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• Evaluate organic transparent photovoltaics (TPV) for buildings in the US. • Transparent photovoltaics produce electricity and reduce energy consumption. • Life cycle assessment is used to calculate the net energy benefit. • The energy payback time varies from 51 days to 1.1 years depending on the location. Transparent photovoltaics is a new technology that can be used in buildings applications to simultaneously save energy and produce electricity. This study evaluates the potential of transparent photovoltaic (TPV) in window and skylight applications for four cities in the United States: Detroit, Los Angeles, Phoenix and Honolulu. Building energy demand simulation, photovoltaic generation, and life cycle assessment (LCA) are combined to evaluate the net energy benefit (NEB). The use of TPV on windows is evaluated for both new windows, for which the solar cell is deposited in the interior surface of the glass pane, and for the refurbishment of existing windows, for which plastic encapsulated solar cells are placed on the interior surface of existing windows. The NEB was found to be positive for all scenarios considered, and the cradle to gate energy to manufacture a transparent organic photovoltaic module was found to be negligible. The NEB was used to calculate the energy return on investment (EROI) and the energy payback time (EPBT). Both were found to be either better or comparable to other photovoltaic technologies. For glass modules, the best EROI was 102 in Phoenix for window and 208 in Honolulu for skylights. The EPBT varied from 51 days to 1.1 years, depending on the location and type of module. The use of transparent photovoltaics in the US was found to have both environmental and cost benefits due to the combined reduction in building energy consumption and electricity production. [ABSTRACT FROM AUTHOR]

Concentration – discharge (c-q) hysteresis loops are used to qualitatively understand solute transport pathways to streams. The majority of c-q studies involve non-urban areas in environmental settings such as the subtropics, mountains, and high latitude rivers. Only a few involve urban or urban salted watersheds. In this study, we explore c-q hysteresis plots and pollutographs for a variety of inorganic solutes (Cl − , Na + , K + , SiO 2 , NO 3 − ), dissolved organic carbon and an indicator of the aromatic fraction (SUVA 254 ), and a microbiological indicator ( E. coli ) in an urban salted watershed. The major hydrologic events are snow melts. The overarching hypothesis is that the hysteresis behavior can be explained by extending the pathway analysis (i.e., relative importance of storm event water, C SE ; groundwater C G ; and soil water, C SO ) from the Evans-Davis classification scheme that describes six behaviors to account for differences in source locations and the biogeochemical behavior of the solutes along these pathways. Data sets for the years 2013, 2014, and 2015 were assembled from a series of undergraduate and graduate research projects performed over this period. The results of these studies indicate that: 1) Cl − and Na + exhibit a combination of C2 (C SE > C SO > C G ) and C3 (C G > C SE > C SO ) behavior during salting season and A1 (C SO > G G > C SE ) and A2 (C SO > C SE > C G ) behavior in non-salting times; 2) SiO 2 shows A3 (C G > C SO > C SE ) behavior in all events, 3) K + changes from C2 to C1 (C SE > C G > C SO ) with concentration depletion over subsequent events; 4) NO 3 − changes from A2 to C1 or C2 with concentration depletion over subsequent events; 5) DOC and SUVA 254 exhibit C2 and A1 behavior, respectively; 6) E. coli changes from C2 to A2 over subsequent storms; 7) Cl − and Na + peak before the rising limb with a slight lag in the Na + peak and 8) E. coli does not exhibit first-flush behavior. An integrative pollutograph for a snow melt event shows, 1) K + and DOC peak together three times, unrelated to any additional event such as rain; 2) DOC becomes more aliphatic at its first peak, and 3) NO 3 − has a concentration decrease at the second DOC/K + peak and peaks on the declining limb after the third DOC/K + peak. These observations can be explained in terms of the c-q plots (e.g., importance of event water), environmental behavior (e.g., conservative solute), the nature of the urban landscape (e.g., pavement), and season (e.g., damped microbial activity). We interpret the multiple concentration peaks to indicate water masses originating from different compartments in the watershed are reaching the stream at different times and with different chemistries. These results extend the work of previous studies and may serve to help develop a fingerprint of solute behavior that can be used to more fully explore early season biogeochemical dynamics in an urban, salted, snow-melt dominated watershed. [ABSTRACT FROM AUTHOR]