In Poquoson, Virginia, rock beds were not needed for thermal storage. The concrete floor slab – with insulation beneath it, to prevent downward heat loss into the earth – proved to be sufficient.

The water table in Poquoson – which adjoins Chesapeake Bay – is only two feet down. Cool pipes need to be 6 to 7 feet down. Instead, the Garden Atriums use a closed-loop geothermal. Instead of earth-to-air heat exchange, Garden Atriums use earth-to-liquid heat exchange. The system cost more to install, but uses a fraction of the energy, has a fraction of the maintenance cost, and a much longer life than traditional.

Buyers are accustomed to comparing homes on a cost-per-square-foot basis. Garden Atriums (and other sustainable homes) need to be compared on a total monthly cost basis … mortgage and utilities. In 2007, Garden Atriums cost the same as a traditional house costing $120,000 less. As energy costs rise, that gap will widen. But – asking buyers to look at house costs differently is a difficult paradigm shift.