by Lura Griffiths, EMIT, LEED Green Associate
Simple and Powerful Energy Analysis in the Earliest Design Stage
Integrated Project Delivery (IPD) is a familiar phrase within the building industry. IPD has been promoted as the ideal process for ensuring maximum effectiveness of coordination amongst the design and construction team in creation of superior high-performing buildings. Coordinating multiple disciplines during schematic design (SD), however, limits the benefits of IPD because many fundamental design decisions may have already been made. For example, architects bidding on a potential project may need to offer clients multiple design options; until a bid is awarded, the ability to obtain performance data and the effects of the design options on building performance is limited at best. Historically this has been due to time constraints and a lack of tools to develop an adequate energy model early on.
Architects and engineers require a simple, accessible and powerful tool that shows the effects of design changes on the building performance, and can create intelligent solutions that truly integrate form and function. Autodesk’s Conceptual Energy Analysis (CEA) plug-in for Revit 2011allows initial energy modeling and analyses to be modified later in the design process as more information becomes available. CEA models can be exported to more advanced energy modeling programs such as eQUEST, Visual DOE-2, and energyPLUS for complete analysis by energy professionals.
Model Creation: Masses, Constructions, Building Types, and Systems
For users already comfortable with Revit, learning how to use the CEA plug-in is straightforward and can usually be accomplished in a day. For those not familiar with Revit or who need a quick update, Autodesk provides tutorials and videos on their Revit 2011 website under the "Analyze the Design" section. Revit massing tools are intuitive in their use; however, care must be taken to properly define and join masses in a way that accurately reflects the desired building geometry. Users unfamiliar with massing tools in Autodesk Revit® 2011 should review these tutorials and videos online prior to creating their first model.
In an early phase model, only information such as building geometry and type, construction and basic systems need to be entered. Inputs are intentionally simplified to avoid confusion, although customizing some inputs is possible. One baseline model can generate multiple design iterations to be analyzed.
Results: Reasonable, Usable, and Accessible
For the conceptual/feasibility stage of design, refined accuracy is not critical, but results that establish general “good, better, best” parameters for each decision tied to a specific design component are needed to help make informed choices. (Typically, accuracy of +/- 25% is considered acceptable for initial studies.) The inputs are reviewed by a team of energy analysts to certify the data in the model is within acceptable standards of practice. Even with extremely simplified inputs, most building types modeled well within a suitable conceptual accuracy range.
The ability to quickly assess the impact of design changes to building energy use is the true power of CEA. The energy savings can be used to avoid any potential (and costly) design changes that may be required later to meet building performance goals.
Framework for Use: CEA as Part of the Complete Design Process
The CEA plug-in for Revit 2011 is intended for use early in the design process; however, the models created by CEA can be extended using additional tools. After the first conceptual model has been completed, the user can further refine the model using GBS online. As the design process progresses, more detailed systems and schedules can (and should) be included by the energy analyst by using advanced modeling software.
The Autodesk Conceptual Energy Analysis plug-in for Revit 2011 is an effective and simple tool for early integration of building performance and design. While not a replacement for advanced energy modeling software required for LEED, it does provide a sound way for building performance to be considered at the beginning of the design process. CEA will prove to be a valuable tool for architects and energy professionals to create true integrated building design.