Thermal performance of climber greenwalls: Effects of solar irradiance and orientation

Jim, Chi Yung

doi:10.1016/j.apenergy.2015.05.077

Cited by 95 publications

(36 citation statements)

References 39 publications

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“…These replicated experiments reinforce previous observations about the value of green facades and walls to building cooling in other countries (e.g. Jim, 2015). The most dramatic decreases, were associated with the more extreme scenarios presented within the experimental periods, i.e.…”

Section: Discussionsupporting

confidence: 89%

To green or not to green! That is the question. Does green infrastructure provide significant thermo-regulation in a maritime temperate climate?

Taylor¹,

Cameron²

2017

Acta Hortic.

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Presenting author 1,2 Joint first authors AbstractThe ecosystem service delivery of urban green infrastructure (UGI) is now manifest. Types and level of service provision, however, can alter radically, based on factors such as location, species choice, planting design and vegetation management. The value of vegetation to provide a cooling service is generally understood in hot climates, but the merit in temperate climates remains ambiguous. Indeed, policy makers within cooler countries (e.g. UK) remain to be convinced that expenditure on UGI is justified, at least from the point of view of city cooling alone. Occasional warm days do occur of course, and climate change models predict that heat wave events will become more frequent within the UK, including those that pose a risk to human health. To help UK policy makers make better-informed decisions around UGI, a number of our research programmes have targeted the role vegetation plays in regulating temperature, but specifically within the context of a maritime-temperate climate Two examples of green interventions are discussed here. The first documents the role of green façades to cool a wall system and the second illustrates the cooling influence conferred by roadside trees. Both experiments used a replicated sampling approach to ensure statistical robustness, and hence convince policy makers that data is representative of UK scenarios and results are reproducible. In the first experiment, 10 separate wall sections are used to investigate the cooling influence of two different plant genotypes (Prunus and Phaseolus) on both exterior and interior wall spaces. In the second study, road surface temperatures are documented with respect to both built and green infrastructure, i.e. we compare the influence of buildings and street trees on the surface temperatures across a road profile Again replicate data are used to provide a generic summer temperature profile for the city of Sheffield, rather than just specific locations at one point in time. Results show that green facades can reduce exterior and interior (cavity) wall air temperature by 3 o C and 5 o C respectively. Likewise, large street trees have a mean cooling influence of 4.5 o C on road surfaces near their base compared to comparable sections adjacent to buildings. To maximise cooling, the data suggests that trees need to be provided on both sides of a roadway, i.e. a single tree did not manage to cool the pavement at the opposite side of the road. The implications of the results for temperate climates are discussed.

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Section: Discussionsupporting

confidence: 89%

To green or not to green! That is the question. Does green infrastructure provide significant thermo-regulation in a maritime temperate climate?

Taylor¹,

Cameron²

2017

Acta Hortic.

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“…In both cases, the average Ta was reduced by 0.5 • C-1.2 • C in the area shaded by GFs comparing to the outdoor environment, and the results showed the optimization of the thermal environment on summer days. The results for average Ta reduction are in agreement with the measurements of Wang et al [10], Jim [52], and Perini et al [17]. Further comparison of Ta, Tg, and MRT for points unshaded, in front of, and behind the GF also demonstrated the shading and cooling effect of the GF.…”

Section: Thermal Comfort In Field Measurementssupporting

confidence: 90%

Green Façade Effects on Thermal Environment in Transitional Space: Field Measurement Studies and Computational Fluid Dynamics Simulations

et al. 2019

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High-density urban development areas have several problems associated with them, such as the formation of urban heat islands, traffic noise, and air pollution. To minimize these problems, the green façades (GFs), which are used to guide climbing plants to grow vertically on building facade, are focused on by researchers and architects. This study focuses on GF application strategies and their optimizations for thermal comfort in a transitional space in a hot-humid climate. First, field measurements were collected from GF projects located in Guangzhou, China, in summer 2017. Second, a simulation method using computational fluid dynamics (CFD) was used to investigate the thermal effects of the GF’s foliage. Finally, seven GF typologies and one unshaded comparison model were used for simulations in three scenarios with south, east, and west orientations and compared to evaluate the effects of GFs on the thermal environment of the transitional space. The results of field measurements reveal that the GF reduced average Physiologically Equivalent Temperature (PET) by 2.54 °C, and that of CFD simulations reveal that three typologies of GFs are more effective in regulating the thermal environment in the summer. The results of this research provide support for further studies on the thermal effectiveness and design options of GFs for human comfort.

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“…This is important as rapid urbanization in China has resulted in a high utilization of sky spaces with taller buildings, and in a dramatic reduction of bare soil areas for plant survival. Li et al (2011) reported that the vertical cooling effect of green plant canopy in residential areas was significant above 1.5 m. Moreover, vertical greening vines or roof greening to enhance cooling and humidifying effects along the vertical profile have also been suggested (Alexandri & Jones 2008, Perini et al 2013, Jim 2015. In this study, using infra-red temperature monitoring techniques, we found that canopy temperature was lower compared with under-canopy.…”

Section: Discussionmentioning

confidence: 53%

“…Our results strongly support this conclusion. Jim (2015) argued that plants play a greater role in cooling when solar radiation is higher. Alexandri & Jones (2008) found that the cooling effect of urban green spaces was remarkable in dry and hot weather.…”

Section: Discussionmentioning

confidence: 99%

Microclimate regulating functions of urban forests in Changchun City (north-east China) and their associations with different factors

Wang¹,

Wang²,

Lu³

et al. 2018

iForest

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Microclimate regulating functions of urban trees and their associations with environmental factors and tree-growth characteristics are important for management and ecological evaluations. In this study, a total of 637 trees distributed in the Changchun urban region (ca. 400 km 2 , northeastern China) were sampled in four different types of urban forests (AF: affiliated forests; RF: roadside forests; LF: landscape and relaxation forests; EF: ecological welfare forests). Tree growth-related parameters and environmental factors (inside and outside the forest) were simultaneously measured, and location-dependent differences in shading, cooling and humidifying effects were assessed, along with their associations with the measured variables. We found that urban forests in Changchun reduced the incident sunlight by 74-86% and increased air relative humidity by 3-7%, on average. Air, soil, and upper-canopy temperatures were decreased approximately by 3 °C, <1 °C and 1 °C, respectively, showing a 3-dimensional cooling effect of urban forests on both air and soil. Shading, cooling and humidifying effects significantly differed among the four forest types, with AF stands showing the highest comprehensive scores for all the microclimate regulation functions. Regression analyses and redundancy analysis revealed that urban forests had much stronger effect in terms of microclimate regulation at sunny days with high temperature, and low air humidity. In general, stands with larger trees showed the higher regulating functions, regardless of the stand structure and composition. The results of this study may help urban forest management and planning aimed at maximizing their ecological services.

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Thermal performance of climber greenwalls: Effects of solar irradiance and orientation

Cited by 95 publications

References 39 publications

To green or not to green! That is the question. Does green infrastructure provide significant thermo-regulation in a maritime temperate climate?

To green or not to green! That is the question. Does green infrastructure provide significant thermo-regulation in a maritime temperate climate?

Green Façade Effects on Thermal Environment in Transitional Space: Field Measurement Studies and Computational Fluid Dynamics Simulations

Microclimate regulating functions of urban forests in Changchun City (north-east China) and their associations with different factors

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