Researching the context

The project started when we were given the following brief: people have a hard time feeling the rate of their electricity consumption due to it being immaterial, abstract, and often thought of as unlimited. Our first task was to really understand the context we were designing for. What was stopping people from monitoring their usage? What kind of usage were they most interested in? Were they interested in comparing their usage to the one of their neighbours? Or did they want to locate the highest-consuming appliances in the house?

After some desk research, we developed paper prototypes to use during quick interviews with potential users. Our goal was to use these low fidelity materials to discuss the use context by filtering for the data that the users were interested in. By using paper prototypes, we discovered that people were interested in monitoring their room-by-room consumption.

Testing different modalities

At this point of the project we had an idea of what data we needed to display. The next step was to decide what modality would be best received by users. While we considered a wide array of modalities such as temperature and haptics, we only performed tests on sound and light as they were the most suited for interactions where users didn't have to be in close proximity with the artefact. In the end, sound was perceived negatively due to its non-directional nature so we ultimately chose to work with light.

Choosing a metaphor

Candles are the precursors of the light bulb. Before electricity, candles were the tool people used to light up their houses even at night. Today, the candle is less of a necessary tool and more a piece of decor that is used to add coziness to a home. But most importantly, candles last only so long before they need to be replaced. These qualities made a candle the ideal shape for an ambient display that can blend in everyone's home while subtly shedding light on the scarcity of electricity.

Delivering rich information with light

The light behaviour of Cand-EL was designed to portray as much information as possible in a way that feels subtle yet meaningful. A constant, pulsating light in the middle of the candle gives a constant frame of reference for users to compare their usage to. The usage amount is portrayed with a light that moves up and down the body of the candle to display if the current usage is above or below the user's average. Lastly, the moving light leaves a trail that signals if consumption is rising or falling.