Outdoor thermal comfort by different heat mitigation strategies- A review

Taleghani, Mohammad

doi:10.1016/j.rser.2017.06.010

Cited by 257 publications

(166 citation statements)

References 70 publications

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“…As a result, several studies have suggested using 'cool' reflective surfaces with higher albedo to decrease the surface temperature. These surfaces include both cool roofs [49][50][51][52][53][54] and cool pavements [55][56][57][58][59]. Synnefa et al [60] conducted a numerical evaluation of the benefits of the large-scale deployment of reflective surfaces in Athens, Greece and found a potential reduction of ambient air temperatures by up to 2 • C. Another study by Georgiakis et al [61], also in Athens, suggested a more moderate decrease in ambient air temperature, of about 1 • C, although only for a single urban canyon.…”

Section: Introductionmentioning

confidence: 99%

Cool Pavement Strategies for Urban Heat Island Mitigation in Suburban Phoenix, Arizona

et al. 2019

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Urban areas are characterized by a large proportion of artificial surfaces, such as concrete and asphalt, which absorb and store more heat than natural vegetation, leading to the Urban Heat Island (UHI) effect. Cool pavements, walls, and roofs have been suggested as a solution to mitigate UHI, but their effectiveness depends on local land-use patterns and surrounding urban forms. Meteorological data was collected using a mobile platform in the Power Ranch community of Gilbert, Arizona in the Phoenix Metropolitan Area, a region that experiences harsh summer temperatures. The warmest hour recorded during data collection was 13 August 2015 at 5:00 p.m., with a far-field air temperature of about 42 ∘ C and a low wind speed of 0.45 m/s from East-Southeast (ESE). An uncoupled pavement-urban canyon Computational Fluid Dynamics (CFD) model was developed and validated to study the microclimate of the area. Five scenarios were studied to investigate the effects of different pavements on UHI, replacing all pavements with surfaces of progressively higher albedo: New asphalt concrete, typical concrete, reflective concrete, making only roofs and walls reflective, and finally replacing all artificial surfaces with a reflective coating. While new asphalt surfaces increased the surrounding 2 m air temperatures by up to 0.5 ∘ C, replacing aged asphalt with typical concrete with higher albedo did not significantly decrease it. Reflective concrete pavements decreased air temperature by 0.2–0.4 ∘ C and reflective roofs and walls by 0.4–0.7 ∘ C, while replacing all roofs, walls, and pavements with a reflective coating led to a more significant decrease, of up to 0.8–1.0 ∘ C. Residences downstream of major collector roads experienced a decreased air temperature at the higher end of these ranges. However, large areas of natural surfaces for this community had a significant effect on downstream air temperatures, which limits the UHI mitigation potential of these strategies.

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Section: Introductionmentioning

confidence: 99%

Cool Pavement Strategies for Urban Heat Island Mitigation in Suburban Phoenix, Arizona

et al. 2019

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“…This paper is focused on pedestrians' thermal comfort in outdoor environment where there is limited access to a cool spot or a cold drink. Thermal comfort is defined as "that condition of mind which expresses satisfaction with the thermal environment" (ISO-7730 2005).Thermal comfort includes environmental factors (such as air temperature and wind speed), biological factors (such as age and gender), and physiological factors (such as clothing and metabolism) (Ali-Toudert and Mayer 2007;Nicol et al 2012;Taleghani 2014).…”

Section: Introductionmentioning

confidence: 99%

The impact of increasing urban surface albedo on outdoor summer thermal comfort within a university campus

Taleghani

2018

Urban Climate

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The impact of increasing urban surface albedo on outdoor thermal comfort was studied in two phases: Firstly, the thermal conditions of three locations with different ground surface materials were compared. The study used CFD modelling followed by a measurement campaign to validate the control simulation. It was observed that the physiological equivalent temperature (PET as the outdoor thermal comfort index) in the campus park (covered with grass) was 11.0 °C lower than the parking lot (paved with concrete) at 16:00 CET. As the next step, the albedo of the roofs and walls were increased from 0.2 to 0.6. It was found that increasing the albedo made the open space of the courtyard uncomfortable due to the higher reflectivity of high-albedo materials. An increase of every 0.1 albedo of the surfaces led to 1.2 °C higher mean radiant temperature, and consequently, 0.8 °C higher PET. The study also showed that the increase of albedo radiated more sun to the ground surface. This increased average ground surface sensible heat flux (6.7 W/m 2) and surface temperature (0.4 ᵒC) during the day. This finding shows that the position and orientation of high albedo materials can significantly affect pedestrians' thermal comfort in urban open spaces.

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“…This trend shows that these serious urban climate hazards have not been adequately tackled, especially considering that it has a relevant impact at the energy, environmental and social levels, as widely documented in several exemplary studies [10][11][12][13][14][15]. On the contrary, several mitigation strategies and technologies are available to counter this phenomenon.…”

Section: Introductionmentioning

confidence: 99%

Lighting Implications of Urban Mitigation Strategies through Cool Pavements: Energy Savings and Visual Comfort

Rossi

Iacomussi

Zinzi

2018

Climate

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Cool materials with higher solar reflectance compared with conventional materials of the same color are widely used to maintain cooler urban fabrics when exposed to solar irradiation and to mitigate the Urban Heat Island (UHI). Photo-catalytic coatings are also useful to reduce air pollutants. Many studies related to these topics have been carried out during the past few years, although the lighting implication of reflective coatings have hardly been explored. To investigate these aspects, reflective coatings were applied on portions of a road and intensely analyzed in a laboratory and on the field. The applied cool coatings were found to have much higher solar and lighting reflectance than the existing road, which lead to lower surface temperatures up to 9 • C. Non-significant variations of chromaticity coordinates were measured under different lighting conditions. However, these materials showed a relevant variation of directional properties depending on the lighting and observation conditions with respect to conventional pavements. The optical behavior of these materials affects the uniformity of visions for drivers and requires ad-hoc installation of light sources. On the other hand, potential energy savings of up to 75% were calculated for the artificial lighting of a reference road.

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Outdoor thermal comfort by different heat mitigation strategies- A review

Cited by 257 publications

References 70 publications

Cool Pavement Strategies for Urban Heat Island Mitigation in Suburban Phoenix, Arizona

Cool Pavement Strategies for Urban Heat Island Mitigation in Suburban Phoenix, Arizona

The impact of increasing urban surface albedo on outdoor summer thermal comfort within a university campus

Lighting Implications of Urban Mitigation Strategies through Cool Pavements: Energy Savings and Visual Comfort

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