POSTER 23: UDC - Building climate and energy consumption
Study on the effect of morphologic features and material properties on microclimatic development and pedestrian comfort
1Kobe University, Japan; 2Nikken Sekkei Ltd, Japan
The purpose of this study is to evaluate the effect of morphologic features and material properties on microclimatic development and pedestrian comfort, through the case study in the redevelopment buildings in front of Osaka station based on the observation results. Several urban heat island measure technologies such as green cover and water surface are applied to the redevelopment buildings in front of central Osaka station. We have compared outdoor thermal environment in open plaza, roof garden and sunken garden based on the observation results. Thermal environment in each area is influenced by the local conditions of the surrounding. We used SET* for the indicator of outdoor thermal environment, by focusing on the effects of MRT and wind velocity. In open plaza, SET* is high due to high MRT and it is reduced by slightly strong wind at some measurement points. In rooftop garden, SET* is high due to high MRT and it is not reduced so much by wind with a little variation at each measurement point. In sunken garden, SET* is low due to low MRT, because solar radiation is shielded by plantings and high-rise buildings at most of measurement points, while wind velocity is small influenced by planting. Finally, the influence of shade by buildings and trees, and the influence of the material properties of the surface cover have been discussed.
Urban Microclimatic Improvement Effects to Building Blocks Energy Consumption by the Use of Energy Simulation
1Democritus University of Thrace, Greece; 2Democritus University of Thrace, Greece; 3Democritus University of Thrace, Greece; 4Democritus University of Thrace, Greece
It is widely approved that densely urban developments in conjunction with the use of inappropriate external materials, the increased human related thermal energy emission and the lack of green areas, increases environmental temperature leading to significant environmental impacts and increased energy consumption within buildings. The main problems that result from bad thermal conditions include decreased human thermal comfort, decreased air quality, increased heat illnesses and increased energy and water use.
Simulation tools must be employed in order to depict the present situation around the opencast area and inside the building envelope, usually during the warmest day of the hot period. Material identification, construction configuration and building complex with shadowing and radiation exchange must also be taken into account in the simulation process. If a new configuration of materials and bioclimatic techniques as cooling materials and other practices (water surfaces, green roofs) are used in the outer space that may mitigate urban heat island effect then, this would also improve the energy consumption of the inner spaces of the urban complex. Whole building energy simulation in the surrounding building blocks, before and after the outer space bioclimatic reformation, would show energy consumption reduction. Target of this procedure is to realize the microclimatic conditions improvement due to the rehabilitating bioclimatic techniques and practices and their influence to the buildings’ energy performance.
The outdoor surface materials modulate the air temperature of the lowest layers of the urban canopy layer, they are central to the energy balance of the surface and they form the energy exchanges that affect the comfort conditions of people. Their ability to absorb, store and emit radiant energy has a substantial effect on urban microclimate. The thermal behaviour of typical construction materials in an urban center of North Greece, was investigated and proposed the replacement of conventional materials with cool materials. The microclimate improvement has been evaluated in the past by experimental measurements and simulation tool verification. In the present study, those thermal benefits were accounted in the whole building energy simulation in terms of energy consumption reduction and carbon footprint improvement in the building complex and separately for inner spaces e.g. per floor, orientation, date of construction etc.
A coupled modelling approach to quantify the microclimatic effects of green infrastructure on residential buildings
TU München, Germany
Rising temperatures and the further intensification of the urban heat island (UHI) effect are major challenges for cities. They lead to an increase in energy demand for cooling which counteracts climate change mitigation efforts. Adaptation via green infrastructure (GI) can significantly reduce the UHI effect. Our study aims at quantifying GI measures at urban microscale with benefits for outdoor as well as indoor thermal comfort and buildings’ energy demand by coupling microclimate modelling with thermal building simulation.
The microclimate modelling software ENVI-met simulates the surface-plant-air interaction in an urban quarter. We use ENVI-met to analyse outdoor thermal comfort conditions in different urban greening scenarios. In order to evaluate the effect of these scenarios on indoor thermal comfort and buildings’ energy demand, we employ IDA-ICE, a building performance simulation tool. As ENVI-met operates at a temporal resolution of single extreme weather days while analyses of energy demand and thus CO2 emissions are based on yearly records, an approach to coupling needs to be developed. In our approach yearly weather files are clustered into typical-day categories. For each of the typical-days an ENVI-met simulation is realized. The results of these calculations are the input for the building simulation. The input of yearly weather files can be measured data as well as climate change scenarios to study the effects in a projected future climate. The methodological approach is tested for an urban block in Munich, Germany, representing a typical urban fabric with a high degree of compactness and surface sealing.
Coupling microclimate modelling with thermal building simulation allows a detailed analysis of how GI measures at the building side (e.g. green roofs and facades) as well as GI measures in public space (e.g. street trees) are reducing the potential for indoor overheating for the typical-days of a year. Furthermore the impact of GI on cooling measures at building level (e.g. cross ventilation, chiller) will be shown. The results are expected to serve as decision support for urban planners and city administrations when implementing GI measures.
Simulation of indoor climate with façade dynamics & building – atmosphere interaction
Environmental Modelling Group, Germany
The layout and composition of buildings play an essential role in both indoor and outdoor microclimate. Especially in the urban climate the influence of buildings on the microclimate is of utmost importance. Apart from the buildings’ influence on the wind field and the solar access of other buildings, individual physical properties such as heat storage in the building mass, reflection of shortwave radiation or the modification of the urban radiative budget are the driving parameters for outdoor and indoor microclimate. To evaluate these effects, an accurate modelling technique capturing the energy exchange between façades, the interiors, and the atmosphere is needed.
The article will present a newly developed multiple node façade model for ENVI-met which allows, together with the free arrangement of different wall and roof materials for every grid, detailed analyses of building physics.
In order to parmeterize the structure of the building façades and roofs, the new model resolves up to three wall layers which can vary in width and material used. Every material has physical properties such as absorption, transmission, emissivity, thermal conductivity, density etc. The nodes are placed in the center and at the horizontal borders of each material; a wall with three materials thus consists of seven nodes.
The combination of different materials in façades and different façades in a building allows the reproduction of complex structures and patterns of a wall or roof. The calculation of the surface temperature and the heat fluxes in the wall is based on a dynamic solution of the Fourier equation of all wall nodes in the model for each time step. Based on the energy fluxes calculated for each segment of the building envelope, the new model allows the estimation the indoor air temperatures in multiple zones and an estimation of cooling and heating demands. The validation results show that the new façade model together with the more sophisticated view factor analysis IVS (see other paper) allows a more detailed analysis of outdoor and indoor climate as well as building thermal performance and thus provides better insights for urban planners, architects and building engineers.
Reconceptualization of Climate Classifications and Climate Analysis Tools to Support Evaporative Building Cooling Strategies in the Hot Humid Tropics
University of New South Wales, Australia
Evaporative Cooling (EC) is increasingly being regarded as an effective method for building cooling, mitigation of Urban Heat Islands (UHI) and for urban adaptation to climate change. As this cooling technique depends on the adequate supply of water, it is notable that most research gives little attention to water availability, and also that the research community largely ignores the Hot Humid Tropics, despite these being regions with significant water surplus. Evaporative Cooling is still generally omitted in the theory and practice of building and urban cooling for the Hot Humid Tropics, even though diverse experiments and practical applications have confirmed that it can be effective even in hot humid climates.
This paper argues that the problem of marginalization and stigmatization of EC techniques as unsuitable for these regions is rooted in a poor understanding of the nature of hot humid climates and their variations, which has historically permeated approaches to building cooling. The climate responsive design literature effectively dismisses almost the whole range of hot humid conditions as intractable for the passive and low energy cooling strategies. The authors propose the need for a reconceptualization of climate classifications and climate analysis tools for architectural applications, which would allow a more detailed differentiation of hot humid climates than what is usually seen in conventional classifications. This finer grained differentiation is essential to overcome the problems referred to above, and to reconsider promising passive and low energy solutions for buildings and cities for the majority of the hot humid areas of the world, particularly those with less developed economies.
The discussion distinguishes some critical but disregarded aspects in existing classifications and climate analysis tools, as well as key elements around which hot humid climates should be categorized. In proposing a new analysis framework three aspects are highlighted: Indirect Climatic Influences on Comfort, Time Scale and Expression of Humidity Conditions; these aspects are relevant to identify normally disregarded variables for classification and analysis, and to inform a better understanding of hot humid climates in relation to EC. Secondly, three criteria, additional to temperature and humidity, are identified as more convenient to differentiate hot humid climates in detail, namely: Seasonality-Variability-Intensity of conditions, Saturation, and Water Availability.
Through this reconceptualization, it is expected that users of climate classifications and climate analysis tools, novice or experienced, will be able to better understand and describe the diversity of hot humid climates. Such better understanding will expand the awareness of alternative building cooling techniques for these environments, beyond the typical natural ventilation, air-conditioning or dehumidification responses. With an improved analysis framework, researchers, designers, and planners may open their minds to a new gamut of creative solutions for the hot humid tropics based on or potentiated by evaporative cooling principles, in which buildings and cities take advantage of the natural cycles of abundant water in the hot humid tropics, in a practical and responsible manner.
Urban greening and cool surfaces: the effectiveness of climate change adaptation strategies within the context of Budapest
Illinois Institute of Technology, United States of America
Regional climate projections for Central and Eastern Europe indicate a rise in summertime temperatures along with an increase in the frequency of warm temperature extremes by the end of the next century. In the case of Hungary, models indicate a 1.7–2.6°C rise in summer temperatures in the near future, and a 3.5–6.0°C increase is projected for the end of the twenty-first century—based on the A1B scenario. Besides rising temperatures, long term projections also signal a 20–40% decrease in summer precipitation in Hungary. In Budapest, the existing urban heat island (UHI) intensity of 4–8°C is expected to make these already adverse projections worse. Since the combined influences of these phenomena will be most pronounced in the densely built and populated areas of the city, identifying effective UHI mitigation and climate change (CC) adaptation strategies for these ares is of primary importance. This paper investigates the impact of cool roofs and pavements along with the influence of different canopy cover ratios on the urban canopy layer (UCL) climate for a summer day, and assesses their impact on human thermal comfort under projected climate conditions at the pedestrian level. The goal is to evaluate the effectiveness of these popular CC adaptation actions and to contribute to the development of a systematic framework for the assessment of UHI mitigation strategies. The study took four dense urban configurations from Budapest—characteristic to most Central European cities—to examine the effectiveness of these approaches. The numerical simulation study utilizes ENVI-met and MATLAB. Preliminary results indicate that the performance of CC adaptation strategies is the function of the configurations' initial thermal performance. Consequently, the starting point of any adaptation proposals should be the evaluation of the initial thermal behavior of the selected focus area, followed by the selection of appropriate strategies—based on both the shortcomings of the initial local or microclimate, and the available opportunities for improvements. This study is a first attempt to quantify key CC adaptation strategies for Budapest. The results of this research will provide feedback to local authorities on the effectiveness of the assessed approaches and foster the articulation of more precise and economic CC adaptation actions and measures.
Studying the interaction of iranian traditional architecture with nature through Sustainable Development
iran, Iran, Islamic Republic of
Few years, the debate environmentally sustainable architecture and nature Advice in the world will be discussed. But as humans, we are aware of Iranian and Persian architecture of the past is familiar with these issues, both in terms of the Persians of Iran's quad Pollution is considered sacred maintain the illusion of being Muslim in nature respected. Nature has always been a source of inspiration said more than other branches of art, architecture and nature is concerned. To portray the beauty of human nature is Rashyfth physical and spiritual beauty and tranquility of this it is cheaper Iranian Muslim Vmmar light of this reality (nature) it takes to create an architectural space In addition to the physical and spiritual relaxation, conference space, according to the surrounding environment Vaqlym area has guided their efforts towards saving energy and storage resources appropriate to the control light, ecological bring Azmsalh and available Vastfadh be used closes This is precisely what today is called sustainable architecture principles It is hoped that the present era Bhframvshy been entrusted with the re-creation in accordance with the principles of contemporary architecture to create a new approach to architecture. In this paper we provide a brief statement of the principles of sustainable architecture Then to analyze the climatic, physical architecture of this area is mountainous and cold climates are discussed from the viewpoint of stability At the end of a method according to the present climate will mention.
Development to the forecasting system of indoor environment using atmospheric condition of building scale
1National Institute of Meteorological Research (NIMR)/KMA, Korea, Republic of (South Korea); 2Weather Information Service Engine project, Seoul, Rep. of Korea; 3Department of Ecology, Technische Universität Berlin, Germany
It is known that Koreans stay indoors for 20.3 hours (84.5%) of a day. Thus, the importance of the indoor environmental control has been on the rise and the forecasting system of indoor conditions has been needed. However, many studies have concentrated in the predicting variation of outdoor environment by climate change. Therefore, this study developed the forecasting system of indoor temperature and airflow by exterior environment of building-scale. Outdoor environment is modeled by Climate Analysis Seoul (CAS) workbench. The CAS consists of non-hydrostatic numerical model MetPhoMod (Meteorology and Photochemistry Model) and empirical-statistical model for computing local-scale air temperature deviation (LD) based on GIS. MetPhoMod model simulate meso-scale wind and air temperature fields. And the GIS based model conceptualizes three different local-scale processes controlling LD: release of heat from the surface to the atmosphere (and vice versa) by sensible heat flux, dispersion of heat by turbulent mixing, and cooling of air due to cold-air production. CAS provides gridded atmospheric data relevant for local climate assessment at 25 m and 5 m spatial resolutions. Indoor environment is simulated by Energy Plus model. This model was developed by U.S. Department of Energy. It calculates the energy budget of building considering the information such as width and height, materials and layout of walls, ventilation methods, etc.
This work was supported by the "Advanced Research on Applied Meteorology" of National Institute of Meteorological Research (NIMR) funded by the Korea Meteorological Administration (KMA).
Thermal comfort in housing under solar obstruction derived from high building in urban renovation areas.
UNIIVERSITY OF CHILE, Chile
The built environment within cities generates urban microclimate that affects thermal comfort in residential buildings. Urban planning instruments can induce new spatial arrangements through Real Estate in renovation areas. Pressure on site to achieve maximum profit produces skyscraper which modify shadows pattern and irradiance values on urban spaces and neighbour buildings around them. The objective of the paper is to analyse thermal comfort in housing under solar obstruction derived from the surrounding built environment. A comparison is done between two urban scenarios such as with and without solar obstructions in order to compare its effects on thermal comfort. Solar energy simulations were the instruments for comparison alternative spatial arrangements at neighbourhood scale to design better cities. Results exhibit interesting differences in irradiation values which were compared to monitoring values from field work.
Potential of solar energy and the effects on the urban heat island
The main goal of the national building energy regulations is to decrease the primary energy consumption. Besides of the high thermal performance of the buildings themselves it means the use of renewable sources, first of all the solar energy. Electric power has high primary energy content: photovoltaic systems of buildings facilitate to export a part of the power to the national grid, such a way considerably improving the energy balance of the building. The other important item is the domestic hot water supply which can be based on, or supported by solar energy.
Collectors and PV arrays can be allocated on the roofs of the buildings. A case study of a medium size city illustrates the potential of the solar energy. Nevertheless in densely built urban areas the very low reflexivity of the energy collecting elements may have negative effects on the heat island – it is against the conception of “cool roof”. Special problem occurs if a tall building is surrounded by lower ones. The roof albedo of the tall building is not a problem since the upward hot air flow is over the canopy layer moreover it intensifies the urban breeze whilst the upward flows from the surrounding buildings disturb the ventilation potential of the upper stories of the tall building. Taking into account this problem and the fact that the roofs of surrounding buildings (depending on the topological relations) are in the solar envelope of the tall building it should be pondered whether it is worth to use energy in collecting elements on the surrounding buildings.
Comparative Study on Traditional and Modern Urban Textures: Form, Energy and Climate
1Southwest Jiaotong University, School of Architecture, China, People's Republic of; 2Huazhong University of Sci. and Tech.,China, People's Republic of
The elemental revolution from traditional urban texture to modern urban texture shows that: the fractal development of continuous courtyard has been displaced by the replicated copies of isolated building. Huge volume and great height have become the most popular modernism ways to compensate for the reduction in site coverage (urban density), therefore the scale of modern urban texture far exceeds the scale of traditional urban texture. Ventilation, irradiation exchange and other physical phenomena in urban space are deeply influenced by the difference of theses urban texture, which finally lead to the different urban microclimates that determine urban environmental performance.
In this paper, the classical examples of traditional and modern urban texture in hot-summer and cold-winter climatic zone in China are studied comparatively. For the urban form analysis, density, archetype and morpho-climatic indicators are discussed and the case studies of generic built form are extracted from these examples. Their environmental performance such as outdoor thermal comfort, buildings' energy consumption are compared comprehensively. The results lead to further revelation to urban designers for ameliorating urban microclimate and buildings' energy efficiency from the view of urban form.
Comparison of air temperature sensitivity of electric power consumption between Tokyo and Hokkaido region
Kansai University, Japan
Our final aim of this study is to predict the air temperature sensitivity of electric power consumption in future. This index will be able be used to evaluate a warming mitigation measure economically.
According to previous researches, the amounts of local electric power consumption in summer and winter are proportion to the air temperature respectively. Here, among several types of local energy consumption, what the air temperature sensitivity of local energy consumption evaluates is the energy consumption for air conditionings, which depend on the three conditions as follows.
- Weather conditions such as surrounding air temperatures, humidity and so on
- Performance of walls and roofs and purpose or function of buildings
- Building operational and personal issue. (Human factor)
It is difficult to compare the different local air temperature sensitivity of electric power consumption, because scale of local electric power consumption varies. There is no general method to compare. One of our goal is to establish a method to compare air temperature sensitivity of electric power consumption between different regions.
We compared the following methods to compare air temperature sensitivity of electric power consumption between different regions.
- method by the normalization
- weighting method with population
- method with deviation values
- method with the maximum supply capability
As the result, we found the method with the maximum supply capability is the most reliable for this purpose.
Modeling reduction of Urban Heat Island effect by improving radiative properties of buildings and districts
1ZAMG, Zentralanstalt für Meteorologie und Geodynamik, Austria; 2JOANNEUM RESEARCH Forschungsgesellschaft mbH, Austria
Increased intensity or frequency of heat waves due to a changing climate could have far reaching implications. It is expected that the phenomenon of Urban Heat Islands (UHIs) observed in cities will further contribute to heat excess, combined with a higher need for energy for cooling and ventilation (health hazard due to heat waves, e.g. France, summer 2003). The KELVIN project studies effects of changed surface albedo. The improvement of the reflection properties of roofs and other surfaces is one possible way to increase the energy efficiency in residential areas and at the same time to contribute to the climate protection by addressing the problem of the UHIs. Within the KELVIN project, low-cost adaptation to reduce the heat excess is exploited. At the same time, in historical city centers, colouring of tile roofs should not be changed significantly, so that the appearance remains unchanged as much as possible. This project examines the potential of a climate adaptation measure to reduce the UHI effect through changes in properties of the urban surfaces (roof albedo, green roofs etc.) and related emission-reduction through decreased cooling demand, exemplarily for the city of Vienna. The required input parameters for climate modeling such as surface albedo are determined based on the satellite image time series for Vienna covering the period 2000 to 2014. Urban climate model simulations are conducted based on the high-resolution topography and land use data for Vienna. Potential changes in local climate in the urban environment resulting from the changes in surface albedo are examined and the potential to reduce the heat load on a city scale is quantified. Results of the city climate modeling serve as a base for calculation of the potential for reducing electricity demand for cooling (including CO2-equivalent savings) in metropolitan landscapes. In addition, the potential change in radiative forcing induced by changing the surface albedo is estimated.