Constructed Wetlands

Goals of Innovation: Help clean the effluent, provide a haven for water-loving plants and animals, and reduce the required size of the septic drain field.

Description: Initially, wastewater enters the septic tank. After its sediments settle, the effluent flows out of the tank and into the wetlands area. There a thick rubber liner, covered with small, smooth rock holds several inches of effluent. Elephant ears, giant fragmiti, cattails, and other assorted native plants grow on and around the "wet zone". These plants draw nutrients directly from the effluent. Excess water continues on to the drainfield.

Obstacles: The county health department needed to approve this system, so a septic engineer was hired to design the wetlands and present it to the county health department. As this wetlands was the "first of its kind", the process took over a year before approval was given.

Cost Information: The construction cost of the wetland added about $4,000 to the cost of a normal septic system and totalled $18,000. The septic engineer's time and drawings cost $1,000.

Additional Benefits/Drawbacks: The system has worked trouble-free since the house was completed, and the plants are thriving. The wetland reduced the size of the drainfield necessary and no pumping has yet been required.

Ground-coupled Foundation

Goals of Innovation: Deisgn and build a foundation that makes use of the area's warm subsoil during the cool season in a way that does not cause uncomfortable heat gain during the summer.

Description: The ground at the foundation level varies from 63 to 77 degrees Fahrenheit throughout the year in central Texas. Most temperature variatiion occurs in the upper two feet of earth, so the top 2 - 4 feet of the foundation is insulated with rigid foam along the perimeter to disconnect it from fluctuating upper soil temperatures. The foundation's insulation goes as deep as four feet on the south side of the house and no more than two feet on the north side of the house.

The lower part of the foundation is not insulated; it is coupled to the warmer subsoil, which stays at about 70 degrees all year. This system allows the home's thick thermal mass walls to dissipate heat during the summer, and absorb and retain heat when it is cool. The system helps maintain a relatively consistent indoor year around temperature without the need to use a nonrenewable energy source.

Obstacles: The main concern was to balance heat gain during the winter with heat dissipation during the summer. Subsoil temperature fluctuations on this particular site were determined, and used to determine how deep the foundation's insulation should go on each side of the house.

Cost Information: The entire foundation cost about $25,000, but serves "double-duty" as part heat sink and heat dissipator.

Additional Benefits/Drawbacks: The goal was met as the house's internal temperatures stay within a comfortable range year around, with very minimal use of a space heater during cold and cloudy times.