Energy company British Gas has installed 1.5 million smart meters in the UK.
The milestone was reached at a home in Whitwick, Leicestershire this week.
Smart meters allow households to see a breakdown of their energy use by day, week and month, showing details of their consumption for lighting, heating and different appliances. They also receive tips on how to be more energy efficient.
They are expected to bring estimated billing to an end as information is automatically sent to energy suppliers.
British Gas claims 79% of its smart meter customers are now more aware of their energy consumption and 90% are taking steps to reduce their energy use.
Bills have reduced on average by around £26 for customers, the firm adds.
Jorge Pikunic, Managing Director of British Gas Smart Metering, said: “We’ve taken the lead in giving our customers greater levels of control and insight into their energy use through smart meters.
“But we’re not stopping there – we’re continuing to innovate in smart-enabled technology.
“We’re already trialling a tariff which gives people the choice of having free electricity on Saturdays or Sundays along with new apps which give our smart meter customers information about their energy use on their phone.”
This week workers at EDF Energy voted for strike action in a dispute including extended working hours to install smart meters.