Brookhaven Solar EarthCraft House: A Net-Zero Energy House demonstrates ultimate water saving techniques by Emily Mitchell

Not only is the Brookhaven Solar EarthCraft House to be energy efficient—it employs technologies and strategies to minimize water use as well. The landscape plan utilizes the principles of Xeriscaping™: plants specified to be drought-tolerant, which helps to reduce water demand. Rainwater collection, a grey water system and drip irrigation eliminate the need for a municipal water supply for irrigation. Additionally, the installed indoor fixtures and faucets are all “low flow.” This showcase home features impressive methods of water conservation.

Challenges

Like electricity, water is usually abundant and cheap so we don’t think much about conserving it. In fact, water seems limited only when demand outpaces supply during a drought season. But what most people don’t realize is that it takes an enormous amount of energy to treat and deliver water. Therefore, water conservation not only ensures the availability of a limited resource, it decreases air pollution because power plants don’t have to produce the electricity.

Georgia residents are uninspired to conserve water because homeowners can easily obtain it at low cost: the municipality charges about $2 per 1,000 gallons. Residents only feel the pinch of a limited supply when they are asked to water their lawns less in a drought—and usually they suffer through it with few complaints.

In a typical household, 30 - 45 percent of total water usage goes to landscape plants and grasses. Inefficient water sprinkling systems are partly to blame. Sprinkler heads are often poorly chosen or incorrectly installed. When water is thrown on impervious surfaces it contributes to runoff or it evaporates before it’s ever been used. Some systems create a “mist” because they operate under too much pressure and the water evaporates without being used. Exotic and ornamental plants require large amounts of water and are notorious water wasters.

The Brookhaven house sought to reduce water demand by developing an integrated plan to reduce total water usage—both indoors and outdoors.

History of the House

The house was featured at the 2002 International Builders’ Show in Atlanta. It highlighted the building products and techniques that enabled it to be the state’s first “zero-energy home” built under the EarthCraft House program and with the support of the U.S. Department of Energy’s Building America program.

Cahner’s Publishing funded the initial construction and then donated the home to a local organization. Sona Chambers and Debbie McMinn bought the house and moved it to Brookhaven. Chambers and McMinn were the general contractors and celebrated its completion in the summer of 2003.

Since that time, Chambers and McMinn have opened the house for tours to over 400 people interested in its energy-efficient and environmentally responsible design and construction.

Results

Water usage was reduced with outdoor conservation strategies. Xeriscaping™ is a water management concept developed by the Front Range Xeriscape Task Force of the Denver Water Department in the early 1980s that uses native and drought resistant plants in landscaping. Approximately 98 percent of the grasses, shrubs, vines and other ground covers in the yard are native.

The use of these plants, instead of exotic species, reduced the amount of water needed to establish the landscape. Smartly selected plants conserve water throughout the life of the landscaping. Only two non-native plants have died since the landscaping was installed and conventional municipal water usage—typically between 30-40 percent of the total demand—is 0 percent in the Brookhaven home!

The Brookhaven home has a rainwater catchment system that stores and distributes rainwater for irrigation. The RainHarvest Company installed a 1,200-gallon underground cistern to collect rooftop rainfall. A 1” rainfall event produces 2/3 of a gallon of water for each square foot of the footprint of roof area.1 The 2,550 sq. ft. roof therefore directs approximately 1,700 gallons of water into the cistern. Since the Atlanta region receives an average of 50 inches of rain a year, or 85,500 gallons annually, that’s 235 gallons daily! When the cistern reaches its maximum holding capacity of 1,200 gallons, it directs the overflow to irrigate and percolate along the natural drainage plane of the backyard.

The water is supplied to plants (and not the turf grasses) through high efficiency drip irrigation. Drip irrigation reduces water loss caused by evaporation and runoff because it delivers water directly to the roots steadily over a period of time instead of in short excessive increments.

The house has a greywater collection and delivery system that irrigates 1,600 square feet of turf grasses. Greywater is wastewater generated in the home—excluding toilets and the kitchen sink—used for non-agricultural irrigation. Water is supplied to the turf grasses after it’s used for laundry and bathing. The amount of total wastewater output from the Brookhaven house has been reduced 60 percent. The Atlanta sewer system receives only the blackwater—toilet water and water containing oil, grease and food scraps.

The final component of this comprehensive water management system is the Weather Trak system by Hydro Point. The system relies on weather satellites that automatically transmit water loss information to controllers that then adjust irrigation timing to match the daily needs of the landscape. Studies have shown this water management method can reduce landscape irrigation needs by a minimum of 25 percent.

Brookhaven Water Conservation Strategies

Contacts and Resources

(Footnotes)
1 Taken from Texas Guide to Rainwater Harvesting, published by the Texas Water Development Board in Cooperation with the Center for Maximum Potential Building Systems, 1997 edition,
http://www.twdb.state.tx.us/publications/reports/RainHarv.pdf