Our clients, Sam and Penny, approached us with a vision to grow their South London home through adding a rear extension and converting their unused loft space. But they didn’t stop there; they saw an opportunity to future-proof their home, choosing to retrofit the property with new insulation and modern mechanical services to significantly reduce their annual energy bills. Initially, the home had a less-than-ideal EPC rating of D and poor insulation.

On the dormer roof, the homeowners installed an array of solar panels for generating renewable energy all year round. Even on cloudy days, these panels continue to produce electricity which can be stored in a battery, making the home even more self-sufficient.

They also decided to opt for an air source heat pump, which is essentially a refrigerator working in reverse, moving heat from a cold place into a warm one. Air source heat pumps can be anywhere between 200 - 400% more efficient than a conventional boiler system.

When it came to insulation, the client wanted to retain the brick façade while improving the home’s thermal performance. They chose internal wall insulation, carefully balancing thermal efficiency with interior space. To achieve this, we used cork cell, a natural, breathable material with excellent thermal properties and a slim profile. Crucially, it allows moisture to pass through, preventing the risk of trapped condensation.

Every home is unique, and that’s why it is important to tailor retrofit solutions to your specific needs—whether it’s insulation, materials, energy systems, or balancing floor space with thermal efficiency. A whole-house retrofit, when done right, dramatically lowers carbon emissions and energy costs while enhancing comfort, property value, and climate resilience. With smarter energy solutions, this home is now more efficient, sustainable, and ready for the future.

Now that Sam and Penny have completed these extensive fabric and mechanical upgrades, we estimate that their EPC rating has improved from a D to a B. This family is already reaping the benefits of reduced heat loss and the free, renewable energy generated by their air source heat pump and solar panels.

Although they only moved in a few months ago, they're already saving hundreds of pounds on their winter energy bills, and are on track to save over £1,000 annually based on current energy prices. Given how volatile energy costs can be, their savings will only grow over time. And the best is yet to come. Thanks to the winter weather, the solar panels haven’t even had the chance to shine at full capacity yet. As summer approaches, they’ll generate even more energy, storing excess power in the battery system and further reducing the cost of running the house.

Photography by Peter Furlong.