Analyzing the thermal comfort conditions of outdoor spaces in a university campus in Kuala Lumpur, Malaysia

doi:10.1016/j.scitotenv.2019.01.284

Science of The Total Environment

Volume 666, 20 May 2019, Pages 1327-1345

https://doi.org/10.1016/j.scitotenv.2019.01.284 Get rights and content

Highlights

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Adequate attention to shading and vegetation results in enhancing outdoor thermal comfort.
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The outdoor spaces with the highest PMV/PET values embrace similar characteristics.
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The fully shaded areas can be used by users for 80% of the studied period.
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The unshaded spots embrace high thermal discomfort levels for over 80% of the time.

Abstract

The rapid urban expansion in East-Asian cities has increased the need for comfortable public spaces. This study presents field measurements and parametric simulations to evaluate the microclimatic characteristics in a university campus in the tropical climate of Kuala Lumpur, Malaysia. The study attempts to identify the thermally uncomfortable areas and their physical and design characteristics while debating on the circumstances of enhancing the outdoor comfort conditions for the campus users. Simulations in Envi-met and IES-VE are used to investigate the current outdoor thermal conditions, using classic thermal metric indices. Findings show high levels of thermal discomfort in most of the studied spaces. As a result, suggestions to improve the design quality of outdoor areas optimizing their thermal comfort conditions are proposed. The study concludes that effective re-design of outdoor spaces in the tropics, through adequate attention to the significant impacts of shading and vegetation, can result in achieving outdoor spaces with high frequency of use and improved comfort level.

Graphical abstract

Introduction

The rapid urban expansion in East-Asian cities in current years has radically expanded the necessity for liveable outdoor environments (Ghaffarianhoseini et al., 2015; Ruiz and Correa, 2015). In particular, in the tropics, due to the abundant solar radiation and the relatively high air temperature and relative humidity levels, long periods of outdoor thermal discomfort are common (Ahmed, 2003; Niu et al., 2015). Considering also the impact of urban heat island (UHI) effects in the urban areas, the need for designing outdoor spaces for outdoor comfortable criteria is critical (O'Malley et al., 2015; Wang et al., 2016; Salata et al., 2016; Aflaki et al., 2017; Sharmin et al., 2017).

According to recent studies (Sailor, 2014; Aflaki et al., 2017; Lu et al., 2017; Salata et al., 2017; Zhao and Fong, 2017), factors contributing to the UHI phenomenon and outdoor thermal discomfort include vast surface grounds with low albedo and high admittance materials such as concrete and asphalt; minimized green areas and permeable surfaces, which reduce chances of shade and evapotranspiration; highly elevated building blocks and narrow-sized streets/sidewalks that increase the total wind velocity but also trap the heat; and anthropogenic of heat-producing factors such as cars and HVAC systems. To overcome this, the efficient use of shading, greeneries and water bodies has the potential to significantly reduce the radiant air temperature in outdoor urban spaces (Berkovic et al., 2012; Makaremi et al., 2012; Taleghani et al., 2014b; Ghaffarianhoseini et al., 2015; Lobaccaro and Acero, 2015; Berardi, 2016; Fabbri et al., 2017).

The UHI in hot climates has distinctive challenges as a result of its critical impacts on users' health, outdoor thermal discomfort, air quality and building energy consumption (Sailor and Dietsch, 2007; Gartland, 2012; Martins et al., 2016; Santamouris et al., 2017). In this regard, design and development of thermally comfortable urban spaces with large green areas and sufficient shading potentials are common UHI mitigation strategies (Santamouris, 2014; Taleghani et al., 2014; Sailor, 2014).

Understanding the factors that allow a comfortable outdoor space is fundamental for urban designers (Brown et al., 2015; Morckel, 2015; Del Carpio et al., 2016; Chatzidimitriou and Yannas, 2016; Zinzi, 2016; Piselli et al., 2018). Designing climate-responsive urban outdoor spaces can provide thermally comfortable conditions, enhance satisfaction, and improve human health for users (Jamei et al., 2016). Likewise, the efficient use of outdoor spaces helps to decrease the building energy demand too (Niu et al., 2015; Berardi, 2016).

In this study, outdoor thermal comfort conditions have been evaluated using on-site measurements and parametric simulations in Kuala Lumpur, Malaysia. The study aimed to explore the thermal performance characteristics of different outdoor areas, to identify the key influential parameters affecting thermal comfort, and to suggest design guidelines for more thermally comfortable outdoor environment in the tropical climate of Kuala Lumpur.

Section snippets

Research method

This study is organized in two phases. Firstly, primary field measurements of outdoor spaces were completed. Since the study focused on both sunny and cloudy sky conditions, the analysis was conducted during May, which has highly variable cloudy sky conditions (Malaysian Meteorological Department, MMD, 2018). Secondly, parametric simulations using ENVI-met and IES were performed to further investigate the thermal interactions among different outdoor settings.

Results and analysis

The study examined the values and variations of several microclimatic parameters. Due to the highly variable sky conditions, ranging from sunny to partially and mostly cloudy, the changes of these parameters over the time were noticeable. In all six cases, air temperature continuously increased from 11:00 to 14:00, however, for three of the cases (study areas 2, 3 and 5) air temperature drastically decreased after this period due to cloudy and rainy conditions. Meanwhile, rapid and continuous

Discussion and conclusions

It has been highlighted that the increased ambient air temperature in urbanized areas, particularly in the tropical climates, can result in enormous negative impacts on the social and environmental dimensions of cities (Aflaki et al., 2017). Nevertheless, there have been very limited studies in tropical contexts focusing on outdoor thermal comfort using heat mitigation strategies. Among these limited studies, the most effective cooling approaches include the utilization of materials with high

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Analyzing the thermal comfort conditions of outdoor spaces in a university campus in Kuala Lumpur, Malaysia

Highlights

Abstract

Graphical abstract

Introduction

Section snippets

Research method

Results and analysis

Discussion and conclusions

Cities

Energy Build.

Front. Archit. Res.

Energy Convers. Manag.

Energy Build.

Sol. Energy

Build. Environ.

Landsc. Urban Plan.

Sustain. Cities Soc.

Sustain. Cities Soc.

Build. Environ.

Renew. Sust. Energ. Rev.

Urban Clim.

Sustain. Cities Soc.

Build. Environ.

Sustain. Cities Soc.

Urban For. Urban Green.

Build. Environ.

Sustain. Cities Soc.

Sustain. Cities Soc.

Build. Environ.

Environ. Model. Softw.