Center for Earth Systems Engineering and Management

Vehicle trips presently account for approximately 50% of San Francisco’s greenhouse gas emissions (San Francisco County Transportation Authority, 2008). City and county officials have developed aggressive strategies for the future of passenger transportation in the metropolitan area, and are determined to move away from a “business as usual” future. This project starts with current-state source data from a life-cycle comparison of urban transportation systems (Chester, Horvath, & Madanat, 2010), and carries the inventoried emissions and energy usage through by way of published future scenarios for San Francisco.

From the extrapolated calculations of future emissions/energy, the implied mix of transportation modes can be backed out of the numbers. Five scenarios are evaluated, from “business as usual” through very ambitious “healthy environment” goals. The results show that when planners and policymakers craft specific goals or strategies for a location or government, those targets, even if met, are unlikely to result in the intended physical outcomes. City and state governments would be wise to support broad strategy goals (like 20% GHG reduction) with prioritized specifics that can inform real projects leading to the goals (for instance, add 5 miles of bike path per year through 2020, or remove 5 parking garages and replace them with transit depots). While these results should not be used as predictions or forecasts, they can inform the crafters of future transportation policy as an opportunity for improvement or a cautionary tale.

This LCA used data from a previous LCA done by Chester and Horvath (2012) on the proposed California High Speed Rail, and furthered the LCA to look into potential changes that can be made to the proposed CAHSR to be more resilient to climate change. This LCA focused on the energy, cost, and GHG emissions associated with raising the track, adding fly ash to the concrete mixture in place of a percentage of cement, and running the HSR on solar electricity rather than the current electricity mix. Data was collected from a variety of sources including other LCAs, research studies, feasibility studies, and project information from companies, agencies, and researchers in order to determine what the cost, energy requirements, and associated GHG emissions would be for each of these changes. This data was then used to calculate results of cost, energy, and GHG emissions for the three different changes. The results show that the greatest source of cost is the raised track (Design/Construction Phase), and the greatest source of GHG emissions is the concrete (also Design/Construction Phase).

The ultimate goal of this LCA is to give Arizona State University specific advice on possible changes in lighting systems that will reduce environmental impacts and support ASU’s sustainability efforts. The aim is to assess the potential for a decrease in specific environmental impacts (CO2 emissions and energy use) and economic impact (cost) from changing to a different type of lighting in a prototypical classroom in Wrigley Hall. The scope of this assessment is to analyze the impacts of T8 lamps lasting 50,000 hours. Thus, a functional unit was defined as 50,000 hours of use, maintaining roughly 825 lumens. To put this in perspective, 50,000 hours is equivalent to 8 hours of use per day, 365 days per year, for approximately 17.1 years.

Building energy assessment often focuses on the use of electricity and natural gas during the use phase of a structure while ignoring the energy investments necessary to construct the facility. This research develops a methodology for quantifying the “embedded” energy and greenhouse gases (GHG) in the building infrastructure of an entire metropolitan region. “Embedded” energy and GHGs refer to the energy necessary to manufacture materials and construct the infrastructure. Using these methods, a case study is developed for Los Angeles County.

Mitigation of urban heat islands has become a goal for research and policy as urban environmental heat is a rapidly growing concern. Urban regions such as Phoenix, AZ are facing projected warming as urban populations grow and global climates warm (McCarthy et al. 2010), and severe urban heat can even lead to human mortality and morbidity (Berko et al. 2014). Increased urban heat may also have social and economic consequences such as by discouraging physical activity, reducing outdoor accessibility, and decreasing economic output (Stamatakis et al. 2013; Karner et al. 2015; Obradovich & Fowler 2017; Kjellstrom et al. 2009). Urban heat islands have been well documented in academic literature (Oke 1982; Arnfield 2003), and anthropogenic waste heat is often a major factor. The American Meteorological Society (2012) has said that anthropogenic waste heat may contribute “15 – 50 W/m2 to the local heat balance, and several hundred W/m2 in the center of large cities in cold climates and industrial areas.”

Anthropogenic waste heat from urban vehicle travel may be a notable contributor to the urban heat balance and the urban heat island effect, but little research has quantified and explored how changes in vehicle travel may influence local climates. Even with recent rapid improvements to engine efficiencies, modern automobiles still convert small amounts of fuel to useful energy. Typically, around two-thirds of energy from fuel in internal combustion engine vehicles is lost as waste heat through exhaust and coolant (Hsiao et al. 2010; Yu & Chau 2009; Saidur et al. 2009; Endo et al. 2007), and as much as 80% of fuel energy can be lost to waste heat under poor conditions (Orr et al. 2016). In addition, combustion of fuel generates water vapor and air pollution which may also affect the urban climate. Figure 1 displays where a typical combustion engine’s fuel energy is used and lost. There has been little research that quantifies the influence of vehicle travel on urban anthropogenic waste heat. According to Sailor and Lu (2004), most cities have peak anthropogenic waste heat values between 30 and 60 W m-2 (averaged across city) and heating from vehicles could make up as much as 62% of the total in summer months. Additionally, they found that vehicle waste heat could account for up to 300 W m-2 during rush hours over freeways. In another study, Hart & Sailor (2009) used in situ measurements in Portland, OR to evaluate spatial variability of air temperatures on urban roadways. They found that air masses near major roadways are some of the warmest in the region. Although some of the warming is attributed to pavement characteristics (imperviousness, low albedo), an average increase of 1.3 C was observed on weekdays relative to weekends along roadways. The authors offer increased weekday traffic density and building use as the likely contributors to this discrepancy. These previous studies indicates that vehicle related waste heat could be an important consideration in the urban energy balance. If significant, there may exist viable strategies to reduce anthropogenic waste heat from urban vehicle travel by increasing the fleet fuel economy and shifting to electric vehicles. This could offer cooling in urban areas around roadways were pedestrians are often found. Figure 2 visually demonstrates waste heat from vehicles (including an electric vehicle) in two thermal images.