Building Commissioning is gaining traction as a popular Energy Conservation Measure (ECM) with a very high Return on Investment (ROI) and low payback period. So what exactly is commissioning, and why is it required for LEED certification?
Commissioning, Re-Commissioning and Retro-Commissioning
According to an article in the February 2011 edition of ASHRAE Journal by Dr. Evan Mills, a staff scientist at Lawrence Berkley National Laboratory (LBNL):
“The aim of commissioning new buildings is to ensure that they deliver – if not exceed – the performance and energy savings promised by their design” and commissioning is “a systematic, forensic approach to improving performance, rather than a discrete technology.”
Re-commissioning is the commissioning of an existing building that has gone through an initial commissioning process, or has been commissioned at least once previously. Retro-commissioning is the commissioning of an existing building that has never been previously commissioned.
Building owners often ask, “Why should I have to pay extra for this? Why shouldn’t the building simply perform as designed? What am I paying these design engineers for anyway?” These are all very good questions, and in a perfect world, the building owner would be correct.
However, the world is not perfect, and neither are engineers or technicians. Building systems typically don’t perform as designed for numerous reasons. The system might have been installed wrong, or may have been incorrectly calibrated. The controls and set-points might not be at the optimal setting, or the equipment might actually be designed inefficiently.
Commissioning by an independent, third party will ensure the building systems are designed and installed the correct and most efficient way, and the cost of commissioning is (almost) always gained back through energy savings within a very short period of time. Also, over time building systems tend to drift away from optimum performance due to degradation, changes in building use or even building alterations.
When Should I Commission?
Commissioning is NOT simply testing and balancing at the end of construction. Commissioning is a holistic process that should begin at the project planning stage, and should be continuous all the way through from design to final construction and building acceptance through a recurring recommissioning program. It should include defining the project requirements, reviewing the building designs at various stages, and verifying installation and performance of building systems (including testing and balancing). Commissioning can also include preparing a systems manual for the maintenance technicians and providing O&M training on the new energy efficient technologies.
According to Dr. Mills’s article, LBNL completed a study on commissioning of 643 commercial buildings, and found that commissioning existing buildings had 16% energy savings on average and the payback was 1.1 years, while the payback for new construction was 4.2 years with a median energy savings of 13%. Dr. Mills believes that “these findings demonstrate that commissioning is the single most cost effective strategy for reducing energy, costs and greenhouse gas emissions in buildings today.”
Benefits of commissioning go beyond energy savings however. According to the Whole Building Design Guide (www.wbdg.org), “Commissioning assists in the delivery of a project that provides a safe and healthful facility, optimizes energy use, reduces operating costs, ensures adequate O&M staff orientation and training, and improves installed building systems documentation.” Cost savings achieved through improved workplace performance, lower O&M costs and reduced risk might actually outweigh the energy cost savings!
Commissioning and LEED
For LEED projects, commissioning is a must. EA Prerequisite 1 is “Fundamental Commissioning of the Building Energy Systems” and must be accomplished to achieve LEED certification. There is an additional Credit, EA Credit 3 for “Enhanced Commissioning, “which is well worth the additional cost. Many federal agencies including GSA, NAVFAC and USACE are making this particular credit mandatory for its new construction projects. EA Credit 5, “Measurement and Verification” can also be considered a form of commissioning and should be given proper consideration in any green building project.
In the end, building commissioning is just a smart thing to do for both existing buildings and new construction. The costs are relatively minor (on average $0.30/SF for existing buildings and $1.16/SF for new construction according to Dr. Mills), and the ROI is large, direct savings in both in energy and O&M costs and indirect savings in workforce productivity. Commissioning is gaining traction from being just a “good idea” to a “must do” for building systems, and is an easy way to make your building green.