AIA Top Green Buildings 2010
At street level, elements such as paving patterns, street trees, glass awnings, and large wood windows in the retail spaces are intended to foster activity and connection with the urban fabric. Higher up, a visual connection with the city is maintained through a highly transparent building envelope.
The low-e glazing helps reduce heat gain while allowing over half the building to be daylit, with metallic-coated roller shades and operable windows offering occupants some control over the indoor environment. Exposed concrete ceilings and structure provide thermal mass and also minimize finishes.
The $138 million building is projected to use 46 percent less energy than a baseline building as defined by ASHRAE 90.1-2004, thanks to features and strategies such as fan-assisted night flush of thermal mass for the office floors and carbon dioxide sensors for ventilation demand control. Total annual energy use is estimated at 7.8 kWh/ft2/year (84.4 kWh/m2/year), of which about 4 percent is generated by solar thermal collectors, with a small contribution from four building-integrated wind turbines.
Addressing Waste Holistically
The Omega Institute for Holistic Studies set out to develop a sustainable wastewater treatment facility for its 195-acre (79-hectare) campus in Rhinebeck, New York. BNIM Architects helped the organization create the Omega Center for Sustainable Living, an integrated zero-net-energy building housing a classroom, laboratory, and an Eco Machine™ ecological filtration system by John Todd Ecological Design, which uses plants, bacteria, algae, snails, and fungi to process about five million gallons (20 million liters) of wastewater per year.
Balancing the needs of the system's plants with the comfort of people was a central challenge. The plants growing in the interior lagoons require precise solar energy levels on both their south and north exposures, so the building section, windows, and skylights were carefully designed as an integrated system to meet those needs.
The building is oriented and shaped for optimal control of light and solar heat gain. Daylight reaches almost everywhere, and over three-quarters of spaces are naturally ventilated, thanks to a system of operable, fixed, and solar-tracking fenestration. The insulated thermal mass of the building and the thermal mass of the water passing through the treatment cycle (at 55 degrees Fahrenheit, or 13 degrees Celsius) play a key role in reducing demands on the mechanical systems.
With a PV array sized to exceed its electrical needs, generating 10.5 kWh/ft2/year (112.5 kWh/m2/year), the $2.8 million center achieves net-zero energy use. It is expected to receive a Platinum rating under LEED-NC v2.2, and to meet the standards of the Living Building Challenge, a program run by the Cascadia Region Green Building Council.
San Francisco Adaptive Reuse
Matarozzi/Pelsinger Builders and architects Aidlin Darling Design took a derelict early-1900s industrial structure in San Francisco and carefully transformed it into a sustainable mixed-use building. The renovated three-story, 14,000-square-foot (1,300-square-meter) building at 355 11th Street received a Gold rating under LEED-NC v2.2. It now serves as offices for the general contractor and for an architecture firm, with a restaurant space at ground level.
The building's original timber frame structure was retained and seismically upgraded, but the original corrugated metal siding was unsalvageable. Because the building is part of the Jackson Brewing Company site, listed on the National Register of Historic Places, the San Francisco Planning Department required that new siding be an "in-kind" replacement, and that overall window area remain the same.
The design team met these requirements while improving daylighting and natural ventilation through the use of subtly perforated zinc cladding. The perforated outer skin limits solar heat gain and allows cross-ventilation of the interior through operable windows hidden behind the zinc. Customized using CNC (computer numerical control) milling, the perforations form an opacity gradient across the facade, revealing reflections and nighttime glow from the glazing beyond.
New operable skylights help ensure the building is naturally ventilated and largely daylit. Other sustainable features include drivable permeable pavers, a drought-resistant planted roof, in-floor radiant heat from a high-efficiency condensing boiler, and access to ample public transit. A 30-kilowatt rooftop PV array is projected to provide about 38 percent of energy needed for the building.
Like Twelve West in Portland, the new Manitoba Hydro Place tower stands in a dense urban environment: downtown Winnipeg, Canada. The 22-story, 698,000-square-foot (64,800-square-meter) building serves as the consolidated headquarters for Manitoba Hydro, the primary energy utility in the province.
Kuwabara Payne McKenna Blumberg Architects and executive architect Smith Carter Architects and Engineers designed the building in a formal integrated design process, developing the form and massing in response to Winnipeg's abundant sunshine and dominant gusting south winds. The resulting US$278 million structure is projected to be 64.9 percent more energy-efficient than the baseline established by Canada's Model National Energy Code for Buildings (MNECB), and is expected to earn a Platinum rating under LEED Canada-NC 1.0.
The building comprises two office towers atop a three-story podium. The towers form an A-shaped plan, converging at the north end to minimize north-facing surface area, and diverging at the south end to maximize solar gains in winter and wind exposure in summer and the shoulder seasons. The building benefits from a solar chimney, a large geothermal system, and the thermal mass of exposed concrete structure.
The east and west tower facades are double-glazed with motorized windows on the exterior, and single-glazed with manually operable, hopper-style windows on the interior, with a radiant slab between the glazing layers. These features, along with extensive daylighting and efficient systems, help keep energy use down to a projected 8.2 kWh/ft2/year (88.3 kWh/m2/year).
Simply Green School
At Sacred Heart Preparatory in Atherton, California, a new building that combines science classrooms and community functions recently received a Platinum rating under LEED for Schools v2.0. In the design of the Michael J. Homer Science and Student Life Center, Leddy Maytum Stacy Architects emphasized simple solutions that maximized energy efficiency, user comfort, and connections to nature while reducing first costs and long-term maintenance.
The Homer Center includes a 700-seat auditorium, a 350-seat dining hall with full commercial kitchen, classrooms, and administrative offices for the 550-student high school, located on a K-12 campus. The compact configuration of the 44,100-square-foot (4,100-square-meter) building, with minimal articulation, translates into structural, mechanical, and material efficiencies, with a net-to-gross floor area ratio of 82 percent — high for school buildings of this type.
The building is organized on an east-west axis, with the two-story classroom mass to the south and the auditorium and offices to the north. All the classrooms and over half the spaces in the building are naturally ventilated and use daylight as the primary light source, aided by lightshelves and daylighting tubes.
With a seasonal wetland rain garden and retention basin, and a roof planted to resemble a native redwood understory, over 90 percent of precipitation is managed onsite. Water-conserving fixtures help cut potable water use in half.
The projected energy use is 10.0 kWh/ft2/year (107.8 kWh/m2/year), of which about 12 percent is generated by a 40-kilowattt PV array. That's 49 percent less energy use than the ASHRAE 90.1 2004 baseline, and 69 percent less than a typical school building, according to the Commercial Buildings Energy Consumption Survey (CBECS) 2003.
The COTE Top Ten Green Projects for 2010 were announced by the AIA on April 21. The award-winners will be recognized at the AIA National Convention and Design Exposition in Miami, Florida, June 10 to 12.
The 2010 COTE Top Ten Green Projects jury included Peter Busby, Assoc. AIA, Int'l. Assoc. AIA, Busby Perkins + Will; Robert Harris, FAIA, Lake Flato Architects; Denis Hayes, The Bullitt Foundation; Lisa Heschong, Heschong Mahone Group, Inc.; Alison G. Kwok, AIA, University of Oregon; and Elizabeth I. Ogbu, Assoc. AIA, Public Architecture.
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