Sandra Kobler lives with her husband Dominique and two children in Balham in a semi-detached Edwardian home they bought in 2001. Earlier this year, they read about Green Homes Concierge Service in a newspaper article, and as they needed to insulate their roof, contacted the service immediately.

"We had a builder in at the time and had asked him to insulate the roof,' said Sandra, "but he clearly didn't know how, as it was left unfilled. We thought the Green Homes Concierge Service sounded like a really good idea, especially as we wanted advice on other plans for the house and they were clearly the best people to speak to."

A Home Energy Advisor examined how efficient the house was at retaining heat and created a detailed, bespoke report for the Kobler family that took in what they could achieve easily and quickly to feel the benefits immediately.

"Within days of talking through the report to discuss our priorities, we had an insulated roof and draught-proof house. The difference was enormous. Normally it's freezing in the hall in the mornings, but it immediately felt warmer. The living room doors used to shake whenever it was windy, and that stopped too."

While they were the family's main priorities, they have also started making minor changes as recommended in report, such as using low-energy lightbulbs and using Save-a-flush bags in the toilets. The report also gave them advice on how to build a wormery and how to choose and find water-efficient shower heads.

"What I liked about the service was the fact that they showed us we didn't have to rip out the walls to make a difference; we can do a lot to save energy by doing actually very little. If every house in London would do that, it would make a big difference. Our house is now so much better at retaining its heat, and we're undoubtedly going to see our money back through lower energy bills over the years."