Roza Vakilinezhad
Abstract
Extended AbstractBackground and Objectives: Energy simulation in an urban environment can be accomplished considering two major objectives: first by analyzing the environmental thermal ...
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Extended AbstractBackground and Objectives: Energy simulation in an urban environment can be accomplished considering two major objectives: first by analyzing the environmental thermal comfort and second by defining the impact of the environment on buildings energy consumption. Three factors affect the creation of pedestrian thermal comfort including climate (global radiation, air temperature, relative humidity and wind speed), microclimate (sky view factor, direct and indirect radiation, mean radiant temperature, surface temperature, ground temperature, building and ground albedo) and pedestrian physical properties (metabolic activity and coatings; these factors are usually not considered in current software. In order to evaluate the thermal components of urban or regional climates, it is necessary to gather accurate data about the radiant conditions in the surrounding environment. This data can be measured experimentally or calculated using the appropriate radiation model. Thus, there are two general methods of using questionnaires and computational simulations to evaluate the effective factors. For applying energy simulation, selecting the proper tool is the first step, which would not be possible without a detailed understanding of how the tool works. On the other hand, it is difficult to choose the proper tool among the growing number of simulation software. Considering designers’ recent tendency in this field, it is essential to be aware of the modeling capabilities and limitations of each tool. Some studies have compared the capabilities of building energy software, but no similar studies have been done on the urban scale.Methods: By identifying outdoor thermal indices, this study classifies different types of energy simulation at urban scale while introducing six software of Envimet, Rayman, UMI, Meteodyn, Solene and SOLWEIG for pedestrian thermal comfort evaluation. This study aims to define the capabilities, potential, weakness and efficiency of the mentioned software in urban environment. By applying comparative and logical analysis research method, the study is conducted in four steps. In the first step, outdoor thermal comfort indicators have been identified considering effective factors in creation of urban microclimate. The second step is dedicated to identification and classification of related software to be distinguished from urban energy analysis software. In the third step, software performance and the related features are examined and in the final step, selected software properties have been compared in different fields to define strengths, weaknesses and proper application. Capability of the above-mentioned software are compared in terms of climatic parameters, outdoor thermal comfort indicators, solving equations, defaults and neglected factors, extractable parameters, numerical and graphical output data, application simplicity, interaction with other software, graphical interface, accessibility and cost.Findings: In order to perform a simulation with proper accuracy, it is necessary to consider three basic models of radiation, heat transfer and CFD airflow in combination with each other. However, in many energy simulation tools, some equations in the analysis process are overlooked for simplification. In Envimet and Solene software, the three equations are analyzed. The analysis in Rayman, SOLWEIG and UMI models is based on the radiation and heat transfer models only ignoring the airflow model that is assumed to be constant. In Meteodyn, the radiation model in Urbasun and the airflow model in Urbawind tool are analyzed. In Envimet and Solone, four parameters of dry temperature, relative humidity, wind speed and radiant temperature are calculated. Apart from wind speed, Solone calculates three other parameters, while in Rayman, dry temperature and radiant temperature are considered regardless of relative humidity and wind speed. The only parameter examined in UMI and Meteodyn is wind speed.Conclusion: By computing radiant fluxes, Rayman calculates six thermal comfort indicators. Envimet and Solone calculate four indicators including PMV, PET, UTCI, and MRT and in SOLWEIG model, three indicators including PET, UTCI, and MRT are calculated, while none of the common indicators for thermal comfort is listed as the output data in UMI and Meteodyn. Envimet, Solene and Rayman provide more outdoor thermal comfort indicators as output results. In UMI and Meteodyn data is estimated as the average radiation and wind speed while in other the tools it could be extracted precisely at any desired time. While UMI is a simple free tool, using Envimet and Solene is not free and requires training. However, currently no single tool considers the best combination of all factors and includes all physical processes. The results of this research can help architects, urban designers and software users to choose the proper software in each design stage considering project goals.
