•The thermal environment was simulated with a validated ENVI-met model.•Daily 3D spatial temperature variation was identified with and without green spaces.•Green spaces below mean building height ...provided variable cooling benefits.•The temperature reduction through fragmented green spaces was translated into cooling energy equivalents.
Urban green spaces help to moderate the urban heat island (UHI) effects, and can provide important temperature regulating ecosystem services and opportunities for savings in cooling energy. However, because explicit market values for these benefits are still lacking, they are rarely incorporated into urban planning actions. Green spaces can generate a three-dimensional (3D) cool island that may reduce the cooling energy requirements within and around urban areas, but such 3D cooling effect has not been considered in previous studies quantifying energy savings from green spaces. This study presents a new and simple approach to quantify potential energy savings due to the temperature regulating ecosystem services of small-scale fragmented green spaces using the 3D simulation of the summer-day outdoor thermal environment in Nanjing, China. Field survey data and the microclimate model ENVI-met were applied to examine the outdoor 3D thermal environmental patterns at Gulou Campus of Nanjing University under two different scenarios: “with” and “without” green spaces. Modeling results were applied to quantify potential cooling energy savings based on the effect of green spaces on the outdoor urban environment and to calculate the cumulative temperature reduction due to green spaces using a regression model. The results show that, in the horizontal direction, the simulated distribution of wind speed and mean air temperature at 1.5m height were closely related to the spatial distribution of the underlying surface types. Removal of green spaces increased mean air temperature by 0.5°C (33.1°C vs. 33.6°C). In the vertical direction, removal of green spaces had little effect on the near-surface wind field; however, above the surface, the turbulence perpendicular to the main wind direction significantly increased. Quantification of the cooling benefits of green spaces in relation to the mean height of buildings on Gulou Campus yielded 5.2W/m2 cooling energy, saving totally 1.3×104kWh during a single daytime hot summer period. This case study corroborates the importance of green space for cooling and informs city planners and decision-makers on how microclimate is impacted by the loss of green spaces. These findings will facilitate preservation, planning, and design of green spaces to increase urban environmental benefits and to improve the microclimate of urban areas at neighborhood, city, and regional scales.
This paper discusses current state-of-the-art features of the “plant evaluation model”, a framework which, starting from the representation of vegetation and its effects in microclimate models, ...defines a number of indices which can be employed for the evaluation of outdoor microclimate in terms of thermal environment and comfort in the urban environment. The key point of taking into account the impact of vegetation on microclimate is to implement appropriate parameterizations of such impact in a microclimate model. The paper, based on a review of literature studies, thus illustrates the basic principle and technical path of the impact assessment model of vegetation on microclimate and introduces related software. The aim is to provide the scientific community with a summary of (i) the current definition of vegetation in models employed for the evaluation of the impact of vegetation on urban outdoor microclimate, (ii) main models and evaluation indices and (iii) main input, output, vegetation-related processes implemented, strengths and weaknesses of those models, with suggested measures for output improvement. This review is not exhaustive but may help the user to select the proper model, which takes into account the effects of vegetation on outdoor urban microclimate, depending on the specific objective.
•Available DLF methods for DES are reviewed comprehensively (attributes, applications and merits).•Impact factors of DES district load should be selectively considered in DLF modeling.•The existing ...DLF methods are restricted to accuracy and workload.•A framework of DLF is proposed for DES planning, design and service.
Distributed energy system (DES) has successfully aroused increasing interests among energy policy makers and system designers, as its potential of replacing conventional energy system. The optimal modeling of district load forecasting is essential to guarantee the best design and operation of DES. This paper presents a comprehensive review of district load forecasting (DLF) models to support the application of DES. The main factors affecting district load are discussed from inside to outside, including building indoor condition, building design characteristics, district layout, local microclimate, and social & economic factors. Through classifying and comparing top-down and bottom-up methods in terms of their key features and applications, it is found that the existing methods are either lack of forecasting accuracy or burdened with forecasting workload. Previous literatures reviewed in this paper show that the hybrid forecasting models including scenario analysis, physical-statistical numerical simulation and least square support vector machine based intelligent approaches have a superior ability to balance these two contradictions under different conditions. Based on the comparison results and current trend, a framework of district load forecasting, as well as corresponding future research work, is proposed for DES planning, design and service.
•UHI recorded in Muar, Malaysia was 4°C during the day and 3.2°C during the night.•Effect of different urban geometry modifications on the wind flow was investigated.•Step up configuration was most ...effective as it can distribute the wind evenly.•Step up configuration allows the wind to reach the leeward side of each building.
Urban Heat Island (UHI) has become a growing concern to the quality of densely built urban environments, particularly in tropical cities. Wind speed has widely been reported to have decreased the intensity of heat island effect in urban areas. The cooling effect of the wind helps to mitigate the adverse effects of heat island on the micro climate and human thermal comfort. This paper investigates the existence of heat island in Muar, one of the fast growing cities in southern part of Malaysia and its possible causes, and then examines the effects of different urban geometry on the wind flow. The results of this study indicate that the chaotic development in Muar has caused reduced ventilation in urban canyons. The heat island intensity in the city center was recorded as 4°C during the day and 3.2°C during the night. Investigation of various urban geometry modifications showed that step up configuration was the most effective geometry as it can distribute the wind evenly allowing the wind to reach even the leeward side of each building.
Phase Changing Materials (PCM) portrays proficiency to liberate perceptible amount of latent heat on the course of phase transformation between liquid-solid or solid-liquid, thereby creating ...momentary warmth or cooling effect. PCM has been utilized in garments for introducing thermoregulating effect to diminish thermal discomfort of clothing. Assimilation of thermal energy by PCM causes delay in upsurge of microclimate temperature and results in substantial diminution of moisture release from skin thereby leading to inhibition of heat stress conditions and enhancement of thermo-physiological wearing comfort. Simultaneously, the insulating characteristic of such garment can also avert wearer from certain pivotal corollaries like hypothermia or heat syncope, keeping the individual in consolation owing to their automatic acclimatizing attribute in accordance with body and ecological temperature. As the assimilation of PCM into various textile materials have been extensively studied by researchers, an attempt has been made to explicate the recent existing literatures that have successfully integrated and implemented PCM in textile, concentrating on characteristics of PCMs integrated into fibers, and fabrics for potential industrial applications. Finally, various methodologies like coating, spinning & lamination being utilized for applying PCMs onto textiles for developing thermoregulated clothing have been discussed & concludes with challenges & future prospects.
Visual and thermal comfort for occupants significantly depend on exterior environmental climatic conditions, which are continuously changing. In particular, optimizing visual and thermal comfort ...simultaneously is a difficult topic due to mutual conflicts between them. This literature review article studies the façade, as a complex interface between inside of buildings and the outside that has a capability to function as a protective or regulatory element against severe fluctuations of external climate. Six interrelated subjects are studied including kinetic façade, biomimicry, building form as a microclimate modifier, energy efficiency, comfort condition, parametric design thinking. The literature review process answers following research questions: (1) what are the interdisciplinary subjects corresponding to kinetic façade design process for creating an innovative architectural process? (2) What is the most important factor in kinetic façade design with the aim to improve occupants’ visual and thermal comfort simultaneously based on multidisciplinary investigation?
Many research has been carried out about kinetic façade concepts strategies, principles, and criteria. However, interdisciplinary studies for proposing kinetic façade form is relatively rare. Also, adaptive daylight façade with daily solar geometry variation has been highly required. Therefore, generative-parametric and quick form finding method for responding to different climates would be a solution for providing more adaptability to dynamic daylight. This study aims to propose a kinetic façade design process which have capability to improve occupant visual & thermal comfort simultaneously by controlling on-site renewable energy resources consist of solar radiation and wind. Façade as an only interface between inside and outside of building, far from the literal and historical perceptions, is recognized by intrinsic functional attributes including complexity, heterogeneity and multidisciplinary. Moreover, the interrelated subjects impact façade form individually and aggregately regard to functional scenario that is changed the perception of kinetic façade from elegant and fashionable state to a functional and practical element.
Indoor greenhouse temperature exceeds tolerable range for plants growth mostly during the summer in Ahvaz-Iran. Attempts for improving ventilation in summer was not adequate despite a huge energy ...consumption. Computational fluid dynamic models of a full scaled gable greenhouse covered by semitransparent materials among several adjacent greenhouses inside a greenhouse paradise for predicting the dynamics of its microclimate during a day as well as a year 2017–2018 were developed. The accuracy of the models was approved by comparing to the physical experiments and meteorological reports. The results approved the capability of the model for predicting variable solar heat load and higher indoor temperature than ambient in several hours of a day as well as surface heat transfer coefficient of the walls as affected by regional dominant wind profile. This study enhanced the understanding of required solar heat load removal during the hot months while the average temperature exceeds 40 °C for more than 11 h a day. This finding also indicates the critical periods in which the fan assisted natural ventilation system can be applied to cool down the greenhouse from more than 40 °C to 25–35 °C.
•The effects of variable solar load on greenhouse temperature were simulated.•Covers heat transfer as affected by local wind profile was modeled.•The accuracy of the numerical model was approved by physical experiments.•Temperature exceeds 40 °C for more than 12 h a day during Jun.–Aug in greenhouse.•Required solar load removal and ventilation during hot months was suggested.
This study has successfully formulated artificial neural network models to predict thermal comfort evaluation in outdoor urban parks in Hong Kong, a sub-tropical city, for both summer and winter ...periods. The artificial neural network models embracing two-hidden layers outperformed other types of commonly adopted thermal comfort models. The model prediction performance was considerably improved by including perceptions of microclimate, perceptions of environmental features and personal traits as additional predictor variables. Sensitivity analysis determined that thermal sensation is the most important factor influencing thermal comfort evaluation in outdoor urban parks, followed by air temperature for both summer and winter. Solar radiation is another important factor immediately following air temperature for winter. In contrast, perceived density of trees and perceived number of water bodies in a park were found to be more important than solar radiation for summer. The findings arising from this study should provide valuable insights for formulating effective strategies for improving the thermal environment in urban parks in different seasons.
•Artificial neural network models were formulated to predict the thermal comfort evaluation in outdoor urban parks.•Thermal sensation and air temperature were important factors influencing thermal comfort evaluation for summer and winter•Solar radiation was important for thermal comfort evaluation in winter.•Perceived density of trees and perceived number of water bodies in a park were found to be more important for summers.
•Heat waves and human health.•Urban microclimate mitigation during the summer.•Microclimate simulations of an area located in the center of Rome through ENVI-met V 3.1.•Thermal perception analysis ...through the Mediterranean Outdoor Comfort Index (MOCI).•Resilience strategies to the Urban Heat Island (UHI) effect.
Over the past years the concern of the international scientific community towards the study of the Urban Heat Island (UHI) phenomenon has been growing. Such issue is particularly important in cities as Rome, where it is possible to experience intense heat stress conditions especially when heat waves intensify this phenomenon. Therefore this study wants to examine different mitigation strategies of the urban microclimate by taking into consideration the campus of the Sapienza University of Rome. It was carried out through the software ENVI-met V 3.1 which gave the possibility to reproduce the model of the site (experimentally calibrated) and examine, in terms of MOCI (Mediterranean Outdoor Comfort Index), the different mitigation strategies implemented. This index was also related to the Apparent Temperature and to the health risk. Among the main results provided through this study, it is possible to notice how the solution combining cool roofs, urban vegetation and cool pavement leads, with respect to the current configuration of the site, to a mean and maximum decrease in the MOCI of −2.5 and −3.5. Finally it is able to determine a decrease of about 60% in the health risk for those who are exposed.
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