Life cycle assessment (LCA) is used to evaluate the benefits, primarily from reduced energy consumption, resulting from the addition of a green roof to an eight story residential building in Madrid. Building energy use is simulated and a bottom-up LCA is conducted assuming a 50 year building life. The key property of a green roof is its low solar absorptance, which causes lower surface temperature, thereby reducing the heat flux through the roof. Savings in annual energy use are just over 1%, but summer cooling load is reduced by over 6% and reductions in peak hour cooling load in the upper floors reach 25%. By replacing the common flat roof with a green roof, environmental impacts are reduced by between 1.0 and 5.3%. Similar reductions might be achieved by using a white roof with additional insulation for winter, but more substantial reductions are achieved if common use of green roofs leads to reductions in the urban heat island.

This paper details the role of infrastructure in promoting sustainability at the neighbourhood scale. A sustainable neighbourhood design process is outlined and the importance of adopting a systems perspective and considering infrastructure interconnections is emphasized. The performance of local infrastructure systems (e.g., buildings and local transportation network) is influenced by interactions with the greater urban region and with other local infrastructure. Through a broad review of the literature on transportation, water, building, and urban forestry systems, this paper identifies many of these extra- and inter-neighbourhood interactions. The paper concludes that it is difficult to achieve neighbourhood sustainability objectives without infrastructure systems at the urban scale that support these micro-scale goals. Furthermore, interactions between local infrastructure systems can have a positive or negative impact on infrastructure performance and environmental impacts. Careful consideration of these relationships during neighbourhood design could yield significant improvements in infrastructure resource efficiency as well as reductions in pollutant emissions and overall costs.Key words: sustainable neighbourhood design, infrastructure systems, transportation, water, buildings, urban forestry.