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 Cambridge, MA
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容积率: |
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建筑面积: |
5,850 sq. meters |
| 竣工日期: |
January 1998 |
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| 能源利用: |
Cambridge Cohousing is designed to require a minimum of energy for heating and cooling. These loads are met with a district heating/cooling system consisting of heat pumps and a boiler. Each unit is connected to a unique air distribution system that draws off water circulated from the central plant to provide heating, cooling, and ventilation.
The most technologically innovative aspect of the project is the HVAC system, designed by GreenVillage engineers Mark Kelley and Paul Raymer. The entire project is heated and cooled from a central plant, consisting of eight 10-ton (35.2 kW) ground-source heat pumps. These heat pumps are served by coolant loops in three 1,500-foot-deep (460 m) wells on site. The heat pumps produce water at 120 degrees F (49 C) for circulation to individual air handlers in each dwelling unit. A gas boiler boosts the temperature further to provide domestic hot water and to increase the heating capacity of the system for very cold weather. During the summer, the heat pumps are switched to the cooling mode.
The townhouses also have an innovative new air handler. This system has up to nine separate ducts coming out of the fan coil enclosure, serving the various rooms or zones. Instead of the usual large blower, each duct contains its own small fan, controlled by a thermostat in each zone. According to Raymer, these fans collectively draw a maximum of 530 watts, compared with 1,200 watts for a typical blower. This electricity savings, together with the zoned controls, allow for significant overall energy savings. A prototype installed in another GreenVillage house used an estimated 40% less energy than a standard heating system. With Cambridge Cohousing, says Raymer, they learned that vertical duct runs are very tricky to connect in prefabricated housing units.
The exterior walls of the housing are all 2x6 (38x140 mm) construction with R-19 (RSI-3.3) fiberglass batt insulation. Cellulose insulation was blown on-site into the band joist areas and roofs. Steel studs are used in the full basements, for interior partition walls, and around the perimeter to hold insulation at the exterior walls. Windows are aluminum-clad and low-e.
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| 选址和节水方案: |
The housing itself is a mix of apartments (flats) with one, two, or three bedrooms, and three-story townhouses.
An interesting effect of the manufactured housing approach is that, since each section has both a floor and a ceiling, there is duplication of joists between floors. Although this results in some wasted material, it makes for excellent sound transmission control between the floors. The double platforms are less justifiable in the townhouses, where they make for higher floor-to-floor heights with little benefit. They are one example, however, of the unusually sturdy construction used with prefabricated houses, allowing them to be transported without damage.
Diversion of Construction & Demolition Waste
All units are assembled from prefabricated sections that were constructed at Epoch Homes’ factory in Pembroke, New Hamphire. The GreenVillage Company had already been working with Epoch on the Building America program, so they were comfortable with the quality and energy-efficiency of the manufactured units. They also note that factory construction creates relatively little waste, and what there is can be collected for recycling more easily than on a construction site.
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| 室内环境品质: |
In order to preserve open space, the parking lot (allowing one space per housing unit) is underneath one block of apartments.
Cambridge Cohousing specified and installed water-efficient toilets and showerheads beyond the minimum requirements of the Energy Policy Act of 1992. Water-efficient European dishwashers were selected for use in the housing units, and water-conserving horizontal-axis washing machines are installed in the central laundry facility in the common house.
Green Strategies
Development Impacts
Cluster buildings to preserve open space and protect habitat
Minimize building footprint
Limit parking area
Water-Efficient Appliances
Specify horizontal-axis washing machine
Specify low-water-use residential dishwasher
Low-Water-Use Fixtures
Install showerheads using less than 2.2 gallons per minute
Low-Impact Siting
Site buildings so as to minimize access road length |
| 材料选择: |
To promote healthy indoor air, the air handlers in each dwelling are connected to ducts bringing in fresh air to mix with recirculated room air. A controlled air regulator is used to keep too much air from being driven in due to wind or other pressures. High-quality bathroom exhaust fans can be programmed to run on a schedule (typically set to coincide with times the residents are home), with a manual boost to high power on a 20-minute timer. Kitchen range hoods also vent directly to the outside, and all kitchen ranges are electric so as not to generate combustion gases.
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