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The 8,000 square foot zero net energy Bosarge Family Education Center is part of the Coastal Maine Botanical Gardens in Boothbay, Maine, USA. It is only the third net zero non-residential building in New England (as of August 2011). It offsets all of its energy needs by producing electricity on-site using photovoltaics. The solar arrays generate about 55,184 kilowatt hours with two grid-connected arrays: 135 photovoltaic panels on the south side of the roof, plus an additional 102-panel array on the ground. Payback from the solar system is estimated at 10 years. The building also utilizes passive orientation and employs 12-inch-thick walls and roof with an efficiency rating of R40 in the walls and R60 in the roof. Efficient triple-glazed windows provide passive solar gain in the winter, while keeping out the heat in summer; in fall and spring, much of the heating will come from the sun streaming through large south-facing windows. To supplement this and to provide cooling during the warmest days of the summer when open windows are not sufficient, the building has a heat-pump system powered by the PV system. Four compressors on the east end of the building send refrigerant through a network of copper tubing to small wall units in the rooms; these extract heat from the refrigerant in the winter or add heat removed from the air in the summer. (Scroll down for additional resources)
Because the building is airtight, another sytem recirculates air inside the rooms and pulls in a small percentage of outside air to keep it fresh. A computer controls the whole system for peak efficiency as conditions change inside and outside. Rainwater is stored in a 1,700-gallon graywater tank and is used for flushing toilets, reducing potable water consumption by more than 75 percent.
The Education Center and adjacent Visitor Center form the hub of the 250-acre waterfront property, which offers spectacular ornamental gardens including children’s and sensory gardens, miles of trails, art exhibits, events and programs. The building site is designed in five distinct planting zones to address the microclimates in each area, from full sun to full shade to boggy conditions. Native plants were matched to each climate to eliminate the need for irrigation. Rain garden areas will collect runoff that will then be filtered to the underground cistern.
Dozens of illustrated interpretive panels indoors and out - plus an electronic dashboard that explains the building features and energy use in real time - help visitors understand what makes this super-green project special, and provide ideas they can use at home.
The education center was designed by Scott Simons Architects of Portland, Maine, and Maclay Architects of Waitsfield, Vermont. It provides space for classes, workshops, meetings, artists in residence, and cultural events. In addition, the structure includes gallery spaces for art exhibits.
Another positive aspect of the Education Center is its impact on the local and state economy. Its construction created jobs directly and indirectly. Another advantage to the community and state is the opportunity for residents and those in the building trades to see firsthand how green technology can be put to practical use in a structure that is not only efficient, but also beautiful and functional.
How Does It Work?
by Maine business
While it represents the latest science, the Education Center’s design is based on a theory that at first seems whimsical: If a plant designed a building…. Yet, the concept is immensely practical. After all, a building designed by a plant would function efficiently and generate more energy than it uses without a dependence on fossil fuels or toxic emissions. It would shape its structure to fit the character of the bioregion and maintain, or even add to, the value of its ecosystem. It would only produce waste that could be used by another system. It would conserve water by on-site capture and recycling. And it would adapt to changing environmental conditions, such as temperature and climate. The Bosarge Family Education Center does all this and, through tours and signage, will teach visitors how to follow its examples.
The walls and beams were constructed in a special shop run by the Bensonwood company in New Hampshire and brought to the Gardens, minimizing impact on the building site. Construction waste, too, was minimized. Super-efficient triple-glazed windows, foot-thick walls with an R-value of 40 and even-thicker roofs with an R-value of 60, and “smart” air-to-air heat pumps are among the features that will help keep the building cool in summer and warm in winter.
With 135 photovoltaic panels covering the entire south side of the roof, and another 102-panel array on the one-time tennis courts (a vestige of the housing development the Gardens’ property was once intended to be), the Bosarge Family Education Center will generate a total of 55,184 kilowatt hours of energy annually. Energy not immediately needed will be transferred to an off-site grid to be returned and used as required. To help conserve energy, the building’s design makes optimum use of natural lighting and high-tech light-detection features.
Water conservation is also built into the design. Faucets and fixtures use much less water than those in typical buildings. Rainwater collected underground in a 1,700-gallon cistern will be used for toilets, radiant heating, and cooling.
In designing the five distinct planting zones surrounding the building, landscape architect Herb Schaal, FASLA, took into account the conditions and microclimates in each area – from full sun to full shade and from boggy to very dry – and matched the plants to the site, rather than vice-versa. Only native plants that will thrive are used, and no irrigation will be necessary. In fact, the rain garden areas will capture runoff and send it to the cistern for use in the building. Large deciduous trees on the south side of the building will help shade it from summer sun but, after they lose their leaves in the fall, will let in the sun’s warmth in the winter.
Sustainable Features • Bicycle storage and changing room
• Preferred parking provided for low-emitting, fuel-efficient vehicles
• Extensive habitat protection and restoration
• Stormwater quality and quantity control
• Reduced light pollution and heat island effect
• Innovative wastewater technologies used
• Optimized energy performance: Expansive solar array, passive solar, heat pump system, energy dashboard
• Large quantity of construction waste diverted from landfill
• Materials: Reuse, high recycled content, abundant use of regional materials
• Improved indoor environmental quality through introduction of outdoor air, use of low-emitting materials, occupant controllability, access to daylight and views