As valuable as an LCN is, no specific standard for creating one exists, DiLouie says. However, effective LCNs contain several common attributes. First, the narrative should follow from the owners' project requirement. The LCN should include a general description of the project goals and the control strategies that will be used to satisfy the goals, DiLouie says. For instance, the narrative might indicate that the lighting system will satisfy applicable ASHRAE standards as well as any local regulations.
Based on the owners' project requirement, the LCN might say, "in this space, we'll have these controls, and the lighting system will do this when a certain input happens," DiLouie says. In other words, the LCN might indicate that when a person walks into a particular space, the light will turn on. Then, when the space has been unoccupied for at least 15 minutes, the lights will turn off. This information could be presented in a written format. Or it might be shown with a matrix that allows the reader to quickly see how the lighting system in each space will operate.
The LCN should include a summary of its purpose, a list of the systems covered, as well as descriptions of the various lighting systems specific to different types of spaces, such as common areas or private offices or boardrooms, McKay says. Moreover, the sequence of events that will occur — such as "occupant enters a room and must hit a switch for the first preset to be activated" — should be outlined in terms that both professionals and laypeople can understand. "Expectations are clearly expressed," McKay says.
The LCN also should describe any special lighting control systems that are to be used, says Avraham Mor, partner with Lightswitch Architectural. One example would be DALI, or a digital addressable lighting interface.
The document helps to answer the question: "What does all the equipment do?" says Dane Sanders, principal with lighting design firm Clanton & Associates, Inc. The lighting control narrative is sent to the lighting manufacturer, along with the lighting schedule and plan. The schedule describes what the controls devices are; the plan shows where the devices will be installed; and the narrative tells how the systems will operate and perform, Sanders says. The manufacturer should refer back to the narrative when developing its proposal. If this step is overlooked, which happens more frequently than it should, Sanders says, the likelihood that the equipment won't operate as intended increases.
"The LCN should be as detailed as needed to ensure that all project participants can specify, bid, purchase, install and test a lighting control system," increasing the likelihood that it realizes the basis of design and satisfies the owners' project requirement, DiLouie says.
Lighting Control Narrative Helps with Purchasing, Installation of Systems
Lighting Control Narrative Includes Project Goals, Lighting Systems, Specialty Controls
