In my last newsletter article, I discussed new trends in energy codes, conservation requirements and required benchmarking reporting for both new construction and existing buildings. I stated that future articles would explore energy savings initiatives that owners could take right now as part of their normal operating procedures and capital replacement plans. These initiatives are wide ranging with varying costs and payback timelines, but will make immediate improvements to the buildings’ energy efficiency.
In this article, we will explore an often-overlooked method to improve the operation, comfort and energy efficiency of your buildings – re-commissioning of your HVAC systems. Retro or re-commissioning focuses on identifying and correcting poor performance of your equipment and controls and making adjustments and calibrations that will improve the energy efficiency and operation of your heating, air conditioning and ventilation systems. This is always a recommendation that zumBrunnen makes as part of our capital reserve planning and budget studies that we do for owners. Obviously, capital replacements of all equipment is eventually needed, but implementing retro/re-commissioning will not only have immediate benefits of lower operating costs, but will likely extend the life of these expensive systems and equipment.
Heating and air conditioning costs are a major component of your operating expenses. When buildings and HVAC systems are new, they are normally put through a series of testing, check-out and commissioning procedures that ensures the original design intent of the mechanical design engineers is achieved. For certification through the US Green Building Council’s LEED process, a detailed and thorough commissioning process is required, in addition to the normal testing and balancing that contractors normally do, to achieve the LEED ratings. However, over time as various components of the systems are serviced (or not serviced) and replaced, the intended functionality and design parameters may become compromised. Individual components of the system may quit functioning as designed and energy performance is affected.
Re-commissioning a building that has already been commissioned once or retro commissioning of a building that has never been through this process will put the HVAC equipment and control systems through tests and procedures that will identify these problems that are much less expensive to correct than replacing systems wholesale. Sometimes this retro commissioning will identify problems from the original installation and construction that were never addressed or done improperly.
Some examples of recommendations that may be made in this process are:
• Adjusting the operation of chillers and boilers to match the needs and loads of your buildings, which may have changed over time.
• Repair of air duct dampers that control air flow through buildings.
• Other minor repairs and calibration of control devices, such as thermostats, that have been changed over the years. Controls can also be re-set to match the occupancy of various areas of the building as they are used presently.
• Minor repairs to steam traps, condensate drains, natural gas connections and other system components that may have been neglected.
• Checking of refrigerant levels in A/C equipment and inspecting for leaks and damaged insulation.
• Re-balancing of air systems that have become compromised over the years due to service (or lack of service) and replacements of individual components.
• Identification of maintenance procedures that need to be changed or adopted including schedules and recommendations for filter replacements, cleaning of evaporator and condenser coils.
• Identification of more major capital replacements that may be needed including recommendations for energy saving items such as variable frequency drives for motors.
There are numerous consultants in the industry who can perform re-commissioning with energy savings from 5% to 25% based on recent studies depending on location and type of building. Some states also offer rebate programs if these re-commissioning efforts are coordinated through the proper utility company channels. For instance, Pacific Gas and Electric (PG&E) in California offers a formal program called RCx that offers incentives to their customers based on the actual energy savings. They also offer technical support for the entire re-commissioning process.
As we discussed in our first article, energy saving measures and reporting of energy costs are a growing requirement that will affect all building owners across the country. The retro commissioning or re-commissioning process described in this article is a good first step for building owners to lower their costs before major capital replacements are started on a wholesale basis for their older buildings. In future articles, we will describe how similar efforts to the HVAC re-commissioning can be implemented for building lighting and exterior envelope systems that will also have energy savings benefits.
About the Author:
Doug McMillan, P.E., is President of zumBrunnen, Inc. He began his engineering career in 1980, and he joined zumBrunnen, Inc. in 1998. McMillan received his Bachelor of Science degree in Civil Engineering from the Georgia Institute of Technology in Atlanta, GA. He is a former Resident Engineer with the U.S. Army Corps of Engineers, and he is a member of the Society of American Military Engineers (SAME) and the American Society of Civil Engineers (ASCE). McMillan is a licensed professional Civil Engineer in the state of California.
