Ian and Sue Collins were living on the outskirts of Cambridge in a 1930s house when, in 2008, they decided to build a progressive eco-friendly home in their back garden. They appointed Mole Architects; the brief was to preserve mature trees and the rich biodiversity of the plot, and to create a home that used natural materials, as little energy as possible and was kind to its surroundings.

Mole Architects didn’t disappoint, delivering an L-shaped single-storey structure that winds around the existing trees, maximises natural light, opens out onto green spaces and is clad in timber and ‘green walls’.

As the house comes onto the market, retired engineer Ian talks us through life in an eco-home and why the time feels right for him and Sue to take on a new project.

Ian: “For us, modern living means having a strong connection with the natural world, a home with high sustainability values, natural materials, low energy costs and no consumption of fossil fuels. And an environment that is well designed and aesthetically pleasing.

“We lived in a 1930s detached house, which was very different, and we built our current home in its back garden. It was completed in 2010 and the build took two years. The architect was Meredith Bowles of Mole Architects. We very much enjoyed working with Meredith and the project architect, Helen Stratford. They have a collaborative style, a strong commitment to designing beautiful, sustainable homes and are happy to involve the clients in the design process.

“Our brief to them is well summarised by our definition of modern living, plus a desire for minimal exterior maintenance. We value sustainability and natural materials, so we have used a timber frame construction on a steel, concrete and polystyrene insulation floor structure, which sits on concrete screw piles. Walls are insulated with hemp, with wood fibre panels outside, clad in oak. We have a green roof on 60 per cent of the roof, and collect rainwater into an underground tank for flushing toilets and watering the garden.

“Inside, we have used basalt, limestone, American black walnut and Marmoleum for the flooring. Some of the internal walls are made from clay blocks for thermal storage as well as aesthetics, and those in the bathrooms have a glazed finish on the inside.

“We also have a ground-source heat pump, underfloor heating and a solar hot-water array. The house is ventilated via mechanical ventilation with a heat recovery unit in the utility room.

“All the glazing is double, powder-coated aluminium on the outside and natural timber on the inside. Both the kitchen-dining room and the living room have substantial glazing to the garden, which is several metres long and full-height. The bedrooms all have full-height glazing to the west elevation. There are five roof lights as well to bring in light from above.

“We like both modern and retro design, so our spare room has 1950s wardrobes bought new by my parents. Our dining room has a Habitat table and sideboard which we bought in the 1970s and Starck chairs bought on eBay after we moved in. Our living room sofa was bought from Habitat soon after we moved in, and we have a lot of Ladderax storage in the living room too (also from eBay!). A lot of the art on the walls includes photos that I have taken of the natural world, either representational or abstract. We also have paintings and prints created by family and friends.

“One of the spaces that all of us, and our visitors, like a lot is the corridor, which combines circulation with a library, a place to hang art, and two bays with day beds that overlook the garden. It’s great for the grandkids to tear up and down, as well.

“The living room is warmed by the morning sun, the kitchen and dining area face south and have sun for most of the day, but in the summer the liquidambar tree that the house wraps around provides shade to minimise overheating.

“The outdoor space is varied: there’s the entrance garden with bike, log and bin storage; a courtyard overlooked by the bathroom of the main bedroom; a garden on the west side with a path that winds past trees and bushes; a wildflower meadow outside the kitchen and the living room; and a vegetable and fruit garden behind it, which gets a lot of sun and has a greenhouse and garden studio. The liquidambar is one of the largest in the city and has spectacular autumn foliage.

“During lockdown, the house has been home to four of us. Our daughter Sophie and son-in-law Paul live with us when not touring in their camper van. They write a food blog called Vegan on Board and we get to try out all their recipes here at home before they are published, so the kitchen is very well used. Sue works part-time as an environmental policy adviser on European programmes, and I’m retired. Part of the spec for the house was separate studies for Sue and me, so we anticipated the working at home trend by some 15 years.

“The local area is a mix of residential and university buildings. We are opposite Churchill College and back onto the Department of Applied Maths and Theoretical Physics, so there is a lot of interesting architecture in the vicinity.

“We have another project left in us. As an engineer I’m accustomed to creating things and then moving on to the next project. We have a strong commitment to the natural environment and although we have done a lot in our garden to support wildlife (newts, lizards, dragonflies, damselflies, butterflies, moths, bees and birds all live in the garden) we would now like to do this on a much larger scale, so we are looking for somewhere with space and existing wildlife that we can further develop. We are flexible about the house we buy, as long as we have the freedom to mould it to meet the objectives that we set out with this project.

“We hope that whoever buys the house will be sympathetic to the way in which it has been developed and value the sense of being in a country environment while living in a city.”