Nevertheless, he calculates that operating the heat pump has cost him only 500 — resulting in a net saving of 700 a year on fuel.

Some experts doubt whether people will actually make impressive savings from the new meters, with one study predicting a net saving of only 14 a year on bills.

The net saving can be more than 40%.

The facility achieves a net saving of approximately 40,000 tonnes of carbon dioxide per year compared to a high efficiency coalfired power station.

This produces a net saving of power so long as the control devices themselves use less power than the controlled equipment in standby mode.