The UK hub insists that the savings could be delivered without compromising on its commitments to local communities or passenger experience.
And it says "the reduced cost options", which could see the estimated development bill drop to £14 billion, have been developed with input from the airlines, and will be consulted on in January.
The proposals – which will be released in detail as part of Heathrow’s public planning consultation in January – would ensure that Heathrow expanded with airport charges staying close to today’s levels.
The options that would enable the identified £2.5bn cost reductions involve three things:
Heathrow’s executive director expansion, Emma Gilthorpe, said: “The Secretary of State set us the challenge to deliver an expanded airport for Britain with passenger charges staying close to current levels.
"We have now identified potential savings of £2.5bn and are increasingly confident we can meet the affordability challenge.
"We are looking forward to presenting detailed options on how to do it in our consultation in January, and while we will continue to work to reduce the cost of expansion, we will not compromise on our local commitments.”