Comparing the effects of urban heat island mitigation strategies for Toronto, Canada

Wang, Yupeng; Berardi, Umberto; Akbari, Hashem

doi:10.1016/j.enbuild.2015.06.046

Cited by 401 publications

(193 citation statements)

References 58 publications

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“…This was different from the insignificant correlations between SUHII and ∆EVI in previous studies [3,10]. The vegetation reducing the nighttime SUHII has been demonstrated using ground observations [53,54]. The decreasing vegetation and increasing impervious surfaces can increase heat stored during daytime.…”

Section: The Relationships Between Suhii and ∆Evicontrasting

confidence: 43%

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Urbanization Effects on Vegetation and Surface Urban Heat Islands in China’s Yangtze River Basin

et al. 2017

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Abstract:In the context of rapid urbanization, systematic research about temporal trends of urbanization effects (UEs) on urban environment is needed. In this study, MODIS (Moderate Resolution Imaging Spectroradiometer) land surface temperature (LST) data and enhanced vegetation index (EVI) data were used to analyze the temporal trends of UEs on vegetation and surface urban heat islands (SUHIs) at 10 big cities in Yangtze River Basin (YRB), China during 2001-2016. The urban and rural areas in each city were derived from MODIS land cover data and nighttime light data. It was found that the UEs on vegetation and SUHIs were increasingly significant in YRB, China. The ∆EVI (the UEs on vegetation, urban EVI minus rural EVI) decreased significantly (p < 0.05) in 9, 7 and 5 out of 10 cities for annual, summer and winter, respectively. The annual daytime and nighttime SUHI intensity (SUHII; urban LST minus rural LST) increased significantly (p < 0.05) in 10 and 4 out of 10 cities, respectively. The increasing rate of daytime SUHII and the decreasing rate of ∆EVI in old urban areas were much less than the whole urban area (0.034 • C/year vs. 0.077 • C/year for annual daytime SUHII; 0.00209/year vs. 0.00329/year for ∆EVI). The correlation analyses indicated that the annual and summer daytime SUHII were significantly negatively correlated with ∆EVI in most cities. The decreasing ∆EVI may also contribute to the increasing nighttime SUHII. In addition, the significant negative correlations (r < −0.5, p < 0.1) between inter-annual linear slope of ∆EVI and SUHII were observed, which suggested that the cities with higher decreasing rates of ∆EVI may show higher increasing rates of SUHII.

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Section: The Relationships Between Suhii and ∆Evicontrasting

confidence: 43%

“…In order to solve the increasingly serious problem of UHI, some effective measures should be adopted immediately. In addition to planting more trees, pavements and roves with high albedo and low heat storage should be applied to mitigate the UHI [52,53].…”

Section: Temporal Trends Of Ues On Vegetation and Suhii In Yrb Chinamentioning

confidence: 99%

Urbanization Effects on Vegetation and Surface Urban Heat Islands in China’s Yangtze River Basin

et al. 2017

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“…Previous studies have elaborated on the validation of the ENVI-met model, and we conducted the model validation too by comparing measurement data and ENVI-met results, which showed a good agreement in comparison with some previous studies, e.g. Chow and Brazel (2012), Wang, Berardi, and Akbari (2015). The good performance of a model provides researchers opportunities to conduct exploratory investigations by setting various scenarios, which may be impracticable in reality.…”

Section: Validation and Uncertainty Of This Modelmentioning

confidence: 80%

Optimizing the spatial arrangement of trees in residential neighborhoods for better cooling effects: Integrating modeling with in-situ measurements

Chen

2017

Landscape and Urban Planning

109

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A B S T R A C TTrees have long been recognized as effective for mitigating urban heat islands by reducing air temperature through evapotranspiration and intercepting shortwave radiation that heat up land surfaces. Many studies have shown that both the composition and configuration of vegetation can contribute to heat reduction at the city scale. Fewer studies, however, have focused on cooling mechanisms at the neighborhood scale. Here, we integrate modeling with in situ measurements to investigate how different spatial arrangements of trees in residential neighborhoods affect their cooling effects. We conducted the research in a residential neighborhood with high-rise apartment buildings in Beijing. We tested four scenarios with different spatial arrangements of trees, and quantified their effects on cooling. We used the high spatial and temporal resolution microclimate model ENVI-met and validated the model with in situ measurements. We found: (1) Different spatial arrangements had differentiated effects on intercepting shortwave radiation, which led to variations in air temperature. For example, new trees that were completely exposed to solar radiation had stronger cooling effects (air temperature was 0.22°C lower) than new trees that were located in the shadow of surrounding buildings. (2) Different spatial arrangements led to obviously different effects of sensible heat reduction, with a maximum difference of 14.84 × 10 8 J/ha. Our results underscore the importance of the spatial arrangement of trees on cooling in residential neighborhoods. These results have important implications in urban planning and design at the neighborhood scale.

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“…However, in an experimental study conducted in Hong Kong (a typical compact city), it was found that sites with higher density experienced lower air temperature [36]. A study in Toronto, Canada also found that the high-rise area was cooler than middle-rise and low-rise areas, since deep urban canyons could provide more shading and reduce direct solar radiation during daytime [37]. Some researchers [38] claimed that the compact urban form is the best approach to achieve sustainable urban development, since densification of the population and urban functions leads to a highly effective public transport system, which accounts for a great part of urban total energy consumption.…”

Section: Land Use Intensity Descriptorsmentioning

confidence: 99%

The Impact of Urban Design Descriptors on Outdoor Thermal Environment: A Literature Review

et al. 2017

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This paper presents a literature review on urban design indicators addressing the impact of urban geometry and vegetation on the outdoor thermal environment at the pedestrian level, as urban geometry and vegetation have been regarded as the most influential urban design factors that affect outdoor microclimate. The thermal balance concept is first introduced to elaborate how each component of energy fluxes is affected by the urban built environment, which helps to explore the underlying thermophysical mechanisms of how urban design modifies the outdoor thermal environment. The literature on numerous urban design descriptors addressing urban geometric characteristics is categorized into five groups in this paper according to the design features that the parameters entail, including land use intensity, building form, canyon geometry, space enclosure and descriptive characteristics. The literature on urban vegetation descriptors is reviewed together, followed by the combined effect of urban geometry and vegetation. This paper identifies a series of important urban design parameters and shows that the impact of design parameters on thermal environment varies with time, season, local climate and urban contexts. Contradictory impacts often occur between daytime and nighttime, or different seasons, which requests trade-offs to be achieved when proposing design strategies.

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Comparing the effects of urban heat island mitigation strategies for Toronto, Canada

Cited by 401 publications

References 58 publications

Urbanization Effects on Vegetation and Surface Urban Heat Islands in China’s Yangtze River Basin

Urbanization Effects on Vegetation and Surface Urban Heat Islands in China’s Yangtze River Basin

Optimizing the spatial arrangement of trees in residential neighborhoods for better cooling effects: Integrating modeling with in-situ measurements

The Impact of Urban Design Descriptors on Outdoor Thermal Environment: A Literature Review

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