The second structure on the Ordway Campus, the Carriage House, employed a similar approach. By further reducing direct HVAC loads through super-insulating the walls and ceiling, heating and cooling equipment needs were reduced. As result, even more efficient mechanical systems were needed, which results in further reductions in electrical demand. And the overall reduced peak heating and cooling loads allow the use of air-source heating and cooling equipment, which is a simpler and less expensive system than the ground-source system needed for the Woodwell Building.
Consistent with the design intent of the Woodwell Building, an integrated design-build approach achieved a super-insulated building envelope, high-performance glazing, energy recovery ventilation, low energy use lighting, and other efficiency strategies. This resulted in the replacement of the existing oil heating system with an air-source heat pump system.
Both projects applied efficiency-efficient principles to reduce power usage so significantly that CO2-laden fossil sources could be eliminated from the campus.
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Heating, ventilation and air-conditioning (HVAC) account for about 39 percent of the energy load of the average office building. Consequently, to secure a tight building envelope, and prevent uncontrolled exchange of heat from the inside to the outside of the structure, insulation is very important. But it is also vital to control air leakage, which prevents what is known as structural thermal “bridges.”
Insulation and Offset-Stud Framing
To deal with the related issues of insulation and air leakage, the Center chose to use the icynene spray foam insulation system in the roof and exterior walls of the Woodwell Building, providing an insulation that is both a thermal and an air barrier. Icynene is a safe, open-cell, low density polyurethane. Offset-stud framing complements the application, eliminating the thermal bridge created by attaching interior and exterior walls to common studs.
Another common point of energy loss in any structure is through windows, which transmit energy into the building as solar gain, and out of the building through radiation from the glass, conductance from frame edges, convection within multiple glazed surfaces, and via simple leakage around movable window components. The average building has about 20 percent of its wall area devoted to windows, and a well-insulated building might expect up to 20 to 50 percent of its total energy loss to be related to windows.
To minimize window energy loss, we selected two high performance window models from Loewen’s Heat Smart™ Plus series which includes double- and triple-pane argon-filled glazing with Low Emissivity (Low-E) coatings to reduce radiative heat transfer. Additional conservation strategies include enhanced seals and weather-stripping, and thermal breaks (airspace) between the outer metal cladding and the wood window frame.
Minimized Lighting, Plug, & HVAC Loads
With a building envelope designed to minimize waste in the heating and cooling cycles, the second strategy for reducing energy usage involves the specification of efficient lighting fixtures, office equipment (plug loads) and mechanical systems for heating and cooling the building. All incandescent lighting was replaced with fluorescents, 85 percent of our computer desktop systems were replaced with notebook computers (which use just 10 percent of the power), and laser printers were replaced with inkjet printers. Motion detectors assure that lights are turned off when staff are gone. Further gains are achieved by eliminating redundant equipment and adopting Energy Star appliances wherever possible.
Maximized Daylighting and Minimized Ventilation Energy Loss
After HVAC, lighting is the second largest energy load in a standard office building. An important addition is the maximizing of natural daylighting. To this end, project architects strove to introduce natural lighting (and operable windows) to all areas of the building.
In a building that is tightly sealed, the introduction of fresh air is a necessity to avoid what has been termed “Sick Building Syndrome” or “Building Related Illness” for building occupants. Currently, ventilation standards provide for 20cfm (cubic feet/minute) for office occupants as established by ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers).
For a High Performance building, an unfortunate consequence of responsible ventilation is that a great deal of energy is heading out of the building in the exhaust air that has supplied the offices. To compensate for this, the Center installed three Energy Recovery Units in the Woodwell Building to minimize the transfer of both sensible heat (temperature) and latent heat (moisture). During the winter months, the slowly rotating wheel captures moisture and heat from the outgoing “return air,” and passes this energy to the incoming outside air, effectively pre-heating and moisturizing what is to become supply air to building occupants. In the summer months, the process is reversed, with warm, moist incoming air being cooled and dried by the outgoing return air from the offices.
The Woodwell Building has a 26.4kWp (kilowatts peak) rooftop photovoltaic power system which annually provides approximately 30,000 kWh of electrical power. Funded in part by the Massachusetts Renewable Energy Trust, the 88 ASE-300-DGF50 modules are manufactured by Massachusetts-based ASE Americas. Each module has an area of 26 square feet and a rated power of 300 Watts.
In 2009, the Center installed a 100kW wind turbine to provide additional renewably generated power for the campus.
The Northwind 100 was chosen based on the following factors:
- Modern design: This wind turbine is a direct drive (having no gearbox), permanent magnet generator, with a robust design heritage from tested Arctic installations.
- Quiet operation: Our wind turbine is the quietest one available in its size-class. A comprehensive sound analysis was undertaken by a third party with confirmation by Center scientists.
- Appropriate size for our electrical requirements: It provides surplus generation which serves as a modest revenue source to defray deployment costs, and is available to serve additional requirements as staff and facilities expand.
- Carbon cycle benefits: Perhaps more important than the monetary benefits accruing to the Center through the deployment of the wind turbine are the pollution and carbon dioxide reductions.
The wind turbine is mounted on top of a 120-foot monopole tower.