In the United States, buildings are responsible for almost half
of all annual greenhouse-gas emissions and consume about three-
fourths of the electricity generated by power plants. That,
coupled with the fact that the majority of the buildings in
which we will live and work over the next 30 years have not yet
been built means we have significant opportunity to reduce the
carbon footprint of buildings and stem climate change. The
sustainability of a new building is based on many factors,
including water savings, energy efficiency, and materials
selection. These factors are influenced heavily by a building's
architectural, site, and building-systems design and supporting
civil infrastructure. Mechanical engineers can support
sustainable design by providing input about green approaches
early in the design process, designing more efficient and
better-sized mechanical systems, and producing metrics and
supporting documentation for evaluation and green certification
when needed. This article will describe how build