What unsustainable behavior needs to change: Well, I confess it: I used to brush my teeth during a long, hot shower. It just felt comforting and self-indulging. But it started to feel wrong- to waste so much water and energy. But wait, was it a lot? How much water and energy is needed for a shower? Does it make a big difference if I shower for 2, 5 or 10 minutes? I had no clue, because it was too abstract.
In most households the shower is the 2nd biggest energy consumer (after heating). In Germany, people spend between 8-12 minutes under a running hot shower with 40°C (104°F). That means approximately 20% of the total energy used to heat water and ~16 liters of water per minute.
In order to saving energy, we could either shower shorter or reduce the temperature of the water. The first problem here: showering is extremely habitual and the shower is also the place where your mind wanders and you forget time easily. The second problem: although reducing the temperature by 2-3°C would make a difference, guessing the temperature is as inaccurate as trying to hear the decibel of a winter car tire.
What we need is a feedback mechanism that makes the abstract energy and water consumption more concrete, more salient. Something that nudges people into shorter and colder showers.
The Green Nudge: Swiss company Amphiro came up with a digitally enabled behavioural intervention: a smart shower meter that provides real-time feedback of your energy and water consumption during the shower.
Researchers from the ETH Zürich and the University of Bamberg conducted a natural field experiment with an uninformed sample of guests at 6 Swiss hotels (265 rooms, N = 19,596 observations).
The rooms were equipped with smart shower meters in their hotel rooms. The devices measured the energy and water consumption of every shower taken, and displayed feedback on each ongoing shower in real time.
Information that was shown on the display:
- total water consumption in liters,
- total energy use in kWh,
- a dynamic rating of the current energy-efficiency class (A–G) and
- a four-stage animation of a polar bear standing on a gradually melting ice floe
The result: a large and significant energy-conservation effect of 11.4% or 0.215 kWh per shower (vs control group that was shown only temperature).
While this does not fully translate to household settings, it demonstrates that feedback can be an impactful nudge to preserve resources like energy and water. Especially when you scale this up for a larger group.
Full article in Nature.