Urban microclimate parameters for buildings energy strategies

Journal of Urban and Environmental Engineering

This research work focuses on the study of microclimate conditions of two squares of Madrid, a city with a considerable Urban Heat Island. The process includes field measurements of the surface and radiant temperatures of materials on buildings façades, pavements and urban furniture. Air temperature, relative humidity and wind speed and direction were also measured. A virtual 3D model was used for sun exposure and solar radiation simulations. The urban microclimate regulation capacity of the finishing materials and shading are numerically defined. Considering the results obtained from measurements and simulations, a procedure for open spaces’ microclimate variety classification and identification is proposed: An approach to describe the thermal level for open spaces, in order to help the urban designers and planners to provide high microclimate variety for the users to meet their difference thermal demand. This is a key element to identify environmental quality and to obtain thermal...

Acta Scientiarum. Technology, 2012

This study aimed at analyzing the effect of buildings height on the thermal comfort in Ourinhos city-São Paulo State. The following variables were analyzed: air temperature, specific humidity, solar radiation and heat flows. Ourinhos is located in the Southwest of the São Paulo State, on the border with the North of Paraná State. The climate is tropical, with hot humid summer, and cold dry winter. The city has an urban area of 40 km2, with few buildings with more than one floor. In this study the threedimensional micro-climate ENVI-met model was employed, providing the comfort indices. Two simulations were accomplished, one with the actual height of existing buildings, average height of 5 m, and the other with the hypothetical height of 30 m, in order to examine the changes generated in the thermal comfort caused by the change in the city structure. The date chosen (February 15st, 2010) for the simulation was a summer day at this latitude. The increase in the buildings' height led to changes in the studied variables modifying the dynamics of local microclimate.

2017

Städtische Gebiete sind dynamische und komplexe Einheiten, die durch Klimaveränderungen beeinflusst werden. Neue Studien haben nachgewiesen, dass städtische Agglomerationen eine Reihe von unterschiedlichen Klimabedingungen umfassen, die zu spezifischen lokalen Mikroklimaten führen. Diese Arbeit zielt darauf ab, die Auswirkungen der lokalen städtischen Mikroklimate auf die thermische Leistung von Gebäuden zu bewerten. Sie analysiert und beschreibt die Größenordnung der Abweichungen im Energiebedarf als Funktion von Standort und Gebäudetyp über einen bestimmten Zeitraum. Genauer gesagt wird der Energiebedarf von drei Neubauten (Familienhaus, Mehrfamilienhausgebäude und Bürogebäude) an drei verschiedenen Standorten innerhalb der Stadt Wien, Österreich, über einen Zeitraum von 5 Jahren (2008 bis 2012) mit Tas (Thermal Analysis Simulation Software) simuliert. Die lokalen Mikroklimate werden durch die empirischen Wetterdaten beschrieben, die von nahe gelegenen meteorologischen Stationen a...

Energy and Buildings, 2013

The local climate of an urban area can be greatly affected by the urban thermo-physical and geometrical characteristics, anthropogenic activities and heat sources present in the area. A growing interest in microclimate issues has been raised as they represent important factors in achieving energy conservation and sustainability inside the cities, where a big amount of the population lives. This paper presents the analysis of microclimatic conditions in urban street canyons in a city of Northern Greece, Serres. A number of field measurements were carried out during summer 2011 aiming at investigation of the microclimate parameters that affect thermal conditions in the city's streets. The present study focused on the experimental investigation of wind characteristics (speed and direction) and thermal profile (air temperature distribution) of an area consisted by several building blocks in the city center. The data analysis concentrated at the differences that were observed inside the canyons, along different streets and the comparison between the microclimatic parameters in the urban center and the suburban area. Estimation of the cooling degree days for the area shows the increased energy needs of the surrounding buildings during the summer period.

DOAJ (DOAJ: Directory of Open Access Journals), 2012

Uno dei principali obiettivi della progettazione ambientale nei contesti urbani è la creazione di quartieri dotati di spazi aperti confortevoli. I parametri microclimatici, pertanto, sono di importanza centrale per le attività che vengono svolte all'aperto e in larga misura ne determinano l'uso. Le risposte al microclima possono essere inconsce, ma molto spesso si traducono in un uso differenziato degli spazi aperti a seconda delle diverse condizioni climatiche. Per tale motivo, comprendere la ricchezza delle caratteristiche microclimatiche negli spazi urbani esterni, e le implicazioni in termini di comfort per le persone che li usano, apre nuove possibilità per la progettazione degli spazi urbani sia in termini di nuova progettazione che di riqualificazione degli agglomerati esistenti. I parametri ambientali che influiscono sulle condizioni di comfort termico esterno, benché simili a quelli relativi agli spazi interni, sono caratterizzati da una maggiore e più complessa variabilità. Pertanto, a causa della complessità in termini di variabilità spazio-temporale di tali parametri e della vasta gamma di attività nelle quali le persone sono impegnate, ci sono stati finora pochissimi tentativi di comprendere le condizioni di comfort all' esterno ma soprattutto di come, gli effetti climatici esterni possono ripercuotersi sulle condizioni di Introduzione Abstract. In most of the contemporary urban spaces built in recent decades in Italy little attention is evident on the creation of environmental niches that are able to mitigate the microclimate. The following research aims to verify how the physical design of the outer space affects either the immaterial dimension of the space itself (livability, comfort), and the environmental performances of the surrounding buildings. The research supports the definition of the energetic-environmental requalification techniques to be used in the recovery phase of buildings. The analysis of the microclimatic features in the outdoor urban spaces, together with the implications in terms of comfort for those people who use them, opens new possibilities for the development of urban areas for what concerns both the new design and the requalification of the existing built-up area. Because of the complexity in terms of space-time variability of such parameters and of the wide set of activities in which people are committed, there have been so far very few attempts to understand the external comfort conditions, but mainly of how the external climatic effects could have an impact on the internal comfort conditions of the inhabited area.

The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2018

In this study, it is aimed to understand the relation between micro-climate and urban planning in the case of a cold-climate city, Erzurum. The effects of different urban patterns on micro-climate are analyzed in the context of this study. As a methodology, ENVI-met is used for processing micro-climate simulation of selected urban areas by using measured and obtained climate data such as air temperature, relative humidity, average reflected temperature, surface temperatures, sky view factor, wind velocity and direction. In order to check the accuracy of the simulation for the case study area, obtained data (from meteorology station) is simulated with ENVI-met and results were compared with measured data in the area. Also, land uses and field searches based on the observation of existing situation of urban environment were included into analysis. The findings show that irregular building plot sizes and building heights are mostly existing in historical areas and those urban forms increase thermal comfort under cold climate conditions. The results of simulations provided that same heights of the buildings, regular separation of buildings and regular plot sizes have led to severe urban micro-climates. In contrast, it is observed that variety of those urban physical environment features supported comfortable micro-climate conditions. Urban geometry and climate variables are two of the most important factors shaping outdoor spaces thermal comfort feeling.

Sustainable Development and Planning IV, 2009

The thermal conditions within cities as well as the energy efficiency of buildings are determined by the urban climate, which is in turn influenced by the thermalfluid characteristics of the built environment and particularly transfer effects to the atmosphere. A good example of this interaction is the urban heat island phenomenon. In this case heat generated from urban activities has a direct impact on the urban microclimate, resulting in increased night time temperatures and a reduction in the observed temperature range.

Energies, 2020

This paper deals with the interactions between biophysical and microclimatic factors on the one hand with, on the other, the urban morphology of intermediate urban open spaces, the relationship between environmental and bioclimatic thermal comfort, and the implementation of innovative materials and the use of greenery, aimed at the users’ well-being. In particular, the thermal comfort of the open spaces of the consolidated fabrics of the city of Rome is studied, by carrying out simulations of cooling strategies relating to two scenarios applied to Piazza Bainsizza. The first scenario involves the use of cool materials for roofs, cladding surfaces, and pavement, while the second scenario, in addition to the cool materials employed in the first scenario, also includes the use of greenery and permeable green surfaces. The research was performed using summer and winter microclimatic simulations of the CFD (ENVI-met v. 3.1) type, in order to determine the different influences of the mate...

Energy and Buildings, 2015

The wellbeing and life quality also depend on the climatic conditions of the surrounding environment. In this case study the focus is on those interventions that can be performed, especially on enclosed urban contexts, to control the thermal environment. It pays attention on the effect of the vegetation and high albedo materials characterizing horizontal and vertical boundaries of the site and the Cloister by Giuliano da Sangallo, a historical site in Rome, is taken as case study. The model of the site was simulated with the software ENVI-met and it was verified thanks to a measurement campaign in situ. Five scenarios with different vertical and horizontal materials of the present buildings were simulated together with an analysis of the variations of physical quantities (air temperature, mean radiant temperature, relative humidity, wind speed) affecting the perception of environmental comfort (calculated through the Predicted Mean Vote). The result is that in those areas characterized by a Mediterranean climate, where the summer months with high temperatures must be mitigated, the vegetation can be a significant benefit to the environment, and high albedo materials can ease the thermal load of the buildings with a higher thermal stress for the pedestrians.

2009

In contemporary urban development, to improve the quality of public urban spaces has become one of the most outstanding goals of local urban policies, in order to increase pedestrian activities and people’s social interaction. In this context, to promote outdoor thermal comfort has an utmost importance, especially considering the heat island phenomenon. This paper recalls the use of urban design as an instrument to the mitigation of the negative effects of heat islands, through the inclusion of microclimatic principles namely based on the relationship established between the buildings and the public pavements facing materials and the vegetation with outdoor air temperature in its projected process.

11th Conference on Sustainable of Energy, Water and Environmental Systems, SDEWES2016.0442, 1-15, Lisbon, September 2016, ISSN 1847-7186 (book of abstracts) ISSN 1847-7178 (digital proceedings) , 2016

Globally, the 54 % of the world's population reside in urban areas and in 2050 the projections are of 66 %. Then the sustainability and liveability of urban spaces are rising the attention of the scientific community. Particularly, in this work, the microclimate of outdoor spaces is investigated considering the different outdoor air temperatures registered by various weather stations in the City of Turin (Italy). The air temperature variations were correlated with the characteristics of the different spaces as the built urban morphology, the solar exposure of urban spaces and the albedo coefficients of outdoor spaces. Finally, with a multiple linear regression analysis the outdoor air temperatures have been correlates with the urban variables to obtain a model for the prediction of the average monthly temperature in the city of Turin. This model will be used to understand the different microclimates in the city Turin but also to evaluate the most influential urban variables on the outdoor air temperature. The resulted model could help urban planners to predict the microclimate in new districts as a function of the urban form and of the outdoor materials chosen, with the aim of improving the liveability of the city in all the seasons.

Raega - O Espaço Geográfico em Análise

Cuiabá city is nationally known as "green city" because of to its large afforestation, has experienced progressive urban expansion for years, with deforestation possibly causing a rise in temperature and the development of heat islands In this context the afforestation can be an alternative for the improvement of the thermal comfort of the residents of this city. So the study objective was to analyze the microclimate differences of vegetated and non-vegetated urban areas in rainy and sunny conditions, analyzing also the heat index and the thermal discomfort index. The sampling took place at a public place and great flow of pedestrians. Data on the air temperature (Tair), sidewalk surface temperature (Ts), and relative air humidity (Rh) were recorded using two linear transects, starting at 7 am and ending at 7 pm, in two-hour intervals. Due to the seasonality of the city's climate, measurements were taken in the dry and humid period of the year. There was a statistical difference for sidewalk surface temperature between the sites (p-value < 0.001) and an increase of approximately 10°C in both periods in non-vegetated areas. There was no statistically significant difference for the heat index and thermal discomfort index among the analyzed transects, especially in the wet season, periods of discomfort occurred. Was verified that for open sites vegetation decreased air and surface temperature, increased relative humidity, but it was not enough to have thermal comfort at all times of the day, concluding that the presence of vegetation was not enough to cause a difference in the index of each transect.

Fuel and Energy Abstracts, 2011

This paper presents a parametric approach to the definition of a proper building shape compared to the building heating requirement in the very first stage of the design process. A new simplified index is introduced, namely the south exposure coefficient C fs . In fact, as far as bioclimatic architecture is concerned, the relationship between buildings and natural environment is very important both for the control of indoor comfort conditions and energy requirements. The building shape is a fundamental aspect of this relationship. Usually, in thermal behavior analysis this parameter is considered only from the point of view of compactness. This is a reductive approach, because two buildings with the same coefficient could have different shapes and so a different thermal behavior. Some aspects such as orientation, openings, exposure to atmospheric agents and natural elements must also be strictly considered. Moreover, in scientific literature no indications are given to designers who operate in mild and warm climate conditions. This is why the results of a research activity focused on heating requirements of buildings with different shapes and laid in the Italian territory are presented. Monthly calculations have been performed following the quasi-steady-state method suggested in the European standard. Outputs show that better results in the building energy performance can be achieved considering a bioclimatic (though simplified) approach since the very beginning.

2016

This research has tested the effects on the urban microclimate of the transformations induced in the outdoor urban spaces and, in parallel, how these modifications effect the reduction of temperature in the confined indoor spaces of the built environments. Open spaces and the surface of urban volumes are considered, measured and evaluated as a unique interacting environment. The volumetric configuration of the urban textures and the materials that constitute the external surfaces, are the main factors that influence the microclimate of a city. Comprehend and being able to transform in an adequate way the urban settings could contribute to the improvement of the thermal comfort in outdoor and indoor built environments. By using as a principal indicator thermal comfort the variation of the external temperatures in an unprecedented collaboration between different scales and different environmental simulation systems, this paper analyses the energy saving potential given by the use of green and passive techniques and shows the synergies that may arise between outdoor and indoor spaces. Volumetric configuration, urban microclimate, thermal comfort, environmental simulation systems, green and passive techniques

Climate change and the deriving impacts on the built environment certainly represent one of the most challenging issue for several key players involved in shaping the cities of tomorrow. This is not simply a matter of adapting buildings to new requirements, but rather to rethink the way the urban fabric reacts to new and sometimes unpredictable phenomena. The process is related to increasingly evident extreme conditions in the summer time, that strongly improve the energy demand for cooling with negative impacts on the energy balance as well as on thermal comfort conditions of the end users and of urban population with severe implication on health and wellbeing. Outdoor comfort depends on a number of interrelated factors: the characteristics of the built environment, the relationship between materials and energy use, global climate change and local micro-climate: Temperature, Solar Radiation, Wind distribution, Wind Speed, Absolute and Relative Humidity. The objective of this specific study is to test the microclimate modeling of a city portion in a demo-case – a plot of building blocks with inner courtyards – as a tool for supporting the regeneration phase addressing technological choices and design solutions to improve outdoor comfort conditions. The outcomes of the performed envi-MET simulations, comparing the situation before and after intervention, are consequently discussed. In the specific case, the developed project involving the courtyard has led the Thermal Comfort perception, evaluated in terms of PMV, to shift from " very hot " (+3.50, +4.00 red zone) and " very very hot " (above + 4.50 violet zone) to " Warm " (+1.50, +2.00) at urban plot scale.