This white paper explores the links between community design and energy efficiency, and establishes a research agenda for the new Center for Resource Efficient Communities (CREC) at UC-Berkeley. The paper describes the context of resource efficient design in California (especially with respect to climate change), and identifies five links between community design and energy efficiency: 1. The Transportation-Land Use connection 2. The Street Design-Transportation Connection 3. The Urban Heat Island Effect and Cool Communities 4. Solar Access and Building Energy Use 5. Community Resource Use and Embedded Energy Management For each of these areas, the paper summarizes the major findings in the research literature and identifies major research gaps. In addition, it discusses development code barriers and other institutional impediments to resource-efficient community design, and briefly summarizes the literature on the property value implications of resource efficient design features. Overall, the white paper argues that dramatic reductions in carbon emissions – on the order of 88 percent per capita by 2050 – are necessary throughout California’s economy, and that community design must play a central role in achieving them. Community design sets the physical context for the energy demand associated with both surface transportation and building operations, which collectively produce about 60 percent of CO2 emissions in the state.

Public transportation systems are often part of strategies to reduce urban environmental impacts from passenger transportation, yet comprehensive energy and environmental life-cycle measures, including upfront infrastructure effects and indirect and supply chain processes, are rarely considered. Using the new bus rapid transit and light rail lines in Los Angeles, near-term and long-term life-cycle impact assessments are developed, including consideration of reduced automobile travel. Energy consumption and emissions of greenhouse gases and criteria pollutants are assessed, as well the potential for smog and respiratory impacts. Results show that life-cycle infrastructure, vehicle, and energy production components significantly increase the footprint of each mode (by 48–100% for energy and greenhouse gases, and up to 6200% for environmental impacts), and emerging technologies and renewable electricity standards will significantly reduce impacts. Life-cycle results are identified as either local (in Los Angeles) or remote, and show how the decision to build and operate a transit system in a city produces environmental impacts far outside of geopolitical boundaries. Ensuring shifts of between 20–30% of transit riders from automobiles will result in passenger transportation greenhouse gas reductions for the city, and the larger the shift, the quicker the payback, which should be considered for time-specific environmental goals.

Nonpotable water reuse (NPR) is one option for conserving valuable freshwater resources. Decentralization can improve distribution system efficiency by locating treatment closer to the consumer; however, small treatment systems may have higher unit energy and greenhouse-gas (GHG) emissions. This research explored the trade-off between residential NPR systems using a life-cycle approach to analyze the energy use and GHG emissions. Decentralized and centralized NPR options are compared to identify where decentralized systems achieve environmental advantages over centralized reuse alternatives, and vice versa, over a range of scales and spatial and demographic conditions. For high-elevation areas far from the centralized treatment plant, decentralized NPR could lower energy use by 29% and GHG emissions by 28%, but in low-elevation areas close to the centralized treatment plant, decentralized reuse could be higher by up to 85% (energy) and 49% (GHG emissions) for the scales assessed (20-2000 m³/day). Direct GHG emissions from the treatment processes were found to be highly uncertain and variable and were not included in the analysis. The framework presented can be used as a planning support tool to reveal the environmental impacts of integrating decentralized NPR with existing centralized wastewater infrastructure and can be adapted to evaluate different treatment technology scales for reuse.