The Electrical Semaphore, designed by Gilles Belley in collaboration with EDF, changes colour to indicate variations in energy production during the day; green for off-peak, blue during busy periods and orange to indicate peak hours in local production. The idea is that if you know when energy is most in demand you can reduce your consumption at these times.

The intent of this product is similar to that of the Home Joule. However, whereas the Electrical Semaphore provides feedback on energy production variations, the Home Joule shows the real-time price of energy per kilowatt. In motivational terms, the added dimension of cost is, perhaps, a more powerful incentive for behaviour change.

In terms of design, the colour arrangement of the Home Joule is probably more intuitive than that of the Electrical Semaphore as it follows a traffic light sequence to indicate the relative cost per unit at different times of day - green (low) through yellow (medium) to red (high).