The recent dramatic increase in oil prices as well as a growing worldwide concern with climate change has brought renewed attention and interest in energy efficiency and consideration for the environment among all areas of industry, in particular the built environment. According to the U.S. Department of Energy, operational energy consumption in residential and commercial buildings accounted for 40% of total energy consumed in the United States in 2007, and produced nearly 48% of the country's greenhouse gas emissions. While architects have been making their contribution to the environmental cause, designing more efficient buildings with tools such as the U.S. Green Building Council's Leadership in Energy and Environmental Design (LEED) rating system, historic preservationists are edging their way into the "green" movement within a complex set of constraints and guidelines, such as the Secretary of the Interior's Standards for the Treatment of Historic Properties, but equally motivated to reduce the historic building stock's adverse effect on the environment and energy consumption.