Nature-Based Designs to Mitigate Urban Heat: The Efficacy of Green Infrastructure Treatments in Portland, Oregon

Urban heat is a growing environmental concern in cities around the world. The urban heat island effect, combined with warming effects of climate change, is likely to cause an increase in the frequency and intensity of extreme heat events. Alterations to the physical, built environment are a viable option for mitigating urban heat, yet few studies provide systematic guidance to practitioners for adapting diverse land uses. In this study, we examine the use of green infrastructure treatments to evaluate changes in ambient temperatures across diverse land uses in the city of Portland, Oregon. We apply ENVI-met® microclimate modeling at the city-block scale specifically to determine what built environment characteristics are most associated with high temperatures, and the extent to which different physical designs reduce ambient temperature. The analysis included six green infrastructure interventions modeled across six different land-use types, and indicated the varying degrees to which approaches are effective. Results were inconsistent across landscapes, and showed that one mitigation solution alone would not significantly reduce extreme heat. These results can be used to develop targeted, climate- and landscape-specific cooling interventions for different land uses, which can help to inform and refine current guidance to achieve urban climate adaptation goals.

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An urban climate service to manage heat risks in UK and Chinese cities

10.5194/egusphere-egu21-5158 ◽

2021 ◽

Author(s):

Victoria Ramsey ◽

Claire Scannell

Keyword(s):

Urban Climate ◽

Evidence Base ◽

Extreme Heat ◽

Climate Services ◽

Extreme Heat Events ◽

Climate Service ◽

Urban Heat ◽

The Uk ◽

Heat Hazard ◽

The City

<p>Recent extreme heat events in the UK are likely to become more frequent over the 21st Century and exacerbated in cities due to the urban heat island effect. Due to high population densities and a concentration of assets, urban areas are more vulnerable to climatic extremes with impacts that traverse health, infrastructure, built environment and economic activity. Risks to health, well-being and productivity from high temperatures is one of six priority areas from in UK Climate Change Risk Assessment (2017) where more action is needed to manage risks, prompting local authorities to understand heat risks within their city.&#160;<br>City based climate services are needed for day-to-day operations in cities, emergency response and to inform urban design and development. &#160;Recent advances in high resolution modelling enable better representation of urban processes and provide greater understanding of extreme events. &#160;By exploiting such advances in underpinning science, the Met Office is generating urban climate services for city stakeholders to plan for and manage heat stress in their city.<br>The Met Office has been engaging with local authorities and city stakeholders in the UK and China to co-produce a prototype, two tier, urban heat climate service to enhance the resilience of urban environments to extreme heat events. &#160;The prototype is based on a strong requirement from several cities to develop an evidence base of the heat hazard and understand current and future hot spots vulnerable to extremes of heat within the city. &#160;Tier 1 uses observations and high-resolution climate data to provide city specific information of the heat hazard in a graphical factsheet format. &#160;This includes information on future changes in temperature, extreme heat indicators, frequency and duration of heatwave events, and spatial distribution of heat across the city. &#160;Tier 2 involves working closely with city stakeholders to combine the hazard information with data on health, built environment and socio-economics, to provide tailored information on heat exposure and vulnerability. &#160;This will allow users to identify highly vulnerable parts of the city network and neighbourhoods for priority action. &#160;This two-tier service can provide an evidence base to inform urban policy, design and adaptation strategies, and prepare authorities and city stakeholders for future demand on city services.&#160;</p>

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Temperature-Related Mortality in Helsinki Compared to Its Surrounding Region Over Two Decades, with Special Emphasis on Intensive Heatwaves

Atmosphere ◽

10.3390/atmos12010046 ◽

2020 ◽

Vol 12 (1) ◽

pp. 46

Author(s):

Reija Ruuhela ◽

Athanasios Votsis ◽

Jaakko Kukkonen ◽

Kirsti Jylhä ◽

Susanna Kankaanpää ◽

...

Keyword(s):

Heat Stress ◽

The Elderly ◽

Land Uses ◽

Hospital District ◽

Distributed Lag ◽

Temperature Ranges ◽

Distributed Lag Nonlinear Model ◽

Urban Heat ◽

The City ◽

Related Mortality

Urbanization and ongoing climate change increase the exposure of the populations to heat stress, and the urban heat island (UHI) effect may magnify heat-related mortality, especially during heatwaves. We studied temperature-related mortality in the city of Helsinki—with urban and suburban land uses—and in the surrounding Helsinki-Uusimaa hospital district (HUS-H, excluding Helsinki)—with more rural types of land uses—in southern Finland for two decades, 2000–2018. Dependence of the risk of daily all-cause deaths (all-age and 75+ years) on daily mean temperature was modelled using the distributed lag nonlinear model (DLNM). The modelled relationships were applied in assessing deaths attributable to four intensive heatwaves during the study period. The results showed that the heat-related mortality risk was substantially higher in Helsinki than in HUS-H, and the mortality rates attributable to four intensive heatwaves (2003, 2010, 2014 and 2018) were about 2.5 times higher in Helsinki than in HUS-H. Among the elderly, heat-related risks were also higher in Helsinki, while cold-related risks were higher in the surrounding region. The temperature ranges recorded in the fairly coarse resolution gridded datasets were not distinctly different in the two considered regions. It is therefore probable that the modelling underestimated the actual exposure to the heat stress in Helsinki. We also studied the modifying, short-term impact of air quality on the modelled temperature-mortality association in Helsinki; this effect was found to be small. We discuss a need for higher resolution data and modelling the UHI effect, and regional differences in vulnerability to thermal stress.

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Solar Irradiance Reduction Using Optimized Green Infrastructure in Arid Hot Regions: A Case Study in El-Nozha District, Cairo, Egypt

Sustainability ◽

10.3390/su13179617 ◽

2021 ◽

Vol 13 (17) ◽

pp. 9617 ◽

Cited By ~ 1

Author(s):

Wesam M. Elbardisy ◽

Mohamed A. Salheen ◽

Mohammed Fahmy

Keyword(s):

Climate Change ◽

Urban Heat Island ◽

Green Infrastructure ◽

Solar Irradiance ◽

Urban Trees ◽

Heat Island ◽

Physiological Equivalent Temperature ◽

Urban Climatology ◽

Urban Heat ◽

The City

In the Middle East and North Africa (MENA) region, studies focused on the relationship between urban planning practice and climatology are still lacking, despite the fact that the latter has nearly three decades of literature in the region and the former has much more. However, such an unfounded relationship that would consider urban sustainability measures is a serious challenge, especially considering the effects of climate change. The Greater Cairo Region (GCR) has recently witnessed numerous serious urban vehicular network re-development, leaving the city less green and in need of strategically re-thinking the plan regarding, and the role of, green infrastructure. Therefore, this study focuses on approaches to the optimization of the urban green infrastructure, in order to reduce solar irradiance in the city and, thus, its effects on the urban climatology. This is carried out by studying one of the East Cairo neighborhoods, named El-Nozha district, as a representative case of the most impacted neighborhoods. In an attempt to quantify these effects, using parametric simulation, the Air Temperature (Ta), Mean Radiant Temperature (Tmrt), Relative Humidity (RH), and Physiological Equivalent Temperature (PET) parameters were calculated before and after introducing urban trees, acting as green infrastructure types that mitigate climate change and the Urban Heat Island (UHI) effect. Our results indicate that an optimized percentage, spacing, location, and arrangement of urban tree canopies can reduce the irradiance flux at the ground surface, having positive implications in terms of mitigating the urban heat island effect.

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Urban Heat Management in Louisville, Kentucky: A Framework for Climate Adaptation Planning

Journal of Planning Education and Research ◽

10.1177/0739456x19879214 ◽

2019 ◽

pp. 0739456X1987921 ◽

Cited By ~ 6

Author(s):

Brian Stone ◽

Kevin Lanza ◽

Evan Mallen ◽

Jason Vargo ◽

Armistead Russell

Keyword(s):

Green Infrastructure ◽

Climate Adaptation ◽

Waste Heat ◽

Management Strategies ◽

Tree Planting ◽

Heat Management ◽

Management Plans ◽

Urban Heat ◽

The Impact ◽

Related Mortality

We explore the potential for cities to develop urban heat management plans to moderate rising temperatures and to lessen the impact of extreme heat on human health. Specifically, we model the impacts of heat management strategies, including tree planting and other green infrastructure, cool roofing and paving, and a reduction in waste heat emissions from buildings and vehicles, on estimated heat-related mortality across Louisville, Kentucky. Our assessment finds a combination of urban heat management strategies to lessen summer temperatures by as much as 10°F on hot days and to reduce estimated heat-related mortality by more than 20 percent.

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Night Thermal Unmixing for the Study of Microscale Surface Urban Heat Islands with TRISHNA-Like Data

Remote Sensing ◽

10.3390/rs11121449 ◽

2019 ◽

Vol 11 (12) ◽

pp. 1449 ◽

Cited By ~ 2

Author(s):

Carlos Granero-Belinchon ◽

Aurelie Michel ◽

Jean-Pierre Lagouarde ◽

Jose A. Sobrino ◽

Xavier Briottet

Keyword(s):

Surface Temperature ◽

Land Surface ◽

Image Resolution ◽

Urban Heat Islands ◽

Land Uses ◽

Regression Kriging ◽

Heat Islands ◽

Urban Heat ◽

Land Covers ◽

The City

Urban Heat Islands (UHIs) at the surface and canopy levels are major issues in urban planification and development. For this reason, the comprehension and quantification of the influence that the different land-uses/land-covers have on UHIs is of particular importance. In order to perform a detailed thermal characterisation of the city, measures covering the whole scenario (city and surroundings) and with a recurrent revisit are needed. In addition, a resolution of tens of meters is needed to characterise the urban heterogeneities. Spaceborne remote sensing meets the first and the second requirements but the Land Surface Temperature (LST) resolutions remain too rough compared to the urban object scale. Thermal unmixing techniques have been developed in recent years, allowing LST images during day at the desired scales. However, while LST gives information of surface urban heat islands (SUHIs), canopy UHIs and SUHIs are more correlated during the night, hence the development of thermal unmixing methods for night LSTs is necessary. This article proposes to adapt four empirical unmixing methods of the literature, Disaggregation of radiometric surface Temperature (DisTrad), High-resolution Urban Thermal Sharpener (HUTS), Area-To-Point Regression Kriging (ATPRK), and Adaptive Area-To-Point Regression Kriging (AATPRK), to unmix night LSTs. These methods are based on given relationships between LST and reflective indices, and on invariance hypotheses of these relationships across resolutions. Then, a comparative study of the performances of the different techniques is carried out on TRISHNA synthesized images of Madrid. Since TRISHNA is a mission in preparation, the synthesis of the images has been done according to the planned specification of the satellite and from initial Aircraft Hyperspectral Scanner (AHS) data of the city obtained during the DESIREX 2008 capaign. Thus, the coarse initial resolution is 60 m and the finer post-unmixing one is 20 m. In this article, we show that: (1) AATPRK is the most performant unmixing technique when applied on night LST, with the other three techniques being undesirable for night applications at TRISHNA resolutions. This can be explained by the local application of AATPRK. (2) ATPRK and DisTrad do not improve significantly the LST image resolution. (3) HUTS, which depends on albedo measures, misestimates the LST, leading to the worst temperature unmixing. (4) The two main factors explaining the obtained performances are the local/global application of the method and the reflective indices used in the LST-index relationship.

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Climate Bubbles: Games to Monitor Urban Climate

Leonardo ◽

10.1162/leon_a_00097 ◽

2011 ◽

Vol 44 (1) ◽

pp. 64-65

Author(s):

Drew Hemment ◽

Carlo Buontempo ◽

Alfie Dennen

Keyword(s):

Urban Heat Island ◽

Air Flow ◽

Urban Climate ◽

Heat Island ◽

Local Climate ◽

Flow Circulation ◽

Urban Heat ◽

The City

Climate Bubbles was a playful, participatory mass observation project on local climate. Bubble blowing games were devised to enable people across the city of Manchester to test air flow circulation and, by sharing the results online, enabled the Met Office to create a snapshot of the effect the Urban Heat Island has on wind.

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Features of the formation of urban heat islands effects in tropical climates and their impact on the ecology of the city

E3S Web of Conferences ◽

10.1051/e3sconf/20199105005 ◽

2019 ◽

Vol 91 ◽

pp. 05005 ◽

Cited By ~ 2

Author(s):

Minh Tuan Le ◽

Nguyen Anh Quan Tran

Keyword(s):

Urban Areas ◽

Building Materials ◽

Urban Landscape ◽

Urban Climate ◽

Ecological Systems ◽

Urban Heat Islands ◽

Heat Islands ◽

Urban Heat ◽

Tropical Climates ◽

The City

The cumulative heating in some urban areas due to the urban growth and its types of industry, energy and transport, is the effect of urban heat island (UHI). It is recognized as one of the characteristics of the urban climate. The temperature increase caused by the effect (UHI) affects the energy flow in urban ecological systems, creates an unusual urban climate. By studying the effects of climate factors, local building materials to optimize energy efficiency, urban landscape, UHI phenomenon could be significantly moderated.

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A historical approach to understanding governance of extreme urban heat in Fukuoka, Japan

Disaster Prevention and Management An International Journal ◽

10.1108/dpm-01-2020-0010 ◽

2020 ◽

Vol ahead-of-print (ahead-of-print) ◽

Author(s):

Leslie Mabon

Keyword(s):

Urban Climate ◽

Historical Context ◽

Extreme Heat ◽

Content Type ◽

Environmental Evaluation ◽

For Profit ◽

Success Stories ◽

Not For Profit ◽

Science Policy Interface ◽

Urban Heat

PurposeThe purpose of this paper is to contribute to emergent understandings in research into urban climate change-related disasters (such as extreme heat), which recognise that present-day actions or failures of cities to address climate risk are rooted in a historical context.Design/methodology/approachThe paper analyses content of scientific journals produced by the not-for-profit Kyushu Environmental Evaluation Association in Fukuoka since the 1970s. The aim is to evaluate the shifting understanding and conception of a liveable urban environment within Fukuoka over time and assess how this narrative has informed capability to understand and manage extreme heat as an emergent disaster risk.FindingsThe strong technical competences enabling Fukuoka to undertake evidence-based management of risks from climate-related disasters today exist at least partially because of earlier environmental concerns within the city and an early emergence of techno-scientific competence within the city's research institutions working at the science–policy interface.Originality/valueThe findings suggest a need to avoid uncritically exporting “lessons” from apparent urban climate “success stories”, without full recognition of the historical context enabling production and utilisation of weather and climate knowledge in specific locations.

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Lisbon Urban Heat Island Updated: New Highlights about the Relationships between Thermal Patterns and Wind Regimes

Advances in Meteorology ◽

10.1155/2013/487695 ◽

2013 ◽

Vol 2013 ◽

pp. 1-11 ◽

Cited By ~ 22

Author(s):

António Lopes ◽

Elis Alves ◽

Maria João Alcoforado ◽

Raquel Machete

Keyword(s):

Urban Heat Island ◽

Urban Climate ◽

City Centre ◽

Heat Island ◽

Local Wind ◽

Urban Heat ◽

Thermal Patterns ◽

Wind Regimes ◽

The Relationship ◽

The City

Urban growth implies significant modifications in the urban climate. To understand the influence of the city of Lisbon on the urban boundary layer, a mesoscale meteorological network was installed in 2004. The main goals of the present study are to update the results of the research published in 2007 and to bring more precise information about the relationship between the Urban Heat Island (UHI) and the regional and local wind systems. The highest frequencies of the UHI were found in the city centre (Restauradores). In the green park of Monsanto, the highest frequency occurred between −2 and 0°C. During the summer, the effect of the breezes was observed in Belém, lowering the temperature. The “strong” UHI (intensity >4°C) occurred more often during the summer, with median values of 2°C by night and 1.8°C by day. The highest frequencies of UHI occurred for winds between 2 and 6 m/s and were not associated with atmospheric calm, as pointed out in the literature. Winds above 8 m/s inhibit the occurrence of strong UHI in Lisbon. Summer nighttime strong UHI should be further investigated, due to the heat stress consequences on the population and probable increase of energy consumption.

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Green Roofs and Greenpass

Buildings ◽

10.3390/buildings9090205 ◽

2019 ◽

Vol 9 (9) ◽

pp. 205 ◽

Cited By ~ 5

Author(s):

Scharf ◽

Kraus

Keyword(s):

Climate Change ◽

Thermal Comfort ◽

Green Infrastructure ◽

Climate Adaptation ◽

Urban Climate ◽

Green Roofs ◽

Well Being ◽

Status Quo ◽

Assessment System ◽

Urban Energy Balance

The United Nations have identified climate change as the greatest threat to human life. As current research shows, urban areas are more vulnerable to climate change than rural areas. Numerous people are affected by climate change in their daily life, health and well-being. The need to react is undisputed and has led to numerous guidelines and directives for urban climate adaptation. Plants are commonly mentioned and recommended as one key to urban climate adaptation. Due to shading of open space and building surfaces, as well as evapotranspiration, plants reduce the energy load on the urban fabric and increase thermal comfort and climate resilience amongst many other ecosystem services. Plants, therefore, are described as green infrastructure (GI), because of the beneficial effects they provide. Extensive green roofs are often discussed regarding their impact on thermal comfort for pedestrians and physical properties of buildings. By means of Stadslab2050 project Elief Playhouse in Antwerp, Belgium, a single-story building in the courtyard of a perimeter block, the effects of different extensive green roof designs (A and B) on the microclimate, human comfort at ground and roof level, as well as building physics are analyzed and compared to the actual roofing (bitumen membrane) as the Status Quo variant. For the analyses and evaluation of the different designs the innovative Green Performance Assessment System (GREENPASS®) method has been chosen. The planning tool combines spatial and volumetric analyses with complex 3D microclimate simulations to calculate key performance indicators such as thermal comfort score, thermal storage score, thermal load score, run-off and carbon sequestration. Complementary maps and graphs are compiled. Overall, the chosen method allows to understand, compare and optimize project designs and performance. The results for the Elief Playhouse show that the implementation of green roofs serves a slight contribution to the urban energy balance but a huge impact on the building and humans. Variant B with entire greening performs better in all considered indicators, than the less greened design Variant A and the actual Status Quo. Variant B will probably bring a greater cost/benefit than Variant A and is thus recommended.

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