Note that Amazon rolled out a second revision of the Dash button that is 4x more energy efficient: "I measured the new Dash Button’s energy usage to be 4.3±2.2 

Note that Amazon rolled out a second revision of the Dash button that is 4x more energy efficient: "I measured the new Dash Button’s energy usage to be 4.3±2.2 J per activation and the original Button’s energy usage to be 16.4±0.1 J per activation." Source: https://mpetroff.net/2016/07/new-amazon-dash-button-teardown-jk29lp/ https://mpetroff.net/2016/07/new-amazon-dash-button-teardown... Although the Dash is still much over-engineered: for every activation it has to establish (I believe) an HTTPS session and exchange a few requests with Amazon servers. A much dumber wifi button sending a single packet should be able to use 1/10th of this energy.