The owners of this new home live in the close-in Zilker neighborhood. Several years ago they purchased a lot a few doors down the street and and planned to build a home there. They wanted the greenest, most energy-efficient home possible, including a geothermal heat pump system that would heat and cool the house and heat their water. They decided that now's the time to build, so they brought us their wish list. They worked closely with our designer on the plan, which includes a carport with an outdoor kitchen and a covered deck where they'll enjoy sitting in the treetops.

A geothermal heat pump uses the ground as a heat source in winter and a heat sink in summer. For this house, the system includes three 300-foot deep geothermal wells and a heat pump with a SEER >37. (SEER is a measurement of the efficiency of an air conditioner. The higher the SEER, the better. The Austin Energy Green Building Program requires at least 14 SEER. (More about SEER.) Installing a geothermal heat pump system is expensive, but the owners expect to reduce their home utility costs by at least half.