FIGURE 1 U.S. energy consumption by sector. Source: U.S. DOE, 2010.
largest source of carbon emissions in the United States, buildings also represent a significant opportunity (Figure 1). The Intergovernmental Panel on Climate Change (IPCC) has identified buildings as the sector offering the greatest potential for carbon reductions (IPCC, 2007). Similarly, the World Business Council for Sustainable Development (WBCSD) has demonstrated that global energy use of buildings could be reduced 60% by 2050 using existing technologies (WBCSD, 2009). McKinsey Consulting has identified the building sector as the most cost-effective strategy for carbon abatement, with most building improvements providing carbon reductions at a negative cost (McKinsey Consulting, 2007). In short, there are a range of strategies in the building sector to save both money and carbon emissions. Clearly engineers have a major role to play in helping to reduce the carbon emissions of existing and new buildings, though a number of challenges exist.
Several current initiatives in the United States provide targets for improved carbon performance of buildings. The 2030 Challenge establishes targets for carbon reductions of new buildings, with increasing standards in the coming two decades (Architecture2030, 2011). The current aim is to design buildings to use 60% less energy than average for the building type. The reduction target increases by 10% every five years (e.g., lowering to 70% reductions by 2015), until carbon-neutral buildings are the target in the year 2030. These design goals are to be met through three primary approaches: (1) improved design strategies, (2) more efficient technologies and systems, and (3) off-site renewables (up to a maximum of 20%). While the 2030 Challenge is voluntary at present, many