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Mitigation techniques aiming to counterbalance the Urban Heat Island (UHI) phenomenon deal with the intensive usage of green spaces, application of highly reflective materials, materials having high thermal resistivity, decrease of the anthropogenic heat, solar control of open spaces, use of environmental heat sinks and increase of the wind flow in the canopy layer. Though materials having high thermal resistivity do not directly mitigate the UHI effect however upon using them as constructional materials, the buildings become naturally cool which reduces the anthropogenic (waste) heat from the buildings thereby mitigating the UHI effect. In addition to this, the reduction in the power demand would eventually lead to the reduction in the burning of coal in the thermal power plants and consequently reduces the release of CO2 (a green house gas). Moreover, if naturally grown materials (like bamboo in the present case) are used for construction applications, it would pave way for ‘profitable greening’ which would significantly reduce the UHI effect in two ways (1) by increasing the latent heat flux through evotranspiration (2) by sequestering CO2. The embodied energy of local materials having high thermal resistivity like Rammed Earth is significantly less than that of the popularly used Cement and Bricks which makes it a greener option having relatively low carbon footprint. Cumulating these facts it can be stated that usage of ‘natural materials’ having adequate strength and high thermal resistance offers high potential for mitigating the UHI effect. With this background, the present study of investigating the thermal performance (in terms of energy consumption for space cooling) of composite materials like Bamcrete (bamboo-concrete composite) and natural materials like Rammed Earth along with energy intensive materials like bricks and cement was undertaken. In addition to this, the thermal performance of building envelope modifications like (i) increasing the thickness of wall, (ii) construction of a cavity wall was also attempted. Of the 6 scenarios simulated, the use of 6″ bamcrete in walls depicts the highest cooling potential (around 7.5%) when compared to the popularly used 5″ brick thick wall. The present study is first of its kind to quantitatively report the performance of ‘bamboo’–a wonder grass of India, in reducing the cooling load of a building. The results should definitely help the green building community to take suitable actions at their ends for designing buildings having low carbon footprint and effectively mitigate the UHI effect.
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... In another study, the researchers attempted to investigate the thermal comfort conditions inside a house with HW material (high thermal inertia) walls, and reported that the HW enhances thermal comfort . The UHI mitigation effort by reducing energy consumption is studied for different wall materials/modifications to determine the façade type impact on the building and the external environment . According to the results, up to 7.5% reduction in cooling load can be achieved with bamboo-concrete wall. ...
... The summary of the studies given in Table 1 are also presented in Figure 1 by outlining the impact of the materials on the outdoor and indoor environments.  • High thermal inertia provides thermal comfort  • HW reduce energy for air conditioning  • HW stabilizes indoor air temperature  Thermal Mass Impact • Increase in outdoor air temperature with HW in the afternoon  • HW can increase UHI phenomenon  • Façade type has significant impact on UHI  • Local climatic conditions are critical on heat transfer through wall   ...
... Adding a cavity on a brick wall offers the highest reduction in the power consumption for space cooling .  • ACP provides lower surface temperatures  • Palm particle coating on the surface results temperature difference of nearly 4.5 °C  • Texture geometry of façade surface is important  • External insulation is better than internal by 8%  • Internal insulation costs 50% less  • 64% reduction in energy demand during summer  • Polyurethane gives highest advantage  Additional Metal Sheet -Alter the Impact • UHI mitigation is provided with green wall  • Plants on façade (green wall) effectively reduce outdoor air temperature and wall heat gain [ • The sandwich wall provides a better indoor environment with cooler indoor air temperature and lowers energy consumption for the air conditioning system . ...
This study experimentally investigates the effect of different façades systems on thermal comfort and urban heat island (UHI) phenomenon by using experimental tools. Outdoor field measurements are conducted for brick, concrete, low-E glass, aluminium composite panel (ACP), and clear glass to observe the effect of morning solar exposure on the east-west façade surface temperatures. Two different types of insulation materials, namely newspaper and corn husk mat, are also manufactured and considered. Then, laboratory experiments are performed with 1 m × 1 m panel under two 1000 W halogen lamps by measuring air, surface and material temperatures using a thermocouples data-logger with a recording interval of 5 min and IR thermovision for visual confirming. The lamps simulate solar exposure during morning (8.00 a.m.–12.00 p.m.). It is noted that the brick wall stores heat during solar exposure, and then emits that heat to indoor and outdoor environments. Additional ACP to the brick wall reduces indoor air temperature significantly whereas direct impact on the outdoor temperature should also be accounted to avoid UHI. Besides, insulation material is found to be only beneficial during heating period in terms of reducing the indoor air temperature, however it slightly incremented the outdoor air temperature. This study shows how different façade systems of buildings significantly affect both the indoor and outdoor environments. It is revealed that, in the design process, the indoor air temperature should be considered for thermal comfort while the outdoor air temperature should be considered for UHI phenomenon.
... Besides, UHIs directly influence urban residents' health and welfare . It has critical and long-term consequences for public health like COPD and lung cancer (LC), Heat Stress, Vector-borne disease, strokes, Drowning, ischaemic heart disease (IHD), and mental health [20,21]. ...
... Thermal resistivity is another critical factor in building materials. Not directly affecting the UHI effect, the high thermal resistivity of constructional materials causes buildings to become naturally cool, reducing the anthropogenic (waste) heat from the buildings, thereby reducing CO2 emissions and mitigating the UHI effect . ...
... Many experimental research works focused on evolving cool materials, coating, and cool roofs, with high solar reflectance and high thermal emittance, reducing the cooling load, thereby mitigating the heat island effect [37,38]. Other researchers focused on quantifying the thermal performance (in terms of power consumption for space cooling) of wall materials by simulating their cooling loads . ...
Scholars and researchers worldwide are shifting the focus from the well-being in the internal spaces of buildings to the well-being in the external spaces, especially in large cities where pollution and heat island effect threaten the comfort and health of citizens. Calculation models aimed at studying comfort in outdoor spaces of cities are becoming more and more efficient and effective. However, all require large amounts of data that can only be collected automatically using the potential of the most innovative technologies available today. Among these, computer vision techniques are used in this study to extract some of the information needed to model the heat island phenomenon. This study introduces a convolutional neural network architecture to recognize the materials and colors of buildings' façade automatically. Despite some limitations, mainly due to the number of images used to train the algorithm, the results are promising and show how computer vision can be a valuable tool to obtain automatic information about the built environment.
... One of the causes of the increase in temperature of microclimates in an area is due to the physical development of urban areas. Urban areas characteristic are commonly indicated by the low percentage of green area, high density of buildings, and high transportation pollution of anthropogenic heat emission . The physical development of urban areas never separated from the use of building materials both heavyweight materials and lightweight materials. ...
... IOP Conf. Series: Earth and Environmental Science 532 (2020) 012021 IOP Publishing doi: 10.1088/1755-1315/532/1/012021 2 The building sector contributes to the largest energy consumption in the world. Almost 33 % of national energy consumed by the household sector in Indonesia and around 40% in the European Union . ...
The development of urban area such as a Transit Oriented Development (TOD) involves a lot of building materials that are forming the physical environment which rises problems of urban heat island (UHI) and energy consumption. The TOD forming urban corridors that rise urban canyon issues with high air temperature, poor air quality, high energy consumption for air cooling and purifying (HVAC). The common heavyweight building materials that dominate the physical environment of TOD and other urban areas have low specific heat and high heat capacity. Another thermal property of concrete and brick storing the heat energy influence the air temperature during the night. The lightweight modern building materials that are cheap in construction cost show the worse phenomenon in the UHI perspective due to its lower specific heat. This review paper discusses the role of building material in the urban thermal environment such as the TOD area in the energy and environment perspective. The early result shows that both heavyweight and lightweight modern building material have a bad performance for the environment and should be mitigated otherwise our future will become worse. The energy consumption that rises uncontrollably due to bad air quality and high temperature will decrease the liveability level of the urban area.
... In the area of numerical simulations, in 2018 Kandya & Mohan published an article evaluating UHI mitigation strategies through modifications of the building envelope using eQUEST software . A composite of bamboo and concrete (bamcrete) was analysed, which can be used for the construction of building walls in climatic conditions in India. ...
... A composite of bamboo and concrete (bamcrete) was analysed, which can be used for the construction of building walls in climatic conditions in India. The authors showed that the use of bamcrete is economical and has important energy-saving and cooling benefits . In addition, simulation of the urban environment (in certain parts of the city) was developed to identify the possibility of replacing currently used surfaces with cooler surfaces, to evaluate the potential transformation of the urban landscape for the mitigation of UHI . ...
The growth of the population in cities and the increase in the use of construction materials caused the cities' internal temperature to increase, producing the effect known as urban heat island. For this reason, there is scientific interest in mitigation methods of adaptation to this effect in the construction area.
The main objective of this research is to analyse the scientific articles published from 1990 to 2019 that relate to pavements and the urban heat island phenomenon, using the SciMAT tool for bibliometric analysis to evaluate the general evolution of this area of science.
The analysis was carried out on 107 articles, and a clear evolution was found in the research methodologies of studies of pavements in urban heat island conditions. Until 2008, 73% used all type of field experiments. In 2019, this ratio had decreased to 36%, while investigations with laboratory experiments were the most prevalent, at 37% of all investigations. In recent years, interdisciplinary research has focused on the issues of mitigating the effects of urban heat islands together with improving the energy performance of dwellings.
... By understanding the building's thermal loads and its intended using, we can more effectively use energy from the sun to save energy from the passive heat system . We can even generate energy onsite using resources that would otherwise be thermal loads that would demand energy. ...
... By using formula (1), (2) and the heat transfer coefficient of the material in Table 1, we could also describe the total of heat losses and heat gains by relationships with general areas of these buildings. Q T = 6.3·S 1 ...
... Nonetheless, the energy demand and associated emission of this building typology are high due to the increased number of materials and equipment per floor area, particularly for office buildings [3,4,26]. To promote cost-beneficial urban sustainability among high-rise buildings, integrated ECMs supported by passive strategies were encouraged [27,28]. Given a particular climatic condition, several passive strategies developed by 'Passivhaus' Institut Darmstadt in Germany were adopted toward the ecological design of buildings . ...
... Of the four generic core positions, the split core position promoted a passive low-energy performance in high-rise buildings . Other prominent passive strategies included improving thermal mass effects , natural ventilation, evaporative cooling (both direct and indirect) and solar heating effect [39,40]. However, the effect of these strategies was either beneficial or detrimental to the building comfort level depending on the climate features within that geographical location. ...
Attaining sustainability in high-rise office buildings necessitates determining the major elements and their associating impacts on the energy performance of this building typology. This study investigates the impact of architectural and engineering features on the energy performance of high-rise office buildings within a warm-summer-cold-winter climate. A rectangular building plan form with a 1:1.44 plan ratio, vertical split core position and central atrium presented the best building performance. The plan form, core position and atrium effect accounted for 59, 30 and 11%, respectively, of an estimated 20.6% building energy savings. Furthermore, exploiting passive strategies founded on the climate and building features as defined by 'PassivHaus' standards further reduced the building energy usage.
... In the area of numerical simulations, in 2018 Kandya & Mohan published an article evaluating UHI mitigation strategies through modifications of the building envelope using eQUEST software . A composite of bamboo and concrete (bamcrete) was analysed, which can be used for the construction of building walls in climatic conditions in India. ...
... A composite of bamboo and concrete (bamcrete) was analysed, which can be used for the construction of building walls in climatic conditions in India. The authors showed that the use of bamcrete is economical and has important energy-saving and cooling benefits . In addition, simulation of the urban environment (in certain parts of the city) was developed to identify the possibility of replacing currently used surfaces with cooler surfaces, to evaluate the potential transformation of the urban landscape for the mitigation of UHI . ...
Although researchers have investigated the concept of self-healing asphalt materials for decades, only recently has scientific interest in methods triggering self-healing properties of asphalt increased. Self-healing technologies are expected to increase the service life of materials and reduce their maintenance, decreasing raw materials consumption, greenhouse gas emissions, and negative effects of construction on climate change. Self-healing of asphalt materials has the potential to make important changes in the road construction materials industry, making it more sustainable; however, the literature has not exactly reported a quantitative analysis of the progress or evolution of this scientific topic. Bibliometric and science mapping analyses are methodologies to study through quantitative analysis, the scientific evolution of any knowledge area. Hence, this paper presents a bibliometric and science mapping analysis of the self-healing technology of 292 selected documents found in widely accepted scientific databases, using SciMAT open access software. In addition, the article presents a description of the most important articles based on SciMAT analysis. The results of the study show that the production of documents related to self-healing has been growing since 1994, reaching a peak in 2018 with 60 published articles (21% of the total). In addition, China and the USA have an outstanding performance in the production of documents followed by the Netherlands, UK, Spain, and Chile, although the European continent has the largest number of countries actively developing this research area. The analysis also showed that the most productive authors in the topic of study are Wu, S.P., Little, D.N., Lytton, R.L., and Garcia, A. In addition, analysis showed an increasing development of self-healing pavements topics in new and more specific research areas such as microwave heating, nanocomposites, and microcapsules. Overall, this analysis shows that self-healing asphalt materials technology has been catching the scientific interest of many researchers in recent years; hence, there are many techniques and areas that are being developed and are expanding the branches and different niches in this research area. Therefore, opportunities for researchers to work in this field are developing and are also far from reaching a stage of maturity.
... However, most of the healthcare buildings did not take into consideration of the microclimate conditions and the same construction type could be found independently of geographical latitude or specific location. As, construction materials and the envelope systems have a key role in the improvement of the thermal performance and reducing energy demand [43,44] by the mitigation of heatwaves, this research presents, an evaluation of a hospital built during this period in terms of indoor setpoint temperature and energy efficiency. ...
... The thermal performance of buildings could be improved by implementing some passive strategies. Several studies have confirmed that the application of shading devices , higher thermal mass materials [44,61] incorporation of vegetation  and higher insulation value , could help to mitigate the UHI effect and reduce the energy demand of buildings. In the case of this building, we recommend the implementation of a shading device system that can be operated accordingly during summer and winter based on the prevailing heat conditions. ...
Construction materials and systems for the thermal building envelope have played a key role in the improvement of energy efficiency in buildings. Urban heat islands together with the upcoming rising global temperature demand construction solutions that are adapted to the specific microclimate conditions. These circumstances are even more dramatic in the case of healthcare buildings where the need to preserve constant indoor temperatures is a priority for the proper recovery of patients. A new neonatal hospital, located in Madrid (Spain), has been monitored, and building energy simulations were performed to evaluate the effect of the building envelope on the energy demand. Based on the simulation results, the design of the building envelope was found to be insufficiently optimised to properly protect the building from the external heat flow. This is supported by the monitored results of the indoor temperatures, which went over the standard limit for about 50% of the hours, achieving up to 27 °C in June and July, and 28 °C in August. The results showed, on one hand, that solar radiation gains transmitted through the façade have an important impact on the indoor temperature in the analysed rooms. Heat gains through the opaque envelope showed an average of 8.37 kWh/day, followed by heat gains through the glazing with an average value of 5.29 kWh/day; while heat gains from lighting and occupancy were 5.21 kWh/day and 4.47 kWh/day, respectively. Moreover, it was shown that a design of the envelope characterised by large glass surfaces and without solar protection systems, resulted in excessive internal thermal loads that the conditioning system was not able to overcome.
... Research has also shown that variations in household energy expenditure are influenced by geographical location [23 , 37 , 83] . In particular, the significant positive relationship between electricity expenditure and location in urban areas has been linked to a phenomenon known as urban heat island effect ; which states that temperatures in heavy built-up environments tend to be higher than those in less dense areas due to the positive urban thermal balance  . According to Gupta and Gregg  , Kandya and Mohan  as well as Arifwidodo and Chandrasiri  , excessive heat associated with the urban island effect creates thermal discomfort and heat burns. ...
... In particular, the significant positive relationship between electricity expenditure and location in urban areas has been linked to a phenomenon known as urban heat island effect ; which states that temperatures in heavy built-up environments tend to be higher than those in less dense areas due to the positive urban thermal balance  . According to Gupta and Gregg  , Kandya and Mohan  as well as Arifwidodo and Chandrasiri  , excessive heat associated with the urban island effect creates thermal discomfort and heat burns. This leads to an increase in electricity demand for cooling purposes. ...
... Although the conditions that favour the appearance of the UHI are well-established and understood, the implementation of the best strategies to combat this phenomenon within cities that have already experienced quick and unplanned urbanisation remains controversial. Among the solutions proposed are reroofing and repaving in lighter colours; installing cool asphaltic and concrete photocatalytic pavements; decrease of the anthropogenic heat; building envelope modifications using natural materials; harnessing natural wind; covering of roofs, walls and façades with vegetation and introducing green infrastructure and urban water surfaces (Kandya and Mohan 2018;Gunawardena et al. 2017;Kyriakodisa and Santamouris 2018;Kleerekoper et al. 2012;Rosenfeld et al. 1998). Of special interest to this study is the effect of green and blue spaces in cities, whose implementation is usually reliant upon the availability of open areas for trees or water bodies, the amount of financial resources and the climate. ...
We measured air temperature at 14 sites with different land cover composition within the urban canopy layer of a mid-sized Brazilian city. The intensity (ΔT) of the urban heat island (UHI) was calculated using data collected above a lake and at an urban park as references. We investigated the spatio-temporal variability of ΔT during four contiguous days with varying weather. The first day was overcast and rainy, giving rise to a moderate UHI. The second day was sunny, which caused the diurnal ΔT fields to become heterogeneous, due to larger heating rates at sites with more man-made surfaces compared to natural surfaces. A high-pressure system observed on the last days brought cloudless skies, causing smaller ΔT during the day and greater at night. We hypothesise that the effect was due to the reduction of cooling via evapotranspiration caused by closing of the stomata as the soil dried out, which reduced the daytime temperature differences among the sites. The night-time effect was caused by stronger radiative cooling due to clear skies. The temperature within the park was always lower than over the lake, confirming that urban forestry is a more effective mechanism to combat the UHI. Introducing a park would be about sevenfold cheaper than building a city pond. Hence, green spaces are not only more efficient to combat the UHI but it is also a cheaper strategy compared to blue spaces. Moreover, vegetation delivers other benefits, such as removal of air pollutants, attenuation of urban noise, improvement of city aesthetic and their use as recreational spaces.
... An urban heat island  is defined as the temperature anomaly observed over urban areas with respect to the suburbs  and is due to significant changes that urbanization brings to Earth's surface . It heavily affects the local microclimate, influenced by the solar radiation absorbed and retained by traditional construction materials (e.g., cement and asphalt)  and released in the form of infrared radiation [28,29]. All this worsens the conditions under which buildings are subjected during the summer, increasing their energy needs; on the other hand, the contribution of the urban heat island effect on the mitigation of the outside temperature during the cold season often does not counterbalance the major energy needs required by the cooling systems during the hot season . ...
The simulation of the energy consumptions in an hourly regime is necessary in order to perform calculations on residential buildings of particular relevance for volume or for architectural features. In such cases, the simplified methodology provided by the regulations may be inadequate, and the use of software like EnergyPlus is needed. To obtain reliable results, usually, significant time is spent on the meticulous insertion of the geometrical inputs of the building, together with the properties of the envelope materials and systems. Less attention is paid to the climate database. The databases available on the EnergyPlus website refer to airports located in rural areas near major cities. If the building to be simulated is located in a metropolitan area, it may be affected by the local heat island, and the database used as input to the software should take this phenomenon into account. To this end, it is useful to use a meteorological model such as the Weather Research and Forecasting (WRF) model to construct an appropriate input climate file. A case study based on a building located in the city center of Rome (Italy) shows that, if the climatic forcing linked to the heat island is not considered, the estimated consumption due to the cooling is underestimated by 35–50%. In particular, the analysis and the seasonal comparison between the energy needs of the building simulated by EnergyPlus, with the climatic inputs related to two airports in the rural area of Rome and with the inputs provided by the WRF model related to the center of Rome, show discrepancies of about (i) WRF vs. Fiumicino (FCO): Δ = −3.48% for heating, Δ = 49.25% for cooling; (ii) WRF vs. Ciampino (CIA): Δ = −7.38% for heating, Δ = +35.52% for cooling.
... Roof is the important part that has to be considered to create thermally comfortable interior environment. Researches were undertaken for evolving a cool roof technology to reduce the cooling load thereby, researched the performance of various organic 'phase change materials' and increased the roof reflectance cooling energy savings . ...
Gili Meno is located on Northwest coast of Lombok, Indonesia. Surrounded by crystal water and microclimate tropical weather. Nowadays, modern materials for building in Gili become choices due to the access from suppliers from the big islands surroundings. The use of indigenous materials such as bamboo become rare for wall, ceiling and roof. However, bamboo is a promising choice for cooling down the interior thermal of the building and considered as a sustainable building material. The project is designed as a sustainable architecture for boutique villa that aims to attract tourist by its concept of holistic design and to embrace bamboo as indigenous local material for sustainable holistic design. This journal focused on bamboo for wall, ceiling, roof and shading as design elements to create thermally comfortable interior of the villa. It uses a research by method of implementing research bamboo that has been done by other researchers and site observation, observing the type of bamboo and designing the holistic architecture. The research found that the use of bamboo with holistic approach for the wall, ceiling, roof and shading with the understanding of the nature will be promising with further research needed to create thermally comfortable interior environment.
... Nowadays, understanding and limiting the global warming and thus the UHI phenomenon have become of crucial importance for governments and scientific communities (Environmental Protection Agency [EPA], 2008;Hu, White, & Ding, 2016;Kandya & Mohan, 2018;United Nations [UN], 1998, also taking into account the chronical diseases and mental health in urban populations as well as the related negative impacts on environment and economy (Bank of Greece, 2011;Burke, Craxton, Kolstad, & Onda, 2016;Deschenes & Greenstone, 2007;World Health Organization, 2009;Yang, Qian, Song, & Zheng, 2016). ...
The issues related to the global warming are increasingly becoming of crucial importance for governments and scientific communities, which are trying to develop policies and solutions to slow down this problem in order to limit the related negative effects on environment, human health and economy. The Urban Heat Island (UHI) phenomenon, i.e. the increasing of temperatures within cities with respect to the neighbouring rural spaces, is one of the main aspects related to such a global warming. In this regard, cool road pavements can be really considered as a valuable technological solution to mitigate such a phenomenon. Given this background, the present paper illustrates a comprehensive experimental investigation principally aimed at providing a specific overview of the main thermal behaviour of selected clear and coloured mixtures for pavement surface courses as mitigation strategy for the UHI phenomenon. To this aim, specific indoor (laboratory) and outdoor monitoring were carried out on samples subjected to artificial radiations and sun exposure, respectively. Basic chromatic characteristics and mechanical properties of such materials were also investigated to evaluate prospective correlations with the thermal response as well as real field applicability. Clear mixtures were prepared using “traditional” limestone or “unusual” white marble aggregates bound with a synthetic transparent resin whereas the coloured mixtures were obtained by adding oxide pigments (red or yellow) to a plain bituminous blend. A traditional reference “black” bituminous mixture was also studied for comparison purposes. The experimental findings mainly showed that an optimisation of the thermal response of pavement surface can be achieved leading to remarkable temperature reductions also interesting the surrounding environment, in particular when a transparent binder is used. However, some issues related to the mechanical properties of clear mixes should be addressed since they could limit the real applicability of such materials.
... In this study, the warming associated with building AHR was chosen as the dependent variable. To capture the potential impact of building properties on AHR warming, building density and building height were selected as the independent variables, based on previous studies (Santamouris, 2014;Guo et al., 2015;Kandya and Mohan, 2018), which found that building height and density are the two key factors affecting residential AHR and influencing the urban thermal environment. ...
... Strategies related to the building component include the implementation of cool pavements and green roofs [24,25], shading design for buildings and open spaces [26,27], controlling albedo with a reflective surface for unshaded areas [28,29]. Currently, numerous new building materials have been proposed as alternative green materials, including lightweight concrete, insulated metal panels, and insulated wood panels . The concept of energy balance, as stated by Dernie, is a very potential concept for controlling the microclimate, which has been previously unrecognized in the era of brick wall buildings . ...
The heat island phenomenon in major cities is partly due to the excessive use of concrete and brick, which causes many problems regarding thermal comfort and energy expenditure. The thermal behaviour of the envelope wall material depends on its density, heat capacity, and thermal conductivity, and its effect on the heat island intensity (HII) is reported in this paper. Experiments and simulations were carried out on the four most popular building materials: brick, aerated concrete, wood with glass-wool insulation, and glass fibre-reinforced concrete with glass-wool insulation, with each material having a dimension of 1 m × 1 m. Experiments to analyse the thermal behaviour of the wall materials were performed by exposing each material to heat radiation from 2 × 1000 W halogen lamps for 4 h, followed by 4 h of cooling. The HII simulations were carried out in a simple urban kampong in a tropical area using Energy2D software. Heat flow analyses confirmed the thermal behaviour of the four walls, which can be categorised into two types: heat storage of block wall (BW) type and heat flow inhibition of insulated sandwich wall (ISW) type. The BW type showed 0.32 °C higher indoor air temperature than the ISW type, while the HII simulation showed ISW to be 0.74 °C higher than BW; however, both types increase the intensity and need mitigation treatment. The results of this study are important for the technological approach for dealing with local warming to lower the energy expenditure of poor people in an urban area.
... Studies have shown that UHI alone can increase the cooling loads of building up to 50% . Hence, building retrofit strategies such as solar reflective materials, shading trees around buildings, ambient cooling achieved by urban vegetation and high albedo surfaces can contribute to mitigating the UHI effect, which in turn contributes to reducing building cooling loads . ...
Villas are a very common building typology in Abu Dhabi. Due to its preponderance in residential areas, studying how to effectively reduce energy demand for this type of building is critical for Abu Dhabi, and many similar cities in the region. This study aims to show the impact of proposed energy efficiency measures on a villa using a calibrated model and to demonstrate that to be accurate, the model must be driven using urban weather data instead of rural weather data due to the significance of the urban heat island effect. Available data for this case study includes construction properties, on-site (urban) weather data, occupancy-related loads and schedules and rural weather data. Four main steps were followed, weather data customisation combining urban and rural weather variables, model calibration using a genetic algorithm-based tool and simulating retrofit strategies. We created a calibrated model for electricity demand during 2016–2017 with a 4% normalized mean bias error and an 11% coefficient of variation of the mean square error. Changing from none to all retrofit strategies results in a 34% reduction in annual energy consumption. According to the calibrated model, increased urban temperatures cause a 7.1% increase in total energy consumption.
... The phases include selection of raw materials, manufacturing, distribution and installation to ultimate reuse or disposal (Sheth, 2016). Some of the ecofriendly materials used presently are, composite materials like Bamcrete (bamboo-concrete composite) and natural local materials like Rammed Earth had better thermal performance compared with energy-intensive materials like bricks and cement (Kandya A, 2018). Mixture of fly ash, stone crusher and lime has proven to be one of the high density blocks with maximum strength, which are decentralized products from small scale industries, industrial waste products, energy efficient and environment friendly (Reddy, 2009). ...
Day by day impact of climate change is getting severe and leading to many challenges and problems before mankind as well as on other ecosystems. The use of various technologies and appliances has upper hand in raising the graph of climate change. The majority of cause is contributed by industrial sector and followed by construction sector. In day to day life of individual most of the carbon footprints are produced from the residential place, which carries a large-scale impact at global level. Considering the crises arising in future, scientists as well as renewable engineers suggest the shifting of traditional construction sector to sustainable and green approach method. Sustainability is a green technology, which is a link between environment and society. This method will result in less harm to natural cycle of environment and reduce the rate of climate change. The study carried out highlights, the importance sustainable buildings variety of sustainable materials and methods used for construction. Also it will address the management of resources.
... In other words, urbanization promotes the change of the land profile on Earth. The urban building has greater thermal properties, which results in higher temperatures in the urban area compared to the surrounding rural area . The maximum temperature difference between the urban area and rural area is the effect of urban heat islands [13,14], as described in Figure 1 below. ...
Greenery systems are sustainable ecosystems for buildings. Many studies on greenery systems, such as green roofs and green walls, have demonstrated that greenery systems support energy saving and improve thermal conditions in the building sector. This paper summarizes, discusses, and compares greenery systems and their contributions to the reduction of the urban heat index, the reduction of internal and external buildings' wall temperatures, and the reduction of the energy consumption of buildings. The fundamental mechanisms of greenery systems, which are thermal insulation, evapotranspiration, and shading effect, are also discussed. The benefits of greenery systems include the improvement of stormwater management, the improvement of air quality, the reduction of sound pollution, the reduction of carbon dioxide, and the improvement of aesthetic building value. The summarized materials on the greenery systems in the article will be a point of references for the researchers, planners, and developers of urban and rural areas, as well as the individual's interest for future urban and rural plans.
... High-intensity solar radiation in hot weather will cause asphalt aging and urban heat island (UHI) effect [1,2]. In recent years, UHI has attracted widespread attention, and there are many studies on the means to mitigate the UHI effect, such as reducing energy consumption , modifying building envelope , configuring urban vegetation , modifying albedo , etc. ...
Road Pavement Solar Collector (RPSC) is one of the inevitable products of the diversified development of pavement, which can reduce the temperature of the road surface to mitigate the urban heat island (UHI) effect. The arrangement of the heat pipes in RPSC mainly includes the straight arrangement and the serpentine arrangement. In this study, in order to study the influence of the serpentine heat pipes on the structural response of pavement, the 3D Computational Fluid Dynamics (CFD) - finite element model (FEM) is established and verified. The structural response of conventional pavement and RPSC under three different loading conditions is analysed and compared using ANSYS static structural module. The structural response is analysed from the three indexes of the bottom tensile stress, surface deformation, and equivalent stress. The results show the introduction of heat pipes has a significant effect on the mechanical response, thermal response, and coupling response, and the weakest part of the overall pavement structure is the surrounding of the heat pipe specifically at the bending zone. This study can be a reference for future work to attract the attention of balance the efficiency of heat collection and the structural response for RPSC.
... The S-curve of cement is in the later period of the growth stage, which will reach 90% of the total saturation in 2028. Composite materials like Bamcrete (bamboo-concrete composite) and natural local materials like Rammed Earth had better thermal performance compared with energy-intensive materials like bricks and cement (Kandya and Mohan 2018). Novel bricks synthesized from fly ash and coal gangue have better advantages of energy saving in brick production phases compared with that of conventional types of bricks (Zhang et al. 2014). ...
Buildings account for nearly 2/5ths of global energy expenditure. Due to this figure, the 90s witnessed the rise of green buildings (GBs) that were designed with the purpose of lowering the demand for energy, water, and materials resources while enhancing environmental protection efforts and human well-being over time. This paper examines recent studies and technologies related to the design, construction, and overall operation of GBs and determines potential future research directions in this area of study. This global review of green building development in the last two decades is conducted through bibliometric analysis on the Web of Science, via the Science Citation Index and Social Sciences Citation Index databases. Publication performance, countries’ characteristics, and identification of key areas of green building development and popular technologies were conducted via social network analysis, big data method, and S-curve predictions. A total of 5246 articles were evaluated on the basis of subject categories, journals’ performance, general publication outputs, and other publication characteristics. Further analysis was made on dominant issues through keyword co-occurrence, green building technologies by patent analysis, and S-curve predictions. The USA, China, and the UK are ranked the top three countries where the majority of publications come from. Australia and China had the closest relationship in the global network cooperation. Global trends of the top 5 countries showed different country characteristics. China had a steady and consistent growth in green building publications each year. The total publications on different cities had a high correlation with cities’ GDP by Baidu Search Index. Also, barriers and contradictions such as cost, occupant comfort, and energy consumption were discussed in developed and developing countries. Green buildings, sustainability, and energy efficiency were the top three hotspots identified through the whole research period by the cluster analysis. Additionally, green building energy technologies, including building structures, materials, and energy systems, were the most prevalent technologies of interest determined by the Derwent Innovations Index prediction analysis. This review reveals hotspots and emerging trends in green building research and development and suggests routes for future research. Bibliometric analysis, combined with other useful tools, can quantitatively measure research activities from the past and present, thus bridging the historical gap and predicting the future of green building development.
... On the other hand, previous studies mostly focus on the urban scale [19,20], and few dives inside the city to make a detailed UHI description. Moreover, the elaborate implications caused by the multi-scale urban spatial structure , building material , ventilation condition , and urban green index  result in multi-peak temperature surface, which is too complex to be represented by conventional surface fitting methods, thus the spatial distribution details of the thermal environment inside the city cannot be precisely described. ...
The urban heat island (UHI) effect accelerates the accumulation of atmospheric pollutants, which has a strong impact on the climate of cities, circulation of material, and health of citizens. Therefore, it is of great significance to conduct quantitative monitoring and accurate governance of UHI by calculating the index rapidly and expressing spatial distribution accurately. In this paper, we proposed a model that integrates UHI information with the GeoSOT (Geographic Coordinate Subdividing Grid with One-Dimension Integer Coding on 2n Tree) grid and subsequently designed the calculation method of UHI indices and expression method of UHI spatial distribution. The UHI indices were calculated on Dongcheng and Xicheng District, Beijing, in the Summer of 2014 to 2019. Experimental results showed that the proposed method has higher calculation efficiency, and achieved a more detailed description of the spatial distribution of the urban thermal environment compared with the Gaussian surface fitting method. This method can be used for large-scale and high-frequency monitoring the level of UHI and expressing complicated spatial distribution of UHI inside the city, thus supporting accurate governance of UHI.
... Cities are the most evident form of transformation of the natural landscape. The change in the elements of the climate has great ecological repercussions as it immediately affects the inhabitants through thermal discomfort and the concentration of pollutants . ...
This study aims to identify the relationship between changes in temperature regarding urbanization processes and seasonality in the city of São Paulo, located in the Tropic of Capricorn. The land surface temperature (LST) results were compared to official weather stations measurements, identifying in the spring–summer period 65.5% to 86.2% accuracy, while in the autumn–winter period, the results ranged from 58.6% to 93.1% accuracy, when considering the standard deviation and the temperature probe error. The mean MAE and mean RMSE range from 1.2 to 1.9 °C, with 83.0% of the values being ≤2.7 °C, and the coefficient of determination values are R = 0.81 in spring–summer and R = 0.82 in autumn–winter. Great thermal amplitude was estimated in the spring–summer season, with a difference in LST of the built-up space and rural area ranging from 5.8 and 11.5 °C, while in the autumn–winter season, the LST is more distributed through the city, with differences ranging from 4.4 to 8.5 °C. In addition, the current study suggests remote sensing as a reliable, cheap, and practical methodology to assist climate in order to support public policies and decision-making actions regarding environmental and urban planning.
... 65 The wavelength 8-15 μm ranges are frequently for the origin of LST. 66 The sensor receives EMR as top of atmosphere (TOA) radiance and reflected from the ground. 67 The inverse of Planck's law (the energy emitted by a surface is directly related to its temperature) is used to derive blackboard/brightness temperatures from TOA radiances. ...
The paper provides a systematic review of satellite-based regional and urban heat island (RHI and UHI) studies in cities and their challenges, from 2010 to the present based on visualizing scientific landscapes (VOS) viewer analysis and Scopus and science database search using a set of standard criteria. The review results show that 52.17% of the studies used Landsat images followed by MODIS (36.65%). Based on VOS viewer analysis author keywords, remote sensing was strongly linked to urban heat island, urban greenspace, and improvise surface, respectively. Regarding, Co-authorship network China, Canada and the United kingdom’s authors actively collaborated with different world researchers. The most frequently studied regions and periods of research are China and summer daytime, respectively. A total of 55% of the articles reported the use of a mono-window algorithm for retrieving LST from sensors. On the other hand, remotely sensed UHI studies have been facing a series of challenges, including differences between remote sensing satellite-derived LST and air temperature, impacts of clouds and other factors on LST data, methods to quantify UHI, accuracy assessment and attribution of RHI and UHI. Thus, consideration was given to the understudied cities, the methods to compute RHI and/or UHI intensity, inter-annual variability and modeling in the future.
... For the current case study, the HoF resorts to Linate or Malpensa weather stations, where Linate is often more preferable considering its proximity to Milano city center, where the studied building is located. However, it is argued that weather stations located in open flat areas outside the city (e.g., airports) cannot adequately characterize the urban heat island (UHI) intensity of the city center . To address UHI intensity in the cooling load calculations, in this work, we use on-site climatic data from Brera weather station, which is located in the center of Milano city . ...
Optimal sizing of peak loads has proven to be an important factor affecting the overall energy consumption of heating ventilation and airconditioning (HVAC) systems. Uncertainty quantification of peak loads enables optimal configuration of the system by opting for a suitable size factor. However, the representation of uncertainty in HVAC sizing has been limited to probabilistic analysis and scenario-based cases, which may limit and bias the results. This study provides a framework for uncertainty representation in building energy modeling, due to both random factors and imprecise knowledge. The framework is shown by a numerical case study of sizing cooling loads, in which uncertain climatic data are represented by probability distributions and human-driven activities are described by possibility distributions. Cooling loads obtained from the hybrid probabilistic-possibilistic propagation of uncertainty are compared to those obtained by pure probabilistic and pure possibilistic approaches. Results indicate that a pure possi-bilistic representation may not provide detailed information on the peak cooling loads, whereas a pure probabilistic approach may underestimate the effect of uncertain human behavior. The proposed hybrid representation and propagation of uncertainty in this paper can overcome these issues by proper handling of both random and limited data.
The high rate of urban densification has facilitated the vertical expansion of cities, with 75% of high-rise buildings designated as office buildings. To promote building energy conservation, management and sustainability, it is essential to establish during the design phase the major impactful elements on the building energy performance. Hence, this study investigates the performance-based effect of architectural and engineering elements of high-rise office buildings in different climate environments. Thereafter, the most sustainable building model was developed using the assessment results obtained from exploiting the advantages of the climate features. The results demonstrate that the building performance varies with its characteristics such as plan ratio, core position and atrium effect under different climates. While a rectangular building plan (1:1.44 plan ratio, split-core position and central atrium) presented the best performance in the warm-summer-cold-winter (WSCW) climate zone, a square building plan (with a split core and no atrium) displayed the best performance in the hot-summer-mild-winter (HSMW) climate zone. Furthermore, by exploiting the advantages of the building and climate characteristics, a mix of passive strategies was established to be suitable for attaining sustainability and comfort standards in the WSCW zone. Contrarily, active strategies are required for buildings in the HSMW zone.
Cement stabilized compressed earth brick is an important industrial raw material, and its mechanical and thermal properties have not been fully studied. The mechanical properties can be characterized by compressive strength index and thermal properties can be characterized by thermal conductivity index. The experimental scheme is arranged to solve the relationship between the performance of cement stabilized compressed earth brick and the influencing factors. The experimental results show that the compressive properties of cement stabilized compressed earth bricks are negatively correlated with the water binder ratio, positively correlated with the m (cement): m (water), and not significantly correlated with the m (earth): m (cement + water) and the fiber content. The thermal conductivity of raw soil cement curing mechanism brick is negatively correlated with m (earth): m (cement + water), positively correlated with water binder ratio, and not significantly correlated with m(cement): m (water) and fiber content.
Climate change mitigation is a recurrent consciousness topic among society and policymakers. Actions are being adopted to face this crucial environmental challenge, with a rising concern with a big impact on the building sector. Construction materials have a high carbon footprint as well as an energy-intensive activity. To measure the environmental damage and effects, life cycle assessment (LCA) is the methodology most widespread. However, the LCA methodology itself and the assumptions done to carry it out leads to a generalized burden to compare the case studies outcomes. LCA method and for instance geographical location are incompatibilities also revealed in embodied energy and embodied carbon assessments. Urgent actions are needed to clarify the confusions arisen in the research, considering a detailed study on the embodied energy and embodied carbon values. From a material level point of view, this paper aims to illustrate the chronological overview of embodied energy and embodied carbon through keywords analysis. Moreover, to support and corroborate the analysis, an organized summary of the literature data is presented, reporting the range of embodied energy and embodied carbon values up to now. This systematic analysis evidences the lack of standardization and disagreement regarding the assessment of coefficients, database source, and boundary system used in the methodology assessment.
High-rise buildings degrade the thermal environment of their surroundings through wind turbulence, cooling, and excessive heating. This study identifies the role and relationship of geometric (form, orientation, dimension) and material (type, volume) parameters in conditioning the thermal environment around high-rise buildings. We performed the field measurements at four widely separated high-rise apartment buildings at different elevations (675–1050 m above sea level) in Bandung, Indonesia. Temperature, air velocity, and humidity were measured within a 150 m radius around each building three times daily (08–10 a.m., 12–04 p.m., and 06–08 p.m.) for three days in February. Airflow and shading patterns were analysed with Ansys-Fluent CFD and SketchUp software, respectively. Both direct observation and simulations showed that different orientations of buildings relative to the sun and wind can heat or cool the surrounding areas. The sail effect of a high-rise building exposed to direct sunlight can cause hot spots behind the building; choice of building material and use of shadowing can reduce this effect. The wind-tunnel effect can cause cold paths, especially if the area is shaded. Air turbulence and high-velocity airflow can result in uncomfortable conditions in the surroundings, based on the building height. Thus, high-rise buildings profoundly affect local thermal conditions. The results of this study are therefore essential for designing new buildings (and mitigating environmental quality around existing ones) in tropical cities.
In view of the current self-embedded landscape wall cannot be combined with the courtyard type ecological energy-saving buildings, self-embedded landscape wall energy consumption, and affect the overall beauty of the courtyard type ecological energy-saving buildings, so it cannot meet the requirements of ecological energy-saving buildings. The principle of overall system, the principle of cultural sustainability and functional principle, and analyzes the energy consumption of the building. On this basis, the location and details of the landscape wall were designed, and the landscape wall was combined with the paving, terrain and lighting to achieve the organic unity of the landscape wall and the courtyard-style ecological energy-efficient building, and ensure its overall aesthetics. The experiment shows that the landscape wall designed by this method can be unified with the whole landscape, and the overall aesthetic feeling of the landscape wall can be guaranteed.
It is widely accepted that the climatic factors—including solar load, wind flow pattern and external air temperature—strongly affect building energy consumption. Meanwhile, the microclimate of semi-closed spaces between buildings has direct and indirect consequences on heat transfer through building envelopes.
This study demonstrates how courtyard configuration can modify the climate and external air temperature and how the microclimate condition can be considered for functionally accurate calculation of heat loss and thermal loads of buildings.
Based on the experimental and computational results, increasing the courtyard's depth by restricting the sky view factor (SVF) and the heat exchange with courtyard's outside at low levels, creates the individual microclimate. The thermal environment of this middle space is affected more than outside by surrounding rooms and the thermal properties of the building walls.
The findings, which are limited to experimental cases in the Hanover climate region, propose to consider the temperature of courtyard depending on its aspect ratio and glazing percentage with a temperature correction factor (Fx, Heat load) between 0.9 to 2.2.
In hot-humid climates, porous external surfaces of the buildings with high water sorption capabilities could contribute to the surface temperatures reduction through the release of latent heat by evaporative cooling. On the other hand, compact and low permeable finishing materials could have mechanical and durability benefits respect to the underlying supports, for example reducing the permeability to degrading agents. In this paper, the properties of lime base coat renders with pore modulating additives (sepiolite and colloidal nano silica) have been surveyed to evaluate their effectiveness in water absorption, thermal performance, and the fulfilment of mechanical requirements for the application on the external side of the walls. A traditional lime–sand formulation was taken as reference. After preliminary tests on workability and shrinkage, the optimal mix designs were selected and the samples were subjected to several mechanical and thermo-hygrometric tests, before and after accelerated aging. The results allowed demonstrating that the use of sepiolite in substitution of sand, enhances the render ductility, thermal resistance and water uptake but worsens its mechanical stability, increasing the shrinkage effects and slightly reducing the ultimate strength values. The addition of colloidal nano silica, either to lime–sepiolite or to lime–sand renders, fails to produce any improvement in their either physical or mechanical behavior. Mixed formulations (lime–sand with sepiolite and nano silica) behave as simple lime–sand solutions, showing optimal compressive and flexural strength but reduced water uptake capabilities. This demonstrates that the presence of sand prevails in the performance of the render, and that the adoption of other additives doesn’t worth the cost for the benefit presented.
Sudhakar has developed various structural components using bamboo concrete composites (bamcrete) and demonstrated them in building houses as is presented in a companion paper. This paper presents the initial experimental verification of one of the structural arch forms proposed by Sudhakar using bamboo as a structural element. In this case, two bamboo arches vertically separated are connected using Ferro-Cement Band ties to generate a Bow Beam Arch as a load bearing member. This paper presents the manufacturing details of the bow beam arch and the initial experimental results.
Bamboo has been used in housing since time immemorial but its use has been restricted as a load distributor in roofs. Limitations like the variability in the properties of bamboo with topography and environment have been a deterrent to standardisation of bamboo based technologies for housing. Moreover, the absence of the cost effective test set-up for ascertaining the structural safety aspects of bamboo structures, at decentralised locations, have prohibited the massive use of bamboo in building construction. Addressing these limitations and various research gaps in using bamboo as the main load bearing material in building construction, the present experimental study evaluates the load carrying capacity of the innovative bamboo based structural beam elements, which were tested in full sizes in a specifically designed test set-up. The highly encouraging results as obtained from the load deflection analysis of the beam elements put across a strong possibility of using bamboo as a structural load bearing element for building construction. The simplicity and ease in the installation of the test set-up makes it possible for envisaging mass scale housing projects using bamboo. The massive application of bamboo in construction will not only solve the problem of affordable housing but will also address the environmental concerns.
This paper is concerned about the experimental study of twin round bamboo concrete infill composite parabolic tied arch. Experimental investigation is undertaken to validate the structural load bearing capacity of haritha infill arch. The infill arch is tested under three types of loading condition viz a) crown point loading, b) centre half loading and c) distributed point loading. The experimental results brings out the stiffness of the arch to be 1 kN/mm under crown point loading, 1.67 kN/mm under centre half loading and 1.17 kN/mm under distributed loading. The stresses in the materials are well within their allowable limits. Thus this paper is able to successfully report the structural strength of parabolic tied infill arch which promises to be a structural load bearing element. Since, there is no additional formwork required in casting of the arch, apart from the bamboo which itself acts like the formwork, lesser quantity of steel and very small thickness of concrete being involved, the arch qualifies to be a potential structural element for affordable housing and green constructions.
Urban heat island intensities (UHI) have been assessed based on in situ measurements and satellite-derived observations for the megacity Delhi during a selected period in March 2010. A network of micrometeorological observational stations was set up across the city. Site selection for stations was based on dominant land use–land cover (LULC) classification. Observed UHI intensities could be classified into high, medium and low categories which overall correlated well with the LULC categories viz. dense built-up, medium dense built-up and green/open areas, respectively. Dense urban areas and highly commercial areas were observed to have highest UHI with maximum hourly magnitude peaking up to 10.7 °C and average daily maximum UHI reaching 8.3 °C. UHI obtained in the study was also compared with satellite-derived land surface temperatures (LST). UHI based on in situ ambient temperatures and satellite-derived land surface temperatures show reasonable comparison during nighttime in terms of UHI magnitude and hotspots. However, the relation was found to be poor during daytime. Further, MODIS-derived LSTs showed overestimation during daytime and underestimation during nighttime when compared with in situ skin temperature measurements. Impact of LULC was also reflected in the difference between ambient temperature and skin temperature at the observation stations as built-up canopies reported largest gradient between air and skin temperature. Also, a comparison of intra-city spatial temperature variations based UHI vis-à-vis a reference rural site temperature-based UHI indicated that UHI can be computed with respect to the station measuring lowest temperature within the urban area in the absence of a reference station in the rural area close to the study area. Comparison with maximum and average UHI of other cities of the world revealed that UHI in Delhi is comparable to other major cities of the world such as London, Tokyo and Beijing and calls for mitigation action plans.
In this study the performance of organic PCMs used as latent heat storage materials, when incorporated in coatings for buildings and urban fabric, is investigated. Thirty six coatings of six colors containing different quantities of PCMs in different melting points were produced. Accordingly, infrared reflective (cool) and common coatings with the same binder system and of the same color were prepared for a comparative thermal evaluation. The samples were divided in six groups of different color and eight samples each: three PCM coatings of different melting temperatures (18 °C, 24 °C, 28 °C) each one of two different PCM concentrations (20% w/w, 30% w/w), an infrared reflective and a common coating of matching color. Surface temperature of the samples was recorded at a 24 h basis during August 2008. The results demonstrate that all PCM coatings present lower surface temperatures than infrared reflective and common coatings. Analysis of the daily temperature differences showed that peak temperature differences occur between PCM and common or cool coatings from 7 am to 10 am. Investigating the temperature gradient revealed that for this time period the values for PCM coatings are lower compared to infrared reflective and common. From 10 am to 12 pm, temperature gradients for all coatings have similar values. Thus coatings containing PCMs store heat in a latent form maintaining constant surface temperatures and discharge with time delay. PCM doped cool colored coatings have the potential to enhance thermal inertia and achieve important energy savings in buildings maintaining a thermally comfortable indoor environment, while fighting urban heat island when applied on external surfaces.
The local temperature is one of the major climatic elements to record the changes in the atmospheric environment brought about by industrialization, increasing population and massive urbanization. The present study deals with the annual and seasonal temperature trends and anomalies for maximum, minimum and mean temperatures of the four meteorological stations of the National Capital Region (NCR) of India namely Safdarjung, Palam, Gurgaon and Rohtak for the past few decades and their association with the development through urbanization processes. The annual mean maximum temperature did not show any specific trend; however a consistent increasing trend was seen in the annual mean minimum temperatures indicating an overall warming trend over the NCR especially after 1990. This warming trend is contrary to the cooling trend observed by earlier studies till 1980's in various other cities of India including Delhi. However, the temperature trends in annual mean minimum temperatures reported in various countries (USA, Turkey, Italy, etc.) across the world showed warming trends to be associated to the urbanization process of the cities also. The current warming trends in temperature in the NCR Delhi based on the annual mean minimum temperatures have thus been supported by the trends in other parts of the world and could be utilized to infer the development proc-ess in this region. The urbanization pattern within Delhi is reflected by the trends of differences in annual mean mini-mum temperature of the two stations within the city namely Safdarjung and Palam. The significance of the warming trends of the annual minimum temperature for the urban heat island effect is also discussed.
There has been paucity of field campaigns in India in past few decades on the urban heat island intensities (UHI). Re-mote sensing observations provide useful information on urban heat island intensities and hotspots as supplement or proxy to in-situ surface based measurements. A case study has been undertaken to assess and compare the UHI and hotspots based on in-situ measurements and remote sensing observations as the later method can be used as a proxy in absence of in-situ measurements both spatially and temporally. Capital of India, megacity Delhi has grown by leaps and bounds during past 2 -3 decades and strongly represents tropical climatic conditions where such studies and field cam-paigns are practically non-existent. Thus, a field campaign was undertaken during summer, 2008 named DELHI-I (Delhi Experiments to Learn Heat Island Intensity-I) in this megacity. Urban heat island effects were found to be most dominant in areas of dense built up infrastructure and at commercial centers. The heat island intensity (UHI) was ob-served to be higher in magnitude both during afternoon hours and night hours (maximum up to 8.3˚C) similar to some recent studies. The three high ranking urban heat island locations in the city are within commercial and/or densely populated areas. The results of this field campaign when compared with MODIS-Terra data of land surface temperature revealed that UHI hotspots are comparable only during nighttime. During daytime, similar comparison was less satis-factory. Further, available relationship of maximum UHI with population data is applied for the current measurements and discussed in the context of maximum UHI of various other countries.
This study proposes the development of thermal and energy consumption maps to generate useful planning information. A residential neighbourhood in a medium-sized city was selected as the study area. In this area, 40 points were taken as urban reference points where air temperatures at the pedestrian level were collected. At the same time, rural temperatures made available by the city meteorological station were registered. Data of electrical energy consumption of the building units (houses and apartments) were collected through a household survey that was also designed to identify the users’ income levels. Then, maps were developed so that the configuration of urban heat islands and electrical energy consumption could be visualised, compared and analysed. The results showed that the income level was the most important variable influencing electrical energy consumption. However, a strong relationship of the consumption with the thermal environment was also observed.
As the United Nations Development Programme (UNDP) points out, the science is clear and the debate is over: climate change is happening and there is a need to act now. World wide research is being done for developing green and ecofriendly constructional materials. The present paper puts forward the thermal and structural experimental results of using bamboo as a construction material and as a solar energy collector. The thermal behaviour of bamboo was quantified experimentally by observing the temperature inside the cubicals made of 'half split bamboo', 'half split bamboo-concrete composite' and was compared with the cubical made of bricks with cement concrete roof while its structural behaviour was quantified by making bamboo bows (bamboo parabolic arches), which are the proposed beam elements, and tested for the load bearing capacity and deflections through experimentations. Half split bamboo panels were fabricated to harvest solar energy using air and water as the heat transfer agent. The design philosophy of bamboo structures is developed on the lines of concrete and steel and attempt is made for the possible replacement of steel with bamboo. The experimental results present a strong possibility of using bamboo as a green constructional material which can not only reduce the 'indoor temperature' thereby reducing the building energy requirement and combating the urban heat island effect but also will reduce the GHG emissions which can help in fighting global warming and climate change. Its paves the way for its high value application in construction which can make bamboo cultivation an economically viable way of greening the vast wastelands and thereby improving the environment.
The effect of heat-island reduction (HIR) strategies on annual energy savings and peak-power avoid-ance of the building sector of the Greater Toronto Area is calculated, using an hourly building energy simulation model. Results show that ratepayers could realize potential annual energy savings of over $11M from the effects of HIR strategies. The residential sector accounts for over half (59%) of the total savings, offices 13% and retail stores 28%. Savings from cool roofs are about 20%, shade trees 30%, wind shielding of trees 37%, and ambient cooling by trees and reflective surfaces 12%. These results are pre-liminary and highly sensitive to the relative price of gas and electricity. Potential annual electrticity sav-ings are estimated at about 150 GWh and potential peak power avoidance at 250 MW. Published by Elsevier Ltd.
The influence of temperature on tropospheric ozone (O3) concentrations in urban and photochemically polluted areas in the greater Athens region are investigated in the present
study. Hourly values of the ambient air temperature used for studying the urban heat island effect in Athens were recorded
at twenty-three experimental stations while ozone concentration values were measured at three of the above-mentioned stations
and for a period of two years (1996–1997). The linear correlation between ozone concentration and air temperature values as
well as the temporal variation of temperature and ozone concentration, for the above-mentioned experimental stations, were
calculated and analysed. Moreover, a neural network approach was used for investigating the impact of temperature on the ozone
concentration values over the greater Athens area. The neural network model used ambient air temperature as one of its input
parameters and it was found that temperature is a predominant parameter, affecting considerably the ozone concentration values.
Heat island is a very well documented climatic phenomenon that has an important energy and environmental impact in the urban
environment. The main energy problems are related to the important increase of the energy consumption for cooling purposes
as well as to the important increase of the peak electricity load. Heat island in Athens, Greece, is measured during the last
decade and its energy impact is calculated in details. The aim of the present paper is to estimate the direct and indirect
environmental impact of the heat island effect in Athens. This is achieved through the estimation of the additional ecological
footprint caused by the urban heat island phenomenon over the city. The ecological footprint estimation is performed at a
first step by calculating the increase of the cooling demand caused by the heat island over the whole city and then by translating
the energy to environmental cost. Two years annual experimental data from many urban stations have been used. The results
show that the ecological footprint because of the heat island ranges 1.5–2 times the city’s political area that have to be
reserved every year to compensate the additional CO2 emissions caused by the presence of the heat island effect while the maximum potential ecological footprint, provided that
all buildings are air conditioned, is almost 110,000 hectares.
Climatic measurements from almost 30 urban and suburban stations as well as specific measurements performed in 10 urban canyons in Athens, Greece, have been used to assess the impact of the urban climate on the energy consumption of buildings. It is found that for the city of Athens, where the mean heat island intensity exceeds 10°C, the cooling load of urban buildings may be doubled, the peak electricity load for cooling purposes may be tripled especially for higher set point temperatures, while the minimum COP value of air conditioners may be decreased up to 25% because of the higher ambient temperatures. During the winter period, the heating load of centrally located urban buildings is found to be reduced up to 30%. Regarding the potential of natural ventilation techniques when applied to buildings located in urban canyons, it is found that, mainly during the day, this is seriously reduced because of the important decrease of the wind speed inside the canyon. Air flow reduction may be up to 10 times the flow that corresponds to undisturbed ambient wind conditions.
It is a fact that the construction industry is the main consumer of energy and materials in most countries. The pursuit of sustainable development, defined in the Brundtland Report 1987 as “development that meets the needs of the present without compromising the ability of future generations to meet their own needs”, has become a major issue when trying to meet the challenges in providing proper housing for the ever-increasing world population. To increase the amount of information concerning bamboo several successful research programs have been carried out since 1979 at PUC-Rio and in Brazil. Vegetable fibres can be used either alone or as reinforcement in different types of matrices such as soil and cement composites. This paper presents the results of some of the recent studies of the microstructure of bamboo as a functionally gradient material. These studies led to the establishment of bamboo’s composite behaviour through the rule of mix. A concise summary regarding bamboo reinforced concrete beams, permanent shutter concrete slabs and columns is discussed. Finally, some recommendations for future studies are proposed with the hope that the newly developed material could contribute, on a large scale, to sustainable development without harming our globe.
Occupants’ behavior can significantly affect building performance, in particular in massive institutional buildings occupied by a wide variety of users. This work aims at highlighting the importance of peers’ personal attitudes in determining building thermal-energy, lighting performance and openings’ schedule. A university building located in central Italy was selected. Different rooms with equivalent end-use, geometry, exposure, construction characteristics, occupancy, and appliances were considered. Occupants were peers, since they carry out the same job and schedule and have the same education and age. Nevertheless, they presented different attitudes and thermal perception, therefore producing different energy need. In order to assess peers’ behavior, office rooms were continuously monitored in terms of indoor visual-thermal comfort parameters, electricity consumption, and door/window opening rate in spring, summer and winter conditions. Occupants’ attitudes were compared by considering also the outdoor climate conditions. Results demonstrated that occupants’ individual behavior represented a key variable affecting building management of large buildings even if the occupants can be theoretically assumed to be “peers”. Significant discrepancies were found between the monitored rooms, demonstrating that peers do not behave the same at all, but require differential energy needs that should be considered while predicting thermal-energy and lighting behavior of massive institutional buildings.
This paper describes a step-by-step procedure for using measured end-use energy data from a campus building to calibrate a simulation model developed in EnergyPlus. This process included identification of key input parameters for reducing uncertainties in the model. Building thermal zones were modeled to match the actual heating ventilation and air conditioning (HVAC) zoning for each individual variable air-volume (VAV) zone. We evaluated most key building and HVAC system components, including space loads (actual occupancy number, lighting and plug loads), HVAC air-side components (VAV terminals, supply and return fans) and water-side components (chillers, pumps, and cooling towers). Comparison of the pre- and post-calibration model shows that the calibration process greatly improves the model's accuracy for each end use. We propose an automated model calibration procedure that links the model to a real-time data monitoring system, allowing the model to be updated any time. The approach enables the automated data feed from simple measuring and actuation profile (sMAP) into the EnergyPlus model to create realistic schedules of space loads (occupancy, lighting and plug), performance curves of fans, chillers and cooling towers. We also field-tested demand response (DR) control strategies to evaluate the model's performance in predicting dynamic response effects. Finally, this paper describes application of the calibrated model to analyze control systems and DR strategies with the goal of reducing peak demand.
This research work deals with an Environmental Research Institute (ERI) building where an underfloor heating system and natural ventilation are the main systems used to maintain comfort condition throughout 80% of the building areas. Firstly, this work involved developing a 3D model relating to building architecture, occupancy & HVAC operation. Secondly, the calibration methodology, which consists of two levels, was then applied in order to insure accuracy and reduce the likelihood of errors. To further improve the accuracy of calibration a historical weather data file related to year 2011, was created from the on-site local weather station of ERI building. After applying the second level of calibration process, the values of Mean bias Error (MBE) and Cumulative Variation of Root Mean Squared Error (CV(RMSE)) on hourly based analysis for heat pump electricity consumption varied within the following ranges: (MBE)hourly from −5.6% to 7.5% and CV(RMSE)hourly from 7.3% to 25.1%. Finally, the building was simulated with EnergyPlus to identify further possibilities of energy savings supplied by a water to water heat pump to underfloor heating system. It found that electricity consumption savings from the heat pump can vary between 20% and 27% on monthly bases.
The investigation presented in this paper has three main objectives. The first one is to study, through a case study, if it is possible to acceptably predict the energy consumption of a massive residential free-running building, when the exact behavior of the occupants is unknown or actual indoor conditions are not monitored, assuming standard use and occupation schedules, for the dry climate of the Argentinean Northwest. The second objective of the paper is to detect the possible causes of differences between actual and predicted energy consumption through an exhaustive thermal monitoring and occupant's behavior, in order to obtain an improved model of the building giving more accurate predictions of the energy consumption. The third objective is to analyze the effect on the annual energy consumption of changing the massive envelope by a lightweight one. The comparison of real and simulated consumptions under comfort conditions defined by ASHRAE Standard 55 shows that simulations overestimated the energy consumption for heating and cooling. The main causes were detected from the experimental monitoring, indicating a lower use of the air conditioning equipment than the supposed initially. Simulations were improved to consider actual use and occupation conditions. Finally, an annual simulation of the improved model performed by changing the envelope material to a lightweight one showed that energy consumption for heating was increased, while energy consumption for cooling was decreased. In an annual balance, the massive walls are preferable over lightweight ones in arid sunny climates as in the Argentinean Northwest, giving energy savings of around 25%.
The short but intense heat wave in mid-July 1995 caused 830 deaths
nationally, with 525 of these deaths in Chicago. Many of the dead were
elderly. and the event raised great concern over why it happened.
Assessment of causes for the heat wave-related deaths in Chicago
revealed many factors were at fault, including an inadequate local heat
wave warning system, power failures, questionable death assessments,
inadequate ambulance service and hospital facilities, the heat island,
an aging population, and the inability of many persons to properly
ventilate their residences due to fear of crime or a lack of resources
for fans or air conditioning. Heat-related deaths appear to be on the
increase in the United States. Heat-related deaths greatly exceed those
caused by other life-threatening weather conditions. Analysis of the
impacts and responses to this heat wave reveals a need to 1) define the
heat island conditions during heat waves for all major cities is a means
to improve forecasts of threatening conditions, 2) develop a nationally
uniform means for classifying heat-related deaths, 3) improve warning
systems that are designed around local conditions of large cities, and
4) increase research on the meteorological and climatological aspects of
heat stress and heat waves.
The impact of microclimatic conditions in urban areas on the thermal loads of buildings has been appreciated fairly recently. The modulation of street canyons has led, inter alia, to temperature conditions that depart from the climatic data monitored at meteorological stations, affecting the heating balance of buildings, while the building operation affects the present conditions. The installation of air conditioning units leads to heat emission, which, at a microscale level, strengthens this phenomenon. The present paper outlines a computational approach to the street canyon phenomenon, with the determination of flow and temperature fields which are developed, and discusses their influence on the dynamic thermal balance of the building.
For the purpose of practical application of CFD for urban climate planning, a building canopy model coupled with CFD was developed, and the effects of building planting were discussed for the decrease of urban heat island phenomena and energy for cooling. In this paper, radiate heat exchange in the building canopy, the drag force model of building walls, the effects of heat released from air conditioning systems are presented. Numerical results show that building planting has possibilities for the reduction of air temperature by 0.4–1.3°C and energy for cooling by 3–25%.
The potential impact of Energy Conservation Building Code (ECBC) of India, that is applicable
on commercial buildings having more than 100kW connected load or 120kVA contract demand, has
been analyzed on six different type of buildings in Jaipur. Calibrated simulation models of these
buildings have been created using their existing specifications to estimate the energy saving potential
through ECBC. It has been found that the specific energy consumption of these buildings lie in the
range of 137 kWh/m2/yr for the case of government building to 386 kWh/m2/yr for the private office.
The energy saving potential with ECBC is in the range of 44 kWh/m2/yr in Government buildings as
lowest effect, whereas in case of the private office, it is estimated to be 128 kWh m2/yr. Percentage
energy savings with ECBC compliance in these buildings vary from 17% in the case of institutional
building to 42% in the case of Hospital building. Using these estimates and the trend of increase in
commercial building energy consumption, the potential of energy saving in the city of Jaipur has been
identified as 12,475 MWh/yr in the next five years.
This paper summarizes recent research on urban heat islands carried out in Europe. Recent studies to identify the amplitude of urban heat islands as well as the main reasons that increase temperatures in urban areas are identified and discussed for southern, mid- and northern Europe. Studies aiming to identify the energy impact of heat islands are presented, as well as those that explore the impact of heat islands on the cooling potential of natural and night ventilation techniques. New deterministic and data-driven models developed to estimate the amplitude of heat islands are discussed and the results are presented of recent research on mitigation techniques and, in particular, the impact of green spaces, as well as the development and testing of white and coloured cool materials.
This paper presents the results of a comparative study aiming to investigate the suitability of materials used in outdoor urban spaces in order to contribute to lower ambient temperatures and fight heat island effect. The study involved in total 93 commonly used pavement materials outdoors and was performed during the whole summer period of 2001. The thermal performance of the materials was measured in detail using mainly infrared thermography procedures. The collected data have been extensively analysed using statistical techniques. Comparative studies have been performed in order to identify the major advantages and disadvantages of the materials studied. Materials have been classified according to their thermal performance and physical properties into 'cool' and 'warm' materials. The impact of color, surface roughness and sizing has been analysed as well. The study can contribute to selection of more appropriate materials for outdoor urban applications, and thus assist to fight the heat island effect, decrease the electricity consumption of buildings and improve outdoor thermal comfort conditions.
Two of several surface modification (heat-island reduction) strategies, increased surface albedo and urban reforestation,
are evaluated via mesoscale meteorological and photochemical modelling of regulatory episodes in central and southern California.
The simulations suggest that these strategies can have beneficial impacts on air quality, with increased albedo being relatively
more effective than urban reforestation. The simulations also show that air quality indices, such as regional 1-h peaks, area
peaks, 8-h relative reduction factors, 24-h averages, etc., improve for both central and southern California and that for
the range of strategies evaluated here, the improvements in air quality can be significant. The simulations of southern California
suggest that there may be a threshold beyond which further surface modifications tend to produce smaller net improvements in ozone air quality.
A simple energy balance model which simulates the thermal regime of urban and rural surfaces under calm, cloudless conditions at night is used to assess the relative importance of the commonly stated causes of urban heat islands. Results show that the effects of street canyon geometry on radiation and of thermal properties on heat storage release, are the primary and almost equal causes on most occasions. In very cold conditions, space heating of buildings can become a dominant cause but this depends on wall insulation. The effects of the urban greenhouse and surface emissivity are relatively minor. The model confirms the importance of local control especially the relation between street geometry and the heat island and highlights the importance of rural thermal properties and their ability to produce seasonal variation in the heat island. A possible explanation for the small heat
The major Athens area is surrounded by high mountains to the north and the east and is influenced by the sea (Saronic Gulf) to the south. As a result of its topography, the city experiences significant variations in its ventilation patterns even over small distances.
The main purpose of the present study is to define places in the major Athens area where the heat island effect occurs. Several important climatic parameters are examined in combination with the application of various statistical tests. From this research it is mainly observed that the central and western industrialized parts of the city of Athens develop the “urban” heat island effect intensely. Nevertheless, district variations as regards the heat island intensity can be found in some regions, located close to the city centre and eastward of it, characterized by thick vegetation of trees or by “open areas”. Moreover, in places near the sea the air temperatures are higher in the cold period of the year, not because of the urbanization but mainly due to the influence of the sea, which favors the maintenance of high air temperatures. Last but not least, the persistence of high air temperatures during the hot period of the year or low air temperatures in the cold period is mostly related to the synoptic weather conditions and it cannot reasonably be considered as an index for the heat island effect development.
An intelligent data-driven method is used in the present study for investigating, analyzing and quantifying the urban heat island phenomenon in the major Athens region where hourly ambient air-temperature data are recorded at twenty-three stations. The heat island phenomenon has a serious impact on the energy consumption of buildings, increases smog production, while contributing to an increasing emission of pollutants from power plants, including sulfur dioxide, carbon monoxide, nitrous oxides and suspended particulates. The intelligent method is an artificial neural network approach in which the urban heat island intensity at day and nighttime are estimated using as inputs several climatic parameters. Various neural network architectures are designed and trained for the output estimation, which is the daytime and nighttime urban heat island intensity at each station for a two-year time period. The results are tested with extensive sets of non-training measurements and it is found that they correspond well with the actual values. Furthermore, the influence of several input climatic parameters measured at each station, such as solar radiation, daytime and nighttime air temperature, and maximum daily air temperature, on the urban heat island intensity fluctuations is investigated and analyzed separately for the day and nighttime period. From this investigation it is shown that heat island intensity is mainly influenced by urbanization factors. A sensitivity investigation has been performed, based on neural network techniques, in order to adequately quantify the impact of the above input parameters on the urban heat island phenomenon.
The rapidly growing world energy use has already raised concerns over supply difficulties, exhaustion of energy resources and heavy environmental impacts (ozone layer depletion, global warming, climate change, etc.). The global contribution from buildings towards energy consumption, both residential and commercial, has steadily increased reaching figures between 20% and 40% in developed countries, and has exceeded the other major sectors: industrial and transportation. Growth in population, increasing demand for building services and comfort levels, together with the rise in time spent inside buildings, assure the upward trend in energy demand will continue in the future. For this reason, energy efficiency in buildings is today a prime objective for energy policy at regional, national and international levels. Among building services, the growth in HVAC systems energy use is particularly significant (50% of building consumption and 20% of total consumption in the USA). This paper analyses available information concerning energy consumption in buildings, and particularly related to HVAC systems. Many questions arise: Is the necessary information available? Which are the main building types? What end uses should be considered in the breakdown? Comparisons between different countries are presented specially for commercial buildings. The case of offices is analysed in deeper detail.
Adopting our ‘cool communities’ strategies of reroofing and repaying in lighter colors and planting shade trees can effect substantial energy savings, directly and indirectly. In our target city of Los Angeles, annual residential air-conditioning (A/C) bills can be reduced directly by about US$100 M and, because these strategies serve to cool the air in the Los Angeles basin and reduce smog exceedance levels by about 10%, an additional savings of US$70 M in indirect cooling and US$360 M in smog-reduction benefits—a total savings of about US$1/2 B per year—is possible. Trees are most effective if they shade buildings, but the savings are significant even if they merely cool the air by evapotranspiration. In Los Angeles, avoided peak power for air conditioning can reach about 1.5 GW (more than 15% of the city's air conditioning). Generalized to the entire US, we estimate that 25 GW can be avoided with potential annual benefits of about US$5 B by the year 2015. Recent steps taken by cities in the warm half of US towards adoption of cool communities include (1) incorporation of cool roofs in the revised ASHRAE building standards S90.1 and (2) inclusion of cool surfaces and shade trees as tradeable smog-offset credits in Los Angeles. Other step underway include (1) plans by the US Environmental Protection Agency (EPA) to approve heat island mitigation measures in the state implementation plan to comply with ozone standards and (2) plans for ratings and labeling of cool surfaces.
The effect of the summer heat island of the western part of the Greater Athens area on cooling energy and peak power is investigated using the building energy estimating software DOE2.1.E [DOE2.1.E User's Guide, Lawrence Berkely Lab., CA, USA] and measured values of temperature and other meteorological data at selected sites. A very large difference between the cooling energy and peak power in the western Greater Athens area on one hand and the eastern edge of the heat island on the other hand, is evidenced for the year 1997. The difference is shown to be smaller for the year 1998 though, which was characterized by an exceptionally hot summer, which apparently affected the eastern part of the Greater Athens area more than the western part. The calculations made based on the typical meteorological year of Athens without taking the heat island related effects into account are shown to underestimate both energy consumption and peak power.
Due to the complexity of the underlying surface, urban boundary layers may exhibit very different wind-temperature field structures compared with rural areas. In this study, an urban boundary layer model with a resolution of 500 m is applied to Hong Kong, a place characterized by complex topography with high mountains and dense urban developments. Five surface land use types are considered; grass and shrub land, trees, water, old urban areas and new town developments. The urban boundary layer model is embedded into the National Center for Atmospheric Research (NCAR) Mesoscale Model, version 5 (MM5). The initial and boundary conditions are obtained from the National Centers for Environmental Prediction (NCEP)/NCAR reanalysis dataset. The modeling approach therefore takes into account both the mesoscale background field and the urban underlying surface. The model is applied to the simulation of a pollution episode in Hong Kong. Results show good agreement with meteorological data for the surface winds and temperature. The model successfully simulates the urban heat island and the occurrence of a sea–land breeze circulation, and their impact on air pollutant transport and dispersion.
The sensitivity of electricity consumption to air temperature and air humidity are effective indicators in evaluating the impacts of countermeasures against urban heat islands. The impacts of these countermeasures vary in time and space and so sensitivities based on finer resolution data are needed. Using actual hourly electric power consumption data from the business districts of Tokyo, we calculated the sensitivity of electric power consumption using multiple regression analysis. The sensitivities appear from 07:00 to 23:00 local standard time (LST) during weekdays during both winter and summer, mainly from 09:00 to 17:00 LST. The sensitivities to air temperature during winter are approximately 0.7–1.1 (W/floor-m2)/°C on an average and those during summer are approximately 1.1–1.4 on an average; the sensitivities to air humidity are approximately 0.6–0.9 on an average. It was found that the sensitivities to air temperature are caused due to heating during winter and cooling during summer; further, the sensitivities to air humidity were caused by dehumidification not for conditioning the air humidity of the room but for the condensation around the air-conditioner's coils with cooling during summer.
In the summers of 1991 and 1992, we monitored peak power and cooling energy savings from high-albedo coatings at one house and two school bungalows in Sacramento, California. We collected data on air-conditioning electricity use, indoor and outdoor temperatures and humidities, roof and ceiling surface temperatures, inside and outside wall temperatures, insolation, and wind speed and direction. Applying a high-albedo coating to one house resulted in seasonal savings of 2.2 kWh/d (80% of base case use), and peak demand reductions of 0.6 kW. In the school bungalows, cooling energy was reduced 3.1 kWh/d (35% of base case use), and peak demand by 0.6 kW. The buildings were modeled with the DOE-2.1E program. The simulation results underestimate the cooling energy savings and peak power reductions by as much as twofold.
This paper presents the results of a comparative study aiming to investigate the effect of reflective coatings on lowering surface temperatures of buildings and other surfaces of the urban environment, and thus test their suitability to lower ambient temperatures and fight the heat island effect. In total, 14 types of reflective coatings, selected from the international market were studied, from August to October 2004, on a 24 h basis. These coatings are used in buildings and some of them are used or could be used in the future in other surfaces of the urban environment (sidewalks, parking lots, etc.). In order to investigate the thermal performance of the reflective coatings, surface temperature sensors and a data logging system as well as infrared thermography procedures were used. The spectral reflectance and the infrared emittance of the samples were also measured. The collected data have been extensively analyzed. It was demonstrated that the use of reflective coatings can reduce a white concrete tile’s surface temperature under hot summer conditions by 4 °C and during the night by 2 °C. It can be warmer, than the ambient air by only 2 °C during the day and cooler than the ambient air by 5.9 °C during the night. “Cool” coatings present superior thermal performance even compared to other “cool” materials. This study can assist in choosing more appropriate coatings for building envelopes and other surfaces of the urban environment, and thus contribute to the mitigation of the heat island effect as well as the reduction of cooling loads and electricity consumption of buildings.
In Singapore, rapid population influx has led to demands for converting natural areas to pubic housing. The heat island in Singapore city has been documented. However, less attention has been placed on the cooling effect of city's green areas. To address this issue, temperature and humidity measurements were conducted in two big city green areas. One is the city's natural reserve—Bukit Batok Nature Park (BBNP) (36 ha) and the other is a neighbourhood park—Clementi Woods Park (CWP) (12 ha). The measurements were conducted at both vegetated areas and their surroundings. The results indicated the cooling effects of city greens are remarkable not only at vegetated areas but also the surrounding built environments. To further explore the role of the green area on moderating the microclimate, two simulation programmes, TAS and Envi-met, were employed, respectively, for the two parks. The aims are to explore the patterns of energy consumptions of a typical commercial building near to Bukit Batok Nature Park and different thermal conditions with and without Clementi Woods.
Energy use and environmental parameters were monitored in two small (14.9 m2) non-residential buildings during the summer of 2000. The buildings were initially monitored for about 1 1/2 months to establish a base condition. The roofs of the buildings were then painted with a white coating and the monitoring was continued. The original solar reflectivities of the roofs were about 26%; after the application of roof coatings the reflectivities increased to about 72%. The monitored electricity savings were about 0.5 kWh per day (33 Wh/m2 per day). The estimated annual savings are about 125 kWh per year (8.4 kWh/m2); at a cost of $0.1/kWh, savings are about $0.86/m2 per year. Obviously, it costs significantly more than this amount to coat the roofs with reflective coating, particularly because of the remote locations of these buildings. However, since the pre-fabricated roofs are already painted green at the factory, painting them a white (reflective) color would bring no additional cost. Hence, a reflective roof saves energy at no incremental cost.
Field observations were carried out to determine the influence of a park on the urban summer climate in the nearby areas. The possibilities of reduction in air conditioning energy were investigated. Air temperature, relative humidity and other meteorological factors were measured at many locations inside a park and in the surrounding areas in the Tama New Town, a city in the west of the Tokyo Metropolitan Area, Japan. The observations indicated that vegetation could significantly alter the climate in the town. At noon, the highest temperature of the ground surface of the grass field in the park was 40.3 °C, which was 19 °C lower than that of the asphalt surface or 15 °C lower than that of the concrete surface in the parking or commercial areas. At the same time, air temperature measured at 1.2 m above the ground at the grass field inside the park was more than 2 °C lower than that measured at the same height in the surrounding commercial and parking areas. Soon after sunset, the temperature of the ground surface at the grass field in the park became lower than that of the air, and the park became a cool island whereas paved asphalt or concrete surfaces in the town remained hotter than the overlying air even late at night. With a size of about 0.6 km2, at noon, the park can reduce by up to 1.5 °C the air temperature in a busy commercial area 1 km downwind. This can lead to a significant decrease of in air conditioning energy in the commercial area.
The impact of climate changes on the urban environment may be assessed by calculating the modifications in energy production and consumption for such daily operations as heating and cooling. In this study climate changes in the southeastern Mediterranean (the area of Greece) were simulated for the year 2030 on the basis of specially constructed climatic scenarios which describe potential reductions in the emissions of greenhouse gases, and were, thereafter, used to calculate the heating and cooling degree days for the same year. The results show that the cumulative amount of heating and cooling degree days will decrease and increase, respectively, as compared to the respective amounts for the year 1990. In terms of the cooling degree days, it was found that the areas most affected were the Attica and central Macedonia regions, the Aegean islands and Crete, whereas in terms of the heating degree days, it was found that a large part of the country will require less energy for heating.
This paper describes the London Site Specific Air Temperature prediction model, which comprises of a suite of artificial neural network (ANN) models to predict site-specific hourly air temperature within the Greater London Area (GLA). The model was developed using a back-propagation ANN model based on hourly air temperature measurements at 77 fixed temperature stations (FTS) and hourly meteorological data (off-site variables) from Heathrow; it also includes six on-site variables calculated for each FTS. The temporal and spatial validity of the model was tested using data measured 7 years later from the original dataset, which include new FTS locations. It was found that site-specific hourly air temperature prediction is within accepted range and improves considerably for average daily and monthly values. Therefore, the model can be used with confidence to predict daily and seasonal variations of air temperature within the GLA and in particular for the calculation of monthly and annual heating degree days (HDD) and cooling degree hours (CDH). It was found that as expected HDD increase and CDH decrease with distance from the urban heat island centre point; however, all variations cannot be explained with distance and six key on-site variables namely aspect ratio, surface albedo, plan density ratio, green density ratio, fabric density ratio and thermal mass have been identified to explain the remaining variation.
Urban Heat Island (UHI) is considered as one of the major problems in the 21st century posed to human beings as a result of urbanization and industrialization of human civilization. The large amount of heat generated from urban structures, as they consume and re-radiate solar radiations, and from the anthropogenic heat sources are the main causes of UHI. The two heat sources increase the temperatures of an urban area as compared to its surroundings, which is known as Urban Heat Island Intensity (UHII). The problem is even worse in cities or metropolises with large population and extensive economic activities. The estimated three billion people living in the urban areas in the world are directly exposed to the problem, which will be increased significantly in the near future. Due to the severity of the problem, vast research effort has been dedicated and a wide range of literature is available for the subject. The literature available in this area includes the latest research approaches, concepts, methodologies, latest investigation tools and mitigation measures. This study was carried out to review and summarize this research area through an investigation of the most important feature of UHI. It was concluded that the heat re-radiated by the urban structures plays the most important role which should be investigated in details to study urban heating especially the UHI. It was also concluded that the future research should be focused on design and planning parameters for reducing the effects of urban heat island and ultimately living in a better environment.
Cooling Our Communities -A Guidebook On Tree Planting and Light Colored Surfacing
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Monitoring the effect of urban green areas on the heat island in Athens
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areas on the heat island in Athens, Environ. Monitor. Assess. 156 (2009)
Santamouris , I. Livada , A study of the thermal performance of reflective coatings for the urban environment
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of reflective coatings for the urban environment, Solar Energy 80 (8) (2006)
Greening red earth: Bamboo's Role in Environment and Socio-Economic Rehabilitation of Villages Devastated by Brick Mining, International Network for Bamboo and Rattan
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Rehabilitation of Villages Devastated by Brick Mining, International Network
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Designing and Building with Bamboo
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Bamboo-the gift of gods
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