ABSTRACT
Commissioning an existing building is referred to by various terms, including recommissioning, retrocommissioning, and continuous commissioning (CC®). A comprehensive study of 182 existing buildings totaling over 22,000,000 ft2 in floor area reported average energy savings of 18% at an average cost of $0.41/ft2 after they were commissioned, producing an average simple payback of 2.1 years. The commissioning process for an existing building involves steps that should include building screening, a commissioning assessment to estimate savings potential and cost, plan development and team formation, development of performance baselines, detailed measurements and commissioning measure development, implementation, and follow-up to maintain persistence. Existing building commissioning has been successfully used in energy management programs as a standalone measure, as a follow-up to the retrofit process, as a rapid payback Energy Conservation Measure (ECM) in a retrofit program, and as a means to ensure that a building meets or exceeds its energy performance goals. Very often, it is the most cost-effective single energy management option available in a large building.
