Design Sensitivity Lab: Let there be light!

Background:

Each floor of the Allen Center is divided into 5 zones that allow all lights in a given zone to be enabled or disabled.

Every night at 11 PM, and again at 1 AM, all zones are disabled, meaning that all lights in the building go off. To reactivate a zone, someone must go to one of the locations marked by red stars in Figure 1, and utilize the interface shown in Figure 2.

Figure 1: Allen Center Map Showing Zones and Panel Locations

Observations:

I have observed the following behaviors from people who were working when the lights went out.

Active Behaviors: User leaves their office and proceeds to the nearest light panel. Once there, they either

a. Press all the buttons on the panel, either in sequence, or using an open hand to press them all at once.

b. Attempt to determine the correct button for just their office. Requires looking at the building diagram, (often tilting head from side to side) and then pressing one or more buttons.

Passive: Wait for someone else to do it

In general, the majority of people in the building take a passive stance, particularly those located farthest from the lighting panels. Naturally, this behavior is not always successful, and in several instances, was followed by one of the active behaviors after a short period of time.

Figure 2: Lighting Panel (Red Stars in Fig. 1) and blowup of a single zone control

Design Analysis: Why the different behaviors?

• Poor mapping between zone diagrams and user's internal model of the building
  • Requires user to perform an explicit rotation to determine the correct zone. This can be deduced from the head tilting observed while looking at the diagram.
  • No clear benefit to being selective. Much faster just to hit all of the buttons
• Non-intuitive design includes two separate buttons that perform the same function.
• Zones can be reactivated from any one of the locations

Discussion of Trade-offs:

Cost:

Cheaper to buy a large number of button panels of one design, and simply wire both of the buttons together when a single function is desired. This likely also motivated the decision to use the same diagram in all locations.

Feedback:

When user activates the zone, button lights up. However, this happens at all panels, regardless of where the button was actually pressed. This can be confusing, as darkened buttons suddenly light up without any noticeable cause. The designers probably wanted a lit button to signify an active zone, and a single button press activates a zone.

Diagrams:

Initially (2003), no diagram was provided, virtually necessitating pushing all of the buttons to prevent multiple trips. Having a diagram is better, but the orientation is identical in all three locations, though the intuitive orientation is different in each one.

Overall Design:

I also think the designers were attempting to allow fine-grained lighting control by providing buttons for each zone. It's also worth mentioning that fire doors split each floor into 2 regions, and all panels are in the same region. At first, having global control over lighting circuits appears wasteful; any light that's not in use will be turned off anyway. However, in the context of fire safety there may be some justification for the design.