Cities increasingly recognize the importance of shade to reduce heat stress and adopt urban forestry plans with ambitious canopy goals. Yet, the implementation of tree and shade plans often faces maintenance, water use, and infrastructure challenges. Understanding the performance of natural and nonnatural shade is critical to support active shade management in the built environment. We conducted hourly transects in Tempe, Arizona, with the mobile human-biometeorological station MaRTy on hot summer days to quantify the efficacy of various shade types. We sampled sun-exposed reference locations and shade types grouped by urban form, lightweight/engineered shade, and tree species over multiple ground surfaces. We investigated shade performance during the day, at peak incoming solar, at peak air temperature, and after sunset using three thermal metrics: the difference between a shaded and sun-exposed location in air temperature (∆ T _a ), surface temperature (∆ T _s ), and mean radiant temperature (∆ T _MRT ). Air temperature did not vary significantly between shade groups, but ∆ T _MRT spanned a 50°C range across observations. At daytime, shade from urban form most effectively reduced T _s and T _MRT , followed by trees and lightweight structures. Shade from urban form performed differently with changing orientation. Tree shade performance varied widely; native and palm trees were least effective, while nonnative trees were most effective. All shade types exhibited heat retention (positive ∆ T _MRT ) after sunset. Based on the observations, we developed characteristic shade performance curves that will inform the City of Tempe’s design guidelines toward using “the right shade in the right place” and form the basis for the development of microclimate zones (MCSz).

Although the integration of sustainability, ecology, and design has been recognized as necessary by scientists and practitioners, most transdisciplinary frameworks are not inclusive of the worldviews, paradigms, aims, processes, and components necessary for sustainability. Landscape sustainability science helps to focus scientist, scholar, practitioner, and stakeholder efforts toward sustainability at a pivotal level; however, collaboration and progress have been slow. Significant potential exists for design to be an integrative and transformational methodology toward landscape sustainability, yet it has not fulfilled this ambitious role. In this paper, we first build a case for regenerative development, a development and design methodology based on an ecological worldview, as an integrative platform for a new paradigm. This new paradigm, which we call regenerative landscape development, has the potential to thoroughly catalyze a shift toward regenerative sustainability. We then detail this new paradigm as a process that could continually enhance the capacities of living systems to increase health, well-being, and happiness. Next, to illustrate regenerative development in practice, we provide brief case studies of projects in Viña del Mar, Chile and Juluchuca, Guerrero, Mexico. Finally, we propose future recommendations and precautions in the construction of regenerative landscape development as a new paradigm. If fully understood, embraced, and realized, regenerative development holds incredible potential for a sustainable future.

Designing cities for thermal comfort is an important priority in a warming and urbanizing world. As temperatures in cities continue to break extreme heat records, it is necessary to develop and test new approaches capable of tracking human thermal sensations influenced by microclimate conditions, complex urban geometries, and individual characteristics in dynamic settings. Thermal walks are a promising novel research method to address this gap. During a thermal walk in Phoenix, Arizona, USA, we examined relationships between the built environment, microclimate, and subjective thermal judgments across a downtown city neighborhood slated for redevelopment. Subjects equipped with GPS devices participated in a 1-hour walk on a hot sunny day and recorded their experience in a field guide. Microclimate measurements were simultaneously collected using the mobile human-biometeorological instrument platform MaRTy. Results revealed significant differences in physiologically equivalent temperature (PET) and modified physiologically equivalent temperature (mPET) and between street segments with more than 18 °C (25 °C mPET) between the maximum and minimum values. Wider range of mPET values reflected the inclusion of individual level data into the model. Streets with higher sky view factor (SVF) and east-west orientation showed a higher PET and mPET overall. Furthermore, we showed evidence of thermal alliesthesia, the pleasure resulting from slight changes in microclimate conditions. Participants' sense of pleasure was related to the mean PET of the segment they just walked, with linear regression explaining over 60% of the variability. We also showed that estimated percent shade was significantly correlated with SVF, PET, mPET, and pleasure, indicating that participants could sense minor changes in microclimate and perceived shade as pleasant. Although generalization of results is limited by a low sample size, findings of this study improve the understanding of dynamic thermal comfort in complex urban environments and highlight the value of thermal walks as a robust research method.

Quantifying ecosystem services in urban areas is complex. However, existing ecosystem service typologies and ecosystem modeling can provide a means towards understanding some key biophysical links between urban forests and ecosystem services. This project addresses broader concepts of sustainability by assessing the urban park system in Phoenix, Arizona’s hot urban climate. This project aims to quantify and demonstrate the multiple ecosystem services provided by Phoenix’s green infrastructure (i.e., urban park system), including its air pollution removal values, carbon sequestration and storage, avoided runoff, structural value, and the energy savings it provides for city residents. Modeling of ecosystem services of the urban park system revealed around 517,000 trees within the system, representing a 7.20% tree cover. These trees remove about 3630 tons (t) of carbon (at an associated value of $285,000) and about 272 t of air pollutants (at an associated value of $1.16 million) every year. Trees within Phoenix’s urban park system are estimated to reduce annual residential energy costs by $106,000 and their structural value is estimated at $692 million. The findings of this research will increase our knowledge of the value of green infrastructure services provided by different types of urban vegetation and assist in the future design, planning and management of green infrastructure in cities. Thus, this study has implications for both policy and practice, contributing to a better understanding of the multiple benefits of green infrastructure and improving the design of green spaces in hot arid urban climates around the globe.

Larson, K., E. Corley, R. Andrade, S. J. Hall, A. York, S. Meerow, P. Coseo, D. L. Childers, and D. Hondula. 2019. Subjective evaluations of ecosystem services and disservices: an approach to creating and analyzing robust survey scales. Ecology and Society 24(2):7. https://doi.org/10.5751/ES-10888-240207

Many cities aim to progress toward their sustainability and public health goals by increasing use of their public transit systems. However, without adequate protective infrastructure that provides thermally comfortable conditions for public transit riders, it can be challenging to reach these goals in hot climates. We took micrometeorological measurements and surveyed riders about their perceptions of heat and heat-coping behaviors at bus stops with a variety of design attributes in Phoenix, AZ, USA, during the summer of 2018. We identified the design attributes and coping behaviors that made riders feel cooler. We observed that current infrastructure standards and material choices for bus stops in Phoenix are insufficient to provide thermal comfort, and can even expose riders to health risks. Almost half of the study participants felt hot or very hot at the time they were surveyed, and more than half reported feeling thermally uncomfortable. On average, shade reduced the physiological equivalent temperature (PET) by 19 °C. Moreover, we found significant diurnal differences in PET reductions from the shade provided by various design attributes. For instance, all design attributes were effective in reducing PET in the morning; however, a vegetated awning did not provide statistically significant shade reductions in the afternoon. Temperatures of sun-exposed surfaces of man-made materials exceeded skin burn thresholds in the afternoon, but shade was effective in bringing the same surfaces to safe levels. Aesthetically pleasing stops were rated as cooler than stops rated as less beautiful. We conclude that cities striving to increase public transit use should prioritize thermal comfort when designing public transit stops in hot climates.