Empirical and Computational Issues of Microclimate Simulation (original) (raw)
A simplified mathematical model for urban microclimate simulation
Building and Environment, 2011
Techniques for modelling urban microclimates and urban block surfaces temperatures are desired by urban planners and architects for strategic urban designs at the early design stages. This paper introduces a simplified mathematical model for urban simulations (UMsim) including urban surfaces temperatures and microclimates. The nodal network model has been developed by integrating coupled thermal and airflow model. Direct solar radiation, diffuse radiation, reflected radiation, long-wave radiation, heat convection in air and heat transfer in the exterior walls and ground within the complex have been taken into account. The relevant equations have been solved using the finite difference method under the Matlab platform. Comparisons have been conducted between the data produced from the simulation and that from an urban experimental study carried out in a real architectural complex on the campus of Chongqing University, China in July 2005 and January 2006. The results show a satisfactory agreement between the two sets of data. The UMsim can be used to simulate the microclimates, in particular the surface temperatures of urban blocks, therefore it can be used to assess the impact of urban surfaces properties on urban microclimates. The UMsim will be able to produce robust data and images of urban environments for sustainable urban design.
Recent Trends and Remaining Limitations in Urban Microclimate Models
Open Urban Studies and Demography Journal, 2015
Problems such as natural ventilation, pollutant dispersion, changes in wind environments, and urban heat islands are gaining increasing prominence in both public concern and research. In response, urban microclimate modelling researchers are continually striving to develop new strategies to rapidly and inexpensively generate more accurate results. Numerical modelling is a common way to address these concerns. However, to generate realistic results requires significant investment in model creation, especially with respect to the detail to which a model is populated. This paper provides an overview about this and other recent trends within the research community by considering nearly 100 recent papers. Findings show that despite more computational capacity there has not been a major trend towards increasing the model complexity to obtain more realistic results.
Review of Strategies for the Geometric Creation and Population of Urban Microclimate Models
The Open Urban Studies Journal, 2012
Heightened demand for larger and more accurate microclimate models for heat transfer, pollution accumulation, and wind level prediction has posed new challenges for researchers working in wind tunnels, as well as those employing computational fluid dynamics modelling. Namely, the problem is how to generate geometrically accurate and up to date models inexpensively and quickly without compromising potentially critical details. The problem is an important and growing one, as there is an increased tendency to use such models as the basis for planning permission and long-term policy decisions in urban areas.
Urban Microclimate Modelling for Comfort and Energy Studies, 2021
Climate change is now pervasive in scientific, social and political communities. There is clearly a detectable global warming trend in the long-term climate records. Vast resources are being processed, transported and consumed in order to accommodate humans in our modern life. As a consequence, exhaustion of raw materials and transformation of chemical substances have generated an increasing level of hazardous residues that may pollute air, water and soil. With over half of the global population residing in cities now and an arguably growing projection of urban settlements in the near future, the scale of this resource demand is profound and the subsequent problems are unprecedentedly intensified in every aspect. Motivated by these challenges, urban sustainability holds great attention to tackle energy and environmental issues. Buildings, which incorporate most human activities in the urban areas, are identified as having the highest economic mitigation potential of any other energy sector. Simulation models play an essential role in the decision-making process for performance-oriented building design and urban planning. Mathematical models are central to high-level human endeavour to formally abstract, understand and change the world. On the other hand, simulation models are low-level computer-aided specializations to numerically implement such mathematical rigor, with various applications in physical observations, engineering systems, social sciences, etc. As we delve into the literature, we have found a rich
Optimization-aided calibration of an urban microclimate model under uncertainty
Building and Environment, 2018
Simulation models play an important role in the design, analysis, and optimization of modern energy and environmental systems at building or urban scale. However, due to the extreme complexity of built environments and the sheer number of interacting parameters, it is difficult to obtain an accurate representation of real-world systems. Thus, model calibration and uncertainty analysis hold a particular interest, and it is necessary to evaluate to what degree simulation models are imperfect before implementing them during the decision-making process. In contrast to the extensive literature on the calibration of building performance models, little has been reported on how to automatically calibrate physics-based urban microclimate models. This paper illustrates a general methodology for automatic model calibration and applies it to an urban microclimate system. The Urban Weather Generator (UWG) is selected as the underlying simulation engine for an optimization-aided calibration based on the urban outdoor air temperature in an existing district area located in downtown Abu Dhabi (UAE) during 2017. In particular, given the time-constrained nature of engineering applications, an online hyperheuristic evolutionary algorithm (EA) is proposed and developed in order to accelerate the calibration process. The validation results show that, in single-objective optimization, the online hyper-heuristics could robustly help EA produce quality solutions with smaller uncertainties at much less computational cost. In addition, the resulting calibrated solutions are able to capture weekly-average and hourly diurnal profiles of the urban outdoor air temperature similar to the measurements for certain periods of the year.
The Effect of Microclimate Simulation on Urban Space
Engineering Research Journal, 2022
With the rapid urbanization and rising affluence, the energy demand and climate change, as well as, health impacts of cities are correlational of increasing importance. Much of this intensive urban growth is wide spreading in parallel with the accelerated climate change detected problems and global warming effects which increasing so broadly as a hot current worldwide stream with facing more of intense and extreme heat waves due to the increase of atmospheric GHG emissions since the industrial revolution. The problem statement is the following: Lack of using climate digital simulation in the conventional urban design process; High dense urban areas are directly influencing the urban heat island effect problems which needs mitigation strategies; Typologies of urban form have a climatic impact on climate orientation inside the districts and also affects the surroundings; Failure of regional climate models to take a consideration of the climatic parameters and human real feeling temperature as on urban microclimate scale and The missing of climate change adaptation strategies in a dynamic design of urban space. The aim of the research will discuss the integrative usage of microclimate digital simulation models to validate the appropriate urban form of an open space in order to be adaptable with climate conditions and to detect the problems of space urban design. Practical urban micro climate scenarios can lead to create a better urban context during different seasons in different climate zones with the consideration of climate parameters through simulating and applying mitigation and adaptation strategies to achieve human thermal comfort in urban outdoor areas and to develop more compatible and healthier urban spaces with enhancing efficient thermal performance using microclimate digital models and find flexible solutions.
Methodologies for assessing urban microclimates
University of Cambridge, Department of Architecture, PhD Symposium, 2018
This paper reviews state-of-the-art simulation methodologies for assessing urban microclimates, which are critical for understanding the thermal environmental loading on urban buildings. It is well-established that cities have distinct climates, typically exhibiting higher temperatures than their rural surroundings due to the urban heat island (UHI) effect. Recognising this uniqueness is essential for the accurate assessment of urban energy interactions. The paper emphasises the necessity of site-specific loading assessments, which require precise data defining the local microclimate. This data can be sourced from monitoring campaigns or calculated from governing variables. By evaluating various simulation approaches, this review aims to provide insights into the most effective tools and techniques for capturing the complexities of urban microclimates. Ultimately, the goal is to enhance the precision of urban energy assessments and support the development of more efficient and sustainable urban environments.
Microclimates Within an Urban Area∗
Annals of the Association of American Geographers, 1977
The geographic delineation of various microclimates within an urban area is determined by the transfers of energy, mass, and momentum at the city surface. This approach requires a method for quantifying urban surface characteristics. The results of specifying the surface textures of Sacramento, California, and the determination of the attendant microclimates through energy transfer modeling were consistent with spot measurements made within the city. The approach could aid greatly in urban microclimate studies and in city design for the determination of ideal microclimate configurations. UANTITATIVE information on the types Q and distribution of urban microclimates can be of value in the design of cities, in engineering urban hydrologic systems, in planning for the efficient removal of air pollutants, and in assuring the success of studies of inadvertent weather modification by urbanizati0n.l Such quantitative information can be made available by applying an energy transfer analysis to the urban surface. Our approach assumes that solar radiation is evenly distributed over the city. The
Monitoring and modeling of the urban micro-climate
2013
Urban heat island phenomenon (UHI) is considered to be one of the major challenges encountered this century by the human kind. This phenomenon is characterized mainly by air temperatures in the city that are higher than those in the surrounding areas. Reasons are, amongst other things, the morphology and density of urban spaces as well as the thermal and radiative properties of outdoor surfaces. The UHI effect represents a challenge for careful and proper building design and operation, as micro-climatic data are typically available only for few locations in the city. As a result, planning, retrofit, and mitigation measures for buildings cannot count on reliable weather information for the exact locations of intended building projects. In this context, this paper presents results of an ongoing research project, which is concerned with prevention, adaptation, and mitigation measures pertaining to the urban heat island phenomenon. An important component of this project addresses the variation in the mirco-climatic conditions in different locations in the city and if and how such variations could be accounted for. Specifically, weather information was collected with a mobile weather station at various locations within the city of Vienna. Collected data from multiplemorphologically differentiatedlocations around the city were compared with the simultaneously monitored general weather conditions via a stationary weather station. The findings are expected to support the development and validation of high-resolution climatic boundary condition models for building design and operation support.