for its High Performance Buildings Database
U.S. Department of Energy - Energy Efficiency and Renewable Energy
Building Technologies Program - Buildings Database
Site Description
This house replaced one that had a 23 percent larger footprint, that did not take particular advantage of the scenic beauty of the site, and that was not energy efficient. The owners and a next-door neighbor jointly acquired the vacant lot between their two properties and consolidated their three lots into two so as to maintain more open space and preserve lake views for other neighbors. The floor area ratio of the new house is 27 percent of that allowed by zoning for the site--a rarity in this built-up suburb.
Although it was necessary to remove one mature tree, seven new trees were added to provide shading and privacy. Echoing the prominent use of bamboo for flooring and stair railings inside the house, an evergreen bamboo hedge was planted on the north property line to screen the house from neighbors. The low-maintenance landscaping includes natural grasses and other drought-resistant plants.
Porous pavers and grassy pavers were used for the driveway to minimize rainwater runoff. The latter increase the appearance of open space.
A subtle gray-green color was chosen for the cedar shingle siding, allowing the house to blend into its surroundings. Particularly when viewed from the lake, the house disappears into the landscape.
- Lot size: 19,042 ft2
- Building footprint: 2,220 sq ft (206 sq meters)
- Previously developed land
Water Conservation and Use
Minimizing water consumption and rainwater runoff was an important design objective. The high-efficiency, dual-flush (0.8/1.6 gallon) toilets used in this house save an estimated 5,480 gallons of water/year. Low-flow showerheads and faucets together with water-efficient dishwasher and front-loading clothes washer reduce consumption still further.
The driveway has two sections. The first is composed of porous pavers laid over an 18-inch-deep bed of fine gravel. This sturdy yet permeable pavement surface facilitates rainwater infiltration and maximizes groundwater recharge. The parking apron leading to the garage is composed of grassy pavers. It both reduces rainwater runoff and adds to the sense of open green space around the house.
Downspouts from the roof are interconnected and feed into a 1000-gallon cistern from which water can be pumped to water the garden. A low berm was constructed along the south property line, raising the ground level where rainwater used to pool and drain towards the lake after heavy storms. All of these features--porous pavers, cistern and berm--have reduced runoff to the lake significantly and help to recharge the water table for the trees and other plantings.
- Indoor potable water use: 33,700 gal/yr (127,000 liters/yr)
- Outdoor potable water use: 74,100 gal/yr (280,000 liters/yr)
- Total potable water use: 108,000 gal/yr (408,000 liters/yr)
- Potable water use per occupant: 53,900 gal/person/yr (204,000 liters/person/yr)
- Potable water use per unit area: 26.9 gal/sq ft (1,100 liters/sq meter)
Green Strategies
- Runoff Reduction
- Consider porous turf-paving systems on low-traffic parking and driveway areas
- Install porous asphalt or concrete
- Water-Efficient Appliances
- Specify horizontal-axis washing machine
- Specify low-water-use residential dishwasher
- Landscape Plantings
- Minimize turf area
- Low-Water-Use Fixtures
- Use low-flow toilets
- Install showerheads using less than 2.2 gallons per minute
- Rainwater Collection
- Collect and store rainwater for landscape irrigation
- Demand for Irrigation
- Select plants for drought tolerance
- Use mulch to improve water retention
