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Manassas Park Elementary School is fundamentally designed around the premise that people, especially children, cannot be expected to preserve or protect something they do not understand. As such, the school is conceived throughout as a teaching tool that shepherds children along a path of environmental stewardship. All elementary "houses” take advantage of direct and diffuse daylight in the classrooms, break-out areas, and stair towers. Sunlight on southern exposures is controlled by projecting shade devices above viewing windows and reflecting light louvers within the higher daylighting window panes. Classroom ceilings are sloped to optimize penetration of natural light entering through the light louvers. A primary consideration of lighting studies was the ability to provide a glare-free teaching wall. North–facing roof monitors provide daylight to pre-K classrooms, while nearly 100 tubular skylights illuminate many other areas of the building. Small windows in the pre-K classrooms were designed as reading nooks and canted north of west, away from the setting sun and towards the wooded camp. Generally, lights in all rooms with exterior windows are automatically dimmed using daylighting sensors. In classrooms, lights are controlled in three zones—each zone parallel to the window wall. Interior and exterior lighting is designed to minimize over-illumination of non-task areas.
Inside and out, sustainable design is integrated with the elementary curriculum. Design decisions were made with the expressed goal of showcasing as many teachable moments as possible. Interior extended learning spaces offer dramatic and surprisingly intimate views of the neighboring mixed oak forest, while elementary classrooms face shady moss- and fern-covered learning courtyards featuring "fallen" trees and other particularities of an eastern deciduous forest floor. Students are offered exceptional views of the forest, and are invited to use the numerous exterior break-out spaces and to explore the piedmont landscape directly. The principal bio-retention area, for example, is detailed to serve as outdoor classroom, performance stage, and parent pick-up queue. In addition, this area has quickly become a popular location for informal gathering. A comprehensive signage program reinforces each teachable moment by highlighting green building facts, demystifying sustainable building systems, and describing flora and fauna found in the adjacent forest.
Manassas Park, Virginia
Manassas Park, Virginia, is a small, independent city surrounded by the affluent northern Virginia suburbs of Washington, D.C. Incorporated in 1975, the city cobbled together a series of pre-manufactured mobile buildings to create its first generation of school facilities from scratch. Ten years ago, the city began rebuilding all of its public schools—an enormous challenge in a city with an extremely low tax base.
The new Manassas Park Elementary School and Pre-Kindergarten (MPES) are the fourth and fifth new schools, and they join the earlier Cougar Elementary School to complete the city's elementary campus. The campus sits tightly surrounded by tract housing, private forest, and the historic landmark Camp Carondelet—forested winter quarters of the Confederacy's Louisiana Brigade between the first and second Manassas campaigns.
MPES serves a diverse population of students—many from immigrant families. The 2009-2010 enrollment includes sixty-eight percent non-white and twenty-six percent Limited-English-Proficient children. Forty-four percent receive free or reduced cost lunches. In the context of this rich diversity, the successful transformation of the school culture testifies to the vision and leadership of the Manassas Park City Schools administration.
The three-story school was built on an existing parking lot, and pushed tightly against the camp forest to preserve existing open space and create a suburban “school in the woods.” All existing trees were protected and moved with tree spades to the perimeter of the playfields, extending the benefits of the urban tree canopy to neighboring homes.
Ecological diversity is enhanced by a broad planting palette of native species, which shapes low-impact educational spaces. Hydric landscapes, previously absent, are featured in a manner giving children a new appreciation for water’s vital role in their lives. Broader disturbed areas were re-vegetated with native warm season grasses and wildflowers, echoing the savanna landscapes created by eastern woodland Native Americans.
The design team used the local ecosystem in a didactic manner whenever possible, and the site ecology is therefore brought inside of the building, as well. The school is organized into three “houses”—each house extensively themed around a season and each floor representing a corresponding level of the forest. Each classroom is named after a species commonly found in that season and place. In this way, children associate their homerooms with plants and animals rather than numbers.
• Lot size: 10.57 acres
• Previously developed land
Water Conservation and Use
Prior to development of MPES, rainwater was managed through the neighborhood stormwater management system. In order to avoid overwhelming this system, 100% of a two-year storm event is now collected for reuse or infiltration on site. Post-development run-off is significantly less than that from pre-development conditions.
All rainwater falling on building roofs is filtered and collected in a 79,000-gallon concrete cistern, yielding an estimated 1.3 million gallons per year. A portion of the harvested rainwater is further filtered and treated for delivery to the building flushing fixtures. The remainder is used for irrigating small portions of the landscape. The top of the cistern, and associated controls house, functions as an outdoor classroom, featuring a 22-foot tank gage. Mounted on the outside of the cistern pump house, a 96-square-foot mural illustrates the system layout and the natural water cycle. Educational maps teach children how rainwater falling at their school flows through Bull Run, the Occoquan and Potomac Rivers, and on to the Chesapeake Bay.
Low-flow and automatic faucets minimize municipal potable water use for flow fixtures – a 62% reduction from EPACT 2005 quantities.
Numerous high-performance design elements are incorporated into the building. Envelope features include solar-selective glazing, tubular skylights, a high-albedo white roof, and spray polyurethane foam insulation.
Efficient mechanical systems include ground-source heat pumps, variable-speed pumping, pre-treatment and total energy recovery for ventilation air, BAS-optimized system operation (building automation system), natural ventilation mode, and high-volume low-speed fans in double-height spaces.
Domestic water heating energy is minimized by the use of low-consumption fixtures and kitchen equipment. The kitchen utilizes a gas water heater with 98% combustion efficiency. Elsewhere, mini-tank water heaters are located close to the fixtures served. Energy Star appliances are used throughout.
Interior and exterior installed lighting power falls below ASHRAE 90.1 energy standard requirements (38% and 54% less, respectively). Savings are achieved through efficient fixture and lamp selections, occupancy- and BAS-controlled light switching, and continuously dimmable daylighting controls for 41% of the connected interior lighting power.
Energy modeling revealed cooling, ventilation and lighting to be the largest baseline energy loads. Overall, the building is expected to consume 52.7% less energy than the baseline design and meet the 2030 Challenge.
Educational signage and “truth” windows in mechanical room walls teach students and visitors about the building systems and their environmental benefits.
The school has been open eleven months (May 2010). Utility data is currently available for nine of those months. Only two of the nine months’ actual utility data reflect complete commissioning of the building because the final commissioning report was delayed until well after occupancy. A full year’s comparison of measured energy use and cost cannot be evaluated. At this date, the team has a plan; however, measurement and verification has not been implemented and the energy model has not been recalibrated.
As an update to the process and results paragraph, the nine-month data has improved slightly over the previously submitted data. MPES total actual energy use (calculated in kBTU/gsf) shows a 32% improvement compared to the adjacent school built ten years ago over the same time period. MPES total actual energy use (calculated in kBTU/gsf) shows a 31% improvement over the ASHRAE baseline for the same time period. Actual nine-month utility data can be made available. The data requested in the COTE submission template has been provided, although it may not be values that accurately represent what is desired by COTE. There are limitations in the data that is reported by the energy modeling software (eQUEST).
The annual heating and cooling energy uses provided in the COTE submission include only gas furnace and compressor energy consumption, respectively, for the base and proposed building simulations. Other HVAC related energy consumption, such as fans and pumps, is not included in the individual heating and cooling values because eQUEST does not calculate energy associated with fans and pumps separately by cooling and heating subcategories. The total HVAC system energy usage – for heating and cooling, including but not limited to compressors, gas furnaces, fans, and pumps – for the base and proposed case is 5,556 and 2,023 MBtu/yr, respectively. The ratio of total heating and cooling energy consumption for baseline versus proposed is 2.75:1.
In addition to the ground-source heat pump system, the project incorporates numerous other technologies and strategies that minimize the cooling and heating loads in comparison to the base case building. These include daylighting controls with dimming ballasts, daylight reflecting louvers and light shelves, and Solatubes (reduction of interior lighting heat load to the space); natural ventilation mode (windows are opened and cooling systems shut down during favorable outdoor conditions); window overhangs (solar heat gain reduction during the cooling season), high performance glazing and envelope, building automation and dedicated outside air systems with both sensible and total heat recovery wheels.
The building form and height are greatly influenced by the site constraints, which offered only a narrow area (stretching southwest to northeast) for building. In order to optimize daylighting in the principal learning spaces, classrooms are organized into three “houses”—with each classroom facing approximately north or south. The three-story educational houses (nearly cubic in volume) minimize building envelope exposure to the climate. The houses are organized around courtyards that maximize the connectivity between indoors and out while providing plenty of controlled daylight and fresh air. Mature deciduous trees, on rising ground to the west, shade the buildings from the setting sun.
The relatively exposed east side of the building is programmed with “closed” spaces (gym, loading dock, mechanical rooms) to minimize unwanted solar heat gain. Although the temperate seasonal climate is humid with light and variable winds, natural ventilation is used for cooling when conditions are favorable. An induced stack effect, established by vertical ventilation ducts, draws fresh air in through manually operable windows and exhausts air through the penthouses. Favorable conditions are signaled by “green lights” which are tied to a weather-predictive mode in the building automation system. The signal lights ensure the children are active participants in energy conservation.
Students and faculty are able to monitor real-time building performance data via a building dashboard or “green screen” in the school’s main lobby. All content is also available online and can therefore be accessed from each classroom. The green screen not only includes energy and water data, it also explains the school’s many green features. Anecdotal evidence indicates that the building and building systems are functioning well. Innovative strategies that are already being re-used by the design team include the “green light mode” and the comprehensive school-as-an-educational-tool approach. Manassas Park Elementary School was recently selected by the American Institute of Architects and its Committee on the Environment as one of the top ten examples of sustainable architecture and green design solutions that protect and enhance the environment.
Green Schools Checklist EPA (368 kb)