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Research has separately existed for life-cycle costs and environmental assessment of photovoltaic systems. This study provides a framework for the identification of the optimal set of residential photovoltaic system options in terms of costs and selected air emissions by assessing the life cycle of the product from manufacturing to disposal. Analyzed air emissions include carbon, nitrogen oxides, sulfur oxides, carbon monoxide, and particulate matter. The study focuses on general residential installations within the San Francisco Bay Area of California. Pareto frontiers are determined for costs and emissions, and the best options for suppliers are identified in each case, including sensitivity analysis of the installation planning horizon. Choosing multicrystalline silicon modules over thin film modules has the greatest impact on cost reduction. The electricity mix with which the modules are produced has the greatest impact on the emissions. [ABSTRACT FROM AUTHOR]

In recent decades, pavement management optimization has been designed with the objective of minimizing user and agency costs. However, recent analyses indicate that pavement management decisions also have significant impacts on life-cycle greenhouse gas (GHG) emissions. This study expands beyond minimization of life-cycle costs to also include GHG emissions. Previous work on the single-facility, continuous-state, continuous-time optimal pavement resurfacing problem is extended to solve the multicriteria optimization problem with the two objectives of minimizing costs and GHG emissions. Results indicate that there is a trade-off between costs and emissions when developing a pavement resurfacing policy, providing a range of GHG emissions reduction cost-effectiveness options. Case studies for an arterial and a major highway are presented to highlight the contrast between policy decisions for various pavement and vehicle technologies. [ABSTRACT FROM AUTHOR]

Research has separately existed for life-cycle costs and environmental assessment of photovoltaic systems. This study provides a framework for the identification of the optimal set of residential photovoltaic system options in terms of costs and selected air emissions by assessing the life cycle of the product from manufacturing to disposal. Analyzed air emissions include carbon, nitrogen oxides, sulfur oxides, carbon monoxide, and particulate matter. The study focuses on general residential installations within the San Francisco Bay Area of California. Pareto frontiers are determined for costs and emissions, and the best options for suppliers are identified in each case, including sensitivity analysis of the installation planning horizon. Choosing multicrystalline silicon modules over thin film modules has the greatest impact on cost reduction. The electricity mix with which the modules are produced has the greatest impact on the emissions. [ABSTRACT FROM AUTHOR]

From 1991 to 2009, U.S. production of ethanol increased 10-fold, largely due to government programs motivated by climate change, energy security, and economic development goals. As low-level ethanol-gasoline blends have not consistently outperformed ethanol-free gasoline in vehicle performance or tailpipe emissions, national-level economic and environmental goals could be accomplished more efficiently by concentrating consumption of gasoline containing 10% ethanol (i.e., E10) near producers to minimize freight activity. As the domestic transportation of ethanol increased 10-fold in metric ton-kilometers (t-km) from 2000 to 2009, the portion of t-km potentially justified by the E10 blend wall increased from less than 40% to 80%. However, we estimate 10 billion t-km took place annually from 2004 to 2009 for reasons other than the blend wall. This "unnecessary" transportation resulted in more than $240 million in freight costs, 90 million L of diesel consumption, 300,000 metric tons of CO2-e emissions, and 440 g of human intake of PM2.5. By 2009, the marginal savings from enabling Iowa to surpass E10 would have exceeded 2.5 g CO2-e/MJ and $0.12/gallon of ethanol, as the next-closest customer was 1600 km away. The use of a national network model enables estimation of marginal transportation impacts from subnational policies, and benefits from policies encouraging concentrated consumption of renewable fuels. [ABSTRACT FROM AUTHOR]

Abstract: A comparative life-cycle energy and emissions (greenhouse gas, CO, NOX, SO2, PM10, and VOCs) inventory is created for three U.S. metropolitan regions (San Francisco, Chicago, and New York City). The inventory captures both vehicle operation (direct fuel or electricity consumption) and non-operation components (e.g., vehicle manufacturing, roadway maintenance, infrastructure operation, and material production among others). While urban transportation inventories have been continually improved, little information exists identifying the particular characteristics of metropolitan passenger transportation and why one region may differ from the next. Using travel surveys and recently developed transportation life-cycle inventories, metropolitan inventories are constructed and compared. Automobiles dominate total regional performance accounting for 86–96% of energy consumption and emissions. Comparing system-wide averages, New York City shows the lowest end-use energy and greenhouse gas footprint compared to San Francisco and Chicago and is influenced by the larger share of transit ridership. While automobile fuel combustion is a large component of emissions, diesel rail, electric rail, and ferry service can also have strong contributions. Additionally, the inclusion of life-cycle processes necessary for any transportation mode results in significant increases (as large as 20 times that of vehicle operation) for the region. In particular, emissions of CO2 from cement production used in concrete throughout infrastructure, SO2 from electricity generation in non-operational components (vehicle manufacturing, electricity for infrastructure materials, and fuel refining), PM10 in fugitive dust releases in roadway construction, and VOCs from asphalt result in significant additional inventory. Private and public transportation are disaggregated as well as off-peak and peak travel times. Furthermore, emissions are joined with healthcare and greenhouse gas monetized externalities to evaluate the societal costs of passenger transportation in each region. Results are validated against existing studies. The dominating contribution of automobile end-use energy consumption and emissions is discussed and strategies for improving regional performance given private travel''s disproportionate share are identified. [Copyright &y& Elsevier]

Abstract: In recent years, the reduction of freight truck trips has been a common policy goal. To this end, policies aimed at influencing load consolidation have been suggested and implemented, resulting in higher gross vehicle weights. The purpose of such policies has generally been to mitigate congestion and environmental impacts. However, trucks cause most of the damage incurred by pavements. The supply chain associated with pavement maintenance and construction releases significant air emissions, raising the question of whether increased vehicle weights may cause unintended environmental consequences. This paper presents scenarios with estimated emissions resulting from load consolidation and changes in load factors. These scenarios reveal several points having to do with the tradeoff between tailpipe versus pavement supply-chain emissions. In some cases, unintended emissions from the pavement supply chain are found to be significant. [Copyright &y& Elsevier]

Construction of commercial buildings consumes significant amounts of energy and produces lots of emissions and waste. Where should environmental improvement efforts be focused during design and construction? The Construction Environmental Decision-Support Tool allows designers and industry practitioners to quantify energy use, emissions, and waste generation rates due to the construction phase of commercial buildings. A case study of the Bren School at the University of California, Santa Barbara, and several relevant construction scenarios are analyzed. When considering the complete building over its entire life cycle, the construction phase comprised 2% of energy consumption, 1% of CO2 emissions, 7% of CO emissions, 8% of NOx emissions, 8% of PM10 emissions, and 1% of SO2 emissions. This is due to the dominance of the long-term use phase (50 years) compared to a relatively short construction phase (2 years). Scaling up to the national level, however, construction impacts of projects are significant. In each of the categories studied (temporary materials, equipment and materials transportation, equipment use, waste generation), there are actions that can be taken by designers and builders to improve construction phase environmental effects. In structural frame construction, particular areas of concern include material and equipment selection and temporary material use. Energy use and air emissions are primarily due to equipment use, which accounts for at least 50% of most types of emissions. The major contributors are concrete mixer trucks, concrete pumps, cranes, and air compressors. A single feasible decision, such as using a concrete mixer truck with a 335 hp engine instead of one with a 565 hp engine (but having the same capacity) would reduce total construction energy demand by 12%, and the emissions of CO, NO2, PM10, SO2, CO2, and HC by 3, 12, 8, 10, 12, and 10%, respectively. The use of significantly older equipment can have a formidable effect on construction phase emissions. In general, equipment larger that 175 hp made prior to 1996 tends to have significantly greater emissions of HC, CO, and NO2 than more recent models. The majority of waste generated during construction of the structural frame consists of concrete and wood. [ABSTRACT FROM AUTHOR]

Telework has emerged as a possible solution to transportation-related air pollution problems. This paper analyzes, both deterministically and probabilistically, a California-based 1-day telework scenario, and explores how the mode of transportation and other parameters such as vehicle miles traveled, vehicle model, occupancy rate, telecommuting frequency, and season (heating or cooling) affect the air pollution effects of telework programs when energy consumption-related emissions due to heating, cooling, lighting, and the use of electronic and electrical equipment (in the home and company office) are accounted for. Among others, the study found that total telework-related CO2 emissions during the cooling season and SO2, NOx, and hydrocarbon emissions in both seasons appear to be lower than nontelework emissions for all modes of transportation (except for light rail with higher NOx emissions and urban transit buses with roughly equal NOx emissions in the heating season). Light rail also has higher telework N2O and CH4 emissions. However, given the uncertainties in the data, the differences may be negligible. Urban transit buses and commuter express buses were found to be associated with more telework than nontelework CO emissions in both seasons. For these two modes, telework PM10 emissions are higher in the cooling and about the same in the heating season than nontelework emissions. Natural gas-powered ferries have more telework PM10 emissions than nontelework emissions. The study also found that for low-frequency telework programs energy use impacts could overturn transportation-related emission reductions independent of the mode of transportation used. Avoiding more polluting modes of transportation, increasing occupancy rates, substituting longer commutes and especially increasing telecommuting frequency could counteract these negative effects. [ABSTRACT FROM AUTHOR]

Office buildings are thought to be significant sources of energy use and emissions in industrialized countries, but quantitative assessments of all of the phases of the service life of office buildings are still quite rare. In order to enable environmentally conscious design and management, this paper presents life-cycle assessments of newly constructed European and U.S. office buildings from materials production through construction, use, and maintenance to end-of-life treatment. The significant environmental aspects indicate the dominance of the use phase in the quantified environmental categories, but draw attention to the importance of embedded materials and expected maintenance investments throughout the assumed 50-year service life, especially for particulate matter emissions. The relevance of the materials, construction, maintenance, and end-of-life phases relative to the use of buildings is expected to increase considerably as functional obsolescence of office buildings becomes more rapid, and complete reconstruction and reconfiguration become more frequent. By quantifying the energy use and environmental emissions of each life-cycle phase in more detail, the elements that cause significant emissions can be identified and targeted for improvement. [ABSTRACT FROM AUTHOR]

In order to create an environmentally-conscious building, the environmental impacts of the entire service life must be known. Life-cycle assessment (LCA), which evaluates the impacts from all life-cycle phases, from “cradle to grave,” is the best method to achieve this goal. In this paper, LCA is used to quantify the energy use and the environmental emissions during the construction phase of two typical office buildings, one with a structural steel frame and one with a cast-in-place concrete frame, and then these are put in the perspective of the overall service life of each building. The concrete structural-frame construction has more associated energy use, CO2, CO, NO2, particulate matter, SO2, and hydrocarbon emissions due to more formwork used, larger transportation impacts due to a larger mass of materials, and longer equipment use due to the longer installation process. In contrast, the steel-frame construction has more volatile organic compound (VOC) and heavy metal (Cr, Ni, Mn) emissions due to the painting, torch cutting, and welding of the steel members. The energy use and the environmental emissions of the two buildings are comparable if the total impacts from materials’ manufacturing, construction, transportation, use, maintenance, and demolition are considered. Energy use and environmental emissions from office buildings can be reduced through a careful selection of embedded and temporary materials and construction equipment. [ABSTRACT FROM AUTHOR]

Abstract: Vehicular air pollutant emissions are characterized by a high degree of spatial variability that is correlated with the distribution of people. The consequences of the spatial association between emissions and exposed populations have not been fully captured in lifecycle and other impact assessments. The intake fraction (iF) quantifies aggregate air-pollutant exposures attributable to sources. Utilizing source–receptor (S–R) relationships derived from the US Environmental Protection Agency''s AERMOD steady-state plume model, we quantify the intake fraction of conserved pollutants emitted from on-road mobile sources and report here the first characterization across approximately 65,000 census tracts of the conterminous United States. Considering exposures out to 50 km from the source, the population-weighted mean iF is 8.6 parts per million (ppm). The population-weighted median generally increases with geographic scale, from 3.6 ppm for census tracts to 4.2 ppm for counties, and 5.1 ppm for states, while the population-weighted interquartile range (IQR) progressively narrows as geographic scale increases: 0.85–8.8 ppm for census tracts, 1.5–8.5 ppm for counties, and 3.2–7.5 ppm for states. Across the four US Census regions, the population weighted median iF varies from 2.2 ppm (South) to 7.5 ppm (West), and the census-tract IQR spans an order of magnitude in each region (2.1–17 ppm in the West; 0.55–6.9 ppm in the Midwest; 0.45–5.5 ppm in the South; and 1.8–18 ppm in the Northeast). The population-weighted mean intake fraction for populous urban counties is about two orders of magnitude greater than for sparsely populated rural counties. On a population-weighted average basis and considering the 50 km analysis range, 75% of the intake occurs in the same county as emissions. [Copyright &y& Elsevier]

Particulate matter (PM) is a significant contributor to death and disease globally. This paper summarizes the work of an international expert group on the integration of human exposure to PM into life cycle impact assessment (LCIA), within the UNEP/SETAC Life Cycle Initiative. We review literature-derived intake fraction values (the fraction of emissions that are inhaled), based on emission release height and "archetypal" environment (indoor versus outdoor; urban, rural, or remote locations). Recommended intake fraction values are provided for primary PM10-2.5 (coarse particles), primary PM2.5 (fine particles), and secondary PM2.5 from SO2, NOx, and NH3. Intake fraction values vary by orders of magnitude among conditions considered. For outdoor primary PM2.5, representative intake fraction values (units: milligrams inhaled per kilogram emitted) for urban, rural, and remote areas, respectively, are 44, 3.8, and 0.1 for ground-level emissions, versus 26, 2.6, and 0.1 for an emission-weighted stack height. For outdoor secondary PM, source location and source characteristics typically have only a minor influence on the magnitude of the intake fraction (exception: intake fraction values can be an order of magnitude lower for remote-location emission than for other locations). Outdoor secondary PM2.5 intake fractions averaged over respective locations and stack heights are 0.89 (from SO2), 0.18 (NOx), and 1.7 (NH3). Estimated average intake fractions are greater for primary PM10-2.5 than for primary PM2.5 (21 versus 15), owing in part to differences in average emission height (lower, and therefore closer to people, for PM10-2.5 than PM2.5). For indoor emissions, typical intake fraction values are ∼1000-7000. This paper aims to provide as complete and consistent an archetype framework as possible, given current understanding of each pollutant. Values presented here facilitate incorporating regional impacts into LCIA for human health damage from PM. [ABSTRACT FROM AUTHOR]