Paul Massara said the actual unit prices of gas and electricity in the UK are among the lowest in Europe, but bills were high "because British houses waste so much energy".
In the supplier's second "Energy Explained" report, Mr Massara said: "If we can increase the efficiency of the UK's old and draughty housing, we can ensure that annual energy bills are some of the lowest too."
The npower chief executive warned consumers that the cost of bills was set to increase unless households introduce efficiency measures.
More top news
A man has been arrested under the Psychoactive Substances Act 2016, less than 24 hours after it came into force, banning 'legal highs'.
Dozens of people are feared to have died after a migrant boat capsized in the Mediterranean off the Libyan coast.
Andrew Nay smashed into a family's car with his 4x4 during a road rage chase leaving two young sisters paralysed, a court heard.