Commissioning is the process of verifying that systems are designed, installed, and tested and can be operated and maintained according to your operational needs. It uses building inspection and systems testing to make sure building systems are performing as intended. Commissioning improves the efficiency and operation of building energy systems, particularly HVAC and air-distribution systems. In addition to saving energy, commissioning often increases comfort for occupants.
When the commissioning process is applied to an existing building that hasn’t been commissioned before, it’s called retrocommissioning (RCx).
RCx addresses a building’s underlying system-level deficiencies rather than isolated quick-fix problems. Some benefits include:
- An energy-efficient building
- Training for your staff or service provider to operate and maintain the building
- A comfortable and safe working environment for your occupants
- Long-lasting energy savings
- Reduced electricity demand and energy consumption
- Fewer calls from tenants complaining about building maintenance
- Increased equipment life
The Lawrence Berkeley National Laboratory (LBNL) 2009 report Building Commissioning: A Golden Opportunity for Reducing Energy Costs and Greenhouse-Gas Emissions remains one of the most comprehensive studies on RCx. LBNL’s findings show that RCx is a cost-effective way to reduce energy consumption in commercial buildings, with average whole-building energy savings of 16%. Median costs of commissioning were $0.30 per square foot (ft2) with an associated payback period of 1.1 years.
LBNL researchers found that commissioning is cost-effective in new and existing buildings—even in the case of smaller buildings (including those under 100,000 ft2). It found that projects with a thorough level of commissioning achieve nearly twice the median level of savings and five times the savings of the least-comprehensive projects. High-tech buildings were found to be particularly cost-effective for commissioning, perhaps because of their high energy use.
What are the steps?
The RCx process typically begins with selecting a commissioning provider who guides the project through the planning, investigation, implementation, and handoff phases.
Five independent organizations offer certification of commissioning providers, but the providers’ technical knowledge, relevant experience, and communication skills are equally or more important than a certification.
A qualified provider:
- Has excellent communication skills
- Cultivates a team approach to problem-solving
- Provides operations and maintenance training
- Has significant experience in energy system design, operations, and troubleshooting for commercial buildings
- Is well versed in diagnostic testing, monitoring, and analysis techniques
If you have experience as an energy manager or energy engineer, you may feel comfortable not involving a commissioning provider at the beginning of the project. You can bring one in later for specific diagnostic, monitoring, and analysis tasks.
Once selected, a commissioning provider will work closely with you and your building staff and follow a four-phase process.
Phase 1: Planning
The building walk-through is an intensive information-gathering session where the commissioning provider talks with you and your operations staff, becomes familiar with the major energy-consuming systems, and identifies potential energy-saving measures.
Before the walk-through, you should prepare a prioritized list of existing problems and necessary improvements, along with insights on current building conditions. You should provide:
- Utility bills for the past three years
- Preventive maintenance records
- Any active service contracts
All this information gives the commissioning provider an in-depth understanding of your building’s energy usage and operations and maintenance (O&M) practices. They can then develop an accurate and realistic RCx plan that defines the project objectives, scope, schedule of procedures, and documentation requirements.
There are several commonly identified areas where RCx can reduce energy usage. The Portland Energy Conservation produced A Retrocommissioning Guide for Building Owners (PDF) for the US Environmental Protection Agency (EPA). It describes energy-saving opportunities that are often identified during a commissioning walk-through, including:
- Systems that simultaneously and excessively heat and cool
- Ineffective use of outside air for free cooling
- Pumps with throttled discharge valves
- Extended periods when the building is unoccupied but equipment remains active
- Improper building pressurization, either negative or positive (such as doors that are difficult to open or close)
- Equipment or piping that’s hot or cold when it shouldn’t be
- Overlit spaces
Phase 2: Investigation
The goals of the investigation phase are:
- Understanding how the building systems are working
- Identifying and prioritizing energy-saving opportunities and system improvements
Start by assembling critical staff, both employees and outside contractors. Their knowledge of the building and its operations is essential to making your RCx successful. The commissioning provider should review the building documentation and current O&M practices, including specific operating requirements, such as:
- Temperature and humidity setpoints
- Outside air requirements
- Occupancy schedules
Diagnostic monitoring comes next. It’s important to measure whole-building and end-use energy consumption by looking at building operating parameters such as:
- Actuator and damper positions
- Outside-air temperature and humidity levels
- Equipment run times
You can perform short-term diagnostic monitoring using an building automation system’s trend-logging capability or with portable data loggers, devices that measure and log temperature. The measurements help you understand the system’s performance under various operating conditions. They also let the commissioning provider calculate potential savings opportunities and identify problems that may require further investigation through functional testing of individual equipment. This diagnostic monitoring forms the energy-use baseline against which you’ll calculate all future energy-saving measures.
The commissioning provider discusses a list of findings with you, including the most cost-effective energy-saving opportunities and the system improvements that are within the scope and budget of the project. The two of you will decide which strategies to implement; the provider will then summarize the recommendations in a report.
Phase 3: Implementation
Depending on your resources and time constraints, you have three options to implement the recommendations:
- Hand the project off to the commissioning provider for full implementation of all recommendations.
- Keep the commissioning provider in an oversight role, where they provide assistance but conduct very little actual fieldwork. You retain responsibility for managing the workflow and contracts with various firms to carry out the implementation plan.
- Oversee all the work yourself. This option may work well if you have significant in-house staff expertise or have ongoing relationships with qualified service providers who can manage and complete the project work.
Regardless of the approach you take, the commissioning provider will develop an appropriate implementation plan that incorporates milestones for documentation and making sure the system is working as planned. The plan organizes and defines the work needed to complete the savings and improvement measures.
After each measure is complete, the commissioning provider tests the system and compares the data to the energy baseline. They also confirm that the expected improvements and resulting energy savings have been realized and that the measures are well integrated and are having the anticipated effect on the building.
Phase 4: Handoff
The commissioning provider puts together a comprehensive record of the entire RCx project that summarizes all of the important information from project deliverables. You should compile O&M manuals for each energy-saving measure and system improvement as resources for your building operations staff. The commissioning provider also trains you and your staff to maintain the improvements and energy savings, as well as perform the O&M functions to keep the building running at an optimum level.
The commissioning provider recommends an ongoing commissioning plan—strategies that you and your operations staff can follow to confirm that savings are persisting.
How to decide if your building needs RCx
Good candidates for RCx include buildings that have:
- An uncommonly high energy-use intensity
- An unexplained increase in energy consumption
- Persistent occupant comfort complaints
Buildings with lots of older equipment that will need to be replaced in two to three years aren’t good candidates for RCx. It’s often more cost-effective to spend RCx project funds on new, more-efficient equipment. Buildings with major design problems also make poor RCx candidates because efficiency improvements are unlikely to ever compensate for a serious system design flaw.
The EPA published energy-performance target ratings in its reference table U.S. Energy Use Intensity by Property Type (PDF). The table provides a quick initial assessment to help you benchmark a building’s energy performance.
For a more comprehensive approach, use the EPA’s free online energy-performance rating tool Portfolio Manager. The tool takes into account source energy by evaluating electricity, gas, process steam, and fuel oil all as one standard unit of measurement. The Portfolio Manager also factors in weather variations and changes in the key physical and operating characteristics of each building, such as operating hours and location.
Additional factors that can contribute to a successful and cost-effective RCx project include:
- High utility costs
- Availability of utility incentives
- An experienced in-house staff
- High-quality building documentation
Many utilities offer incentives for RCx, including paying for part or all of an initial RCx feasibility study or paying for a portion of the cost of implementation.
Energy savings from commissioning have been shown to persist for at least three to five years, but longer-term data remains unavailable. Recommission every five years or so to maintain high levels of building performance. To help better manage the expenses involved in RCx and recommissioning (when an existing building has previously been commissioned), the industry is beginning to move toward a monitoring-based commissioning approach, which allows both commissioners and facility managers to better confirm savings, improve persistence of benefits, and identify further opportunities for improvement on an ongoing basis.
Who offers commissioning certification?
The EPA Energy Star Building Upgrade Manual lists five organizations that offer commissioning certification programs. Each program has different standards and confers a specific title:
- Building Commissioning Association—Certified Commissioning Professional
- AABC Commissioning Group—Certified Commissioning Provider
- University of Wisconsin-Madison—Accredited Commissioning Process Provider
- National Environmental Balancing Bureau—Systems Commissioning Administrator
- Association of Energy Engineers—Certified Building Commissioning Professional
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