.
McDonough + Partners even created a custom biodegradable fabric for the auditorium seats. The material degrades in sunlight over about three years and is actually edible, says William McDonough, principal of the 40-person firm, who admits to having actually taste-tested the fabric.
Specifying environmentally conscious materials, however, was just one component of this dynamic project, which is also meant to serve as a working lesson in sustainability.
'Oberlin represents probably the most ambitious program we've ever been involved with,' says Kevin Burke, project architect with McDonough + Partners. 'It stretched to include energy, water, wastewater, materials everything.'
Net energy exporter
To meet the goal of having the building be a net energy exporter to create more energy than it uses the building team had to employ a mix of simple and complex design concepts to minimize the energy needed to heat, cool and illuminate the interior space.
Solar energy. Photovoltaic (PV) panels were installed on the main building's south-facing roof to power the building. The 3,700 square feet of PV panels are expected to collect about 64,500 kilowatt-hours (kW) of solar energy annually enough energy for the entire building, which is calculated to consume 63,609 kW-hours a year. The array began operation in mid-November 2000, and as of Feb. 1 has generated approximately 3,280 kW-hours of energy. When more efficient solar cells become available and affordable the existing PV panels will be replaced, says Burke.
Building siting. The building is oriented on an east-west axis to take advantage of daylight and solar heat gain. All of major classrooms are situated along the southern exposure to maximize daylight.
'I taught the first class in this building, and the natural light was so nice that we didn't even have to turn the lights on,' adds McDonough. Even with the lights turned on, the energy-efficient fluorescent fixtures require just 0.9 watts per square foot, and occupancy sensors make sure they're operating only when needed.
Solar heat gain. The thermal mass of the building's concrete floors and exposed masonry walls helps to retain and reradiate heat. The walls have an R-21 energy performance rating while the standing-seam metal roof, which utilizes rigid polystyrene foam insulation, boasts an R-30 rating. Overhanging eaves and a vine-covered trellis on the south elevation help to shade the building, and an earth berm along the north wall further insulates the wall. The atrium's glass curtain wall features low-emissivity glass with an R-value of 7.1.
Fresh air. Natural ventilation is utilized in all occupied spaces via operable windows to supplement conditioned air supplied through the heating, ventilation and air-conditioning (HVAC) system. Energy consultants Steven Winter Associates of Norwalk, Conn., performed computational fluid dynamics (CFD) analysis to optimize air flow. For instance, says Adrian Tuluca, principal engineer with the firm, 'In the atrium, CFD simulation proved that the most effective convection air flow would be achieved by introducing air at low-level windows on the south side and exhausting it through clerestory windows on the north face.'
As part of the HVAC control system, the building's ventilation rates are based on carbon-dioxide (CO 2 ) levels in the building. As more students enter the building the CO 2 levels rise, triggering the HVAC system or automatically opening clerestory windows. 'Basically, it ensures that the building is not being ventilated more than it needs to be,' says Andrew Persily, Indoor Air Quality group leader for the National Institute of Standards and Technology (NIST), which is conducting research to evaluate the center's ventilation rates, airflow patterns and emission rates of VOCs.
Geothermal energy. The center utilizes 24 geothermal wells to heat and cool the space. Water circulates through closed-loop pipes to water-source heat pumps located in each space throughout the building. In addition, two larger heat pumps serve the ventilation needs for the building.
Each heat pump is controlled individually, allowing each unit to either reject or extract heat from the circulating water as needed. This reduces energy use by enabling simultaneous heating and cooling within the building.
Loop water temperature is between 30 F and 105 F. When the water is warmer than 105 F, it is circulated into the wells to reject the excess heat. When cooler than 30 F, it is supplemented with heat generated by an electric boiler.
The HVAC system also incorporates a heat-recovery system, which recycles heat from exhausted air and radiant coils powered by a 120,000 BTU/hour electric boiler underneath the concrete slab in the atrium to assist in heating the space.
More than energy efficiency
For McDonough, the notion of sustainable design isn't limited to a laundry list of efficiency measures. 'A sustainable building is much richer than a green building,' he says. 'Sustainable design incorporates culture, art, society, economics a quality of life. It's not just a simple issue of energy efficiency.'
To illustrate, McDonough points to a sundial outside the south entrance that traces the solar year and a pond on the east side that supplies irrigation water. Another example is a wastewater-treatment system that uses natural organic processes to recycle wastewater (see 'Nature's way: 'Living machine' recycles non-potable water,' page 32).
Of course, the building's merits have yet to be fully tested. Currently in the commissioning phase, McDonough admits that the team's original energy-use projection of 63,609 kW-hours annually has not been met. In fact, according to statistics provided by Oberlin professor John H. Scofield, through the first 10 months of operation, the building used 184,380 kW-hours of energy which was 3.6 times the projected amount.
'There were quite a few things that were not done according to design that are currently being fixed,' adds Tuluca. 'For example, certain lights were put on to a circuit that always kept them on, even though they're not security lighting.' Another example that Tuluca points to is the specification of the electric boiler that supplies heat for the radiant coils in the atrium floor, which is 'a very expensive source of energy,' he adds. Plans are to replace the boiler with a more energy-efficient natural-gas boiler.
Both McDonough and Tuluca believe that when commissioning is completed, energy expenditure levels will significantly drop and the building will indeed be a net energy exporter. Orr insists that the project is a long-term work in progress.
'While we can be proud of what's been accomplished, there's more to do,' says Orr. 'We intended for the building to improve, adapt and change over time in effect, a building that learns. This is a beginning, not the conclusion.'
Future plans for the center include the integration of a fuel cell with the PV panels to provide energy at night and on overcast days. Moreover, a monitor in the atrium will display all of the building's vital signs, including temperature, CO 2 levels, PV power generation and energy consumption.