Sunday, November 30, 2008
My Project 3 scope for the ARCH 652 class was to study how Building Information Modeling is used in analyzing the performance of the building in the early design phase, using various conventionally available simulation applications. The intent of this project was to study and identify what are the difficulties involved in utilizing the 3D models developed by the designers to perform energy analysis calculations and what information is missing in these applications while performing the calculations. In this study, I basically studied three different simulation applications namely: Green Building Studio (GBS), eQuest and EcoTec. The building design (3D model) was originally developed in the Revit platform which is quite commonly used by the designers now a days. The 3D model was then required to be transformed into different format, such as, gbxml or CAD in order to be accessed by other simulation applications.
Green Guilding Studio web application
The first simulation application I used for this study was “Green Building Studio (GBS)”. Autodesk Green Building Studio is a free web based application meaning that the designers can calculate building performance governing features directly over the internet, without having any special skills or having any sophisticated software downloaded on their local computers. GBS enables architects to quickly calculate the operational and energy implications of early design decisions. The Autodesk Green Building Studio web service uses gbxml file format to generate geometrically accurate, detailed input files necessary for energy simulation programs.
Following screenshot shows the available features that can be specified manually for calculation purpose.
The drawback of this application is that, the whole calculations are completely based on number of assumption and takes into consideration, only the basic information such as type of building and building location. The gbxml file format used by this application is only a geometric data of the 3D model and does not contain any information regarding the building materials. The application completely neglects the information regarding the building material properties, which is very important for evaluating the building performance. The building performance in terms of energy consumption, day lighting performance, thermal loads etc. is very much dependent upon the building materials used for construction. Thus, we can say this application provides an approximate result of the building performance based on the building geometry, building type and weather data obtained from local weather station. The application does have few design features which can be manually described, but still they are not sufficient enough to provide precise information required for the calculations.
Following screenshot shows the available features that can be specified manually for calculation purpose.
The drawback of this application is that, the whole calculations are completely based on number of assumption and takes into consideration, only the basic information such as type of building and building location. The gbxml file format used by this application is only a geometric data of the 3D model and does not contain any information regarding the building materials. The application completely neglects the information regarding the building material properties, which is very important for evaluating the building performance. The building performance in terms of energy consumption, day lighting performance, thermal loads etc. is very much dependent upon the building materials used for construction. Thus, we can say this application provides an approximate result of the building performance based on the building geometry, building type and weather data obtained from local weather station. The application does have few design features which can be manually described, but still they are not sufficient enough to provide precise information required for the calculations.
EcoTec simulation application
Ecotec is a complete environmental design tool which couples an intuitive 3D modeling interface with extensive solar, thermal, lighting, acoustic and cost analysis functions. ECOTECT is one of the few tools in which performance analysis is simple, accurate and most importantly, visually responsive. ECOTECT is driven by the concept that environmental design principles are most effectively addressed during the conceptual stages of design. The software responds to this by providing essential visual and analytical feedback from even the simplest sketch model, progressively guiding the design process as more detailed information becomes available. Ecotec application utilizes the building geometry created in the Revit. In order to utilize this model created by the designers in Revit, it need to be exported into the CAD format (DXF file) within Revit, and then imported into the Ecotec application. This application can be used to perform a variety of analysis such as, solar study, overshadowing, thermal design and analysis, heating and cooling loads, prevailing winds, natural and artificial lighting, life cycle assessment, life cycle costing, scheduling, geometric and statistical acoustic analysis etc. Following is the snapshot of hourly temperature variation within the building:
However the main drawback in this process is that the element id is completely lost in the model, meaning that the door or window is no more recognized in the DXF file format. All the elements are represented only in the form of CAD geometry in the form of lines. We can no longer select the elements in the 3D model within the Ecotec. Thus it is recommended to create the building geometry once again within this application manually. In this case, whatever models that are generated by the designers can no longer be useful for performing any type of analysis within the Ecotec application and thus will make the design process time consuming and expensive. Another limitation of this application is that it assumes similar atmospheric conditions throughout the building area. It calculates the heat gain/loss based on the square footage per person that we can specify, but this figure is assumed to be equal for all parts of the building. In real situation, no part of the building will have equal square footage occupied by the people. Some parts of the building will have more area per person and thus the atmospheric behaviors will change drastically in such cases. Also the energy consumption calculation are based on the weather file that is required to be stored on a local computer. If we need to import the 3D model from another application such as GBS, the application does not allow to select the project location and weather data file and will assume a random location and weather file. It allows to make such selections only when we create all together a new project within eQuest along with a new 3D model.
However the main drawback in this process is that the element id is completely lost in the model, meaning that the door or window is no more recognized in the DXF file format. All the elements are represented only in the form of CAD geometry in the form of lines. We can no longer select the elements in the 3D model within the Ecotec. Thus it is recommended to create the building geometry once again within this application manually. In this case, whatever models that are generated by the designers can no longer be useful for performing any type of analysis within the Ecotec application and thus will make the design process time consuming and expensive. Another limitation of this application is that it assumes similar atmospheric conditions throughout the building area. It calculates the heat gain/loss based on the square footage per person that we can specify, but this figure is assumed to be equal for all parts of the building. In real situation, no part of the building will have equal square footage occupied by the people. Some parts of the building will have more area per person and thus the atmospheric behaviors will change drastically in such cases. Also the energy consumption calculation are based on the weather file that is required to be stored on a local computer. If we need to import the 3D model from another application such as GBS, the application does not allow to select the project location and weather data file and will assume a random location and weather file. It allows to make such selections only when we create all together a new project within eQuest along with a new 3D model.
eQUEST simulation application
eQuest is another building performance simulation application developed by the US Dept. of Energy. eQUEST was designed to allow you to perform detailed analysis of today’s state-of-the-art building design technologies using today’s most sophisticated building energy use simulation techniques but without requiring extensive experience in the "art" of building performance modeling. The application can utilize the 3D model geometry which was previously used in the Green Building Studio. In GBS, we have an option to save the file in the DOE-2 file format which is also accessible through the eQuest application. The EcoTec program also has a similar option to convert the model into a DOE-2 file format in order to be used in eQuest and EnergyPlus application.
The application is mainly used to calculate peak energy load consumption and the energy consumption distribution through the year. It can also perform Life cycle analysis and DEER (daylighting analysis). Following is a screen shot showing the peak energy consumption distribution throughout the year:
The only drawback in importing the model from GBS is that it does not allow to make any modifications in the model geometry. Although we cannot change the project geometry, we can still change the properties of various building components such as material properties. The variety of building materials (roofs, doors, walls etc.) available in eQuest, are completely different from the building materials that are available in the Revit model. Thus the results obtained may not be exactly the same as the designers intended to have in their design.
The application is mainly used to calculate peak energy load consumption and the energy consumption distribution through the year. It can also perform Life cycle analysis and DEER (daylighting analysis). Following is a screen shot showing the peak energy consumption distribution throughout the year:
The only drawback in importing the model from GBS is that it does not allow to make any modifications in the model geometry. Although we cannot change the project geometry, we can still change the properties of various building components such as material properties. The variety of building materials (roofs, doors, walls etc.) available in eQuest, are completely different from the building materials that are available in the Revit model. Thus the results obtained may not be exactly the same as the designers intended to have in their design.
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