Outdoor Thermal Comfort Levels Research Articles

Energy efficiencies model for thermal comfort in urban applications

Improving people's standard of living has increased their requirements for the environment. Increasing air temperature in urban areas due to urban heat islands (UHI) has been a global concern since industrialization. Apart from suitable facilities and landscapes, a comfortable outdoor thermal environment can improve the efficiency of urban space use. Ensuring outdoor comfort is an integral part of the design agenda where the UHI phenomenon plays a significant role. A study has been conducted on a residential building campus to analyze the effect of these heat island countermeasures (individual and combined) with the help of the simulation tool Grasshopper. A 3D reference model of a small residential campus is developed. The outdoor thermal comfort level is studied for this case, and Universal Thermal Climate Index (UTCI) is evaluated. Further, several UHI mitigation strategies such as wall and roof reflectivity, vegetation, plantation, pavement configuration, and shading are applied to find their effect on the micro-climate and outdoor thermal comfort. Based on the simulation outcomes, urban geometry is identified as the most influential design factor in decreasing the urban heat island effect and outdoor thermal comfort. The study's principal objective is to develop a simulation framework including all mitigation strategies and find the best case for UHI reduction.

Fundamental LCZ Mapping with ArcGIS-Based Spatial and Correlational Analyses to Study the Impacts of Infrastructural Area- Maximum Volume (A-MV) Attributes on OTC – An Urban Aw Summer Case

The aim of this study is to map the study location stretches into 100mx100m local climate zones (LCZs) on the basis of primary observations and secondary photographic data for spatial analysis of various urban infrastructural elements (grey(G)-built structures, blue(B)-water bodies and green (Gr)-natural vegetation) and impact assessment of their estimated area (EA) and maximum volume (EMV)) on the air temperature (Ta) that characterizes the outdoor thermal comfort (OTC). Climate Modification by Urban Infrastructure, Fundamental Concepts of Urban Infrastructure Mensuration Parameters, Fundamental Concepts of Urban Grey Blue Green Infrastructure (UGBGI) and Concepts Of OTC, Koppen Classification and LCZs are the linked areas. Study locations are based on socio-economic and geophysical attributes. Initial 200 pilot survey responses regarding thermal sensation votes and other subjective details were used. Preferred values of Physiological Equivalent Temperature (PET) and optimum Ta have been used. After the mapping in ArcGIS and polygonal delineation of the areas, EA values were compiled in tabular format. Based on primary measurements and secondary studies, a maximum height (hmax) value was assigned to each sub-category for EMV evaluation. Statistically, the EA and estimated perimeter (EP) values were analyzed using QQ, scatter plots, histogram and generate near table tools in ArcGIS. EA and EMV values were correlated with mean Ta values by linear regression. The R-square values generated gave a clear idea about the extent of their impacts on Ta. From the established relationships and preferred PET and optimum Ta values, optimum EA, EMV and hmax values of the broader categories(G,B,Gr) required for preferred OTC levels were finally evaluated.

Effect of Street Asymmetry, Albedo, and Shading on Pedestrian Outdoor Thermal Comfort in Hot Desert Climates

Improving urban walkability in the face of climate change is a critical challenge for urban designers. Street design strategies can mitigate heat stress and enhance pedestrian livability. Most previous studies conducted in hot climates recommend adopting deep canyons to improve summer conditions, overlooking the potential improvement of wide streets as essential structural elements of the urban fabric. This study was conducted in Biskra city, southern Algeria, where several mitigation strategies were applied to ‘Emir Abdelkader Boulevard’, as the main structural street inside the city, to create an optimal street model for arid climates. Five scenarios were developed based on three criteria: (Sc1) asymmetric profile northeast side (NES) > southwest side (SWS); (Sc2) asymmetric profile SWS > NES; (Sc3) cool paving; (Sc4) horizontal shading; and(Sc5) shading with a linear tree arrangement. ENVI-met software version 5.1.1 and the RayMan model were used to estimate the local climate conditions and outdoor thermal comfort levels based on the physiological equivalent temperature (PET). All scenarios reduced PET values across the street, with optimal reductions of −2.0 °C, −3.1 °C, −1.3 °C, −1.7 °C, and −1.2 °C in Sc1, Sc2, Sc3, Sc4, and Sc5, respectively. Concerning pedestrian areas, the optimal results durations were at the southwest side below the arcades’ sidewalks during peak hours: Sc2, Sc3, Sc4, Sc5 (2.2 °C–3 H, 2.3 °C–3 H, 2.4 °C–3 H, 2.5 °C–2 H). Sc1 performed best during daytime hours on the northeast side. The utilizing of these results can strongly help urban planners and landscape architects in creating climate-responsive streets that enhance citizens’ quality of life.

Holistic Approach to Ecological Design Parameters of Building and Landscape Design on Outdoor Thermal Comfort in Hot, Humid Climate

In this study, academic staff residential buildings were studied as part of a university campus located in a hot and humid climate zone in Türkiye. Within the scope of the study, the energy efficient architectural and landscape design decisions of the buildings built in 1976 were examined. The aim was to determine the energy performance of buildings built about 50 years ago and to quantify the effect of changing landscape conditions on thermal comfort. In this aim, the outdoor thermal comfort level was determined by creating microclimate simulations for the hottest day and time of the year. Microclimatic analyses were performed with ENVI-met software and thermal comfort was evaluated with two metrics, average PMV and ASHRAE scale. The energy performance of the buildings was determined using ecological design parameters. An approach to global environmental problems is the use of ecological design principles, including architectural and landscape design principles. It is important to consider both architectural design criteria and landscape design criteria when discussing ecological design in the built environment. Architectural and landscape design decisions for hot and humid climate regions together increased energy efficiency by 51.1% to 75.5%. It was found that although the plant design improves energy performance in buildings by that range value, it improved outdoor thermal comfort by 15% to 22%. As a result, the study evaluated climate-balanced plant design with building energy performance in order to improve outdoor thermal comfort.

Urban green and blue infrastructure effect on the micro-scale thermal environment in a residential neighborhood: Mueller, Austin, TX

ABSTRACT This study examined the role and importance of various green and blue infrastructure elements in improving the deteriorating urban thermal environment from a post-occupancy evaluation perspective of residential neighborhood development. The results showed that the influential variables in this study were the tree canopy coverage ratio (TCR), tree species, yard area, and distance to a waterbody. In addition, a house with a large yard area increases the amount of direct exposure to solar radiation, so the comfort of the outdoor thermal environment was low. Furthermore, the distance to a waterbody parameter did not have a positive impact on the outdoor thermal comfort level because the dominant wind direction within the study area during the day was opposite to the blue infrastructure. Lastly, geographically weighted regression (GWR) analysis was adopted to identify an improvement to compensate for the relatively low explanatory nature of the ordinary least squares (OLS) models due to spatial correlation.

ADOPTING A SUSTAINABLE URBAN DESIGN TO IMPROVE THERMAL COMFORT IN AN ARID CLIMATE

Greenery strategies and shaded pedestrian passages have become requirements for designing smart cities in developed countries. One of the most difficult challenges for designers is designing cities in hot and arid climates while maintaining a proper level of outdoor thermal comfort. The designers focus on creating a comfortable climate for people throughout the afternoon under the hot sun, particularly in countries where summer temperatures rise excessively for more than seven months per year, as in Iraq. This study compares two Baghdad cities: Haifa Street, which was built in 1984 on a Western design pattern, and the second city, which the researchers designed according to the requirements of construction in an arid climate, such as street and building orientation, aspect ratio, sky view factor, the influence of courtyards, and the role of albedo. The second city is planned to cover the same total area as the first. The results of the two cities were compared and analyzed using ENVI-met software. To conduct a comparison between the two cities on a typical summer day, two indices, PMV and Tmrt, were used. The results showed that the proposed new city design reduced Tmrt and PMV, contributing to improved thermal comfort. The proposed design reduced the Tmrt value in the model by 10.5°C in proportions of 90% of the total urban area. Furthermore, the suggested design offers superior thermal values on a typical summer day than Haifa Street.

Research of practical heat mitigation strategies in a residential district of Beijing, North China

The purpose of this study is to investigate different heat mitigation strategies and determine the optimal choice for old neighborhoods renovation. A residential building with the parking lot in front of it was selected as the research object. Various critical factors affecting outdoor thermal condition, such as tree location, pavement material, wind speed and direction, “hedge” type, were simulated and examined with ENVI-met and Rayman model. Air temperature, mean radiant temperature (MRT), physiological equivalent temperature (PET) were used to assess the outdoor thermal comfort level. The results show that: 1) concrete replacing asphalt as pavement material could effectively lower air temperature; 2) planting trees on the west or south side is a better choice in creating a more thermally comfortable outdoor environment when available space is limited in the targeted area; 3) compared with wind direction, wind speed has a more significant influence on outdoor thermal condition; 4) water body's cooling efficiency is superior to that of grassland. The findings of this study could provide useful guidance in the process of renovating old neighborhood in the city.

Urban outdoor thermal environment and adaptive thermal comfort during the summer.

The outdoor thermal environment is an important factor when measuring the livability of a city. Residents will avoid intense heat by reducing their outdoor activities, which decreases the vitality of a city and increases the energy consumed for air conditioning. Outdoor thermal comfort has a great impact on outdoor activities; therefore, we need to evaluate and design the urban outdoor thermal environments in cold regions to improve the outdoor thermal comfort level. In this study, we conducted a questionnaire survey to assess the outdoor thermal comfort and adaptive thermal comfort in four different urban forms in Xi'an during July 2019, and measuring meteorological parameters, such as the temperature, relative humidity, wind speed, and black bulb temperature. The results are showed as follows. (1) In the cold study area, urban residents generally perceived the outdoor climate as relatively hot during the summer. (2) The participants exhibited psychological and physical adaptations in terms of their thermal comfort. In particular, when the PET was 30°C, the MTCV was about 1.25 points higher in the later summer period than the early summer period. (3) The neutral PET differs among regions, and it is affected by the climate zone and latitude. Comparisons of our results with thermal comfort studies in different regions such as Singapore and Umeå in north Sweden showed that the thermal comfort is correlated with the regional climate and latitude. The neutral PET is higher in tropical regions. Our findings support the theoretical understanding of adaptive thermal comfort in cold regions and they provide a reference for formulating policies related to adaptive thermal comfort.

The Impact of Vegetation Arrangement on Outdoor Thermal Comfort: A Simulation Study in a Tropical Urban Public Square

Thermally comfortable urban squares attract people and provide various social benefits to the urbanites. Compared to urban parks, squares are more vulnerable to thermal discomfort due to surrounding buildings and the high percentage of hard surface coverage, especially in tropical climates. The spatial arrangement of green infrastructures can improve Outdoor Thermal Comfort (OTC) by reducing hot air flows, evapotranspiration, and shading to reduce the negative effect of warming urban environments. However, it is not yet adequately discovered the specific correlation of different vegetation arrangements on OTC. Still, urban policymakers are looking for new, quantitative methods to assess the performance of their designs in terms of the cooling effects provided by vegetation. Therefore, the current study investigates the effect of different vegetation arrangements on OTC in a tropical urban public square (Independence Arcade in Colombo) using micrometeorological fluid dynamics (CFD) modeling validated by field measurements. Air temperature (Ta), relative humidity (RH), wind speed (WS), and wind direction (WD) were measured at 1.5 m above ground level as the inputs for the ENVI-met simulation model to assess the cooling performance of proposed scenarios employing Physiological equivalent temperature (PET). Nine scenarios were developed using trees with high leaf area density (LAD) and spherical canopy form to compare OTC improvements of cluster, random and individual planting patterns, and the size of trees (large, medium, small). The results showed that vegetation improves the OTC levels irrespective of the planting pattern. However, linear individual planting pattern with large trees performed the best cooling performance, and scenarios were ranked according to improved PET values. Vegetation parameters are recommended to arrange in different ways to achieve OTC and aesthetics. The study was limited to the existing vegetation database of the ENVI-met software package, but further research could consider the context-specific tree species and the impact of combined landscape scenarios using grass, shrub coverage, and water bodies to find proper arrangements to improve the microclimate and OTC. This study guides urban planners and landscape architects to assess the cooling performance of the proposed designs and arrange urban vegetation to create thermally comfortable urban outdoors in the tropics. 
 Keywords: Vegetation arrangement, Urban square, Outdoor thermal comfort, ENVI-met, PET
 Acknowledgement: Authors acknowledge the assistance of the Accelerating Higher Education Expansion and Development (AHEAD)-DOR Grant, funded by the World Bank

Urban Climate Risk Mitigation via Optimal Spatial Resource Allocation

Decision makers (DMs) who are involved in urban planning are often required to allocate finite resources (say, money) to improve outdoor thermal comfort (OTC) levels in a region (e.g., city, canton, country). In this paper, for the first time, we address the following two questions, which are directly related to this requirement: (1) How can the statistical properties of the spatial risk profile of an urban area from an OTC perspective be quantified, no matter which OTC index the DM chooses to use? (2) Given the risk profile, how much and where should the DM allocate the finite resources to improve the OTC levels? We answer these fundamental questions by developing a new and rigorous mathematical framework as well as a new class of models for spatial risk models. Our approach is based on methods from machine learning: first, a surrogate model of the OTC index that provides both accuracy and mathematical tractability is developed via regression analysis. Next, we incorporate the imperfect climate model and derive the statistical properties of the OTC index. We present the concept of spatio-temporal aggregate risk (STAR) measures and derive their statistical properties. Finally, building on our derivations, we develop a new algorithm for spatial resource allocation, which is useful for DMs and is based on modern portfolio theory. We implemented the tool and used it to illustrate its operation on a practical case of the large-scale area of Singapore using a WRF climate model.

Vegetation Cover Effects on Outdoor Thermal Comfort Around High-rise Developments; A Case Study of Havelock City, Colombo, Sri Lanka

Colombo, with its rapid development, is experiencing an influx of high-rise developments. These developments create a significant influence on the microclimate of the area around them, and therefore impact outdoor thermal comfort. With the intension of mitigating outdoor thermal comfort concerns, the enhancement of the vegetation cover is an often-proposed strategy. This is a research initiative to ascertain the optimum vegetation cover percentage to achieve outdoor thermal comfort around high-rise developments, utilising Havelock City, Colombo, Sri Lanka as a case study. A computer simulation process is adopted, using the software ENVI-met, to explore the optimum form and coverage of vegetation for outdoor thermal comfort. Results show, overall thermal comfort levels diminish, with the increased infusion of vegetation. Vegetation cover had a little or no impact in the daytime, while the strategy had distinct negative impacts in the night-time. The nature of the built morphology of the development together with the vegetation cover increase is shown to have significant impact on wind movement and nocturnal heat loss, therefore outdoor thermal comfort levels. Conclusions highlight the need for the extensive exploration of morphological studies, while encompassing key amelioration strategies, particularly for the high-rise development typology.

Analysis of winter thermal comfort conditions: street scenarios using ENVI-met model.

Rapid migration to cities and the increasing demand for housing negatively affect living areas. Furthermore, uncontrolled population growth, industrialization, urbanization, narrowing of urban areas, and expansion of cities cause physical boundaries. Urbanization growth and the cold climate restrict pedestrian mobility in the city. Therefore, hourly microclimate data of the city center streets were collected 1.5m above ground level in the winter period of 2019-2020. Then, different landscape design scenarios on pedestrian roads were investigated extensively using the ENVI-met V.4.4.2 winter model to determine the outdoor thermal comfort level. The RayMan model was utilized to generate the sky view factor (SVF) and analyze the mean values of the microclimate data. The proposed landscape design scenarios were as follows; (1) hard-covered street, (2) complete street coverage with a canopy, (3) street coverage with a semi-canopy, (4) sage of a combination of different plant species (30% deciduous, 30% coniferous, 30% bush), and (5) usage of ornamental pools in streets. The time period when pedestrians used the outdoor space was taken into consideration in evaluating and interpreting the analysis results. The findings of this study generally indicated that the semi-open canopy design provided roads with high thermal comfort such that people can walk and cycle in winter time. In conclusion, the thermal comfort condition of a street design, which is important for achieving sustainable urbanization, can be changed by making appropriate plan decisions. The findings of this study will help improve the outdoor thermal comfort in the first stage of urban planning and landscape street design for more livable and effective cities. This study emphasizes that a multidisciplinary team should work together to establish a healthy, sustainable, and livable urbanized area with thermal comfort in the streets.

Modelling the influence of high-rise urban geometry on outdoor thermal comfort in Singapore

Tropical cities are exposed to high air temperature and relative humidity throughout the year, causing pedestrian thermal discomfort. In this work, we present an evaluation of the impact of urban geometry on the outdoor thermal comfort (OTC) in Singapore, focusing on a new mixed-use high-rise development. Different urban design strategies/scenarios have been analyzed: two block forms, four street orientations (N-S, E-W, NE-SW, NW-SE), four street aspect ratios (from 1.5 to 3.5) and three building height profiles (arrangement of buildings based on height).The study is based on modelling techniques. Each scenario was analyzed for seven representative weather conditions during the year. The results are analyzed with specific metrics that take into account the spatial and temporal OTC variations. The results are conditioned by prevailing low winds and high frequency of cloudy days. The best OTC levels are observed on high street aspect ratios (2.5–3) and on N-S oriented streets. Although, on a yearly perspective the streets oriented NE-SW show the worst OTC performance, deviation from the acceptable range is not high. Higher differences between street orientations are encountered for specific weather types. The outcomes provide adequate urban parameters for high-rise developments to improve OTC in hot and humid tropical regions.

Field study of pedestrians' comfort temperatures under outdoor and semi-outdoor conditions in Malaysian university campuses.

Difficulties in controlling the effects of outdoor thermal environment on the human body are attracting considerable research attention. This study investigated the outdoor thermal comfort of urban pedestrians by assessing their perceptions of the tropical, micrometeorological, and physical conditions via a questionnaire survey. Evaluation of the outdoor thermal comfort involved pedestrians performing various physical activities (sitting, walking, and standing) in outdoor and semi-outdoor spaces where the data collection of air temperature, globe temperature, relative humidity, wind speed, solar radiation, metabolic activity, and clothing insulation data was done simultaneously. A total of 1011 participants were interviewed, and the micrometeorological data were recorded under outdoor and semi-outdoor conditions at two Malaysian university campuses. The neutral temperatures obtained which were 28.1°C and 30.8°C were within the biothermal acceptable ranges of 24-34°C and 26-33°C of the PET thermal sensation ranges for the outdoor and semi-outdoor conditions, respectively. Additionally, the participants' thermal sensation and preference votes were highly correlated with the PET and strongly related to air and mean radiant temperatures. The findings demonstrated the influence of individuals' thermal adaptation on the outdoor thermal comfort levels. This knowledge could be useful in the planning and designing of outdoor environments in hot and humid regions to create better thermal environments.

Optimization of Building Configuration in Vertical Residential Housing towards Outdoor Thermal Comfort: Case Study of Tambora Flats, Jakarta, Indonesia

Population growth in Indonesia is not offset by the construction of urban facilities and infrastructure and the improvement of urban services. In densely populated urban areas with narrow residential conditions, the demand for shelter is higher, causing an increase in the price of land and housing. One of the efforts in responding to this problem in the Special Capital Region of Jakarta is to build vertical residential or flats. This study aimed to determine the level of outdoor thermal comfort of Tambora flats in Jakarta, which have air temperatures ranging 26–29°C and air humidity of 76–92%. Existing flats were simulated with the Envi-MET 3.1 software, with the first stage being to determine the height of the building and material of the building, the street, and then assessing the existing outdoor thermal comfort level by inputting climatic data. Overall, the thermal comfort index values of both existing and planned model building configurations of Tambora flats and its surrounding area were at the standard level for a humid climate. Of our models, model B had the best potential to provide thermal comfort to humans in the area of the flats. In order to implement the proposed model building configuration with optimal outdoor thermal comfort in real buildings, future research should focus on a wider range of aspects, including diversity and density of buildings, and neighborhood type.

Urban heat resilience at the time of global warming: evaluating the impact of the urban parks on outdoor thermal comfort

BackgroundIn densely populated urban centers, increased air temperature due to urban heat island (UHI) effect can undermine the thermal comfort and health of citizens. Research has shown that large urban parks can mitigate the effect of UHIs and improve thermal comfort, especially in the warmer months of the year when temperature changes are more noticeable. This study investigated the cooling effect intensity (CEI) of the Retiro Park in the center of Madrid at three different distances from its southern edge and the impact of this cooling effect on thermal comfort from physiological and psychological perspectives. This investigation was performed by measuring microclimate data and conducting a survey simultaneously during the summer days.ResultsThe results showed that the CEI of the park varies with distance from its edge. Because of this effect, air temperature within the 130 m and 280 m distance of the park was, respectively, 1.6 °C and 0.9 °C lower than the temperature at the 520 m distance (the nearest heat island). After examining the effect of the park in terms of physiological equivalent temperature (PET), it was found that the PET at the 130 m and 280 m distance of the park was 9.3% and 5.4% less than the PET in the heat island domain. More than 81% of the respondents (in all three areas) had a mental image of the park as the place where they would experience the highest level of outdoor thermal comfort, and this rate was higher in the areas closer to the park. The analysis of citizens’ responses about perceived thermal comfort (PTC) showed that citizens in areas with higher CEI had perceived a higher degree of thermal comfort from the psychological perspective.ConclusionThis study demonstrates the significant role of large urban parks located in the core of the populated cities in providing thermal comfort for citizens from both physiological and psychological perspectives. Additionally, the results of this study demonstrated that among the environmental (natural and artificial) factors around the park (topography, urban structure, etc.), the aspect ratio has the greatest impact on thermal comfort.

Quantitative effects of urban spatial characteristics on outdoor thermal comfort based on the LCZ scheme

Based on the local climate zone (LCZ) scheme, nine typical urban areas in Shenzhen, China were chosen to conduct a field survey to quantitatively analyze the outdoor thermal comfort levels under different urban spatial characteristics. Four integrated indicators, F1, F2, F3, and F4, were defined based on the Fuzzy-AHP method by considering four different considerations for expressing nine different LCZs. Through physical meteorological measurements and simultaneous human responses on local environments, thermal “neutral” value ranges of three thermal comfort indicators (TCI) were obtained, varying from 27 °C to 29.5 °C in PET, from 21 °C to 24 °C in OUT-SET*, and from 28 °C to 29.5 °C in UTCI. Quantitative equations between Fi and TCI were expressed by applying Linear, Logarithmic and Cubic models to the calculated Fi and TCI values in the nine LCZs. Sampling experiments were conducted to generate near-random sampling Fi parameters from a four-dimensional distribution. By referring to thermal “neutral” TCI ranges, six optimal Fi combinations were determined and results show that the LCZ 1 B appears a preferable LCZ class for optimizing local-scale thermal comfort conditions in the high-temperature environments in subtropical regions of China. Additionally, the optimal Fi combinations provide quantitative theoretical guidance in sustainable urban design and planning.

The impact of height/width ratio on the microclimate and thermal comfort levels of urban courtyards

AbstractThe outdoor thermal comfort level of urban spaces is an important contributor to pedestrians’ health. The urban microclimate is also important due to its influence on the energy use of buildings. These issues are likely to become more acute as increased urbanisation and climate change increase the urban heat island effect. However, urban planning must be able to provide urban forms that produce various microclimates that result in different comfort situations for pedestrians. This study aims to define various configurations of urban open spaces by analysing the influence of geometrical parameters on outdoor comfort levels. To achieve it, open spaces are simulated for typical hot and cold days in the semi-arid climate of Constantine, Algeria. The sun exposure is estimated using TownScope 3.1, and assorted models are evaluated according to the geometrical indicator of the height to width (H/W) aspect ratio. ENVI-met 3.1 is used to simulate such factors as the outdoor air temperature, mean radiant te...

Assessment of Outdoor Thermal Comfort and Wind Characteristics at Three Different Locations in Peninsular Malaysia

Urbanization and rapid growth in construction have led to the problems of global warming and urban heat island throughout the world. In order to reduce these problems particularly in hot and humid climatic region, a research on current level of outdoor thermal comfort and wind characteristics based on the local weather conditions around Malaysia should be conducted. This paper reports on the analysis of outdoor thermal comfort level at hottest temperatures and wind characteristics at three locations in Peninsular Malaysia by using hourly climatic data recorded by Malaysian Meteorological Department (MetMalaysia). The level of outdoor thermal comfort was assessed based on the Universal Thermal Climate Index (UTCI). The results showed extreme heat stress conditions have occurred at Alor Setar, Kuantan, and Subang with UTCI values of 51.2°C, 49.7°C, and 49.0°C respectively taking into account only temperature data from the year 2012 to 2014. However, for 20 years data from 1994 to 2014, the calculated UTCI also showed extreme heat stress conditions with their respective values of 49.6°C, 43.8°C, and 49.7°C for Alor Setar, Kuantan, and Subang respectively. Meanwhile, the hourly mean wind speed for three years data at Alor Setar, Kuantan, and Subang, were 1.70m/s, 1.69m/s, and 1.63m/s respectively. The highest mean wind speed of 11.6m/s was observed at Subang, while no wind movement (i.e. 0m/s) was considered to be the lowest hourly wind speed for all three locations. The observed prevailing wind direction for all the three locations was from the north (0°). It can be concluded that Peninsular Malaysia is generally facing extreme heat stress problem due to unfavourable climatic conditions.

Green living roof implementation and influences of the soil layer on its properties

Affected by undeniable climatic change, the temperature of the urban areas rises continually, increasing rapidly the energy problem of cities and amplifying the pollution problems. The thermal stress is increased, thus both the indoor and the outdoor thermal comfort levels are decreased, enhancing the health problems. Green roof implementation in the building envelope is strategy that provides heat island amelioration, thermal comfort for occupants and reduces energy consumption of buildings. Green living roofs are a passive cooling technique, which can stop the incoming solar radiation from reaching the building structure below. In this paper, we assessed the importance of the green roofs in providing environmental and building energy benefits, and brief investigation on the different configuration of the soil layer in the green roof assembly influences to the temperature of the roof surface was presented. Investigation was conducted for first phase of the living roof growth. Four cells were designed in SolidWorks software where the transient thermal study was performed in order to determine differences between the behavior of the conventional roof and three green roof types.