Vehicles with thermal imaging cameras are being used to identify homes in part of Surrey which could benefit from more insulation.
Specially-equipped vans have been taking images of properties in Reigate and Banstead to see where energy is being lost.
Residents are then offered advice on how they can reduce their fuel bills.
Operating at night, during the colder months, each vehicle has the ability to assess up to 1,000 homes an hour.
Reigate and Banstead Borough Council said when the vehicles were last dispatched the technology helped improve energy efficiency in at least 2,000 homes.
Cllr Julian Ellacott said: "This scheme will play an important role in the council's long-term plans to make homes in the borough more energy efficient, cutting residents' energy bills and tackling climate change.
"Many of the residents who had extra insulation installed were vulnerable, so benefited from a grant to have the work carried out."