Common Data Definitions for HVAC&R Industry Applications

During the life-cycle of a building, from concept through design and construction and finally to operation, many software programs are used by various specialists such as architects, engineers, construction managers, consultants, commissioning experts, and building operators.   These software programs include CAD (computer aided design), HVAC load calculation, energy simulation, energy code compliance, project management, data acquisition, operations, and many others, and usually include a description of the building and its contents including the HVAC&R and other systems.  Unfortunately, perhaps due to the splintered nature of the building industry, these software programs use incompatible formats so that the information about the building and its systems is often re-entered and re-interpreted each time.

The research project, performed by GARD Analytics, focused on four of the twelve use-cases described in draft Guideline 20.  The four Use Cases were ENG-01 Calculate Building Thermal Loads, ENG-03 Select Equipment, COM-02 Collect Functional Test Data, and OM-01 Monitor Performance.  For each use-case, detailed process steps describing the use-case were elaborated.  From the detailed process steps, transfers of information were extracted showing the groups of data that were needed to communicate between various parties.  These Use Case elaborations are meant to be used for analytical purposes, not as reference definitive examples of how to perform a service or exchange. The purpose was to expose common data groupings that might be used in exchanges from the perspective of a small group of domain experts. The key goal is the documenting of potential standard data groupings, as opposed to standardization of applications that use them.

The Data Group names were compared to the Data Group names in the draft Guideline 20 document and further refined.  This process expanded some Data Groups, consolidated others, and eliminated some outside the scope of the guideline and resulted in over 180 Data Group names.  A preliminary examination of Data Groups within three existing data models helped to clarify the meaning of each Data Group.  Three existing data models used were IFC, gbXML, and AEX/cfiXML.  These data models were each constructed from different perspectives in three independent activities. Overlaps and complementary aspects of these bodies of work were sought.  Each was examined looking for related Data Groups to help round out the Data Groups needed for each Use Case.

The next step was to create a definition for each Data Group.  Several sources of related definitions were examined for each Data Group including ASHRAE Terminology of Heating, Ventilation, Air Conditioning and Refrigeration, HVAC/R Terminology – A Quick Reference Guide, along with the definitions sections of ASHRAE developed standards and guidelines.  These definitions were compared and a definition for each Data Group was developed. Using these defined Data Groups, the three existing data models were examined in detail for related Data Elements.  For each Data Element found, the definitions from the existing data models, if present, were tabulated.  Approximately one-third of the Data Elements had reasonably detailed definitions based on length.