Commissioning lighting control systems
Codes and standards require lighting engineers to include power allowances, daylighting controls, functional testing, and commissioning in lighting designs to verify lighting controls.
- Illustrate the steps for commissioning a lighting system.
- Summarize the codes and standards that apply to lighting systems, controls, and commissioning.
- Make use of lighting controls to gain efficiency in lighting design.
Commissioning is a quality assurance process intended to ensure that completed facilities perform according to owners’ expectations. Activities involved in commissioning include establishing expectations, design review, submittal review, verifying the installation, functional testing, and post-construction documentation.
Requirements for lighting controls become more complex with each edition of the energy-conservation codes. Codes and standards include ASHRAE Standard 90.1: Energy Standard for Buildings Except Low-Rise Residential Buildings, the International Energy Conservation Code (IECC), and California Title 24. With each level of increased complexity, the benefits of formally commissioning lighting control systems increase. Those benefits include:
- Superior energy performance, generally obtained from operation of lighting controls in accordance with their design
- Improved indoor environmental quality, with maintenance of appropriate lighting levels through changing conditions
- Smoother transition of personnel and operations into new facilities.
There are many steps to examine when commissioning lighting controls, following energy code requirements. ASHRAE 90.1, the International Energy Conservation Code, and California Title 24 all require some form of commissioning activity, in varying levels of detail. Title 24 provides a lot of detail in its commissioning and testing requirements.
Establishing the scope of commissioning services
The appropriate scope of commissioning services will be different for every owner, and for every project. Some owners place a high value on commissioning and call for extensive services. Others may see commissioning as an unwelcome necessity, required by codes or corporate practices, and will contract for the minimum level of service that meets the requirement.
Minimal commissioning projects will generally include only prescribed functional testing services, with limited review services. More thoroughly commissioned projects will call for a complete array of services including any or all of the following items:
- Assistance in defining the owner’s project requirements (OPR)
- Review of the basis of design (BOD)
- Design review
- Submittal review
- Equipment check-sheet documentation, or prefunctional checklists
- Functional performance testing (FPT)
- Post-construction documentation.
Most recommended practices and standards for commissioning strongly recommend that the commissioning firm is independent of the design team, the construction team, and other project participants and reports directly to the owner where project procurement requirements allow. In practice, that means nearly all projects, with the exception of certain government-owned projects with rigid contracting requirements. The entity in charge of the commissioning project is typically called the commissioning authority (CxA).
The elements of an owner’s project requirements
The commissioning process begins with developing a written description of the owner’s needs and expectations for a facility in a document traditionally called the OPR. The OPR describes the expected use, performance, and costs of the facility.
The OPR is created by the owner in conjunction with the CxA and the design team. If the construction team is engaged early in the project, those team members will participate as well. The OPR will include a description of the project, including its size, location, and intended use, along with primary project goals, such as the schedule and total budget. The OPR will also cover more specific requirements for building systems including performance, maintainability, and warranty requirements. It will describe any special requirements and contain a list of the applicable codes and standards.
In practice, the development of the OPR will take the form of a negotiation, with the owner balancing various project goals against one another, and the CxA and design team acting as mediators. It is rare for an initial project budget to be compatible with the goals for project quality, cost, and schedule. In general, some adjustments will be required to harmonize those requirements. In terms of lighting and lighting controls, the requirements of the locally enforced energy-conservation code will establish a basis for functionality and cost.
Certain elements of the OPR will affect the implementation of lighting components and lighting system controls:
- Project cost will, to some degree, determine the general quality of lighting system components, the selection of available lighting technologies, and the level of complexity and functionality of the lighting control systems.
- Required lighting levels and uniformity will affect the number and types of fixtures in the design.
- Requirements for individual controllability will increase the number of control components, the complexity of the control system, and the use of task lighting.
- Indoor environmental quality, in terms of the lighting level and uniformity, will have a strong impact on the lighting system design.
- Space usage and occupancy schedules will determine the types of controls required for various areas of the facility and the initial programming for automatic, scheduled controls.
- Efficiency goals will affect the selection of lighting technologies and the complexity and functionality of the lighting control systems.
- Maintainability requirements will affect lighting and control equipment selections. Different lighting technologies have different maintenance requirements. For example, LED fixtures exhibit extremely long lamp life and are generally provided as integral units with no replaceable components. Fluorescent fixtures require more frequent lamp changes and have replaceable lamps, lamp holders, and ballasts.
- Requirements for adaptability will affect the selection of lighting control systems. Where reconfiguration is expected only infrequently, systems that require reprogramming by outside specialists will often be acceptable, while an expectation of more frequent changes to occupancy patterns will drive the selection toward user-configurable systems.
- Evaluation and testing requirements affect the scope of commissioning services and will have a level of impact on construction cost and schedule.
- Training requirements are normally described in the OPR. Lighting and lighting control selections, though, will generally drive training requirements, as they are normally viewed as specialty systems with specific operation and maintenance requirements. Maintenance and operations staff will require training to operate, maintain, and modify lighting controls, and users will learn to operate the controls.
- Special requirements may take the form of a requirement for a particular technology, a manner of operation, or even a specific manufacturer. Examples are a requirement for an open lighting control protocol, or for LED fixtures.
- Applicable codes and standards—especially energy codes—will affect the total allowable lighting-power density and functional testing requirements. Some jurisdictions, particularly those under Title 24, require prescribed and very detailed functional tests. Other jurisdictions using ASHRAE 90.1 or the IECC will find testing requirements less prescriptive.
The OPR may be periodically updated during the course of the project to reflect design decisions, owner-driven changes, and resolution of unanticipated construction issues. As the design progresses and cost estimates are refined, the OPR adjusts to manage costs or enhance the functionality of the facility with available funds.
Basis of design
The BOD is a document describing the design team’s technical approach to realizing the elements of the OPR and complying with applicable codes. The BOD is developed by the design team. The lighting controls portion of the BOD, often called the “lighting controls narrative,” describes how the control system functions, its sequences of operations, and its user controls for each space.
Recent energy-conservation codes require more functionality and flexibility from lighting control systems than their predecessors did. The lighting controls narrative describes how the system will comply with the requirements of applicable energy codes including:
- Automatic scheduled shutoff controls
- Staged manual controls, providing an initial lighting-power level of roughly 30% to 70% of the maximum power level when activated by user controls, with additional higher lighting-power levels in response to user demand
- Light-reduction controls that are available to users
- A strategy for maintaining lighting uniformity at reduced power levels, if power levels are reduced by switching fixtures rather than continuous dimming
- Dimming technologies
- Daylight-responsive controls, defining areas with daylight controls, and their control sequences. ASHRAE 90.1 and Title 24 require as many as four different illumination levels for daylight-responsive controls, and the IECC requires continuous dimming for certain areas.
The BOD serves as the reference for design reviews throughout the design process. Like the OPR, the BOD is periodically reviewed and updated to reflect changes in strategy as the design progresses.
The CxA reviews the design at least once before construction documents are issued, to determine that the design is consistent with the OPR. Additional reviews may be performed at various stages of the project, in accordance with the scope of commissioning services agreed upon between the owner and CxA. The CxA typically provides comments and observations about the design, and the design team provides written responses.
During the design review, the CxA typically will also review and adjust the commissioning plan to address the developing design. The CxA will frame contractor-testing requirements into project requirements and add these requirements to the contract documents.