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
The fight is said to be ongoing.
The new England Women's head coach Phil Neville has deleted his Twitter account following accusations of sexism.
Legal action has been threatened against the Parole Board if it does not disclose the reasons behind its decision to release John Worboys.