To save energy, the simplest solutions are often the most cost-effective, especially when the use of metals and mechanical equipment can be minimized. Passive solar simply utilizes the sun and thermal mass to provide heating and cooling for lowest life cycle energy cost. The strategy : more south facing windows and glass doors with correct overhangs, more interior materials to absorb and slowly release energy, good natural ventilation, and well-managed openings. The challenge is to integrate this approach into an attractive overall design.