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• Effective strategies for UHI mitigation and building energy saving were evaluated. • Pavement, rooftop replacement and tree planting were effective in UHI mitigation. • Insulation thickness and AC temperature were important for building energy savings. • Planting large deciduous trees was recommended as optimal single strategy. • Recommendations of strategy combinations were finally determined. The urban heat island (UHI) phenomenon and high building energy consumption are increasingly being associated with urbanization. Various strategies have been proposed for UHI mitigation and energy conservation in buildings. Nonetheless, the combined effects of the multiple strategies must be studied. This study clarifies the individual and combined effects of commonly used building-scale strategies (i.e., replacing ground materials, adding greenery, adjusting window-to-wall ratios, using high-performance glazing, increasing insulation thickness in the building envelope, changing roof surfaces, and adjusting air-conditioning operating temperatures) on UHI mitigation and building energy consumption reduction in both summer and winter. The selected strategies were implemented in a city block in Yokohama, Japan using a surface energy balance (SEB) simulation model. The simulation results demonstrated that planting tall deciduous trees was the most effective individual strategy for mitigating UHI and reducing energy consumption. While the highest UHI mitigation and energy savings were achieved by implementing all tested strategies simultaneously, a combination of water-retaining pavement, adjusting the air-conditioning operating temperature (28 °C in summer and 20 °C in winter), and a 100 mm insulation layer in the building envelope along with a green roof, demonstrated substantial effectiveness with fewer strategies. The interactions among these strategies provided either additive or offset effects. Therefore, selecting strategies with distinct action targets is crucial to maximize the combined effectiveness. [ABSTRACT FROM AUTHOR]

This study clarifies the contact cooling effect of bare feet on human thermal physiology and sensation using a floor cooling system under hot environments. An experiment was conducted with 14 healthy young men and women using a water-cooled floor panel to investigate the cooling effects under Japanese summer conditions. The results revealed that the influences of the room temperature on the physiological parameters including blood flow, mean skin temperature, and sublingual temperature were more sensitive than that of the floor temperature. Nevertheless, the contact cooling of the soles with the floor temperature of 28 °C reduced the percentage of "very hot" and "hot" sensations of the entire body by 15.5 % when the room temperature was 30 °C. Moreover, the contact cooling of the soles at the room temperature of 30 °C increased heat flow from the soles while maintaining constant blood flow when the floor temperature was decreased. Thus, contact cooling of the soles was confirmed to be effective for heat mitigation in hot environments. However, the contact cooling was likely to cause thermal discomfort owing to the cold sensation as the room temperature decreased to 24 °C. Individual differences, in addition to the sex differences, occurred in the contact cooling effects on blood flow and skin temperature. Individual differences in blood flow were primarily caused by differences in basal metabolism and muscle mass. Further energy savings for space cooling and improved thermal comfort will be achieved by considering the individual differences for the floor cooling systems. • Influence of contact cooling on thermal physiology and sensation was investigated. • Individual difference of physiological response to floor temperature was observed. • Muscle mass affected the blood flow trends, mainly caused by gender differences. • Contact cooling reduced hot sensation by 15.5 % when the room temperature of 30 °C. • Contact cooling caused thermal discomfort due to cold at room temperature of 24 °C. [ABSTRACT FROM AUTHOR]

• Proposed deep learning method to extract roadway temperatures from infrared images. • Created high-resolution temperature map of Tokyo using 17,000 infrared images. • Wider roads are hotter; roads perpendicular to solar azimuth are cooler. • Deep learning improves analytical efficiency despite imperfect detection. • Method can be applied to 3D evaluation of urban surface temperatures. Urban heat islands (UHIs) have been worsening, and Tokyo, Japan, is among the worst globally. The urban thermal environment requires measurement to formulate effective countermeasures. This study proposes a method for detecting roadways from infrared images of captured by a moving automobile and using deep learning to extract roadway surface temperatures from the detected roadways. Additionally, a roadway surface temperature map of Tokyo was created from 17,000 infrared images covering a route of 37 km and was then used to identify hotter and cooler areas of the city in order to validate the proposed methodology. The surface temperatures were high on wide roadways with a high sky view factor, but were lower and less variable in street canyons. Roadways perpendicular to the solar azimuth had lower temperatures due to shading by buildings. The accuracy of deep learning to detect roadway was imperfect, but a significant improvement in analytical efficiency was achieved. The method could also be applied to three-dimensional evaluation of urban surface temperatures by extracting surface temperatures for various city components, such as buildings and vegetation. [ABSTRACT FROM AUTHOR]

Abstract Evaporative cooling is a widely used passive cooling method to mitigate high ambient temperatures in Japan during the hot and humid summer season. An evaporative cooling louver was developed by Hirayama et al. (2014) to create a cool microclimate in an urban residential outdoor space. This study investigated the potential of using passive cooling methods integrated with the louver to create a cool microclimate in a semi-outdoor space for natural ventilation. A field measurement was conducted to evaluate the microclimate in a semi-outdoor space under different amounts of solar radiation, surrounding vegetation, and distances from louver to window to find the best way that accumulates at most the cool air generated by the louver. Best results were found when the semi-outdoor space was exposed to low solar radiation, was fully surrounded by vegetation, and when the louver was closer to the window. Moreover, to use the cool microclimate created at the semi-outdoor space for natural ventilation, different ventilation settings such as window opening area, indoor cross ventilation, and stack ventilation with a sky window were incorporated and measured to find the best conditions to induce the cool air into the indoor space. Best results were found when the window was fully open and the wind speed of the air crossing the window was more than 0.2 m/s, which maintained a cooler vertical air temperature distribution inside the window. Highlights • We found an integrated passive cooling method to form a cool microclimate at a semi-outdoor space. • The ambient temperature was reduced by 1.0–4.0 °C when passing through the evaporative cooling louver. • Cool microclimate was formed when the semi-outdoor space was surrounded by vegetation. • Formed cool air was induced into the indoor space when wind speed crossing the window was more than 0.2 m/s. [ABSTRACT FROM AUTHOR]

We introduce a multilayer model to estimate mean radiant temperature (MRT) and evaluate the pedestrian thermal comfort in a street canyon. This multilayer MRT model (MMRT) is suitable for urban streets with varying building and tree heights. The model simulates shortwave and longwave radiation exchange for each urban element and area-weighted view factors, then finally obtains MRT of pedestrians on the sidewalk. Probability density profiles of buildings and trees enable the consideration of urban vertical heterogeneity. Furthermore, Monte Carlo ray tracing (MCRT) allows the model to evaluate the radiation transfer in complex urban areas. We verify the effectiveness of MCRT and the probabilistic density profile approach. A sensitivity test conducted in Seoul on September 1, 2017 using the MMRT reveals that MRT can be reduced by 23 °C as the tree leaf area density increases from 0 to 1, and by 18 °C as the tree height increases from 0 m to 12 m in 1300 LST. The model controls urban form and pavement parameters as well as tree parameters. We aim to use this model to compare diverse MRT mitigation strategies and confirm the best strategy for thermal-friendly street design. [ABSTRACT FROM AUTHOR]

This study aims to determine the optimum window-opening control that maximizes annual thermal comfort using ventilative cooling, i.e., night and comfort ventilation, in naturally ventilated buildings where phase change materials (PCMs) are used. A thermal energy simulation (TES) coupled with an airflow network model was constructed to evaluate the comfort ventilation and thermal storage effects of the PCMs by controlling the window-opening patterns. The EnergyPlus-based coupled TES model was validated by comparing with the field measurement results of a full-scale experimental building in Indonesia. The root-mean-square errors of the temperature and air speeds at the center of the target building ranged from 0.2 to 0.5 °C and 0.1–0.2 m/s, respectively. The accuracy of the coupled TES was similar to that of computational fluid dynamics coupled with the heat balance analysis, which can simulate the spatial distributions of temperature and air speeds. The annual simulation results showed that prioritizing the thermal storage effect of the PCMs in the morning and comfort ventilation in the afternoon increases the thermal comfort period. For the optimum window-opening control to maximize thermal comfort in the hot and humid climate, an indoor temperature of 27 °C can be considered a criterion to open the windows for comfort ventilation in addition to night ventilation for the thermal storage effect. When this criterion was applied, the thermal comfort period in the room with PCMs increased to 83.3 %. Accordingly, the reduction in electricity consumption for space cooling was 41 % less than that in a control room without PCMs. • A coupled TES model evaluating thermal comfort was constructed. • The coupled TES calculated wind speed accurately with the light calculation load. • The proposed system using PCM achieved thermal comfort period of 83 % for a year. • An optimum window-opening control to maximize annual thermal comfort was clarified. • Indoor temperature of 27 °C and nighttime can be criteria to open window. [ABSTRACT FROM AUTHOR]

We propose a multipoint measurement method for air temperature in outdoor spaces using polyvinyl chloride pipes with fan-aspirated ventilation. The method is applied to microclimate measurement in the outdoor space of a residential house, and the cooling effects of plants and natural ventilation on the house were evaluated. The accuracy of the proposed method was verified in the outdoor space. Average systematic errors of the method were 0.43 °C during daytime on sunny days and 0.16 °C on cloudy days. Application of the method to microclimate measurement shows that air temperatures were reduced by evapotranspiration of plants and watering in the planted space during daytime. By placing the plants near a floor-level window, wind speed inside the window was reduced, although the cooled air flowed into the indoor space through the window. The cooling effects of the plants and watering in the outdoor space kept indoor air temperature cooler during daytime. The period in which the sensible heat flux from the outdoor to indoor space showed positive values, i.e., when there was a sensible heat load in the room, diminished from 9 to 4 h through the cooling effects. [ABSTRACT FROM AUTHOR]

Air temperature is an important physical indicator of a built space. A novel method for remotely measuring the air temperature distribution using a thermal infrared spectroradiometer is evaluated, and an experiment using the maximum a posteriori method, which uses a priori information, is conducted with a heat source. The a priori information is the probabilistic information that the observer knows about the air temperature prior to the observation. Assuming an indoor scale (10 m), the air temperature distribution is estimated (i.e., retrieved) by discretizing the space into four layers. Accordingly, our method reduces the error in the air temperature estimation compared to the a priori information. When the layer of the heat source is known, the air temperature estimation is sensitive to the air temperature of the heated layer, even when the heat source is away from the sensor (2nd to 4th layers). The root-mean-square error (RMSE) of the heated layer decreased from 10 K (a priori) to 4.8 K. Although the RMSE of the temperature distribution was approximately the same regardless of the number of spectral channels used in the retrieval, the RMSE of the heated layer was smaller when ten spectral channels were used. In the case of a target space and spectrometer, as in this study, ten spectral channels were sufficient. These findings indicate the possibility of remotely measuring the air temperature distribution in a space with a local heat source (e.g., data centers), which is a relatively difficult case for remote sensing methods. • Air temperature distribution was remotely measured by a spectroradiometer. • Maximum a posteriori method was used as a regularization for this measurement. • The effectiveness of the proposed method was validated through the experiment. • Ten spectral channels were sufficient in the spectroradiometer for this method. • When a heat source location was known, sensitivity was seen away from the sensor. [ABSTRACT FROM AUTHOR]

This study investigated the applicability of a thermal energy simulation (TES) for a naturally ventilated building in which a phase change material (PCM)-based radiant floor cooling system was installed. The TES was conducted to determine influential factors to maximize the thermal storage effect of PCMs in the building throughout a year in a hot and humid climate. First, the thermal properties of a full-scale PCM product were measured using the heat flow method. This measurement clearly captured the hysteresis of the PCM depending on the heating and cooling rates; thus, the enthalpy–temperature curve under slow heating and cooling rates was determined for the TES. Based on the results of the PCM measurement, the EnergyPlus-based TES model was validated by comparing it with the results of field measurement at a full-scale experimental building with natural ventilation in Indonesia and a computational fluid dynamics (CFD) simulation coupled with the heat balance analysis. Good correlations (up to R2 = 0.99) were observed in the air and floor surface temperatures between the measurement and TES simulation. Additionally, the TES had a similar accuracy as the coupled CFD, which considers spatial wind and temperature distribution. The results of the annual simulation showed that the proposed PCM-based radiant floor cooling system with night ventilation achieved a thermal comfort period of up to 68.5% a year. Furthermore, a reasonable annual average utilization rate of approximately 70% can be determined to maintain a low floor surface temperature throughout a year. • A thermal energy simulation model considering hysteresis of PCM was constructed. • Two types of PCM measurement methods were compared to determine the thermal properties. • The proposed system using PCM achieved thermal comfort period of up to 68.5% a year. • The maximum liquid fraction influenced the retention of thermal storage effect of PCM. • A reasonable annual utilization rate can be determined as approximately 70%. [ABSTRACT FROM AUTHOR]

In this paper we demonstrate a method for estimating the leaf area density (LAD) distribution of individual trees using high-resolution airborne LiDAR. This method calculates the LAD distribution from the contact frequency between the laser beams and leaves by tracing the laser beam paths. Multiple returns were used to capture the foliage distribution in the inner part of the crown. Each laser beam is traced from a location of the last return to the location of the first or intermediate return that is recorded immediately before the last return. We verified the estimation accuracy of the LAD distribution using terrestrial LiDAR data from single trees ( Zelkova serrata and Cinnamomum camphora ). The appropriate voxel size for representing the LAD distribution from the airborne LiDAR data was determined to be 1 m × 1 m × 0.5 m. The accuracy of the estimated LAD distribution for this voxel size was then examined while considering the number of airborne incident laser beams on the voxel ( N ) and the return type used. When only the first and single returns were used, the LAD was overestimated even for the voxels with large N . LAD was estimated as zero for most voxels with small N , although LAD was significantly overestimated for several voxels. We found that using the last and intermediate returns improved the LAD estimation accuracy even if N was the same. The mean LAD estimation error was 0.25–0.3 m 2 /m 3 for both species. Assigning different weights to the first and intermediate returns improved the accuracy slightly. Estimation error clearly corresponded to N , and N of 8–11 could be a criterion for an accurate LAD estimation. [ABSTRACT FROM AUTHOR]

Mean radiant temperature (MRT) is the primary metric of radiant heat exchange between a human body and the environment, and it dominates human thermal comfort and heat stress. This study develops a new portable recording system for spherical thermography utilizing only commercial devices (an infrared thermal imaging camera and a portable rotation platform) and image processing for panorama synthesis. We use the system to estimate the MRT in a longwave radiation environment. A spherical thermal image is generated by synthesizing 24 source images on the basis of feature point identification. The longwave MRT and plane radiant temperature can be estimated from the spherical thermal image using image projection methods, including the orthographic projection and Lambert cylindrical projection. To validate the developed system, measurements were made using the system in outdoor and indoor environments with various radiant temperature distributions, including sunny built spaces and a tree-shaded space, and the results were compared with those obtained using pyrgeometers. The difference in longwave MRT between the estimation by the developed system with orthographic projection of spherical thermal images and the measurement by pyrgeometers for six directions was within 1 °C in most cases and 1.6 °C at maximum. The results show that the developed system has sufficient accuracy for longwave MRT estimation while evaluating the radiant temperature distribution and radiant asymmetry of spaces. • A portable recording system for spherical thermography was developed. • The developed system was validated for indoor and outdoor spaces. • Mean radiant temperature can be accurately estimated by the developed system. [ABSTRACT FROM AUTHOR]

• A review was made for 157 and 28 papers of GR and PV/GR systems, respectively. • The potential research gaps of GR and PV/GR were specified in different climates. • The GR key factors are LAI, soil depth, insulation, irrigation and coverage ratio. • GR type, irrigation and plant features are the common factors for GR and PV/GR. • The vegetation, urban and irrigation factors aren't studied enough in hot climate. Climate change and urban heat islands (UHIs) pose mounting threats to built-up areas. In this regard, photovoltaic panels and green roof systems (PV/GR) can offer numerous benefits towards promoting environmentally sustainable cities. This review examines the benefits of GR systems, integrated PV/GR systems and their optimal design factors; research gaps in urban scales and building scales in hot climates are highlighted. A systematic review was undertaken on published papers from the Scopus database that investigated the effect of GR (157 papers) and PV/GR systems (28 papers) that addressed UHI mitigation and how Energy-Saving and Indoor Thermal Comfort (UH-ES-ITC) was achieved in urban buildings. It has been found that GR and GR/PV systems have a positive impact on improving dominant parameters in hot arid climates, especially on the building scale. Unfortunately, there are not many studies that investigate GR/PV systems on coupling scales. This review highlights the research gaps concerning the method, scale, climate, target, factors and parameters of this integration in different climate zones. The results would be valuable for researchers and urban planners to guide research implementation and future research. [ABSTRACT FROM AUTHOR]

Bio-receptive façade panels that support the natural growth of mosses, micro-organisms, and small plant species are potential alternatives than traditional green walls. Supporting the moss's development naturally could offer great potential for achieving ecologically richer, healthier, and zero-carbon cities. In particular, a limited amount of hydration is required for mosses to grow on these bio-receptive surfaces, which is ideal for the hot, humid environment of north Egypt. This review paper is aimed at identifying the feasibility and influencing factors of implementing such a façade innovation in a hot, humid climate as north Egypt. To investigate this feasibility, first, it is essential to compare the critical factors for moss growth with the target environmental conditions. These key feasibility factors for the approach were classified as environmental and physical growth factors. Second, a field study was undertaken to confirm the availability of such moss resources in north Egypt since the climatic conditions correspond to the acceptable range necessary for its application of the approach. This study resulted in promising families of mosses being available, in which great potential for the use of bio-receptive concrete with a cover of moss to expand the green areas vertically is expected. Especially, this green expansion will be with moss, which blooms randomly in the natural environment. This technique may bring additional advantages by generating new sustainable materials from low-cost and readily available resources. It is considered to be an approach to enhance greening and reduce urban environment's susceptibility to climate change without requiring extensive irrigation and maintenance. [ABSTRACT FROM AUTHOR]

Abstract: This paper focuses on the development of a thermal design tool for use in planning outdoor spaces by combining a heat balance simulation for urban surfaces, including buildings, the ground and greenery, with a 3D-CAD system that can be run on a personal computer. The newly developed tool is constructed by improving the previous simulation model, which uses the geographic information system (GIS) for the input data. The simulation algorithm is constructed so as to predict the surface temperature distribution of urban blocks while taking into account the actual design of the outdoor space using the 3D-CAD system. A method of multi-tracing simulation to calculate the sky view factor and radiative heat transfer is established. The optimal mesh size is examined for the tool so as to provide detailed spatial geometry within a suitable calculation time. The simulation model is integrated with an all-purpose 3D-CAD software, and the pre-processing method are constructed for practical use. The results obtained by applying this simulation tool to an area of detached houses reveals that the tool is able to evaluate the effects of building shape, materials, and tree shade on the surface temperature distribution, as well as the MRT and HIP, which are evaluation indices of the outdoor thermal environment. [Copyright &y& Elsevier]

We proposed a novel radiant floor cooling system using phase change materials (PCMs) with night ventilation in the hot and humid climate of Indonesia. This study aims to clarify the measures to ensure the thermal storage effect of the proposed cooling system during daytime for a naturally ventilated room within a relatively narrow diurnal temperature range, focusing mainly on the thermal properties of PCMs. We analyzed the relationship between the indoor vertical air temperature distributions and heat flows of the proposed system using an experimental building in Tangerang, Indonesia. The results confirmed that the thermal mass of PCMs and the cooling strategy for the floor structure at night strongly contributed to maintaining a low floor surface temperature during the subsequent daytime. Calm wind conditions and warm nocturnal ambient temperature, which was 0.7–3.2 °C lower than the set-point solidifying temperature and is common in the tropics, prevented PCMs from solidifying in case of natural ventilation for the underfloor space. In contrast, forced ventilation for the underfloor space attaching PCMs was effective in ensuring sufficient solidification. Furthermore, 95% of the thermal storage capacity of PCMs might be utilized when the ambient temperature was 2–3 °C higher than the set-point melting temperature during the daytime. The phase change temperature for PCMs can be determined based on the average ambient temperature, whereas a relatively wide diurnal ambient temperature range, at least 4.7 °C, was required to ensure the latent heat thermal storage effect caused by the supercooling. • Latent heat thermal storage was influential in lowering floor surface temperature. • Forced ventilation ensured the sufficient solidification of PCMs at warm nights. • Diurnal temperature range at least 4.7 °C was required to ensure phase changes. [ABSTRACT FROM AUTHOR]

• Coupled simulation of LiDAR data, longwave radiative transfer, and fluid dynamics. • Airborne LiDAR-derived leaf area density is used to represent the tree structure. • Large leaf area density and a large sky view factor are keys to producing cool air. • Cooled air can flow down to human height even under conditions with incident flow. • Trees have notable potential to produce cool spots in urban spaces at night. The design of urban areas and building that utilizes the microclimatic effects of trees is a promising approach for reducing the severe heat stress caused by urban heat islands and global warming. Although trees can reduce heat stress through solar shading during the daytime, their influence on the air temperature under and around them during the nighttime, which is important for nighttime thermal comfort, has not yet been fully elucidated. In this study, we investigated the nocturnal cooling effect of trees in a physical urban space by the coupled numerical simulation of longwave radiative transfer and computational fluid dynamics. To represent the spatial structure of an actual urban space, airborne LiDAR-derived three-dimensional data of leaf area density distribution and building shape were used. The species-specific convective heat transfer coefficient was also considered. An analysis of the calculated sensible heat flux shows that both leaf area density and sky view factor are important factors in the production of cool air. According to the calculated distributions of air temperature and velocity, even under the condition of a certain degree of incident flow, the cooled air can flow down to the space under the crown, accumulate, and then diverge when the wind speed is sufficiently low in the crown owing to the crown drag. Buildings contribute to both the accumulation and dissipation of cool air. The findings of the present study suggest that cool spots can be produced during nighttime by trees planted near streets by devising a suitable arrangement and morphology of trees and buildings. [ABSTRACT FROM AUTHOR]

• Different neighborhood forms can create inter-neighborhood microclimate variability. • Local-specific characteristics affect microclimate differently across neighborhood area. • Influence of local-specific characteristics on microclimate vary across seasons. • Vegetation is more important in regulating microclimate in shallower than deeper canyon. Although neighborhood is the level where most local plans are realized, little research has been done to understand how neighborhood spatial characteristics can shape its microclimate. This study aims to understand the effect of neighborhood form on its microclimate in a hot arid city, in Egypt. Two neighborhoods with different layouts are selected- a low-density historic area and a modern high-density area. Each neighborhood form was analyzed according to seven spatial characteristics: aspect ratio, street orientation, street trees, green spaces, percentage of tree canopy and impervious surfaces at 20m radii, and sky view factor. Microclimate data was collected using mobile field measurements in summer and winter. In total air temperature, relative humidity and wind speed at 44 sites were measured. The statistical and spatial analysis reveal inter-neighborhood microclimate variation which is more observed in winter than in summer. Moreover, the local-specific spatial characteristics within each neighborhood have resulted in a variation in the microclimate across the neighborhoods. The study also found a seasonal effect on the overall microclimate and on the way local-specific characteristics influence the microclimate. Findings of this research can have implications for future (re)development and planning of climate resilient neighborhoods, in a hot arid context. [ABSTRACT FROM AUTHOR]

The combination of ventilative cooling and radiant cooling is a feasible approach for improving the cooling performance of buildings, thus achieving better thermal comfort of occupants in hot and humid climates. We propose a novel radiant floor cooling system using a phase change material (PCM) in Indonesia. This study aims to determine the window design that optimizes indoor air flow pattern to provide ventilative cooling, while maintaining the radiant cooling effect during daytime. We analyzed several window types through a field experiment using an experimental building in Tangerang, Indonesia. The performance of the windows was analyzed with an air flow pattern and was assessed in convective heat transfers on the floors and by the standard effective temperature (SET*) at the center of the room. The results showed that the horizontal pivot windows led to air inflows to the occupied level regardless of the outdoor wind conditions. The heat transfer coefficient on the floor was reduced by approximately 1.52 W/m2K compared with that of the simple opening. Nevertheless, the increase in thermal mass owing to the PCM had a greater effect on the retention of the floor cooling effect compared with the effect of the window type. Consequently, the SET* was reduced by approximately 0.79 °C during the daytime, showing that the proposed window design with the radiant floor cooling system achieved better thermal comfort in a hot and humid climate. Particularly, the horizontal pivot windows contributed to thermal comfort mainly because of the ventilative cooling effect. • A novel floor cooling system was proposed for a hot and humid climate. • Window type strongly affected indoor airflow pattern. • Heat transfer coefficient was reduced by 1.52 W/m2K by the horizontal pivot window. • Increased thermal mass maintained a cooler surface temperature. • SET* was reduced by 0.79 °C by the floor cooling system and horizontal pivot window. [ABSTRACT FROM AUTHOR]

Subsurface utilization in the tropical regions as a heat sink for ground source heat pumps (GSHPs) leads to thermal buildup in the long term, resulting in the decreased energy performance. However, the applicability of the GSHP in these regions has never been investigated based on the predicted heat sink temperature over a lifetime. This study aimed to evaluate the energy performance of a large-scale GSHP system in representative building models in Thailand based on operating conditions derived from a predicted 50-year heat sink temperature. The proposed system combines a GSHP and an air-source heat pump (ASHP), and, in one scenario, the GSHP also supplies hot water. The results confirm that the combined system achieves a higher efficiency than that of an ASHP system alone, and GSHP supplying hot water realizes substantial energy-saving. However, limitations on the annual GSHP operation hours are essential, resulting in low energy-saving performance for cooling dominated facilities. Further improvements are expected by mitigating the thermal interactions among each borehole heat exchanger. [ABSTRACT FROM AUTHOR]

Systematic simulations were performed in a city block in Yokohama, Japan, on a clear summer day to study the effects of building surface thermal properties on their radiative and thermal exchange with the atmosphere, and the surface energy balance (SEB) model sensitivity to these thermal properties. To study this practically and systematically, the thermal properties used were determined from a database of commonly used materials for building surfaces in urban Japan, characterizing the typical thermal property values and their combinations. Using suitable simplification and assumption, the main findings included: (a) a combined modification of thermal properties enlarges the cooling effects of individual modifications, reaching 131%–149% of the accumulated reduction in the emitted sensible heat flux (Q H); (b) the difference in the cooling effects of a high-albedo strategy applied to roofs between various thermal properties is up to 76 [W m−2] in Q H ; (c) the SEB model sensitivity of the surface temperature (T s) to thermal properties for the façade is close to that of the albedo, at up to approximately 0.1 °C for a thermal conductivity Δ λ c of 1 [W m−2 K−1] and a heat capacity Δ C a of 1 [kJ m−2 K−1]; (d) the range in root mean square error of the simulated daily, daytime, and noon Q H caused by generalizing the roof thermal properties is estimated to be 6%–41%, 7%–50%, and 7%–38%, respectively. Overall, the thermal properties of building surfaces are important for their thermal and radiative behavior, and therefore cannot be ignored in SEB modeling. • Importance of thermal property for surface heat balance is verified systematically. • Combined modification of thermal properties enlarges individual cooling effects. • Thermal properties cannot be ignored to evaluate the cooling effect of cool roofs. • Generalizing the thermal properties causes nonnegligible errors in SEB modeling. [ABSTRACT FROM AUTHOR]

• Combined effects of GR on indoor thermal comfort and PV efficiency are analyzed. • GR soil could reduce maximum indoor air temperature by 10.75 % °C for clay soil. • Medium PV height and high coverage improved average daytime IAT by 3.30%, 3.93%. • PV electricity output increased by 2.27% due to the cooling effect of GR. • PV/GR system saved cooling energy by 19.12 % (59.56 Kg of CO 2 /m 2) yearly in summer. Numerous research has included passive cooling techniques and renewable energy-generating technologies to enhance the near-zero energy community. This study aims to evaluate the impact of various Green Roof (GR) parameters on photovoltaic performance, indoor thermal comfort, cooling energy savings, and CO2 emissions. The study focuses on the effect of parameters such as soil type, soil depth, irrigation, vegetation layer, PV height, and PV coverage ratio on the performance of a green roof compared to a traditional bare roof in a hot steppe arid region in Egypt. Two calibrated small-scale rooms were built and tested with eleven different scenarios to determine the improvement in indoor air temperature, relative humidity, and photovoltaic electricity output. The results showed that GRs made with clay, sandy soil, and vegetation reduced maximum indoor air temperature during the daytime by up to 10.75 %, 7.80 % and 9.09 %, respectively. Increasing soil depth and PV coverage ratio further improved maximum indoor air temperature reduction up to 11.85 % and 9.6 %, respectively. The photovoltaic electricity output was increased by up to 2.27 % compared to the traditional bare roof. The study also found that green roofs with photovoltaic systems reduced cooling energy consumption and CO2 emissions by 19.12 % and 59.56 kg/m2 annually, respectively. [ABSTRACT FROM AUTHOR]

Abstract: A building affects its surrounding environment, and conversely its indoor environment is influenced by its surroundings. In order to obtain a more accurate prediction of the indoor thermal environment, it is necessary to consider the interactions between the indoor and outdoor thermal environments. However, there is still a lack of numerical simulation tools available for predicting the interactions between indoor and outdoor microclimate that take into account the influences of outdoor spatial conditions (such as building forms and tree shapes) and various urban surface materials. This present paper presents a simulation tool for predicting the effect of outdoor thermal environment on building thermal performance (heating/cooling loads, indoor temperature) in an urban block consisting of several buildings, trees, and other structures. The simulation tool is a 3D CAD-based design tool, which makes it possible to reproduce the spatial forms of buildings and constructed surface materials in detail. The outdoor thermal environment is evaluated in terms of external surface temperature and mean radiant temperature (MRT). Simulated results of these temperatures can be visualized on a color 3D display. Building heating/cooling loads and indoor air temperature (internal surface temperature) can also be simulated. In this study, a simulation methodology is described, and a sensitivity analysis is conducted for a wooden detached house under different outdoor conditions (building coverage, adjacent building height, surrounding with trees or no-trees). Simulation results show that the simulation tool developed in this study is capable of quantifying the influences of outdoor configurations and surface materials on both indoor and outdoor environments. [Copyright &y& Elsevier]