A comparison of diurnal variation of pavement albedo between vertical and horizontal surfaces under tropical climatic condition of Thailand

Abstract Albedo is an important indicator of radiation reflectance of pavement surfaces for the building envelope and on the ground level, and their resultant impacts on human comfort and the urban environment in outdoor spaces. Usually, albedo is generally accepted only for horizontal surfaces. This study developed an experimental test set-up for the albedo measurement system with pyranometers and automatic meteorological data acquisition system, which used it to conduct field measurements of albedo on horizontal and vertical surfaces of the used concrete block. The results show that albedo measured on a horizontal surface is not proportional to irradiance on a vertical surface. The albedo value between the two surfaces depend upon time of day, and the horizontal surface also received significantly more incident solar radiation than the vertical surface during all but the central hours of the day, while at reflected solar radiation on vertical irradiances were less than the horizontal. These results can help reduce the uncertainty in understanding and evaluating the thermal behaviour of the building and environmental impacts of pavement surfaces with different albedos in the outdoor urban space.</jats:p

Sidewalk thermal comfort in street canyon and role of pavements under perpendicular sun rays during summer

BACKGROUND AND OBJECTIVES: The reflection of solar radiation by pavements is crucial for managing urban heat, enhancing thermal comfort, and supporting sustainable development. Albedo pavements are a key component of modern urban planning. Despite extensive studies on the influence of pavement reflectivity on heat stress in street canyons, there is still a lack of exploration regarding its impact on pedestrian comfort in Thailand during the peak summer months. This study examines thirteen design scenarios and simulations utilizing a microclimate model, with a specific focus on the combined albedos of road surfaces, sidewalks, and plants in a deep street canyon within a residential townhouse project located in Bangkok.METHODS: The utilization of a microclimate simulation model enabled the calculation of climatic conditions within an east-west-oriented street canyon on April 26, which represents a typical summer day in Thailand. By utilizing the simulated microclimatic parameters, hourly physiologically equivalent temperature values were derived to assess human thermal comfort. This analysis helped identify the threshold for comfortable summer conditions in Thailand. Field data validation showed acceptable errors (R² = 0.91, normalized mean square error = 0.17).FINDINGS: For an east-west-oriented deep street canyon with direct overhead sunlight in summer, low-albedo materials for road and sidewalk surfaces are recommended to enhance thermal comfort. The implementation of these albedo strategies has the potential to enhance thermal comfort by 0.34-0.38 percent and alter the threshold values of the Physiologically Equivalent Temperature Index for thermal sensation, transitioning from hot to cold environments. While the percentage increase may seem small, it signifies a substantial advancement in improving thermal comfort for people in urban settings. This finding carries significant importance in densely populated areas with limited natural shade, where even slight improvements in thermal comfort can have a positive effect on public health and well-being.CONCLUSION: Albedo reduction alone may not significantly enhance outdoor comfort within the street canyons. Urban planners and designers should consider integrating additional strategies such as tree planting, Sidewalks facing different directions, exposed to sunlight, instead of pedestrian arcades and overhead shading structures. The thermal environments and comfort of sunlit north-facing sidewalks in an east-west-oriented deep street canyon during the summer, when the sun's path shifts northward, are greatly influenced by the solar tilt and azimuth angles. It is crucial to highlight the substantial impact of these angles

Effect of Street Canyon Configurations and Orientations on Urban Wind Velocity in Bangkok Suburb Areas

Abstract Urban ventilation is considered as one parameter, which impacts on building energy consumption and outdoor living condition. This study primarily investigates the effect of street canyon characteristics as well as its orientations on wind pattern and velocity in street canyon via using urban microclimate simulation model, ENVI-met. The wind simulations are performed with four aspect ratios or height-to-width ratio (H/W), three canyon lengths, and four canyon orientations. Calculated wind velocity measured at 1.5 m height of the centre of the street and pedestrian on both sides of the street ranges from 0.2 to 0.97 m/s. N-S and NW-SE canyons, which oriented parallel to the prevailing wind has greater wind velocity than those oriented perpendicular to the wind. The wind velocity is sensitive to aspect ratio and canyon length. The wind velocity in shallow canyon is mostly higher than those in the deep canyon. However, increasing the canyon length considerably improves the low wind speed in the deep canyon up to twice.</jats:p

Sensitivity Analysis of Designs of Row House Planning Influencing on Local Microclimate and Building’s Cooling Energy Consumption in A Tropical City

Abstract This study aims to investigate the impact of design characteristics of row house projects on outdoor thermal conditions and the building’s cooling energy consumption. The studied parameters comprise the design combinations of four street canyon orientations, building-two block shapes, four street canyon’s aspect ratios (H/W), and two window to wall ratios (WWR). The study firstly performs the simulations of air temperature and mean radiant temperature across the street canyons via using ENVI-met modeling. The simulated air temperature is used as input in energy modeling to calculate cooling energy consumption in a residential unit. The Standardized Regression Coefficient (SRC) obtained from the multiple regression analysis is used to determine the significant design parameters influencing on outdoor air temperature, mean radiant temperatures, and building’s cooling energy consumption. It is found that the increase of H/W has a positive effect on both outdoor conditions and building energy consumption. At the same time, the impact of street canyon’s orientation and building-block shape on those issues shows an invert direction. Future studies should investigate how to optimize the design for achieving better outdoor thermal conditions and building energy efficiency.</jats:p

Analysis in Integrated Design Potentials Achieving Nearly Zero Energy in Office Buildings in Bangkok Neighborhood

Abstract This study aims to investigate the energy-saving potentials and design approaches to move the small and medium office buildings in Bangkok neighborhood areas to become the Net-Zero Energy Building (NZEB). The envelope designs, such as increasing the material’s thermal resistance, adding shading devices, and using high energy-efficient systems, together with the electricity production from the photovoltaic cell, are applied in the studied buildings. According to the energy simulation results, with the implementation of current design techniques, the annual energy consumption of office buildings cannot reach the NZEB. However, these design approaches can enforce the maximum building’s energy-saving capability at 88 kWh/m2 that is nearly the Economic Building (ECON). The maximum energy reduction occurs when improving the high thermal performance of the building’s envelope and using high energy-efficient systems. To achieve this challenging target. Future studies should account for more energy-efficient systems as well as the building’s operation schedule.</jats:p

A Readiness of Areas and Space Planning in Houses Supporting Emergency Services for Fall Injuries in The Elderly

Abstract The global population structure is currently stepping into an aging society. In the change of the world population structure, critical care of older adults from fall injuries at home is a major public health issue since the falls can lead to disability or death. By reviewing the architectural design research, most studies focus on the design approaches aiming to reduce the risk of fall accidents occurred among the elderly. However, no study has investigated the correlation of architectural design in supporting the medical care of seniors after slip and fall accidents. Therefore, this research aims to evaluate area and space planning of typical three single houses supporting emergency medical care for falling accidents amongst the elderly. The study firstly investigates the activities and the area required for the medical operation by interviewing medical specialists and rescue teams from two hospitals and two related agencies. Then, the activities and area requirements are mapped with the room layout of three typical single houses located in the Bangkok neighborhood areas. It is found that the designed layout and room area of all studied houses inadequately supports for emergency situations, which has only two available areas from a total of thirteen areas. The details of the space availability and obstacles for emergency medical care are discussed and proposed for improving the space planning and layout of the house for future work.</jats:p