Most architects would agree that a green building must be an energy efficient building. To be energy efficient, green buildings must include measures to reduce energy consumption. Over the years, embodied energy has assumed more importance and they make up for as much as 30% of the overall life cycle energy consumption. For instance, a study by the U.S. LCI Database Project reports that the buildings built primarily with wood will have a lower embodied energy than those built primarily with brick, concrete or steel. Green architects recommends passive solar building design. They will orient windows and walls and place awnings, porches, and trees to shade windows and roofs during the summer while maximizing solar gain in the winter. Similarly, windows are placed effectively to attract natural light and lessen the need for electric lighting during the day. Solar water heating further reduces energy costs.
Also, energy efficient buildings must also be water and building material efficient. Reducing water consumption and protecting water quality should be key objectives of these buildings. Green architecture also seeks to reduce waste of energy, water and materials used during construction. Rain water harvesting is also a good idea.