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Mitigating the Urban Heat Island effect through building envelope modifications
Abstract
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.
... Urban built environments are characterized by imbalanced microclimates that are caused by high building density, the concentration of building materials, few green surfaces, and excessive anthropogenic heat generation. These parameters lead to a higher temperature in urban areas (e.g., a UHI) by affecting the radiant surface heat balance, convective heat exchange between the ground and buildings, wind flows, and evapotranspiration processes (Kandya and Mohan 2018). The UHI was coined by the British climatologist Gordon Manley in the 1950s (Adamowski and Prokoph 2013;Manley 1958). ...
... An UHI could cause thermal discomfort inside and outside buildings and affect the well-being of urban residents (Kandya and Mohan 2018) in different climates (Leal Filho et al. 2018;Mazzeo et al. 2023;da Silva Espinoza et al. 2023). In Manaus, Brazil, for example, a 6°C heat index difference between urban and rural areas and a nighttime UHI of 4°C is reported to have caused significant outdoor thermal discomfort (da Silva Espinoza et al. 2023). ...
... In addition, a UHI has bilateral relationships with energy consumption and climate change; where the increased temperature in urban areas leads to greater cooling energy demand in the building sector and a feedback loop is created when higher energy consumption and the corresponding carbon dioxide (CO 2 ) emissions lead to anthropogenic climate change and aggravated UHIs (Kamal et al. 2023;Wang et al. 2022). Specifically, the literature reports a 20%-100% growth in cooling energy consumption due to UHIs (Kandya and Mohan 2018;Santamouris et al. 2001). Other environmental impacts that are associated with UHIs include a contribution to ozone layer depletion (Bartholy and Pongrácz 2018), deterioration in the living environment (Sadik-Zada and Gatto 2022), increase in ground level smog (Fallmann et al. 2016), and the concentration of air pollutants (Santamouris and Osmond 2020). ...
... The surface temperature may be significantly increased for a multitude of reasons, such as an increased urban building density, a decreased amount of green cover, and an increase in the number of different sources of heat production [7], [8]. The high buildings in metropolitan areas are one of the issues because they slow down the wind and decrease the amount of heat that is removed through convection [1]. ...
... This phenomenon, which is commonly known as the "heat island effect," is considered to be one of the most significant challenges that humans will face in the 21st century. It is also related to a very significant increase in the amount of cooling energy that is required by buildings and a global decline in environmental conditions [7], [9]. UHI has become interesting to scientists and engineers due to the negative environmental and economic impacts on society (for example, the worsening of the human living environment, a rise in energy consumption, an increase in ozone elevation level, as well as an increase in mortality rates) The quantity of ozone and smog at the ground level is increased when the temperature at higher levels is present [7], [10]. ...
... It is also related to a very significant increase in the amount of cooling energy that is required by buildings and a global decline in environmental conditions [7], [9]. UHI has become interesting to scientists and engineers due to the negative environmental and economic impacts on society (for example, the worsening of the human living environment, a rise in energy consumption, an increase in ozone elevation level, as well as an increase in mortality rates) The quantity of ozone and smog at the ground level is increased when the temperature at higher levels is present [7], [10]. UHI raises demand for energy costs for cooling, disrupts hydrologic, climatic, and biophysical cycles inside this environment, and harms not only people but also natural ecosystems [3]. ...
Near-Surface Temperature (NST) is defined as air temperatures at two meters
above the land surface; it is affected by many factors like; land surface temperature (LST),
which has been influenced by latitude, solar radiation, day duration length, land cover
type, and elevation. Air temperature (Ta) is traditionally measured by meteorological
stations, but the low density of meteorological stations, the limited coverage, the high
cost, and the errors resulting from the air temperature for areas relatively far from
meteorological stations. There was an urgent need to calculate NST through satellite
images which gives availability to calculate LST and other environmental factors with
more information, wide coverage, and more accuracy than meteorological data.
This thesis includes modeling NST based on metrological data and satellite
images using geomatics techniques to study UHI and studying strategies to mitigate iits
effects. Landsat 8 images were used (after geometric corrections, mosaics, and clipping
of the study area) to estimate independent parameters (LST, Duration Day Length DDL).
Digital Elevation Model (DEM) from Shuttle Radar Topography Mission (SRTM) is also
independent parameter (because SRTM elevation data are used in scientific fields and
application software like a Geographic Information System (GIS)), and (Ta) from the
meteorological station a dependant parameter, these parameters were inputs to estimate
model coefficients for modeling NST using linear regression.
Sentinel -2- images were used after pre-processing to calculate Normal
Distribution Vegetation Index (NDVI) to understand the relationship between NST and
vegetation cover. Super classification applied on Sentinel -2- images to classify the study
area into four categories (vegetation, built-up, water bodies, and bare land) using the
maximum likelihood classify method (MLC) to understand the correlation between NST
and land cover.
The results show that NST and Vegetation areas have a negative relationship,
but the built-up areas have a positive relationship with NST. The difference between air
temperature observed from weather stations and NST calculated by the model was
between -0.44 to -0.48 on 9 July 2021, and it was about 0.93 on 25 July 2021. Linear
regression using SPSS show that the root error estimated is (0.801) on 9 July and (0.519)
on 25 July
... 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 [12]. 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 [13]. 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. [11] • High thermal inertia provides thermal comfort [12] • HW reduce energy for air conditioning [13] • HW stabilizes indoor air temperature [18] Thermal Mass Impact • Increase in outdoor air temperature with HW in the afternoon [11] • HW can increase UHI phenomenon [19] • Façade type has significant impact on UHI [20] • Local climatic conditions are critical on heat transfer through wall [18] [11] ...
... Adding a cavity on a brick wall offers the highest reduction in the power consumption for space cooling [13]. [14] • ACP provides lower surface temperatures [26] • Palm particle coating on the surface results temperature difference of nearly 4.5 °C [27] • Texture geometry of façade surface is important [27] • External insulation is better than internal by 8% [28] • Internal insulation costs 50% less [28] • 64% reduction in energy demand during summer [29] • Polyurethane gives highest advantage [29] Additional Metal Sheet -Alter the Impact • UHI mitigation is provided with green wall [14] • 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 [11]. ...
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 [19]. 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 [19]. ...
... 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 [19]. ...
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.
... Construction in other countries such as India is experiencing great growth due to the increase in buildings, which increased the use of materials and illegal mining to obtain these materials such as brick, cement and sand (Rautray et al, 2019), which generates a problem since in this country there are deaths due to greenhouse gas emissions (Seay et al., 2021), likewise in the United States 1000 Americans die annually caused by extreme heat (Kandya & Mohan, 2018). ...
... The production of cement generates 7% of carbon dioxide CO2 emitted worldwide and the manufacture of bricks that for each brick 0.41 kg of CO2 carbon dioxide is contaminated (El-Mahllawy, 2018), this is how hemp bricks It provides an effective and friendly solution for the environment, likewise the benefits are a lot as well as in the reduction of humidity and keeping the air fresh inside a house and being able to maintain a stable temperature inside the hemp walls 2015), suck the environmental contamination from the beginning of the use until the end of the limit of its life that is 100 years and this thanks to the addition of lime that has the potential to insulate the heat that allows energy savings (Griffiths, 2012). Therefore, Kandya and Mohan (2018) state that the bricks must comply and have larger holes to be able to ventilate and generate greater cooling in places where temperatures exceed what is allowed. do, however for cold climates it is required that they be with smaller holes. ...
In the construction industry there are several problems that negatively impact the environment from the process of obtaining materials, the construction of buildings and their use. That is why the bibliographic review research analyzes the use and application of the hemp-based brick with the support of the Scopus database and the VOSviewer software as data analytics, the characteristics of the brick were taken into account as well As an air pollution purifier, humidity reduction and thermal insulation, graphs related to these characteristics were obtained, highlighting the words with the highest frequency in the research, countries that published and bibliometric maps worldwide. The results help us determine that there is an application of this brick in countries with the greatest needs and growth and also in potential countries, however we believe that in Peru there is no analysis or interest in this brick. This hemp-based brick has positive advantages for the environment and is potentially ecological from the beginning of obtaining the materials, used in the construction of houses and then as waste, in these three phases it contributes to the environment. The purpose of the research is to be the beginning for future investments and research related to the hemp-based brick applied in the construction industry and the other objective is to motivate professionals to use and apply this brick that will have benefits for the environment.
... 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 [81]. 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 [81]. 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 [82]. ...
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 [56], higher thermal mass materials [44,61] incorporation of vegetation [67] and higher insulation value [43], 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.
... 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 [2]. 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 [4]. ...
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 [81]. 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 [81]. 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 [82]. ...
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.
... In this article, we consider the UHI case of India (Table 3). The meta-analysis reveals that among the 17 studies considered, 11 have adopted a macro scale city level UHI assessment (Mallick et al., 2013;Sharma and Joshi, 2014;Kikon et al., 2016;Mathew et al., 2016;Yadav et al., 2017;Choudhury et al., 2018;Dwivedi and Khire, 2018;Mathew et al., 2018;Yadav and Sharma, 2018;Ziaul and Pal, 2018;Mathew et al., 2019) whereas, 2 of the studies consist meso scale LCZ level assessment (Thomas et al., 2014; by employing techniques of remote sensing, and 4 of the studies have analyzed microscale neighborhood level UHI (Borbora and Das, 2014;Dwivedi and Mohan, 2018;Kandya and Mohan, 2018;Chatterjee et al., 2019) with the help of microclimatic simulation modelling. These studies have concluded that anthropogenic heat makes the thermal situation more uncomfortable (Ziaul and Pal, 2018;Mathew et al., 2018;Yadav and Sharma, 2018;Mathew et al., 2019;Singh et al., 2017) water bodies and vegetated areas (Dwivedi and Mohan, 2018) have lesser land surface temperature. ...
... These studies have concluded that anthropogenic heat makes the thermal situation more uncomfortable (Ziaul and Pal, 2018;Mathew et al., 2018;Yadav and Sharma, 2018;Mathew et al., 2019;Singh et al., 2017) water bodies and vegetated areas (Dwivedi and Mohan, 2018) have lesser land surface temperature. Studies have also reported that various surface material options like green roofing and bamboo as a building materials can improve thermal performance (Kandya and Mohan, 2018). Another study has discussed that major commercial and industrial areas are more vulnerable to UHI (Sharma and Joshi, 2014). ...
... Consequently, these surfaces lack the natural cooling mechanism provided by the cycle of water flow and evaporation (M. Ahmad et al., 2024;Kandya & Mohan, 2018). The incorporation of urban greenery has the potential to alleviate air temperatures and subsequently reduce energy consumption for cooling purposes (Akbari et al., 1997;Ali et al., 2024). ...
Alteration in Land use land cover over time have demonstrated their significant role in shaping the patterns of UHI observed across cities worldwide. This research endeavours to examine alterations in LULC, and Land surface temperature (LST) in the Patna Municipal Corporation (PMC), Bihar. The application of remote sensing techniques and GIS methodologies was employed to scrutinize the satellite data encompassing 2002 to 2023. Additionally, ground validation was also executed to authenticate the observed modifications in LULC and temperature changes during the designated time period. Moreover, the correlations between LULC indices such as the NDBI, NDVI, MNDWI, and NDBaI With the Normalised LST (NLST) have been established. The results highlight an increase of 2990.31 ha in the area affected by UHI in zone 5 of PMC. The findings reveal a positive correlation between NLST and all indicators except NDVI and MNDWI. These two indicators exhibit a negative correlation, having coefficients of correlation value −0.606, −0.516, and −0.268, −0.245, respectively, during the specified time periods. The research contributes to a more comprehensive understanding of the spatial dynamics of the heat island effects in a developing country's, and can be proved useful for mitigating its affect to ensure sustainability. KEYWORDS Urbanization; land use land cover; LULC indices; urban heat islands; land surface temperature; normalised land surface temperature
... Since then, there are much research have been conducted to study on the potential mitigation measures and solution of minimizing the effects of UHI. There are various of aspect has been explore and proposing innovative mitigation technologies, such as cool-pavement, green roof, modification of building envelope and reservation of green park [10][11][12][13][14][15]. ...
Cool-pavement technology has emerged as a potential solution to environmental issues posed by the urban heat island phenomenon, with surface temperature acting as a vital parameter in the evaluation of its thermal performance. This study focuses on the thermal performance results of modified asphalt concrete mix, wherein palm oil shell (POS) serves as a replacement for fine aggregate. Modified asphalt samples prepared using the Marshall Mix Design, with varying degrees of fine aggregate substitution (0%, 10%, 20%, 30%, 40%, and 50%), underwent a 24-hour continuous surface temperature measurement over a span of 20 days, under real-world tropical climate conditions. The findings demonstrated that sample P5, comprising 50% fine aggregate substitution, exhibited the highest reduction in surface temperature when compared to control sample P0, registering a significant decrease of up to 3.29°C during the period of peak solar intensity. ANOVA test-based statistical analyses confirmed significantly lower temperatures for all test samples, barring sample P1 (10% aggregate replacement), relative to the control sample. The results highlight the efficacy of POS as a fine aggregate substitute in asphalt concrete, significantly lowering asphalt pavement surface temperature, thereby endorsing the potential use of POS-modified asphalt in cool-pavement applications.
... Goal 11 is specifically directed at making "cities and human settlements inclusive, safe, resilient and sustainable" in urban areas [18]. It is critical to implement the mitigation strategies to lessen the adverse impacts of UHI [19] [20]. So this research focuses on exploring the influence of various urban surfaces and green cover on microclimate. ...
The change of natural land cover to impervious surfaces, dense built forms in cities causes built areas to experience high temperature than surrounding suburbs. This leads to urban heat island phenomenon which affects the microclimate. Despite the various studies supporting the importance of urban fabric, there is still a need to demonstrate how the urban surfaces can impact the temperature of surrounding areas. The purpose of this study is to determine the temperature change due to urban fabric by analyzing the role of materials having different albedo, reflectance and vegetation in changing the air and surface temperatures within a city. Existing case of an institutional campus (State University of Visual and Performing Arts, Rohtak, India) is undertaken for examining the temperature change at different urban surfaces by using the ENVI-met simulation software. The study area is analyzed for two scenarios involving the existing case (EC), proposed case (PC) scenario to understand the impact of different surface materials and vegetation on temperature. Surface and air temperature in both scenarios are extracted at two different heights-pedestrian level and canopy level. It is analyzed that different urban surfaces and construction materials play an effective role in varying the surface temperature and heat island intensities. Result shows potential benefits of increasing the albedo and reflectivity of pavements and roofs inside the city which helps in lowering surface temperature of walls and roofs and also lowering the air temperature around the surfaces. Along with this, vegetation also play an important role by creating a cooler environment by shading and reducing the surfaces temperature of built surfaces in an area. Therefore, adapting to essential urban green strategies can save city’s future from risks of urban heat islands.
... Moreover, research has also indicated that opting for lightweight materials, like gypsum walls, plywood boards, and even glass-fibrereinforced-concrete with appropriate wool insulation, can decrease fluctuations in the temperature of adjacent spaces by improving infrared emissivity (Wonorahardjo et al., 2020;Khadraoui and Sriti, 2018). However, incorporating high thermal inertia materials in buildings has been shown to have mixed effects on outdoor thermal comfortdepending on the time of dayas this is partly influenced by building shell material choices and facade modifications (Khadraoui and Sriti, 2018;Kandya and Mohan, 2018). ...
... Contributing to the knowledge on UHI mitigation strategies, this study breaks new ground by examining the relationship between reflective materials and indoor thermal environments in various geographical settings, thereby advancing our understanding of UHI mitigation strategies. The paper delves into the effectiveness of three reflective materials-DHR coatings, GR coatings, and RR coatings-in shaping indoor thermal conditions, aligning with the holistic approach advocated by Kandya & Mohan [15], Irfeey et al. [16], and Petrucci [17]. Emphasizing the solar reflectance properties of these coatings, the research evaluates their performance across diverse environmental conditions. ...
HIGHLIGHTS • DHR and RR coatings reduce indoor air temperatures, enhancing comfort indoors. • DHR and RR coatings lower external surface temperatures, especially on east, west, and horizontal surfaces. • DHR and RR materials consistently exhibit high solar reflectance, crucial for influencing surface temperatures. • RR material with 76% reflectance closely matches DHR (82%), effective for UHI mitigation. • Context-specific strategies aid UHI mitigation by architects, considering building orientations and environmental factors. ARTICLE INFO Keywords: Urban heat island Reflective materials Indoor thermal environment Solar reflectance Simplified building model ABSTRACT This in-depth study explores the intricate dynamics of reflective materials, emphasizing their impact on the indoor thermal environment and urban heat island (UHI) mitigation. Examining diffuse highly reflective (DHR), general reflective (GR), and retro-reflective (RR) materials on a simplified building model during summer days, the research utilizes outdoor experiments to analyze air and surface temperatures, as well as solar radiation. Prioritizing key metrics-mean radiant temperature (MRT), operative temperature (OT), and solar reflectance (ρ)-the study uncovers nuanced distinctions in DHR, GR, and RR materials. Solar reflectance calculations consistently show higher values for DHR and RR materials compared to GR material, highlighting re-flectance's pivotal role in influencing surface temperatures and indoor thermal environment. When evaluating the impact of exterior wall materials on building temperatures, RR material with a 76% reflectance performs similarly to DHR material (82%). Notably, with a 6% lower re-flectance in RR, the temperature contrast between external and internal walls is only about 1.5°C at its maximum, underscoring RR's effectiveness as an outer wall material for UHI mitigation and building energy conservation, surpassing both DHR and GR materials. Case Studies in Thermal Engineering 57 (2024) 104333 2 J. Yuan et al. Nomenclature UHI Urban Heat Island SR Specular reflective GR General reflective RR Retro-reflective DHR Diffuse highly reflective MRT Mean radiant temperature [ o C] OT Operative temperature [ o C] SAT Sol-air temperature [ o C] SET * Standard effective temperature [ o C] COT Change in operative temperature [ o C] F View factor [-] (a value of 65% obtained from fisheye lens photography) ρ Solar reflectance of the model surface [−] ρ g Ground reflectance [-] (set at 0.15) I i Incident shortwave solar radiation [W/m 2 ] I r Shortwave solar radiation reflected on the model surface [W/m 2 ] θ Room temperature [°C] S i Area of i-th peripheral wall, ceiling, floor, etc. [m 2 ] θ wn Area-weighted average peripheral wall temperature [ o C] θ i Surface temperature of the i-th peripheral wall, ceiling, floor, etc. [ o C]
... The study suggests the adaptation of indigenous design architecture as an effective method to mitigate UHI impacts. A study by Kandya and Mohan (2018) investigated the thermal performance of composite building materials like 'Bamboo-Concrete', 'Rammed Earth', and the impact of building envelope modifications like increased wall thickness and cavity wall through simulation. They suggested a 7.5% reduction in power consumption for space cooling using 'Bamboo-Concrete', and 4.7-5.3% ...
Urbanization results in rising temperature over urban areas forming an ‘urban heat island (UHI)’ phenomenon. Cities worldwide are facing the growing problem of the UHI effect. Internationally, the UHI intensity of up to 12°C and up to 9°C in Indian cities is observed. Although the numerical modeling studies are limited in this sense, simulations suggest up to 5°C UHI intensity over medium to large-size Indian cities. The sustainable development goals at an urban scale can be achieved by improving the UHI mitigation measures. Although UHI and its impacts have been studied extensively over major cities globally, it is relatively less over India. The UHI mitigation technologies are under development, and application is minimal. The various mitigation measures, technologies, and their efficiencies need to be transferred to the designers and planners for practicing sustainable city developments. The current review intends to briefly present the UHI scenarios and available technologies for mitigation measures worldwide. A systematic review of actual developments of UHI mitigation over Indian cities is presented with the possible suggested adaptation process. Adopting suitable UHI mitigation measures requires a specific background understanding of the local climate zone (LCZ) besides the inherent UHI phenomena, which is found limited over Indian cities. Although the knowledge of UHI is taking a leap using the LCZ based studies over India, the mitigation part is yet to be discovered. This review work would possibly help advance the knowledge in the Indian perspectives by aggregating the learnings from international practices.
... Whilst some authors argued that medium resolution LST may be sufficient for understanding the intra-urban heat variation (Kianmehr et al. 2023), others demonstrated that finer resolution LST can be important, especially when ascertaining the cooling distance of UGS (Zawadzka et al. 2021) at a neighbourhood scale. Moreover, micro-scale studies focussing on thermal comfort within buildings (Kandya and Mohan 2018;Alexander 2021;Tian et al. 2021) have brought out the importance of fine resolution imagery. Given that very fine (< 5 m) spatial resolution open-source LST data is not currently available, LST downscaling can be used to sharpen the existing open-source medium to low resolution thermal satellite imagery through their proven relationship with high-resolution ancillary data (Zhan et al. 2013), including spectral indices such as the NDVI (Agam et al. 2007), NDBI and others (Zawadzka et al. 2020a). ...
Context
Urban parks are essential for maintaining aesthetics within cities and keeping their its energy balance by helping mitigate the Urban Heat Island (UHI) effect through controlling ambient and land surface temperature (LST).
Objectives
To investigate the impact of cooling in terms of distance by variously configured urban parks of a humid subtropical city, using landscape metrics and open-source data.
Methods
Land use (LU) was obtained through maximum likelihood classification of 3 m resolution aerial RGB-NIR imagery supported by ground control points and park boundaries collected during field survey. LST at matching resolution was obtained through downscaling of Landsat-8 LST at 30/100m resolution, calculated with the Radiative Transfer Equation (RTE). Landscape metrics for patches of parks were calculated using landscapemetrics R library and related to neighbourhood distances over built-up land use (LU).
Results
Urban parks with homogenous cores and less complex shape provide distinctly higher cooling of neighbouring built-up LU of circa 2.55 °C over the distance of 18 m from park boundaries. Four metrics: contiguity index (CONTIG), core area index (CAI), fractal dimension index (FRAC) and perimeter-area ratio (PARA) represent significant relationship between spatial configuration of parks and their cooling distance. No cooling capacity of parks regardless of their shape and core was observed beyond the distance of 18 m, which remained constant with small fluctuations in the range of 0.5 °C up to the distance of 600 m.
Conclusions
The study concludes that cooling distance of urban parks in their neighbourhood extends up to 18 m, which is shorter than suggested by other studies.
... Building Envelope and Surface Materials can reduce urban heat island (UHI) effect and improve overall building performance [18,19]. ...
With the increasing frequency and intensity of extreme climate events in cities, it is essential to develop multi-scale and multi-hazard design tools to ensure urban climate resilience. A designed approach to urban development across spatial scales offers the opportunity to integrate diverse fields to create a strong multidisciplinary knowledge base and avoid fragmented planning approaches. This paper proposes a process-based methodological framework for climate resilient urban design-integrating analysis of climate impact with concerns of local communities. A combined focus on climate impact and co-benefits enables a design process with the ability to promote adaptation and mitigation while also addressing diverse urban challenges and responding to local needs and priorities. The proposed methodological framework is applied in the context of the climate resilient urban redevelopment of the Porte de Montreuil district in Paris, France. The results show that the Porte de Montreuil area is at risk from heat waves as a result of the urban characteristics of the area. However, it is possible to suggest specific design measures that integrate local planning priorities with climate resilient design measures to decrease the risk and improve climate resilience in the area.
... On the other hand, studies of the phenomenon of infrared emissivity in an examination of heavyweight versus lightweight building envelope component choices [69,70] have also noted that the use of lightweight materials such as, gypsum walls, plywood boards and even glass-fibre-reinforced-concrete (GFRC) -properly lined with wool insulation may account for a reduction of interior temperature fluctuations. In yet another study, the research carried out [70,71] indicated that buildings that incorporate high thermal inertia material choices, have a positive effect on the thermal comfort of a building's users at certain times of day, but of questionable benefit to thermal comfort conditions for users in the outdoors, the thermal behaviour of which is partly governed by material choices and façade modifications of a building shells. ...
... As the built environment affects the surface energy balance and causes UHI, high-performance building envelope approaches should be used to reduce the negative impacts [9]. Modifying the building envelope can reduce UHI [10][11][12] and reduce the energy required for indoor cooling [13]. A successful mitigation strategy for boosting resistance to the effects of global warming is to use methods for reducing heat gain by using urban surface parameters on large spatial scales [14]. ...
Living walls are a nature-based strategy to enhance climate resilience in urban areas. There is a need to study the possible influence of living walls on the thermal performance of building façades, given the rising temperatures in 2022 across the UK. This study aims to analyze the impacts of living walls on façade temperature based on orientation variation through simulation Envi-met 5.0.3. software. The living wall studied is attached to a multistory building located in Manchester city center consisting of seven evergreen plants. An environmental simulation was carried out linked to the 2022 climate, including extremely hot and cold days. Four scenarios of façades with and without greening on the northwest and southeast orientations in summer and winter were analyzed. The results highlighted the living wall’s ability to reduce the surface temperatures on both the northwest and southeast façades on a hot summer day. There is no significant evidence of improvement for the northwest façade in the winter climate, but a modestly increased temperature is shown in the southeast compared to the bare wall. These findings indicate that living walls provide measurable advantages in the building envelope, leading to energy saving.
... The two-thirds distribution of these vernacular buildings with variations is reported to be across Shanxi, Lingnan, Minnan, Hakka, Gan, Yaodong, Tibet, Xinjiang, and others [23,[25][26][27] . Owing to the geographic metric of latitudinal variation, the climatic differentials across subarctic to tropical regions of vernacular building thermal comfort adaptive strategies deployed into modern architecture have shown fitting adoptable efficient potential of ventilation, air tightness, thermal capacity, passive solar gains and passive solar controls [28][29][30][31] . Comparative temperature and psychrometric measurements across these regions with the intent of reporting vernacular building air leakage profile are in this study reproduced for extended treatment [18] . ...
The purpose of this paper is to provide understanding of the seasonal pattern of air leakage (infiltration) in Chinese vernacular buildings across China’s five climate regions. In achieving the set purpose, a grand extensive literature survey was conducted and supported with data drawn from established Meteonorm V6.1 on sensible heat and psychrometric variables. Numerical computations for normalized and specific infiltration from stack effects followed the Gowri method in line with ASHRAE reference 2004. Solar energy admittance into building followed Bouger’s model form Angstrom properties. From the distribution of vernacular buildings across five climate regions of China, evidence from computational and numerical values showed symmetries in terms of minimums and maximums times of occurrence. Further, a reciprocal pattern exists between solar radiative admittance and region’s temperature profile. Knowing that Chinese vernacular building heritage extended to further Asia, this research became limited to only the Chinese region. It became difficult to report if the construction culture away from China has correlation with infiltration and energy admittance value. Earlier works on Chinese climate and vernacular dwellings reported a climate responsive dwelling designed by passive cooling strategy; a gap was closed by extending the previous work to specific infiltration pattern and energy admittance level. Chinese vernacular buildings by virtue of research outcomes are and should be adoptable to modern housing needs for cultural integration.
... The urban heat island phenomenon can result in temperature variations up to 8 • C among cities and their nearby suburban and rural areas [2,3]. Recently, researchers and designers suggested the use of reflective surfaces, cooling materials, and vegetation for considerably increasing the environmental urban conditions, decreasing the radiant temperature, improving the natural ventilation, and mitigating the urban heat island effects [4,5]. ...
The green transformation of the built environment is aimed at improving sustainability and can be supported by digitalization, which has become a significant tool to support the supply, integration, and management of information throughout the construction life cycle. In addition, climate change highly affects human comfort in the built environment and different strategies should be evaluated for adapting cities. This paper developed a digital workflow by integrating existing tools (i.e., Grasshopper, Ladybug, Honeybee, and Dragonfly) to evaluate how different green infrastructure strategies affected the thermal comfort by reducing the UTCI. The workflow was applied to a typical historical urban context (Catania, South of Italy), consisting of a square surrounded by three-floor buildings. Three basic scenarios were created that depended on the pavement material used in the built environment: a black stone pavement (reference material from Mount Etna), a permeable pavement, and grass. These three scenarios were combined with different green infrastructure strategies: tree pattern on the square, green walls and green roofs on the surrounding buildings, and the integrations of all these above-mentioned strategies. The results demonstrated that the integration of different green strategies (a grass square instead of pavement, with trees, and green walls and green roofs) increased the thermal comfort by reducing the UTCI by more than 8 °C compared to the existing urban context (black stone pavement and building envelope). However, this temperature reduction was highly affected by the location of the human body into the urban context and by the evaporation rates from vegetation. The workflow developed will be useful for designers to evaluate the effectiveness of different green strategies during the early-design stage in mitigating and adapting cities to climate change.
... Therefore, building codes stipulated mandatory regulations against the UHI through adopting various retrofit strategies such as using solar reflective materials, improved shading and ambient cooling through urban vegetation, and use of high albedo surfaces. In addition to mitigating the UHI effect, these strategies can reduce building cooling loads [13]. Table 1 lists clauses and requirements stipulated by various building energy codes and regulations in the GCC region related to UHI and relevant requirements for high solar reflective index (SRI) materials applied for building envelopes [14][15][16][17][18][19][20][21]. ...
Energy-efficient retrofitting of building envelopes is necessary to reduce global carbon emissions and to reach net-zero goals. Cooling energy demand-dominated countries in the GCC region require simple and effective strategies to reduce building sector energy loads. One such approach is using high solar reflective index (SRI) paints to retrofit building roofs and walls. However, the hot and desert conditions of the region pose a barrier to maintaining consistent radiative properties throughout their life cycle. To this extent, research is limited in the region. The novelty of this work is to qualitatively assess the aging characteristics of high SRI or cool paints and estimate the energy savings for their application in residential buildings. The work encompasses comprehensive lab, pilot, and real-scale experimental studies combined with theoretical modeling for dynamic evaluation. Dynamic simulations enabled to determine the time-dependent aging effect on the energy savings performance of the building retrofitted with cool roof and wall paints. A case study on a townhouse in UAE showed annual energy savings of 34% considering cool roofs, walls, and window films. Aging studies showed SRI reduction of 36% and 25%, respectively, for cool roofs and walls during the first 3 years. The corresponding energy-saving reductions ranged from 31 to 44% for the white roof to dark wall colors. Using the initial values of SRI in energy models overestimates saving by 10% per year. Considering the aging effects, this work provides insights into cool paint retrofit potential on energy, economic savings, and CO2 reductions for four major cities in the GCC region.
... These materials are impermeable, unlike natural surfaces, so water cannot travel across them and eventually collapse into the soil. These surfaces have no way to stay cold without a cycle of water flowing and evaporating (Kandya & Mohan, 2018). The Normalized difference vegetation index (NDVI) has a strong capacity to communicate across yearly and seasonal fluctuation in the activity of the vegetation cover and vegetation's responsiveness to climate change. ...
The consequences of population growth and urbanization on the urban environment, climate, and water supply have caused a wide range of issues. As a result of the rapid urbanization process, vegetation covers are being replaced by impervious and dry concrete covers. This has led to the growth of "heat islands," where urban areas experience warmer temperatures than the areas surrounding them. Urban Heat Island (UHI) is a human-caused environmental phenomenon that has a wide range of impacts on city dwellers, including changing the vegetation cover and its usage, which alters the thermal energy flow and raises surface and air temperatures. Such heat islands have far-reaching impacts for cities, the most significant of which is an increase in the expense of maintaining a safe living and working environment. The major objective of this study is to examine multi-temporal land surface temperature (LST) and urban heat island (UHI) and the normalized difference vegetation index (NDVI) in the Patna Municipal Corporation (PMC) from 1990 to 2022. The Landsat satellite data sets for the years 1990, 2001, 2011, and 2022 have been used to investigate the impact of UHI and LST in relation to NDVI in the study area. The most significant change has been observed in vegetation cover (NDVI), which has declined compared to other types of land use. According to the study, built-up areas and barren land have high temperatures, whereas vegetated covers and water bodies have lower temperatures. The LST of some portions of the study area is high due to the high population density and high percentage of built-up and concrete cover. The LST over the study area has risen on average by 6.88 °C between 1990 and 2022. The regression line provided a conclusive answer, demonstrating a strong negative relationship between the normalized difference vegetation index (NDVI) and UHI of PMC. According to the findings of this study, a major transition has occurred in PMC in terms of a decline in NDVI due to a rapid growth in urban expansion and other infrastructure projects. To study urban climate and interactions between people and the environment, land surface temperature (LST) variations within cities are of utmost importance with respect to ascertaining the LST/Urban Heat Island (UHI) effect and NDVI variations in PMC. While developing urbanization, the environmental impact must be taken into account.
... Simulation techniques are used to predict building energy consumption by building physical models. Currently, there are several software tools for building energy consumption simulation, such as DOE-2 [11], Energy Plus [12], ESP-r [13], TRNSYS [14], Design Builder [15] and EQUEST [16], etc. These tools can calculate the changes in building energy consumption on a time-by-time basis and are easy and convenient to operate. ...
Reliable energy consumption forecasting is essential for building energy efficiency improvement. Regression models are simple and effective for data analysis, but their practical applications are limited by the low prediction accuracy under ever-changing building operation conditions. To address this challenge, a Joinpoint–Multiple Linear Regression (JP–MLR) model is proposed in this study, based on the investigation of the daily electricity usage data of 8 apartment complexes located within a university in Xiamen, China. The univariate model is first built using the Joinpoint Regression (JPR) method, and then the remaining residuals are evaluated using the Multiple Linear Regression (MLR) method. The model contains six explanatory variables, three of which are continuous (mean outdoor air temperature, mean relative humidity, and temperature amplitude) and three of which are categorical (gender, holiday index, and sunny day index). The performance of the JP–MLR model is compared to that of the other four data-driven algorithm models: JPR, MLR, Back Propagation (BP) neural network, and Random Forest (RF). The JP–MLR model, which has an R2 value of 95.77%, has superior prediction performance when compared to the traditional regression-based JPR model and MLR model. It also performs better than the machine learning-based BP model and is identical to that of the RF model. This demonstrates that the JP–MLR model has satisfactory prediction performance and offers building operators an effective prediction tool. The proposed research method also provides also serves as a reference for electricity consumption analysis in other types of buildings.
... The two-third distribution of these vernacular buildings with variations are reported to be across Shanxi, Lingnan, Minnan, Hakka, Gan, Yaodong, Tibet, Xinjiang, and others ( [19]; [12], [20]; and [25]). Owing to geographic metric of latitudinal variation, the climatic differentials across subarctic to tropical regions of vernacular building thermal comfort adaptive strategies been deployed into modern architecture have shown fitting adoptable efficient potential of ventilation, air tightness, thermal capacity, passive solar gains and passive solar controls ( [32], [17], [3]; [4]). Comparative temperature and psychrometric measurements across these regions with the intent of reporting vernacular building air leakage profile according to [34] are in this study reproduced for extended treatment. ...
The purpose of this paper is to provide understanding on the seasonal pattern of air leakage (infiltration) in Chinese Vernacular buildings across China’s five climate regions. In achieving the set purpose, a grand extensive literature survey was conducted and supported with data drawn from established Meteonorm V6.1 on sensible heat and psychrometric variables. Numerical computations for normalized and specific infiltration from stack effects followed the Gowri method in line with ASHRAE reference 2004. Solar energy admittance into building followed the Bouger’s Model form Angstrom properties. From the distribution of vernacular buildings across five climate regions of China, evidence from computational and numerical values showed symmetries in terms of minimums and maximums times of occurrence. Further, a reciprocal pattern exists between solar radiative admittance and region’s temperature profile. Knowing that Chinese vernacular building heritage extended to further Asia, this research became limited to only Chinese region. It became difficult to report if the construction culture away from China have correlation with infiltration and energy admittance value. Earlier works on Chinese climate and vernacular dwellings reported a climate responsive dwelling design by passive cooling strategy; a gap was closed by extending the previous work to specific infiltration pattern and energy admittance level. Chinese vernacular buildings by virtue of research outcome are and should be adoptable to modern housing needs for cultural integration.
... The Heating Ventilation and Air Conditioning (HVAC) systems are primarily responsible for indoor thermal comfort and ventilation [117]. The development of the green building concept affects the performance of residents and leads to an increase in energy load. ...
A vertical greening system is becoming increasingly crucial in resolving the energy crisis and environmental problems in a sustainable ecosystem. Researchers have conducted a comprehensive study on vertical greening systems from technology, functional and architectural perspectives. These include ecological, economic and social functions. Most of the current studies emphasize the benefits of vertical greening systems to the environment, while vertical greening technology and its socio-economic benefits receive insufficient attention. In order to study the vertical greening field in depth, this paper comprehensively and systematically summarizes vertical greening technology and functions. Meanwhile, based on the Web of Science (WOS), CiteSpace was used to analyze the relevant literature in the vertical greening field from 2012 to 2022, to explore the hot spots, development status and future trends of vertical greening technology, and to build a knowledge map in the vertical greening field. The research shows that as a low impact development technology, the vertical greening system has received the most extensive attention in the past few years. Air quality, microclimate regulation and energy have always been the focus and hot issues of people’s attention. The future research directions are cooling effect, active system and indoor space. This study is aimed at promoting the future development of vertical greening system technology and providing reference and direction for researchers, planners and developers, as well as individuals interested in future urban and rural planning.
... Findings show that bamboo-based structures exhibit better thermal performance in terms of envelope insulation compared to conventional brick-concrete buildings [64,68]. A recent study by Kandya and Mohan show that the use of bamboo concrete composite-Bamcrete walls can produce cooling energy savings of around 7.5% with respect to a traditional brick wall [76]. Bamboo can also be used as an external shading screen in tropical climates like China and effectively reduce transmitted solar radiation in summers while ensuring sufficient daylight ingress [77]. ...
Buildings consume around 40% of total global primary energy and account for one-third of greenhouses gas emissions. In the context of rising average air temperature and growing reliance on air-conditioning for space cooling, energy efficiency in buildings is becoming increasingly important. This is of particular significance to the tropics where a high rate of construction and development is expected in the coming decades. The present study evaluates the impact of several envelope retrofit materials on indoor air temperatures and energy consumption for space cooling for an educational building at IIT Bombay in Mumbai, India. The parametric study is performed using Rhino/ Grasshopper plugins LadyBug and HonyeBee and validated using measured indoor air temperature data. The energy performance is evaluated by applying thermal insulation with and without reflective coating, green roof and bamboo-based shading systems in the simulation environment. From all the retrofit alternatives, it is found that increasing the envelope's insulation followed by the provision of natural shading system results in largest reductions in cooling loads. The combined system has shown to produce maximum energy savings of up to 25% and reduce number of hours with indoor air temperatures higher than 35°C by up to 60% for an annual time period. The results offer ways to mitigate energy consumption and carbon footprint of similar buildings in the tropics.
... The two-third distribution of these vernacular buildings with variations are reported to be across Shanxi, Lingnan, Minnan, Hakka, Gan, Yaodong, Tibet, Xinjiang, and others ( [19]; [12], [20]; and [25]). Owing to geographic metric of latitudinal variation, the climatic differentials across subarctic to tropical regions of vernacular building thermal comfort adaptive strategies been deployed into modern architecture have shown fitting adoptable efficient potential of ventilation, air tightness, thermal capacity, passive solar gains and passive solar controls ( [32], [17], [3]; [4]). Comparative temperature and psychrometric measurements across these regions with the intent of reporting vernacular building air leakage profile according to [34] are in this study reproduced for extended treatment. ...
The purpose of this paper is to provide understanding on the seasonal pattern of air leakage (infiltration) in Chinese Vernacular buildings across China’s five climate regions. In achieving the set purpose, a grand extensive literature survey was conducted and supported with data drawn from established Meteonorm V6.1 on sensible heat and psychrometric variables. Numerical computations for normalized and specific infiltration from stack effects followed the Gowri method in line with ASHRAE reference 2004. Solar energy admittance into building followed the Bouger’s Model form Angstrom properties. From the distribution of vernacular buildings across five climate regions of China, evidence from computational and numerical values showed symmetries in terms of minimums and maximums times of occurrence. Further, a reciprocal pattern exists between solar radiative admittance and region’s temperature profile. Knowing that Chinese vernacular building heritage extended to further Asia, this research became limited to only Chinese region. It became difficult to report if the construction culture away from China have correlation with infiltration and energy admittance value. Earlier works on Chinese climate and vernacular dwellings reported a climate responsive dwelling design by passive cooling strategy; a gap was closed by extending the previous work to specific infiltration pattern and energy admittance level. Chinese vernacular buildings by virtue of research outcome are and should be adoptable to modern housing needs for cultural integration.
... 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.
... (III) Roof-top solar PV modules: Energy required for roof-induced cooling load decreased between 73% and 90% after installation of the PV system (Kotak et al., 2014). (IV) Alternate construction materials: Kandya and Mohan (2018) investigated the thermal performance (in terms of energy consumption for space cooling) of composite materials such as Bamcrete (bambooeconcrete composite) and natural materials such as Rammed Earth. Bambooeconcrete wall was found to reduce the annual cooling load by around 7.5% when compared to the conventional brick wall. ...
Research for urban heat island (UHI) in India has accelerated in past few years covering not only megacities but small towns as well. This chapter presents a discussion on the UHI scenario in India, which is the second largest populated country and one of the top growing economies in the world. It examines UHI quantification across India from multiple assessment methods, possible impacts, mitigation strategies and finally, identifies future research directions. In India, UHI intensities up to 8–10°C have been reported in areas with dense urban and commercial pockets. The varied methods of determination of UHI (such as fixed instruments, mobile surveys, and satellite-derived measurements) at surface and canopy layer are discussed while noting the paucity of research for the boundary layer UHI in India. Measurements alone are not adequate due to limitations of instrumental installation and errors and spatiotemporal continuity. Hence, mathematical tools such as empirical models and numerical mesoscale weather prediction models are used to understand the UHI phenomenon at region of interest, assess major causative factors, and design mitigation strategies. Case studies of such model applications are presented in this chapter. UHI effect has shown significant implications on spatiotemporal rainfall patterns, perceived thermal comfort, and heat-related morbidity and mortality for Indian cities. The review brings out emergence of concepts such as regional heat island and UHI based on local climate zones. Efficacy of various mitigation measures such as increasing green cover/plantation, thermally resistant building materials, reflective coating, etc., on surfaces is discussed in detail. The comprehensive review of different aspects of UHI in this chapter should help the scientific community as well as the regulatory bodies to determine future research focus and action plans with regard to UHI effect, its impact and mitigation in India.
... According to this method, the retained water in the material pores evaporates, and the component surface temperature is reduced due to the release of latent heat [5]. Therefore, the urban temperatures and the crossing heat flux through the building envelope are reduced and the degradation of construction materials is slowed down [6]. ...
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.
... 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.
... 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 [1][2][3][4][5]. ...
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.
... 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 [21], building material [22], ventilation condition [23], and urban green index [24] 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.
... 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.
... 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 [3], modifying building envelope [4], configuring urban vegetation [5], modifying albedo [6], 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.
... 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 [12]. 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.
Urban heat island (UHI) related heat stress and its association with human comfort were mainly conducted mainly in the temperate developed countries. Lack of researches in underdeveloped and developing countries has somehow created a gap in advancing the knowledge on UHI-related issues. Further, it is well acknowledged that the issue of human comfort to the heat stress is more relevant concerning the cities of tropical climate. Therefore, the investigations on the small and medium-sized tropical cities of third world countries become essential. This chapter tried to represent a systematic investigation of the existing researches to provide guidance. This study summarized all the factors that are selected by different studies into three groups i.e. socio-economic, health, and environment for better assessment. Finally, it tried to represent the strategies that can be followed to conduct UHI-related thermal comfort assessment in the small and medium-class tropical cities of the Global South.
The selection of envelope construction technique has the highest impact on sustaining indoor thermal comfort while reducing energy consumed for heating and cooling. Numerous insulation codes are implemented worldwide to improve building envelope modification. Each country has set envelope transmittances criteria, materials, techniques and simulation tools differently based on its climate zones and construction sector adaptability. The housing sector in Syria is the focus of energy conservation being responsible of half of the energy consumption in the country. Syrian post-conflict residential buildings are challenged by the new implementation of Building Insulation Code. This code has opted for a “fabric first” dwellings design approach with mandatory U -value standards. Hence, like many energy-related regulations in Syria it has been dropped because the construction sector has not been able to cope with them, forced by speculators to keep costs low. Another reason is that building thermal performance modeling has not been used to comply with the new insulation code in Syria. The research aims to examine the potential relevance of the Insulation Code in informing post-war social housing envelope structures in Damascus. It evaluates compliant building envelope structures compared to conventional building in terms of transmittance properties, simulated thermal loads (IESVE) and cost–energy trade-off. The research findings reveal an improvement in U -values of 78.5%, 31.5%, 92.7% and 90.2% achieved in compliant cases 1, 3, 4 and 5, respectively, compared to conventional case-2. The simulation demonstrated best improvement in total heating loads up to 85% achieved in case-4. Hence, the improved U -value lead to improvement in winter heating loads but overheating in summertime. The simulation was found useful but not enough to optimize envelope performance through interdisciplinary decision that contributes positively to Syrian post-war circumstances. The cost analysis found an increase in wall initial construction costs, amounting to 36.4%, 27.3%, 54.6% and 45.5% in cases 1, 3, 4 and 5 with long payback periods. These findings spark a new agenda for Insulation Code improvement. The proposed simplified criteria offer practitioners more understanding to customize their own list of envelope structure parameters based on the climatic zone resulting in a shift in envelope selection from input to a more output oriented.
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.
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.
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.
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.
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.
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.
The surface energy balance in an irrigated urban park in suburban Sacramento, CA is observed. Three sites extend from the edge of the park to its centre, along a transect which is aligned with the prevailing wind. Direct measurements of the fluxes of net radiation, soil heat flux and evaporation are made at each site and the convective sensible heat is found by residual. Strong advective effects on evaporation are observed, especially in the afternoon and evening. The driving forces for this are the differences in surface and air temperature, and humidity, between the cool, wet park and its warmer, drier built-up surroundings. The control of the surroundings on park evaporation is demonstrated by comparing values with those from synchronous observations in the surrounding suburbs and at an irrigated sod farm just outside the city. Greatest evaporative enhancement is observed at the upwind edge. Throughout the afternoon evaporation considerably exceeds the net radiation. This is interpreted to be due to the microscale leading-edge effect which appears to be restricted to a fetch of about 20 m. Further into the park evaporation also exceeds the net radiation in the afternoon due to the oasis effect. At all sites the sensible heat flux density in the afternoon is negative. Daily and daytime total evaporation from the park is more than 300% that from the integrated suburban area, and more than 130% that from the irrigated rural grass site. The unlimited water supply and the high temperatures of the park allow it to behave like a wet leaf in that its surface temperature seems to be ‘thermostatically’ controlled—it never rises more than a few degrees above that of the park air and for much of the day is cooler than the park air. Copyright © 2000 Royal Meteorological Society
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.