The University of Portland (UP) in Portland, Oregon (USA) removed four giant sequoias (Sequoiadendron giganteum) from UP's campus in 2017 for a construction project. The loss of these trees provided an opportunity to measure how sequoias influence microclimates, with a goal of quantifying their roles in mitigating urban heat island (UHI) effects, and thus promoting preservation of these and similar trees everywhere. Our study applied a widely-used computational fluid dynamics model called ENVI-met to isolate effects of sequoias on microclimates, and validated results by making field measurements before and after UP removed the four sequoias. Our study is likely the most thorough to ever measure and model microclimate effects of sequoias, or potentially any other large trees. Results show model simulations of plant metabolic processes and their influences on air temperatures, surface temperatures, winds, and carbon dioxide concentrations, with validation statistics ranking model performance comparable to or superior to previous ENVI-met studies. Applications include new methods for running and validating microclimate models, which could lead to better decisions about what kinds of trees to plant where, and greater protection for trees, which can reduce the UHI effect and its detrimental influences on energy demand, human comfort, and human health.

Green roofs have become a common method to increase water retention on-site in urban areas. However, the long-term water quality of runoff from green roofs is poorly understood. This study evaluated the water quality of stormwater runoff from a regular (non-vegetated) roof, a green roof installed 6 months previously, and a green roof installed 6 years ago in Portland, Oregon. Samples of runoff were taken during every rain event for 10 months, and analyzed for total phosphorus (TP), phosphate (PO3-4), total nitrogen (TN), nitrate (NO-3), ammonia (NH3), copper (Cu), and zinc (Zn). Runoff from the green roofs had higher concentrations of TP and PO3-4 and lower concentrations of Zn compared to the regular roof. Average TP concentrations from the 6-year old roof and 6-month old roof were 6.3 and 14.6 times higher, respectively, than concentrations from the regular roof, and average PO3-4 concentrations from the 6-year old roof and 6-month old roof were 13.5 and 26.6 times higher, respectively, compared to the regular roof. Runoff from the 6-month old green roof had higher concentrations of TP and PO3-4 than the 6-year old green roof during the wet season, but lower concentrations during the dry season. The 6-month old green roof installations where receiving waters are sensitive or impaired may need additional treatment methods to reduce phosphorus levels. As green roofs age, water retention decreases and phosphorus leaching increases during the dry season.

This study combines Ordinary Kriging, odor monitoring, and wind direction data to demonstrate how these elements can be applied to identify the source of an industrial odor. The specific case study used as an example of how to address this issue was the University Park neighborhood of Portland, Oregon (USA) where residents frequently complain about industrial odors, and suspect the main source to be a nearby Daimler Trucks North America LLC manufacturing plant. We collected 19,665 odor observations plus 105,120 wind measurements, using an automated weather station to measure winds in the area at five-minute intervals, logging continuously from December 2014 through November 2015, while we also measured odors at 19 locations, three times per day, using methods from the American Society of the International Association for Testing and Materials. Our results quantify how winds vary with season and time of day when industrial odors were observed versus when they were not observed, while also mapping spatiotemporal patterns in these odors using Ordinary Kriging. Our analyses show that industrial odors were detected most frequently to the northwest of the Daimler plant, mostly when winds blew from the southeast, suggesting Daimler's facility is a likely source for much of this odor.

This study analyzed insolation data to account for multiple scattering in calculating optimal tilt angles for stationary and seasonally moving photovoltaics on three different roof types in the US Pacific Northwest: vegetated roofs, white roofs, and dark roofs. Using these results, we modeled the energy savings for vegetated roofs and roofs covered in varying numbers of photovoltaic panels. We then calculated the net present value, internal rate of return, and other economic measures for all possible combinations of covering rooftops in mixes of photovoltaic arrays and vegetation, accounting for installation costs, proposed carbon taxes, stormwater management discounts, and other relevant factors. Our results quantify how, in the US Pacific Northwest and similar locations, photovoltaics produce higher returns on investment than do vegetated roofs for new buildings, while vegetated roofs produce better returns on investment than do photovoltaics for older buildings. This is important because in many areas, some buildings have photovoltaics when a vegetated roof would have been more cost and energy efficient, while other buildings have vegetated roofs when photovoltaics would have been more cost and energy efficient. Potential applications include modifying incentive programs and other policies to account properly for building age, use, and other relevant factors to ensure building owners make the most energy-efficient decisions between photovoltaic versus vegetated roof installation. Our research also demonstrates how positive returns on investment can be realized in the US Pacific Northwest and similar regions through vegetated roofs and photovoltaics provided they are each installed optimally.

In their reflections on Laudato si', the second encyclical by Pope Francis, several authors from the November/December issue of Environment (Hulme, Stinson, Tucker) mention the United Nations 21st ...