The Task at Hand

In absence of this critical collaboration, the lighting professional must resist the temptation to apply indiscriminate fixed lighting to cover any unknowns. Fixed lighting is less accessible to individual users and represents energy that is difficult to reallocate for personal use. Consider the idea that, if the space occupancy is uncertain, it’s probably too early to design the lighting.

PLANNING FOR PLUG LOADS The fact that portable task and ambient lighting operate at 120V and building integrated overhead lighting is typically powered by 277V circuits leads to the misconception that the shift to portable lighting requires additional 120V branch circuits and thus requires larger on-site transformers. On the contrary, the 120V power supplied to most open-office furniture systems is highly underutilized and can easily accommodate the 0.2W to 0.6W per square foot of power consumed by tasklighting or task/ambient systems, respectively. Thus, rather than requiring additional 120V branch circuits and larger transformers, a shift to low-ambient office lighting based on portable task and ambient lighting more often results in a net reduction in wiring and branch circuits due to the elimination of overhead 277V lighting.

Consider that open-office workstations are often arranged in “six-packs” or “eight-packs” (clusters of six or eight workstations) separated by circulation aisles. This arrangement limits the distance one must walk to get to and from any workstation or from one workstation to another. Typically, these workstation “clusters” are furnished with three- or four-circuit modular wiring systems supplied by three- or four-circuit 120V power feeds. Often, one circuit is dedicated to computer loads that can consume 1W per square foot or more. This leaves another circuit for personal and miscellaneous plug loads, and a third circuit is for portable lighting. Applying switching control to the third circuit allows the portable lighting to be switched on and off in unison. Each of the three circuits carries the same capacity (approximately 1W per square foot) and can easily accommodate the entire office lighting load. In fact, with portable lighting power densities at or below 0.6W per square foot, there is often enough capacity to power the workstation video display terminals (VDTs) via the switched “lighting” circuit as well—a good practice that prevents VDTs from unintentionally being left “on” when the space is unoccupied.

The adoption of low-ambient office lighting strategies is also supported by new wireless-control technology that allows plug-load lighting to respond to room daylight sensors, vacancy sensors, and remote manual switches. In the past, portable lighting could not be dimmed remotely because the National Electric Code does not permit standard power receptacles to be dimmed. Wireless controls bridge that gap, allowing office tasklights and other portable furniture-mounted lighting to be included in office energy optimization strategies such as daylight, occupancy, and demand response. Also, radio-controlled relays are easily integrated into existing furniture power circuits and controlled by self-powered sensors and switches that harvest energy from their environment and do not require electrical wiring to facilitate the conversion of existing offices to low-ambient lighting. Whether hard-wired or wireless, plug-load control is becoming a standard for sustainable high-performance building and supports the trend toward task-oriented portable lighting.

SPECIFYING SUCCESS While it is advisable, if not required, that anticipated portable lighting be acknowledged on the project electrical lighting plans along with the required egress lighting, perimeter lighting, and other proposed fixed luminaires, the electrical distributor and electrical contractor are rarely best suited to implement portable task and task/ambient lighting systems. Experience reveals that project delivery is improved when portable luminaires, their plug-and-play control accessories, and any associated self-powered wireless sensors and controllers are handled by furniture suppliers who can coordinate their placement with other workstation elements, are familiar with system details such as cord management, and are most aware of last-minute changes in workstation design, quantities, and arrangements. (Furniture suppliers and facilities personnel can easily install and activate plug-and-play and self-powered control devices with minimal training.)

These items are not part of the electrical rough-in work, and they are required on site long after the conventional fixed lighting equipment begins to arrive. For these reasons, and to minimize conflicts and overlap between the trades during the later stages of construction, the portable lighting is best furnished and installed by the project’s furniture supplier. This arrangement also assures that the portable lighting is counted for depreciation tax benefits and can contribute to the LEED regional materials credit when they are sourced within 500 miles of the project site.

Accordingly, the project lighting documents must clearly assign responsibility for furnishing and installing the portable lighting to the furniture supplier. However, any wired sensors and/or circuit controllers called for by the design should be identified on the plans to be furnished, installed and activated by the electrical contractor. Of course, the corresponding request for furniture proposals must echo these responsibilities and include plans and specifications for the required portable lighting. This is where the earlier collaboration between the lighting professional and the workstation designer, space planner, and end-user sets provides some assurance that the personal lighting will harmonize with the fixed lighting, fulfill the project requirements and not be overlooked. This crucial connection between the lighting professional and the furniture specifier allows the specifier to call on the lighting expert for assistance and the lighting professional to double-check for compliance.

Creating productive and satisfying workspaces in a new energy-limited era is a challenge, but we have the tools and the technology to deliver. The greater challenge lies in getting everyone aligned on the same page and working toward a single composition.

Success will occur when: Lighting professionals are conversant in workstation design and understand the furniture procurement and installation process; furniture professionals understand the critical role lighting plays in occupant comfort and office productivity; lighting professionals are retained to compose a proper balance of task and ambient lighting, manage the respective energy allotments, specify complementary products, confirm compliance, and coordinate controls; and project documents clearly assign responsibility for procurement, installation, and testing of portable tasklights, building-integrated lighting and wireless controls, respectively.

Change takes time, but practice makes perfect.

David Pfund is president of Tambient at the Lighting Quotient in West Haven, Conn., where he focuses on emerging workplace lighting issues and solutions.