This enables the Hopis to enjoy modern conveniences such electric lights, refrigerators, and television while remaining true to their values. Lafayette, Colorado The Nyland CoHousing Community in Lafayette uses passive solar strategies as well as energy efficient measures to lower their homes overall energy use. The arrays were rated at 1kWpDC in size and were roof-mounted. The utility sold the arrays to the homeowners, and guaranteed the components quality. In 1985, the Flood Brook Union Elementary School in Londonderry converted its heating system from oil to wood chips.
Local sawmills supply the wood chips.
A corkscrew-shaped auger automatically feeds the wood chips into the fire. The system has an automatic fire extinguisher and back-burn preventor. Salt gradient ponds have three distinctive layers a top layer with a low salt concentration, a middle layer with a salt concentration increasing with depth, and a very salty bottom layer. Thermal energy from this pond helps heat a swimming pool in summer and a recreation building in winter. For over a decade, a housing development in North Philadelphia has been quietly making a statement about sustainability in American cities.