"I was surprised by how much energy was used, even when I tried to switch everything off," he said. After cutting power to all the obvious appliances and switching off lights the meter was still registering energy usage -- the result of long various sensors and adapters around the home that did unseen and forgotten tasks. These added up to around 200 watts of constant energy use.

The next stage of the technology is to get the meters to communicate directly with gadgets. Initially this will likely work by plugging in appliances via adapters that can talk to the meter but could eventually work with products that have embedded intelligence.