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An energy view for building information modelling

An energy view for building information modelling

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November 4th, 2019

One topic that is consistently under fire in the building room serves as a good example of such an industry hurdle. The debate concerns the current Level of Development (LOD) classification systems and the various naming conventions for LOD levels 100 to 500; why couldn’t they be called levels “1 to 5,” or “A to E”? There is usually no consensus at the end of these debates as to which approach we should use or how we should unify the different perspectives, but it seems clear that far more important than terminology used is the effective application of the information being considered.

Our team is currently in development of a software specification adding thermal values through a building’s envelope using an information delivery manual (IDM), to determine climate conditions and provide energy use calculations over the lifecycle of a building. The project will include data for space boundary relationships between surrounding walls, floors, ceilings, roofs, doors, and windows; general material classification with thermal and solar properties; indication of exterior exposure; and geolocation of the building.

Information management & classification systems

From an overarching information management strategy down to specific measurements taken for a building component, how we manage and apply information is vital. The key lies in selecting the right strategy and applying appropriate data at a suitable stage in order to fulfil its intended purpose within a project. With our industry in its current evolving state, this can be anything but straightforward.

If we included the Level of Information (LOI) and Level of Detail (LODet), we could then add new layers of granularity to this equation. Incorporating LOI and LODet —collectively referred to as Level of Definition (LODef)—would allow us to more effectively configure parameters for each information level or phase. LODef could be used to define a scope of work and form an agreement to deliver certain model uses at each design and construction life-cycle stage. LODef specifications with consistently defined standards can greatly benefit interoperability and collaboration. From concept and design, through construction and operation phases, establishing a standardized approach helps project teams identify and divide responsibilities and also make data more accessible. Although principles exist to help guide Levels of Definition, the standards that will likely define future industry use are still in development. Applying such standards to geometric properties has already proven invaluable;

An appropriate information management strategy is equally important. Will each phase in a project operate largely independent of the previous? Are clear checkpoints for re-evaluation needed at each stage? Are significant adjustments expected based on information collected throughout stages of development? Approaching a project appropriately as a progression or “stream,” with each phase flowing into the next with minimal strategic reassessment or adjustment expected; a development, where each phase will be treated as a separate process, perhaps with forks development proceeds; or a cycle, where circling back to apply information collected during phases of development will guide the following phase(s), is vitally important to project efficiency. A hybrid of these strategies may be ideal as well. The Royal Institute of British Architects’ (RIBA) Plan of Work (PoW) 2013 provides a standardized approach to promote consistency within the industry. Flexible enough to be adapted to the varying needs of projects across the industry, the PoW proposes detailed guidelines for seven work phases and for the exchange of information between phases. At the completion of each work stage, the PoW proposes a formal information exchange to advise the project team and client on matters of key importance for the subsequent phase(s). Also clearly defining roles, responsibilities, and providing a detailed framework for an information management strategy, the PoW provides a solid foundation for the future–hopefully one with less debate given a more structured, standardized, and well-defined direction for BIM.

Energy analysis & future direction

Our technical group is currently exploring a model view definition (MVD) for energy analysis which aims to capture the necessary information to run a simulation. This feature is still under development, but we continue to refine our information classification system to accommodate discipline-specific model uses. Most coordinated drawing sets must comply with local energy regulations, but rarely is the energy analysis included as a use case (UC); large/complex models are rebuilt using a building energy modeling tool. The analysis phase requires a specific LODef to facilitate an effective data transfer using file formats (gbXML/IFC), ensuring that space boundary conditions are met to allow the transfer of information like energy settings and thermal properties. Further, each analysis type (energy, daylight, comfort, etc.) can define its own set of LOI in the exchange requirements (ER). These types of factors make it much easier to increase LOD level than to lower it.

Our development will remain neutral enough to adapt to clients’ varying needs but also structured enough to effectively tackle conventional real-case uses, with a framework designed to populate, access, and export data efficiently at any LODef. Whether to conform to regional specifications, make unexpected adjustments to level of scope, or allow data cross-operability between software applications with minimal human resource requirements. Our project team is developing a design strategy for an energy modeling scope of work and classification system where interoperability is a fundamental concern. Just as the RIBA PoW provides a degree of structure while allowing flexible adaptation for many uses, we hope to develop the rules for design and build a solid foundation and technical framework for an energy model adaptable to a wide range of applications. Integral to that framework is efficient data import and export. However simple or complex a client’s needs, we intend to seamlessly integrate the values and properties necessary to provide required analysis. A comprehensive preset string parameter will allow us to plug in building data to be pulled automatically for model analysis when needed. Like an empty directory structure with a standardized naming format, our model will allow relevant data to prepopulate the appropriate folders, so to speak, where the modeling software expects to fetch it if/when those types of data are required for analysis.

We look forward to diving deeper in dynamic performance verification and the continuous level of information (cLOI). Linking sensors in building models would allow us to bridge the performance gap between design and actual data. Forecasted weather can be considered to avoid unforeseen impacts on thermal comfort and energy usage. Open data protocols are vital to the growth of the information modelling workflow for energy analysis, and we look forward to sharing our progress with the community of researchers and practitioners.

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