HVAC information exchange (HVACie)
ORGANIZATION: USACE ERDC
The Engineer Research and Development Center, working with subject matter experts and software companies, lead the development of a domain-independent facility control framework enabling improved management and control of facilities and the resources that they consume. This framework includes:
- the definition of the expected resources required
- components, assemblies and systems using these required resources
- a feedback loop which compares plan resources to actual resource use
The objective of the HVACie project is to provide an open-standard format for the components, assemblies, and systems that distribute and remove water within a facility.
All "ie" projects begin with a requirements analysis focusing on the essential elements needed to create a performance-based specification for the delivery of shared, structured building information. HVACie required modeling of three separate, but integrated sub-systems present in most facilities. The first is the thermal transmission fluid. The second is the heat transfer equipment. The last is the distribution system.
This analysis identified several model artifacts that require specific support. These three critical components are:
- Connections—connections between flow elements and managed components
- Assemblies—engineered to order units containing multiple sub-components
- Properties—needed to convey design requirements
The requirements for HVACie indicate the need to describe the precise geometric location of components, assemblies, and connections with needed properties. As such HVACie is an extension of the standard IFC Coordination Model View Definition. Primarily, the use of the ifcPort object to provide the explicit connections between objects is needed. Extensions to this standard Model View ensure that product properties needed for the management of the HVAC systems are included.
The application of HVACie requires that modelers consider how information currently split between multiple models is to be merged into a single model describing this complete system. One approach to merge multiple models that may contain the same components was proposed by the buildingSMART alliance and used as part of the Jan 2013 bSa Challenge. This merging algorithm may be found here.
At a minimum, common naming and classification of components and assemblies will likely be needed. If HVACie is to be used to support the analysis of HVAC system, then assemblies will have to be represented as composite components. For example, models of chillers should be developed with information about each of the internally managed sub-components. Some additional properties will also need to be exported from design software products to capture design parameters.
Since HVACie products virtually all require connection to electrical power systems the connections between these systems should be considered. The connections between HVACie and SPARKie can be based on properties that define distribution panel and circuit in the short term. Eventually, such information will be inferred by the designation of the upstream electrical outlet or service disconnect.
Although HVACie is new and most Building Information Modeling software does not claim to have extensive IFC 2X3 export support for MEP systems the results released in 2013 indicated that more than two-thirds of the included concepts were successfully exported to IFC. As the requirement to deliver shared, structured information about electrical systems becomes established by building owners and managers it is expected that additional work on WSie will improve the results obtained in 2013.
The HVAC information exchange by buildingSMART alliance is licensed under a Creative Commons Attribution-NoDerivs 3.0 Unported License.
References to this work should be in the form of: Hitchcock, Robert J., East, E. William (2013) "HVAC information exchange (HVACie)," buildingSMART alliance, National Institute of building Sciences, Washington, DC. http://www.nibs.org/?page=bsa_hvacie (cited DD-MMM-YYYY).
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