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Building EnvelopeCommissioningSuppose the manufacturer of a precision sports car guaranteed to sell all the vehicle parts, fitted together in the correct position, but did not perform any quality control or make any adjustments before sending the car to the dealer. A buyer could not expect to go 0 to 60 in five seconds straight off the dealership's floor, despite the sticker on the window. The buyer would have to first take the car to a mechanic to have it tuned. Office buildings, with their many sophisticated equipment systems that work together dynamically, are much the same as the sports car. Commissioning is the process of ensuring that building systems are designed, installed, functionally tested, and capable of being operated and maintained according to the owner's operational needs. Different commissioning terms are used to refer to when the process is happening in the building's life; see below for definitions of commissioning, retrocommissioning and recommissioning.
Commissioning (often abbreviated as Cx) optimizes building systems in a newly constructed building. Currently, Cx is not considered standard practice, so building owners must make an additional investment to have their building properly tested and fine-tuned before occupying it. Although this adds an extra degree of time and money to the construction process, Cx is worthwhile since it usually results in substantial savings by catching and fixing all too common inefficiencies and deficiencies in building systems. A 1994 study of 60 commercial buildings, for example, found that over half had building control problems, 40 percent had heating, ventilation, and air-conditioning (HVAC) system problems, one-third had sensors that were not working properly, and 15 percent were missing specified equipment. These problems could have largely been avoided with commissioning. Yet most U.S. buildings are not commissioned. To address this lack of commissioning during construction, building owners and managers can choose to undergo retrocommissioning (RCx), sometimes referred to as commissioning of existing buildings. RCx can occur at anytime during a building's life, and can be implemented while the building is occupied. Because typical energy savings achieved can reach as high as 20 percent without investing in new equipment, RCx is fast becoming recognized as one of the easiest and most cost-effective ways to improve energy efficiency. In fact, RCx often achieves a simple payback of less than 2 years, quite significant given the magnitude of savings possible. RCx is generally best suited for larger buildings, though it can be appropriate and effective for buildings of many sizes. Since RCx deals with optimization of building systems, all energy-related upgrades and retrofits should be completed before tackling RCx - it is not cost-effective to fine-tune inefficient, outdated, or malfunctioning equipment systems. Installing an automated energy management system is also a good idea since this is useful for tracking and controlling energy use before, during, and after the RCx program. Besides energy savings and lower utility bills, one of the chief advantages of any commissioning program is the improvement to the indoor environment. Cx and RCx tend to focus on the HVAC, which is both the most energy intensive system in a building as well as the root cause of the most common and most serious complaints. Even if the indoor temperature of a building is within the desired range, poorly tuned equipment can cause excessive noise, drafts, temperature fluctuations, odors, and humidity. Owners of income properties may discover that discomfort stemming from the HVAC system (or equipment restrictions meant to curtail cooling loads) force tenants to relocate. This can be very costly and in most cases, retaining these tenants can pay for the cost of RCx. A study cited by Oregon's Department of Energy, for example, estimates that the cost of losing one five-year office tenant can run from $91,875 to $109,375, which is 35 to 42 percent of the five-year lease value. Benefits of Retrocommissioning Building owners reap a host of benefits from the retrocommissioning process. These include:
Commissioning Adopters
Key Commissioning Resources
Resources California Commissioning Collaborative, Sample Documents, such as plans, logs, RFPs, and final reports. Piette, M. A., "Quantifying Energy Savings from Commissioning: Preliminary Results from the Northwest." Presentation at the 4th National Conference on Building Commissioning, 1994. Portland Energy Conservation Inc., Retrocommissioning Handbook for Facility Managers, March 2001. Portland Energy Conservation Inc., A Practical Guide for Commissioning Existing Buildings, April 1999. Oregon Department of Energy, Information on Building Commissioning Savings. American Council for an Energy-Efficient Economy, Screening Market Transformation Opportunities: Lessons from the Last Decade, Promising Targets for the Next Decade, August 2002. |