ENVI-met Software Research Articles

Evaluation of the cooling effect of green and blue spaces on urban microclimate through numerical simulation: A case study of Iloilo River Esplanade, Philippines

The aggravating impacts of the urban heat island phenomenon in Philippine cities has motivated planners to utilize urban green and blue spaces as a potential mitigation strategy. This study aims to assess the cooling effect (CE), heat reduction (HR), and energy saving potential (ESP) of trees and water along the Iloilo River Esplanade located in Iloilo City, Philippines. Microclimate modelling and simulation during summertime were performed using ENVI-met software and validated using field observations. Results of the study show that the urban park can provide a maximum CE of 2.63°C at 3:00 PM near the southern edge of the river, which is equivalent to a HR of 13,564 J and an ESP of 1.09 × 10−2 kWh. Meanwhile, a temperature increase of up to 0.16°C can be observed at night due to the nocturnal warming effect of water. In terms of spatial distribution, CE, HR, and ESP tend to gradually decrease as the horizontal distance from the park and altitude increases. Moreover, wind direction may also increase the scale and intensity of CE downwind, but it has an opposite effect in areas upwind.

Biomimicry-Based Strategies for Urban Heat Island Mitigation: A Numerical Case Study under Tropical Climate.

In recent years, demographic growth has caused cities to expand their urban areas, increasing the risk of overheating, creating insurmountable microclimatic conditions within the urban area, which is why studies have been carried out on the urban heat island effect (UHI) and its mitigation. Therefore, this research aims to evaluate the cooling potential in the application of strategies based on biomimicry for the microclimate in a historical heritage city of Panama. For this, three case studies (base case, case 1, and case 2) of outdoor thermal comfort were evaluated, in which the Envi-met software was used to emulate and evaluate the thermal performance of these strategies during March (highest temperature month) and October (rainier month). The strategies used were extracted from the contrast of zebra skin, human skin, evaporative cooling, and ant skin. The results showed a reduction of 2.8 °C in the air temperature at 11:00, the radiant temperature decreased by 2.2 °C, and the PET index managed to reduce the thermal comfort indicator among its categories. The importance of thinking based on biomimicry in sustainable strategies is concluded; although significant changes were obtained, high risks of discomfort persist due to the layout and proximity of the building.

Determining the Relationship Between Landscape Structure and Mental Components on Thermal Assessment

Structure of the urban open spaces and the effect it imposes on the body and mental health increases the importance of attention to the quality of such places. The thermal comfort is the environmental factors affecting the reactive behavior of people in urban open spaces. In the present study, aiming at investigating the relationship between psychic components and landscape structure and its effect on the thermal assessment of individuals, three methods are used; the descriptive method for explaining the psychic components and landscape structure as well as the survey method for determining the relation and correlation between research variables along with the experimental method for testing the variables using certain tools. Thermal analysis done by computer simulation method in ENVI-met software in the Karoon river area in Ahvaz city. The index used for assessing the thermal comfort is UTCI. In order to find the relationship between the research variables, the field data collections were accomplished by arranging questionnaires and in a random way by Cochran formula. The findings demonstrated the existence of a relationship between landscape structure and different psychic states in individuals. In fact, the moods of the individuals in open spaces affect their landscape qualification and thermal assessment. Eventually, and based on the findings of the study, it could be stated that the mental condition and psychic state of the individuals in different situations has definitely affected their qualification of the landscape structure, landscape quality as well as their reactive behavior while it would overshadow their thermal assessment.

Simulation on the impacts of tree canopy morphology on thermal comfort at the pedestrian level

To explore the role of tree canopy morphology on the urban thermal environment and human comfort, this paper considers the variation of four factors (Top Canopy Height (TCH), Leaf Area Density (LAD), Bottom Canopy Height (BCH) and Canopy Diameter (CD)) and uses an orthogonal experiment method (OEM) to build 25 simulation scenarios. In an idealized model planted with trees, the effects of changes in canopy morphological parameters on air temperature and Physical Equivalent Temperature (PET) at a pedestrian height of 1.5m are simulated and discussed using ENVI-met software. The results show that the air temperatures for 25 different groups differed significantly during the day and less at night. At the hottest time of the day (15:00), there was a difference of 7.8°C between the coolest (ID 11) and hottest (ID 16) groups. TCH, LAD and CD are all negatively correlated with PET, while the BCH is positively correlated with PET. Among the four canopy morphology parameters, CD has the most significant effect on PET at a pedestrian level of 1.5m.

Summer Thermal Conditions in Outdoor Public Spaces: A Case Study in a Mediterranean Climate

Comfort in public spaces is essential to their attractiveness and continued role in improving human quality of life. Acceptable thermal conditions are determinant to ensuring users’ comfort. This study undertakes an assessment of three urban sites in Arouca, in the north of Portugal, using ENVI-met software. Simulations test the influence of pavement and façade covering material, vegetation, and site morphology. The climate of the region is classified as Mediterranean Csb, with rainy winters and dry and mildly warm summers. A typical summer day is considered. The results reveal that a combination of factors might lead to thermal discomfort even in this mild climate on an average day, mainly due to heat exchange by radiation. In addition, the impact of alterations to surface properties depends on the morphological characteristics of the site, e.g., high albedo of the pavement may lead to a decrease or an increase in mean radiant temperature, depending on the space. This variability is present in the effects observed at the studied sites. A high façade albedo always contributes, in these cases, to thermal discomfort. The conclusions of the present study highlight the importance of performing a specific study for each urban site whenever an intervention is to be planned.

Quantifying the Air Temperature Reduction with Greenery in UiTM Shah Alam: A Microscale Study

Growth in cities population has caused urban sprawl which is the key factor in the issues of high temperatures as well as UHI in many countries. This issue has affected the urban microclimate as well as the indoor and outdoor conditions of human thermal comfort. This issue is also aggravated by the replacement of natural greenery area with building and other man-made features. For that reason, greening the cities, as part of bioclimatic concept of build environment, could be the way to decrease the outdoor temperature and making the surrounding more comfortable. To understand this issue further, ENVI-met software was used to simulate all activities either natural or man-made to attain accurate prediction and evaluation for microclimate changes in certain area. For this study, the simulations were run in three scenarios of pavement, asphalt pavement without plants (scenario 1), concrete pavement without plants (scenario 2), and asphalt pavement with plants (scenario 3). Plants were design in area surrounding the building and in courtyard consisting of pine trees and hedges of 2 metre height. The result shows that greenery plants can influence air temperature and airflow in the surrounding thus improving thermal comfort in the area. Existing plants can decrease temperature from 0.5°C to 2.3°C and air velocity become slower at 0.05 m/s to 0.15 m/s. Overall, although the changes are at small scale, it is shown that plants are able to improve microclimate surrounding better towards thermal comfort standards.

The Effect of Building Layout on Microclimate Characteristic in Settlement Area

Housing is one of human’s primary need, then it has an important role on human life. Not only the building, but also the environment of settlement. People need to have a good quality of settlement area, one of which is microclimate quality to provide health and comfort in living. As a tourism and education city, Yogyakarta has a rapid development which indirectly resulted in increased housing needs. In the era of climate change, it’s very important to consider the environmental aspects in regional planning, including the settlement area. This study aims to determine the characteristics of the microclimate in two different settlement typologies in the city of Yogyakarta. The difference is on the building layout, which is one of the factors that influence microclimate. The study was conducted in two districts, one is settlement in Baciro that represent planned settlement, and settlement in Suryatmajan to represent unplanned settlement. Direct measurement and observation used as a method, supported by simulation with Envi-Met software. The result will show how the building pattern can affect microclimate, so it can be considered in settlement development that can improve the quality of people’s life and also the environment.

Urban geometry as an adaptation strategy to improve the outdoor thermal performance in hot arid regions: Aswan University as a case study

Due to the lack of a comprehensive multiscale campus planning guideline, new universities in Upper Egypt are associated with a lack of environmental considerations of the surrounding climatic conditions. Additional extensions planned for the Aswan University campus located in New Aswan city provide an opportunity to explore thermal improvements in a hot arid environment. This study presents analytical and empirical findings that highlight the potential for their implementation in outdoor spaces. Most of the previous literature address the urban geometry from a single scale perspective. However, in this study coupled scales were adopted to get more effective thermal adaptation guidelines; urban form planning (cluster scale), and geometrical details (canyon scale). The study investigates five urban forms and 18 urban geometry scenarios to quantify their thermal impacts on outdoor spaces. All scenarios were evaluated according to the differences in geometrical variables, with data introduced based on on-site measurements and microclimate simulations using ENVI-met software. The results are ranked according to its influence on pedestrian thermal comfort. The suggested strategy could reduce the average PET value with 6.8 °C in the NS canyons and 4.2 °C in the EW during the peak hour. Design guides are introduced for planners and decision-makers.

The Role of Green Infrastructure in Enhancing Microclimate Conditions: A Case Study of a Low-Rise Neighborhood in Abu Dhabi

Urban heat islands are characterized by the increased temperature in urban areas compared with the rural surroundings due to human-made interventions that replace natural lands with buildings and roads. This study focuses on the assessment and utilization of using local nature-based solutions such as trees, sensitive landscaping types and design strategies to enhance microclimate in neighborhood streets and the public realm in desert areas, taking Abu Dhabi as a case study. The research utilizes a design-based approach to propose landscaping and layouts of urban street trees in low-rise residential urban areas. In this study, two methods namely an on-site measurement using citizen science, and a numerical simulation model in the ENVI-met software are used. Site-measurements included the tree physical characteristics such as tree height, crown width (crown spread/diameter), and trunk height, and the use of technology (photography and the Fulcrum mobile application, Nikon Forestry pro Laser Rangefinder) and air temperature around trees. ENVI-met included four scenarios: 1—“no-vegetation”, 2—“grass-only”, 3—“existing conditions” and 4—“proposed landscape design”. Grass and three types of local street trees are used in the proposed scenarios including Ghaf, Poinciana, and Temple tree. In addition, a standard of 6 and 8 m spacing between each tree is applied to determine the effect of varying vegetation densities on the outdoor temperature. The combined results using citizen science and the model allowed the identification of particular urban tree species that show substantial cooling effects. This is the case of Poinciana trees, which decreased the air temperature up to 0.9 °C when spaced every six meters in pathways and open unshaded areas amongst alleys, improving the overall thermal conditions in neighborhoods of hot-arid landscapes.

Impact of Urban Block Typology on Microclimate Performance in a Hot-Humid High-Density City

Because of their structure, urban areas induce very complex climate phenomena while notably impacting pedestrian safety and comfort in the urban microclimate. This paper presents the results of an investigation into the influence of urban block typology and building intensity on environmental performance in the context of the urban microclimate of a hot-humid high-density city. Qualitative and quantitative characterization of the building geometries used in this study was conducted to compare an existing block typology scenario with five new block typology scenarios in an area of 350 x 350 x 150 (L x W x H) meters. The scenarios investigated were composed of different settings for floor area ratio (FAR) and building coverage ratio (BCR) and different configurations of building elements (tower, podium, and courtyard). They were simulated and analyzed using the ENVI-met software. The simulation results indicate that the five new scenarios all improved the environmental thermal parameters and that the FAR has a greater influence than the BCR. FAR has the strongest correlation with air temperature, followed by solar radiation and relative humidity. The influence of BCR on humidity and wind speed is not as significant as that of FAR. A tower strongly influences wind speed in proportion to the height of the building. Open courtyards correlate with higher temperature and lower humidity than closed courtyards. The combination of a closed courtyard with a hybrid block consistently outperformed the other configurations in thermal performance. Within this framework, the proposed scenarios can provide recommendations for city design regulations and input for urban design methods to further improve microclimate performance.

The effect of various urban design parameter in alleviating urban heat island and improving thermal health-a case study in a built pedestrianized block of China.

Increasing urban heat island and global warming have aroused serious thermal environmental problems and even harm people's thermal health. Because of the importance in people's daily life, a commercial pedestrianized block represents a symbol of a city or metropolis; therefore, focusing the attention on the thermal environment in such regions is very necessary. Most of the researches on the urban thermal environment are calculated by remote sensing data; limited by the low spatial resolution of remote sensing image, it may not obviously reflect the true thermal environment of the research site, especially in some microscale regions. Based on this, the new software ENVI-met is developed to research the thermal environment and forecast people's thermal sensation in a microscale region. Therefore, the objective of this study aims at conducting field measurement and numerical simulation to assess the thermal environment of a typical commercial pedestrianized space in southern China and assess the different urban design parameters in ameliorating the urban heat island effect. Our final results demonstrate a quantitative evidence for establishing a comprehensive standard for improving the thermal environment in a microscale region, and this study also can be a supplementary in the research field about improving thermal health.

Investigating the sans pareil streetscape configuration for creating thermal comfort urban place in Surabaya

The case of climate change expand accelerated than before caused by human-made emissions happened in the street. Coastal cities such as Surabaya are needed a thermal comfort urban place to be the solution. Through the sans pareil streetscape, we can understand which configuration are more (or less) effective for creating thermal comfort urban place. To explore this, we surveyed Raya Darmo Street, Polisi Istimewa Street, and Diponegoro Street Surabaya, Indonesia (N=25). The method using is micro climate analysis with software ENVImet which simulated the micro-scale interactions among urban surfaces, vegetation, and the atmosphere. In this method, it is necessary to measure the thermal comfort index by computing the Temperature Humidity Index (THI) from the data for each thermal station. In the results of this microclimate analysis, six color distributions produced, which showed the climate level. From the color distribution at 12 a.m., showed that no comfortable spaces found on all three streetscapes. There are as many as 90% of streetscape cuts included in the criteria for being uncomfortable on Diponegoro Street. On Raya Darmo Street and Polisi Istimewa Street are included in the requirements of being uncomfortable with a percentage of 49% while the rest are moderate criteria.

Study of microClimate Characteristic in Tamansari Yogyakarta as a Heritage Tourism Area

Yogyakarta is known as a Tourism City because there is a lot of tourist destination that exists. One of the uniqueness of the city of Yogyakarta is the royal system that has been part of the government until this day. Tamansari Water Castle is a historic site used by the King and also the royal family for recreation. As one of the main destinations for tourists, it is important to note how the performance of the space formed in providing comfort for visitors. This study aims to determine how the microclimate characteristics in the Tamansari area, which have an impact on the thermal comfort felt by visitors. Observations are made to discover the elements forming the outdoor space such as the building mass layout and composition, the type of surface material, and also the type of vegetation that exists. This study uses simulation method with Envi-met software, using observational data as input. The simulation process will show how the microclimate conditions are formed in the Tamansari area, which includes air temperature, humidity, wind speed, and wind movement. The results represent that the landscape design in Tamansari has considered the thermal comfort through surface material and vegetation they have.

Impacts of urban form and urban heat island on the outdoor thermal comfort: a pilot study on Mashhad.

There is an increasing demand for cooling cities because of its importance on human health and the quality of life in outdoor urban spaces. However, the development of methods in improving outdoor thermal comfort and zoning cities based on outdoor thermal comfort is still challenging. In this work, we propose a new approach to cities zoning from the lens of outdoor thermal comfort in the arid climate of the city of Mashhad, Iran, and investigate the impacts of urban form characteristics on pedestrian thermal comfort. The effects of complex urban form parameters including height to width (H/W) ratio, canyon orientation, tree canopy cover, and building surface materials on the thermal comfort of pedestrians were studied in the arid climate of Mashhad. Microclimate simulation and analysis is conducted in ENVI-met software, and ArcMap is used to calculate Mashhad urban heat islands. Path analysis in SPSS presents an urban form formulation, which predicts approximate outdoor thermal comfort condition in current and future urban context of Mashhad and other cities with the same climate. We finally demonstrate the use of our research method as an alternative method for all cities: urban heat island (UHI) zoning can be used as a substitute for urban form zonings based on outdoor thermal comfort, especially in large cities where data collection on urban form can be difficult due to limited time and resources.

How Cool Pavements and Green Roof Affect Building Energy Performances

The urban heat island effect amplifies the global warming phenomenon with sensible aftermaths on the building energy consumptions. The absence of green areas, open water channels as well as the lack of free unsurfaced spaces creates a sort of urban cap and a heat reflection effect, from the bottom upwards, which persists in the early hours of the night. This heating effect exacerbates the use of air conditioners which, if on one hand helps to cool houses, on the other hand rejects outside hot air hindering the cooling effect of nighttime air. The aim of this study is to analyze the effects of urban heat island mitigation techniques on the building energy performances, such as cool pavements and green roofs. Measured temperatures were used to calibrate a model of a densely populated district in Rome by means of ENVI-met software. It was subsequently carried out an energy analysis through the use of TRNSYS in order to study the energy behavior of a reference building in its urban context in function of the variation of the boundary conditions.

The quantitative assessment of the effects of the morphology of urban complexes on the thermal comfort using the PMV/PPD model (a case study of Gheytariyeh neighborhood in Tehran)

Abstract In the present age, environmental sustainability has been severely challenged because of the human constructions and changes in the ecological landscape of cities so that the issue of the compatibility of urban development with these changes has become especially important. Changes in morphology, structure, form and geometry of the cities, which are themselves caused by changes in the form of urban complexes and geometry of buildings, have a profound effect on the micro-climate and sustainability of urban environments by the efficient adjustments. To assess environmental sustainability or unsustainability in urban neighborhoods, thermal comfort is considered as a good indicator. The assessment of this qualitative concept requires the use of quantitative indicators and assessment tools that can be spatially presented to urban planners and designers to help them in urban development plans. The PMV/PPD model uses heat-balance equations and empirical studies to calculate the ‘predicted mean vote’ and ‘predicted percentage of dissatisfied’, which are somehow derived from the parameters that affect thermal comfort. The innovation of the present study compared to the background of the researches is the evaluation of urban building design policies in thermal comfort, which fills the gap between the evaluations of the level and scale of architecture and urban planning in previous researches. An applied and descriptive-analytical research method has been used in the present study. Firstly, data needed to evaluate the main purpose of the research in the selected site located in the Gheytariyeh neighborhood of Tehran were collected. They are then simulated and analyzed. The results indicate that the difference in the geometry of the buildings and the city blocks can make a difference in the heating comfort of the different city neighborhoods and residents. The recent study has proven that the difference in the city blocks (3- and 4-dimensional and square shapes) can affect the comfort and temperature factors. Spatial simulations conducted in the present study by ENVI-met software show that compared to other indices studied, the PMV and PPD indices have the least distance from the ideal thermal comfort conditions in the design of trilateral high-rise buildings and have the greatest distance from them in the design of rectangular building blocks. It is worth noting that the adoption of policies and regulations related to the design and architecture of urban neighborhoods by the implementation of urban development policies is one of the measures required when the urban development plans are drafted and approved. The simulations model indicates that the minimum and maximum values of PPD index have been respectively equal to 51.06% and 99.96% for the option 1 (three-sided block), 56.09% and 98.26% for the option 2(four-sided block), 57.32% and 98.19% for the option 3(empty middle block) and 58.76% and 98.05% for the option 4 (rectangular block). The present paper has tried to explain the requirements of it.

Use of Land Surface Temperature Estimation with Geographical Information Tools for Validation of Numerical Microclimate Studies at Urban Scale

For this study, different approaches found in the literature to obtain the Land Surface Temperature (LST) were evaluated through Geographic Information tools, to validate the temperature results obtained from dynamic simulations at urban scale with the Envi-met software. Here, the case study is an urban section of the Historic center of Panama City named Casco Antiguo. From the dynamic simulation results, the surface temperature was analyzed for March at 15:00. Concerning the results obtained for March, the Online Global Land Surface Temperature Estimation tool provided the best characteristics when validating the data obtained with Envi-met. It was found that the Landsat 7 images, applying the emissivity method ASTER and NDVI, provided data more stable and closer to the ones we wanted to validate.

Investigating outdoor thermal comfort of educational building complex in urban area: A case study in Universitas Kebangsaan, Bandung city

Campus building was a place to accommodate various educational activities, which were both carried out indoors and outdoors. The environment, including the building and its exterior, provided thermal comfort that was influenced by the context, such as the mass of the facility, vegetation, and constructing envelope materials. The microclimate also influenced the environment, such as temperature, wind speed, and humidity. This study aimed to investigate the outdoor thermal comfort of campus building in urban area during summer, while also identifying the influential factors. This research referred to a case study, examining the thermal quality of the educational building environment using ENVI-met software, based on the Predicted Mean Vote (PMV) index as an indicator of outdoor thermal comfort, in Universitas Kebangsaan (UK). The results showed that the outdoor environment had low thermal comfort conditions during the day, as it also had different thermal satisfactory situations, due to differences in physical characteristics in each zone. This characteristics included, (1) The SVF determinant as indicators of the shading factor should be supported by the presence of vegetation and the use of pavement material, (2) Although the wind speed factor does not really affect the thermal comfort in the outdoor space, the interconnection between open gaps is likely to make breeze distribution in the area better. This study offered direction for campus planning, in order to maintain the optimal capacity of the natural environment, such as (1) Strategizing to create a better shadowing factor in the outer space, which was supported by controlling the use of pavement materials, (2) Directing the density of buildings by making open spaces more permeable, in order for better wind distribution in the area. From this study, the campus current conditions and future design development potential was also observed.

Evaluation of Biomimicry-based Strategies to Improve Exterior Environmental parameters: A numerical Study at Urban Scale in a tropical Climate

Due to population growth, cities have expanded their urban areas, causing increased temperatures and vegetative scarcity. Therefore, studies have been carried out on the urban heat island phenomenon, its effect on people’s thermal stress, and how to mitigate this problem. This research aims to evaluate the application of biomimetic strategies for improving exterior environmental conditions on an urban scale under a tropical climate through dynamic simulation. The case study takes place in the Casco Antiguo of Panama. Here, two cases were evaluated (base case and proposed case). The proposed case consists of strategies obtained from the application of the biomimetic design methodology. The ENVI-met software was used to evaluate both cases, where the external environmental parameters are compared between both cases for the critical months (March and October) at 15:00. Results showed that the air temperature reached an average reduction for March of 1.9 °C and 2 °C for October, the Tmr had an increase up to 0.6 °C in March and the PET index decreased 1.7 °C in March and in October 2 °C. Although significant changes were obtained, high levels of discomfort persist due to the narrowness and proximity of the buildings in this urban settlement.

Microclimatic behavior of sustainable urban schemes proposed for hillside areas versus existing neighborhoods in the Metropolitan Area of Mendoza, Argentina

The Metropolitan Area of Mendoza (MMA), Argentina, has extended towards peripheral hillside areas without considering the environmental impact of this action. This growth has continued the urban model of flatland development, causing changes in the ecosystem and an increase in outdoor air temperature. This work proposes and evaluates urban schemes that incorporate design criteria with the objective of preserving environmental characteristics and mitigating the effect of urbanization on the microclimate. The proposed grid layouts, located in three predominant slopes, were linear organic and Cul-de-Sac. Methodologically, the microclimatic response of the proposed schemes was evaluated by applying ENVI-met software simulation. The results show that urban growth is possible when carefully considering environmental limitations which grant maximum air temperature reductions of up to 2 °C.