We talk incessantly about "making the invisible visible," a Viridian-derived principle arguing that making people aware of various environmental conditions or choices that normally remain hidden allows for better decision-making, almost invariably in the direction of better use, efficiency and conservation. Typically, energy use is the target application of the principle, and it's easy to see why: aside from a single bill totaling up monthly consumption (or, for some people, quarterly consumption), we normally have no way of knowing how much power we're using, and are quite often wrong in our guesses about which appliances and gadgets are the most hungry for juice. But electricity isn't the only flow amenable to transformational revelation -- water has many of the same characteristics.
Ernesto Arroyo, Leonardo Bonanni, Ted Selker at MIT's Media Lab recognized the need for ways to clarify water consumption, and put some thought into what sorts of signals would both provide useful information and still allow for normal, necessary use of sinks and faucets. Their work resulted in the WaterBot (PDF):
WaterBot presents feedback using non-obtrusive interaction modalities in the form of visual and auditory reminders. Continuous visual feedback helps users track their water usage while appealing color patterns in the water entertains them through the lifecycle of the system. Positive auditory messages and chimes sound every time the tap is closed to act as positive reinforces for having closed the tap. WaterBot chooses feedback modalities depending on how long water has been running and on the type of interaction with the sink. A water flow sensor allows the system to track water usage, water savings and open tap duration. Finally, WaterBot allows researchers to evaluate different feedback types, persuasive techniques and how they interact when placed together.
The WaterBot uses lights and gentle chimes as indicators of water consumption and the need to shut off the tap. The designers note that, "since the bathroom sink is not a common place for multimedia interaction, we took precautions to ensure that the interaction is not perceived as a game that would otherwise reduce water savings" -- a recognition that systems of visual interaction often have metaphorical connections to play (the frequency with which "video game" is used to describe the mileage readouts in hybrid-electric cars is another example of that problem). The WaterBot design is bulky and may be perceived as a hindrance in some households, although the test users at the Media Lab expressed no annoyance with it; a similar system might better be implemented in a way that appears integral to the faucet itself, or as an add-on in combination with other features, such as water purification.
From a design perspective, the most interesting aspect of the paper is the breakdown of principles used by the team to determine the best designs:
"Value-Added" design (device should clearly provide an advantage in use);
Automation (device shouldn't require extra action to trigger);
Just-In-Time Prompts (device should provide immediate feedback and cues);
Positive Reinforcement (device should have features which make users want to use it);
Negative Reinforcement (device should have features which dissuade misuse);
Adaptive Interfaces (device should have features which change behaviors over time, prompting a user desire to pay attention to it);
Social Validation (device should demonstrate how good behaviors benefit everyone).
Taking the aforementioned example of the mileage readout of a hybrid car, some of these principles make sense, while others are inappropriate for a driving context. An "Adaptive Interface," for example, is likely to draw the driver's attention away from the road in order to decipher the signal; in this case, an interface which prompts rapid recognition of the intended information is a better choice. Similarly, while "Social Validation" is certainly a part of why hybrid drivers choose their vehicles, the readout may not be the best location for a display of social benefits -- at least while the vehicle is in motion. I could imagine finding it quite appealing if my hybrid readout could display how many tons of CO2 have been saved (vs. a standard Civic, for example), even if only while in "Park." Other kinds of "make the invisible visible" readouts would emphasize or de-emphasize other listed principles.
WaterBot isn't the only design mentioned in the MIT article (although it is the primary focus). Other suggested tools include: HeatSink -- displaying the temperature of the water with color cues to avoid both an overly-long wait until the water is ready or accidental scalding; SeeSink -- a sink with camera and digital intelligence able to provide the correct water temperature and flow depending upon what it "sees" put into the sink, such as warm for empty hands, cold for vegetables, hot for a sponge, etc.; and CleanSink -- similar to SeeSink, but the camera and computer are used to monitor correct hand-washing time in medical and commercial settings.