To date, the focus in the US has primarily been on promoting conservation measures and increasing the energy efficiency of various residential, commercial and industrial energy consuming systems. Some of these efforts have been encouraged by government subsidy programs, and some have been in the form of regulatory imperatives such as the CAFE standards and gas-guzzler taxes.

Home owners typically have few options available by which their existing houses can be modified to reduce or stabilize their purchased energy budgets.

Many of us have already installed flow-restricting shower heads and faucet in our homes, increased insulation to attics, ceilings, walls, water heaters, foundations, pipes and ductwork, upgraded windows and doors with additional glazing or have replaced them outright, and have replaced inefficient older furnaces, water heaters and other major appliances with energy-efficient units. The problem is that while implementing measures like these can make a significant dent in our energy expenditures, there is a point of diminishing returns and our cost of energy will never be eliminated altogether.