August 01, 2013

Center for a Sustainable Future Lenawee Intermediate Schools

  • Hands-on Education Center

    The Center for a Sustainable Future will serve as an immersive, project-based learning center for agriculture, horticulture, environmental science and renewable-energy technologies. The 75-acre site will allow for teaching traditional and emerging sciences while preparing, updating and retraining people for sustainable careers. The facility and site has been designed to achieve Net-Zero energy use and a LEED Platinum rating. As such, the Center will model best practices for ecologically-responsible design in Lenawee County and will assist in the promotion of natural resource conservation, land stewardship and sustainable agriculture.

  • Mechanical Systems

    The Center features a geothermal HVAC system which uses 400 foot deep wells to transfer heat to and from the ground in order to condition the building. The building uses efficient two stage geothermal heat pumps for the primary HVAC system and a dedicated outside air unit with energy recovery wheel and variable air volume boxes (VAV box) for demand controlled ventilation. Each heat pump is provided with a small horsepower pump for circulation of condensing water. This de-centralized pump activates only when its heat pump is operational. This pumping system eliminates large centralized pumps and unwanted energy usage during low load conditions. Fresh air and temperature set points are controlled by occupancy sensors in each classroom to minimize energy usage when spaces are unoccupied for even a relatively short amount of time. Also, the greenhouse features a radiant floor heat system which uses hot water piping embedded in the concrete slab.

  • Designed to achieve Net Zero Energy Use

    The US Department of Energy’s National Renewable Energy Lab defines Net Zero Energy as “a building that produces and exports at least as much renewable energy as the total energy it imports and uses in a year.” Net Zero design is most effectively achieved when the building’s energy demand is as low as possible. Every reasonable means of reducing energy use is implemented first, then renewable energy sources are tapped to fill the remaining demand. The LISD CSF project is designed to achieve an Energy Use Index of 25.5 kBTU/sf/year (and 17.95 if you exclude the greenhouse). That is approximately 75% less energy than a contemporary code-compliant building of its type! This allows the investment in the solar photovoltaic array to be ¼ the size it might otherwise have needed to be to serve the building’s needs.

  • Renewable Energy

    The Center for a Sustainable Future has two separate photovoltaic generation systems. A 58kW ground mounted system adjacent to the building generates most of the building’s energy. This system uses string inverters located near the array to convert electricity from DC to AC which can then be used inside the building. A smaller 8kW system is located on the roof and features microinverter technology. This means that a small inverter is located on the back of each module which helps to minimize the negative effects of shading. The combined systems will completely offset all energy usage of the building on an annual net-basis. Additionally, students will have the opportunity to monitor the performance of the systems throughout a full range of seasonal conditions.

  • Site Orientation

    The orientation of the building structure benefits from an earth berm, protecting it from north-westerly winter winds while opening to the passive solar opportunities facing south. Sun shades protect windows from the high-angles of summer sun but allow winter sun angles to enter the building. Operable windows will allow natural ventilation in temperate conditions

  • Building Envelope

    The wall and roof assemblies are insulated with 5 & 6 inches of extruded polystyrene rigid board insulation, respectively. Rigorous attention has been given to continuity at roof/wall and wall/slab intersections, minimizing thermal bridging and air infiltration. Concrete, which makes an excellent thermal mass, helps maintain an even interior temperature and buffer day/night heat cycles. Precast concrete roof slabs, concrete block walls and poured concrete slabs are all within the insulated envelope of the building. Window systems are of low-infiltration, double thermally-broken construction with high performance insulating glass. All building entries are provided with heat-lock vestibules. Glass units are insulated with a low solar heat gain coefficient to reduce heat transfer. All windows have sunshades to offset summer glare and are located to maximize views of the property. Each classroom has operable windows to let in fresh air as seasons allow. As part of the building commissioning, the windows will be pressurized to reduce air infiltration.

  • Water Conservation

    The rainwater catchment system uses the rainwater collected from the roof to flush toilets and provide irrigation for demonstration gardens. As a teaching tool, the catchment trench is observable by students as part of the vegetated roof lab. Approximately 7,000 square feet of roof area drains into a 10,000 gallon underground water storage tank. Pumps then force the stored water through a series of filters and a UV disinfection unit before it is distributed throughout the school in a separate piped water system. In times of low rainfall, the system is supplemented by the potable well water system. All plumbing fixtures are “low flow” type fixtures. The pressure assisted toilets use 1.0 gallons per flush, 37 percent less than a standard toilet. Classroom sink faucets will be furnished with 1.5 GPM aerators to use 31 percent less water than a standard faucet. The boy’s bathroom will also feature a waterless urinal.

  • Natural Daylighting

    Solar tubes (brand name: ‘Solatube’) bring a balanced amount of daylight to the interior spaces. The Solar Tube consists of a plastic dome that sits on the roof, over a reflective tube that carries light inside. The dome is a Fresnel lens shaped to maximize light intake; cut out ultraviolet and infrared light; and enhance performance earlier and later in the day. The tube that transports light can be bent to carry light to spaces below. Windows also bring in natural daylight, but they are less efficient when comparing daylight provided against thermal insulation loss. Windows are used primarily to provide views to the natural setting outdoors. The building uses all LED lighting fixtures which automatically dim in most areas to save energy when there are sufficient natural light levels.

  • Storm & Waste Water

    Stormwater will flow from paved surfaces through a series of mitigation elements prior to entering a natural creek that flows into the River Raisin. A raingarden and vegetated berms will first filter stormwater. Moving to the pond, the water will be retained, allowing sediments to settle out and giving the sun time to burn off oils and other contaminants. The project will use an on-site waste disposal system commonly known as a low dose pressure distribution system. All sanitary effluent, or wastewater, is discharged via gravity flow into one of two 1500 gallon septic / holding tanks where the liquids are separated from solids and anaerobic treatment begins. The liquid effluent of the septic tanks flow via gravity to a single 1000 gallon dosing tank. The effluent is then pumped further west to two mounded hillside soil absorption systems. The sand mounds are constructed above the existing grade and are strategically located to blend into the hillside. The dosing tank is programmed to pump small volumes of effluent, alternating between the two mounds, at timed intervals. This maximizes the ability to naturally treat the effluent without over burdening the system.

Emphasizing hands-on learning, sustainable features are immediately visible and purposely put on-display at the Center for a Sustainable Future.

Features such as a solar array, raingarden, wetlands, demonstration crops, and pervious pavement are visible at the site entry. The orientation of the building structure benefits from an earth berm, protecting it from north-westerly winter winds while opening to the passive solar opportunities facing south. Sun shades protect windows from the high-angles of summer sun. Solar tubes bring a balanced proportion of daylight to the interior of the spaces. The walls, roof and floor of the building are insulated to values 1.5 to 2 times the amount required by current energy codes.

The building’s mechanical systems employ geothermal heat transfer and sophisticated controls. The mechanical equipment, duct work and piping are exposed and color-coded to be understood by students and visitors. Monitors displaying energy and water use performance will be displayed in the public corridors.