With energy costs sky rocketing and the future of oil, natural gas and other fossil fuels in question, saving energy is a priority of many building owners and facility managers.  Given that, how can energy be saved without causing other problems and how do energy-saving-related projects stack up against other building projects competing for the same limited capital budgets?  One answer may be retro-commissioning!

A type of existing building commissioning, retro-commissioning is a systematic process for investigating, analyzing and optimizing the performance of building systems through operational and maintenance improvement measures, while ensuring their continued performance over time.  The process assists the interactive performance of building systems to meet the Owner’s Current Facility Requirements (OCFR) in sufficient detail to allow for the documentation and validation of those requirements.

The majority of existing buildings have not undergone any type of commissioning or quality assurance process.  Additionally, over time, their operational efficiencies tend to degrade along with changes in building usage and operational requirements.  Because of these factors, most structures perform well below their potential, use more energy than necessary, and cost more to operate than they should.  Although retro-commissioning may include recommendations for capital improvements, its primary focus is to use operational and maintenance “tune-up” activities and diagnostic testing to optimize building systems.  Typical parties involved in the process include the owner’s maintenance and operations staff; building automation system contractor; testing, adjusting and balancing contractor; contracted service personnel; and, of course, the commissioning agent.  Retro-commissioning is intended to be performed on all systems, including heating, ventilation and air conditioning (HVAC); plumbing; electrical; and the building envelope.

Several reasons to have your building undergo a retro-commissioning process include:

  • Identify and resolve building code, system operational and control, and maintenance issues.
  • Improve building performance by saving energy and reducing operational costs.
  • Identify the operation and maintenance staff’s training needs and provide such valuable training.
  • Reduce or eliminate occupant complaints and increase tenant satisfaction.
  • Improve indoor environmental comfort and quality and reduce the associated liability.
  • Document present system operation and achieve desired performance.
  • Minimize operational risk and increase asset value.
  • Extend equipment life.
  • Ensure continued improvements over the building’s life.
  • Prerequisite if pursuing LEED-EB (Existing Buildings).

Presently, the process has been developed into five distinct phases:

Planning/contract – meet with the owner; document the owner’s current facility requirements; develop a retro-commissioning plan for the facility; and prepare, negotiate and execute a retro-commissioning contract with a services provider

Investigation – conduct a site investigation; compare the building systems’ actual performance and site conditions with the owner’s current facility requirements; and complete a list of facility improvement measures.

Implementation – implement the facility improvement measures to enhance building and system performance, reduce energy costs, reduce O&M costs, improve IEQ, etc.; and verify that predicted results are achieved.

Turnover – provide the owner’s operations and maintenance staff with the necessary tools to ensure that savings and operational improvements persist far into the future.

Continuous implementation/persistence – ensure that facility improvement measures continue to perform properly and that improved operations persist.

Note:  ASHRAE Guideline 0, “The Commissioning Process,” provides a framework for commissioning new buildings and is not written for any particular system or building component.  Instead, it describes the generic process of commissioning, applicable for all elements of construction.  Guideline 1 provides assistance by applying guideline 0 specifically to HVAC Systems.  Guideline 30, “The Commissioning Process for Existing HVAC & R Systems,” will describe the commissioning process for all elements of construction in an existing building, and may in the future be complemented by a guideline specifically aimed at particular systems within existing buildings.  It is expected to be available for public review by January 2009.

The author of this article, A.J. Kindya, is a registered engineer, LEED Accredited Professional, and Certified Commissioning Professional.  He is employed as a commissioning agent for Horizon Engineering Associates, LLP, a leading provider of commissioning and retro-commissioning services.  Mr. Kindya presently serves on the Building Commissioning Association’s (BCA) Retro-Commissioning Standards Committee, is the chairperson of the BCA’s Standards Committee, and serves on the steering committee of GBA’s Laurel Highlands Network.  

Additional resources on this subject can be found through the Building Commissioning Association’s website at; U.S. Green Building Council,; California Commissioning Collaborative,; and ASHRAE,

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