Building diagnostics is a practical methodology that enables HVAC professionals to verify and document to customers that installed systems are meeting defined performance criteria over time, or, if the criteria are not being met, to indicate that interventions are needed to regain expected performance. Contractors and designers should become familiar with the concepts of building diagnostics, which are briefly presented in this article, and to consider incorporating these methods into their work.
As noted by the National Research Council, building diagnostics is a process whereby a "skilled expert, drawing upon available knowledge, techniques, and instrumentation, predicts a system's likely performance over time." The diagnostic procedures may be used during the planning, design, construction, and operational (i.e., actual operation of the building or system) phases of a building or system to focus on the links between occupant responses and overall building system performance.