Lighting controls are now required by energy codes in the large majority of new commercial buildings. As demand for controls continues to increase, so does demand for commissioning as a quality assurance process. This process helps ensure that installed controls satisfy both the design intent and owner requirements by minimizing error across the construction process. At the same time, manufacturers are focusing on making their products easier to start up, use and maintain.
According to the Department of Energy, 30 percent of installed lamps are controlled by some type of device. The 2012 CBECS study suggests controls are more prevalent in larger buildings. As the installed base of controls continues to grow, so does the opportunity to apply commissioning—retrocommissioning or recommissioning—to existing buildings. Many control systems have been installed without the benefit of formal commissioning; many were properly commissioned but may have fallen out of sync with building use. Periodically tuning up installed controls can maximize performance and deliver the greatest value.
The LEED green building rating system and the latest generation of energy codes based on ASHRAE/IES 90.1 and IECC require commissioning. A formal commissioning process is defined in ASHRAE Guideline 0, which formed the basis of ANSI/ASHRAE/IES Standard 202 and IES Design Guide 29. In a new construction project, the commissioning process broadly encompasses defining the owner project requirements, basis of design, functional testing, owner training, systems manual and, in some cases, a post-occupancy evaluation.
In retrocommissioning, we are more often concerned with revisiting functional testing within the context of the defined owner project requirements, which may have changed, and the basis of design. During evaluation, the owner may decide to capitalize on technological advances and install a new lighting control system, which may expand the scope of retrocommissioning to one similar to a new building.
Retrocommissioning is applicable if changes have been made to the space or control system. For example, a renovation may result in new surface finishes, which may change reflectances. A building performance contract may switch to a new vendor. A time schedule may change to address heavier seasonal workload but was never switched back. The lighting control system may have been updated with new features, or certain features existing at time of installation may not currently be utilized.
By reviewing current operation of the control system, deficiencies can be identified for resolution. These reviews may be periodic and scheduled, making commissioning an ongoing process, part of maintenance. Ideally, the party conducting the review will be knowledgeable about lighting controls and specifically the control system that is installed.
Two major studies suggest retrocommissioning can increase energy cost savings and generate a desirable return on investment, positioning it as an upgrade activity.
In 2009, the Lawrence Berkeley National Laboratory published a study based on commissioning of new and existing buildings. They found that whole-building commissioning produced 13 percent median energy savings in new buildings and 16 percent in existing buildings. More than one-third of existing buildings were found to have lighting deficiencies. As an isolated measure, addressing these was found to produce a 1.4-year payback.
In 2013, the Energy Center of Wisconsin published a study of retrocommissioning daylight harvesting controls in 20 office buildings. Major problems reflected a lack of defined light level targets, design document review, functional testing and owner training. Specific problems included improper calibration, zoning and relay connections. In each space, the researchers tuned/calibrated and reoriented sensors, connected components that were disconnected, changed time settings and made other adjustments, spending about 1-2 hours per space. Median energy savings more than doubled as a result.
Basic retrocommissioning starts with a review of the installed system to ensure replacement parts are available, ease of adjustment and understanding of its features. Functional testing is then conducted on a designated portion of the controls to determine the control system is producing good value for its owner. Based on the number of deficiencies discovered, the sampling may be expanded. Controls may then be re-aimed, reprogrammed, recalibrated or reconnected as needed to ensure optimal operation in regards to energy savings, site conditions and user preferences.
The latest version of ASHRAE/IES 90.1 contains detailed requirements for commissioning that may be applied as a general guideline to existing installations. The standard requires that lighting control devices be tested to ensure both hardware and software are calibrated, adjusted, programmed and operating in accordance with construction documents and manufacturer instructions. Specifically, occupancy sensors, time switches, time-scheduling controls and photosensors.
Let’s look at an example. For occupancy sensors, at a minimum, 90.1 requires that functional testing be conducted to verify:
• The sensor is placed and oriented in accordance with manufacturer recommendation.
• Sensor status indicator is working properly.
• Control lighting turns OFF of is reduced to the designated level within the required time when the space becomes unoccupied.
• For auto-ON sensors, that the lights turn ON to the required level when the space becomes occupied. For manual-ON sensors, that the lights turn ON only when activated by the correct manual switch.
• The lights are not improperly activated by movement in nearby spaces or by HVAC operation.
If the project has up to seven occupancy sensors, all must be tested. If more than seven are installed, testing must be undertaken for a sampling based on each unique combination of sensor type and space geometry.
To learn more about commissioning activities, various resources are available, including IES-DG-29, the Lighting Controls Association’s Education Express course on commissioning, and energy codes based on the latest versions of ASHRAE/IES 90.1 and the IECC. Retrocommissioning services may be provided by commissioning agents, certain electrical contractors (in California, Certified Lighting Control Acceptance Test Technicians demonstrate a base of knowledge in lighting controls functional testing), manufacturer field service teams and other professionals.
As the installed base of lighting controls grows, so does the opportunity to periodically review these systems and ensure they are in sync with current owner needs and the basis of design. Retrocommissioning provides an opportunity to retune the lighting controls to maximize the value of the original investment.