Case study: Designing a lighting control matrix

In this office building, control intent and sequence of operations for a lighting control system were created

By Brandon Stanley May 9, 2023
Courtesy: SmithGroup

A lighting control matrix can be a valuable tool for documenting control intent and a sequence of operations. Often it is easier for contractors, lighting controls manufacturers and design team members to track lighting control requirements on a room-by-room or space type basis through information indicated on the drawings. Although its best to include detailed sequences for spaces with complicated or atypical requirements in the specifications, having a quick reference right on the drawings will save time across the board.

On a recent medium-sized, multifloor office tenant improvement project for a confidential client, SmithGroup elected to simplify the controls documentation down to a lighting controls matrix on a space type basis. Because the client didn’t have a standard for lighting control systems, the specification was written on a performance basis and was limited to systems that were familiar to the client and successfully installed at other office sites around the country.

Because the allowable systems had different design requirements like some systems with standalone daylight photosensors and others with combination occupancy sensor and daylight photosensors and different device performance limitations like different occupancy sensor range and room coverage, the lighting control matrix became the primary documentation for what devices were required in the various spaces. The only devices indicated on the plans were the coordinated location of manual control devices (see Figure 3).

Figure 3: Example lighting control matrix. Courtesy: SmithGroup

Figure 3: Example lighting control matrix. Courtesy: SmithGroup

If you take a look at Figure 2, you can see that each room is indicated and combined with other rooms of the same space type and control strategy. Directly from this matrix, the designer and the contractor can determine which spaces need switches, dimmers, occupancy sensors, photosensors, HVAC contacts, etc.

In addition to what devices are present, the matrix also lists the illumination target and the manual control device type, as well as a basic sequence of operation. The contractor can see what the intent is for each control device, whether it is a simple dimmer, a multizone device with presets or a combination control device with integral occupancy sensor.

By indicating the switch type in the matrix, the designer can easily confirm that all similar rooms have similar control devices and can clean up the drawings to make more room for other critical information useful to the contractor, like zoning and circuiting (see Figure 4).

During the bid phase, the bidding contractors reached out to the local representing agencies of the approved manufacturers. The agencies developed preliminary shop drawings as part of their quote to the contractor. The agency representatives had no issues understanding the matrix and were easily able to quote a complete system based on the space-by-space control intent without supporting plans indicating device quantity and location.

Figure 4: Defining setpoints for single-zone spaces via drawing details. Courtesy: SmithGroup

Figure 4: Defining setpoints for single-zone spaces via drawing details. Courtesy: SmithGroup

Documenting control requirements through a matrix was particularly helpful in the open office areas where sensor range and quantity varied between the approved manufacturers. Instead of quoting the number of devices on the drawings, the agencies quoted the number of devices required to meet the sequence of operations.

Because of the performance-based approach, the controls package was aligned with the luminaire package by the awarded contractor and both were procured together to allow for bulk pricing from the local agency. This resulted in a cost savings for the owner.

During the construction phase, the selected manufacturer’s local representing agency provided shop drawings of the lighting controls as a part of the submittal review and approval process. The design team was able to easily verify the control intent was met by comparing the provided shop drawing layouts against the lighting control matrix.

The agency also included the control matrix on each plan of the shop drawings, further simplifying the review and approval process. As a result, the submittals were reviewed quickly and returned promptly with only a few minor comments and there were zero requests for information related to the lighting control system during the construction phase.

Author Bio: Brandon Stanley, PE, LEED AP BD+C, IES, is an electrical engineer, lighting designer, project manager and associate at SmithGroup, where he serves as the electrical discipline lead in its Chicago office.