High-albedo materials for reducing building cooling energy use

Taha, H.; Sailor, D.; Akbari, H.

doi:10.2172/10178958

Cited by 28 publications

(23 citation statements)

References 5 publications

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“…The buildings often have flat concrete or metallic roofs, and/or darker color roofs (red/brown) as were seen on aerial photos. Concrete surfaces are reported to have low albedo from 0.1 to 0.35 [34], low emissivity, and high heat capacity. Also, these areas lack vegetation that could offset hot surface temperatures.…”

Section: Interpretation Of Resultsmentioning

confidence: 99%

Toronto’s Urban Heat Island—Exploring the Relationship between Land Use and Surface Temperature

2011

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Abstract:The urban heat island effect is linked to the built environment and threatens human health during extreme heat events. In this study, we analyzed whether characteristic land uses within an urban area are associated with higher or lower surface temperatures, and whether concentrations of -hot‖ land uses exacerbate this relationship. Zonal statistics on a thermal remote sensing image for the City of Toronto revealed statistically significant differences between high average temperatures for commercial and resource/industrial land use (29.1 °C), and low average temperatures for parks and recreational land (25.1 °C) and water bodies (23.1 °C). Furthermore, higher concentrations of either of these land uses were associated with more extreme surface temperatures. We also present selected neighborhoods to illustrate these results. The paper concludes by recommending that municipal planners and decision-makers formulate policies and regulations that are specific to the problematic land uses, in order to mitigate extreme heat.

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Section: Interpretation Of Resultsmentioning

confidence: 99%

Toronto’s Urban Heat Island—Exploring the Relationship between Land Use and Surface Temperature

2011

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“…The thermal transmittance of the wall Kw was set on the basis of the wall of a typical residential building in Malaysia (Saidur et al [51]). For the albedo coefficient of the walls, it was set at 0.3 for brick walls and 0.4 for timber walls (Taha et al [52], p. 23). At the same time, the albedo of the roof was based on the ENVI-met-material database.…”

Section: The Vegetation Modelmentioning

confidence: 99%

Interrelationships between Land Use Land Cover (LULC) and Human Thermal Comfort (HTC): A Comparative Analysis of Different Spatial Settings

et al. 2021

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A few studies on outdoor human thermal comfort (HTC) have been conducted in the tropical region in a hot and humid climate; however, there is a paucity of discussions on how exactly different spatial settings influence HTC. Thus, this paper aims to examine how land use land cover (LULC) affects HTC on the basis of the simulation of Predicted Mean Vote (PMV) and Physiologically Equivalent Temperature (PET) indices via ENVI-met and Rayman. The results reveal that people living in the urban area have a higher tendency to experience strong heat stress (25% of the areas with PMV ranging from 3.4 to 3.9 and 2% of the areas, where PMV reached 4.1), followed by the rural area (43% of the areas with PMV ranging from 2.1 to 2.4), and the suburban area (more than 50% of the areas with PMV values less than 2.4). Surprisingly, a concrete LULC in the suburb area exhibits a higher air temperature than an asphalt surface at 4 p.m., due to the large area of high albedo that increases the reflection of solar radiation, subsequently contributing to warming up the airmass. Similarly, sandy, and loamy LULC tend to emit more heat during nighttime, while the heat is absorbed slowly during daytime, and it is then slowly released during nighttime after 6 p.m. Spatial settings that promote heat stress in the urban area are mainly contributed by an LULC of asphalt, concrete, sandy, and loamy areas. Meanwhile, people in the suburban and rural areas are less likely to experience heat stress, due to agricultural plantations and lowland forest that provide shade, except for the barren lands-loamy areas. The result also indicates that tree-covered areas near the river in the suburban area afforded the best thermal experience with PMV of 2.1 and PET of 30.7. From the LULC comparison, it is pivotal to consider tree species (canopy density), surface material (albedo), sky-view factor, wind direction, and speed toward designing a more comfortable and sustainable environment.

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“…We calibrated the thermal imagery by using FLIR Tools version 5.9 to adjust temperature related parameters, such as emissivity, reflected apparent temperature, distance, atmospheric temperature, and relative humidity. Because the scale model is mainly constructed by grey concrete blocks, we set the emissivity as 0.91 [18,64]. Atmospheric temperature and relative humidity were decided by the nearby weather station at Sky Harbor To validate the iButton measurements and to collect information on the overall thermal environment, we used a FLIR P620 thermal camera [63].…”

Section: Instrumentation Calibration and Quality Controlmentioning

confidence: 99%

Assessing the Cooling Benefits of Tree Shade by an Outdoor Urban Physical Scale Model at Tempe, AZ

Zhao¹,

Yang²,

Wang³

et al. 2018

Urban Science

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Urban green infrastructure, especially shade trees, offers benefits to the urban residential environment by mitigating direct incoming solar radiation on building facades, particularly in hot settings. Understanding the impact of different tree locations and arrangements around residential properties has the potential to maximize cooling and can ultimately guide urban planners, designers, and homeowners on how to create the most sustainable urban environment. This research measures the cooling effect of tree shade on building facades through an outdoor urban physical scale model. The physical scale model is a simulated neighborhood consisting of an array of concrete cubes to represent houses with identical artificial trees. We tested and compared 10 different tree densities, locations, and arrangement scenarios in the physical scale model. The experimental results show that a single tree located at the southeast of the building can provide up to 2.3 • C hourly cooling benefits to east facade of the building. A two-tree cluster arrangement provides more cooling benefits (up to 6.6 • C hourly cooling benefits to the central facade) when trees are located near the south and southeast sides of the building. The research results confirm the cooling benefits of tree shade and the importance of wisely designing tree locations and arrangements in the built environment.

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High-albedo materials for reducing building cooling energy use

Cited by 28 publications

References 5 publications

Toronto’s Urban Heat Island—Exploring the Relationship between Land Use and Surface Temperature

Toronto’s Urban Heat Island—Exploring the Relationship between Land Use and Surface Temperature

Interrelationships between Land Use Land Cover (LULC) and Human Thermal Comfort (HTC): A Comparative Analysis of Different Spatial Settings

Assessing the Cooling Benefits of Tree Shade by an Outdoor Urban Physical Scale Model at Tempe, AZ

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