The UK's Best Green Homes: Part Two

The Low-Carbon Remodel

Details: Remodel, Sussex
Designer: BBM Sustainable Design (01273 480533 bbm-architects.co.uk)

While many a post-war remodel sports a new, contemporary façade, very few can rate their energy efficiency on par with a Code for Sustainable Homes Level 5 new build. The existing brick cavity walls of this 1960s house (Pictured above) have been externally insulated with 140mm of timber fibreboard — so well insulated that the walls now achieve a typical U-value of 0.14W/m²K. Sweet chestnut cladding provides rain-screening at first floor level, while also making an aesthetic impact. The existing roof remains, but 400mm of sheep’s wool insulation, packed inside voids, again minimises heat loss.

The south-facing roof has also gained 4m² of solar thermal panels which, together with a biomass boiler – in place of an old, inefficient oil boiler – provide energy for hot water. The latter also fuels the underfloor heating — which, due to the highly insulated structure and passive solar gain, is rarely required.

Recycling existing materials to reduce waste was imperative to the project. The former maple flooring has been taken up and ingeniously crafted into kitchen units, while the old PVCu windows – replaced with more energy-efficient models – were given away. A rainwater harvesting system completes the sustainable picture, providing non-potable water for flushing the toilets, running appliances and for watering the established garden.

The Pre-War Renovation

Details: 1930s House Renovation, Bristol
Designer: Archipeleco Architects (archipeleco.co.uk) 

The renovation of this detached 1934 home means it now uses just one third of the gas guzzled by other houses of the same size. “The house had 225mm-thick solid brick walls, a timber roof and leaky single-glazed windows — and not a millimetre of insulation to be seen,” says architect-owner Lucy Pedler, who is also Director of The Green Register, an organisation which advocates sustainable building practices.

Solid-wall insulation – 80mm polyisocyanurate insulative board – has been added externally, the roof insulated with a double layer of Rockwool, and cellulose insulation introduced within the floor. All help to significantly reduce U-values from 2.0W/m²K to 0.22W/m²K.

New low-E double-glazed windows also minimise heat loss, while solar thermal panels and an energy-efficient gas condensing boiler reduce energy bills. Inside, clay paints and locally sourced reclaimed materials have been specified, and low-energy lighting, low-flush toilets and aerated showers fitted.

The Sustainable City Self-build

Details: Self-build, Edinburgh
Designer: Konishi Gaffney Architects (0131 258 6950 konishigaffney.com)

Built on the small site of a former mechanic’s garage in Edinburgh, this green 150m2 self-build is proof that sustainable homebuilding is not just the preserve of those with large rural plots. Architects and owners, Kieran Gaffney and Makiko Konishi, have achieved a careful balance between optimising privacy – the new house abuts a road junction on two sides – while maximising the heat and natural light entering the house through glazed openings.

The highly insulated structure – packed with Kingspan Kooltherm – is constructed upon a 200mm concrete slab foundation to minimise the vibrations from passing traffic. Yet, the concrete ground floor also provides thermal mass, absorbing heat and releasing it back into the open plan living space. The east-facing rear features an expanse of sliding doors: “These doors open the house up to early morning sun, starting the heating cycle,” explains Kieran. “In spring, summer and autumn, while the passive solar cycle functions, the building requires no heating. In winter, underfloor heating is proving comfortable and efficient space heating, while top-up heating is provided by a woodburning stove.” A large south-facing glazed corner allows further sunlight to penetrate down the open stairwell to the ground floor below.

The family have utilised locally sourced materials throughout – including cladding produced just 30km away – and specified recycled and recycleable elements. They also salvaged on-site materials: “We used site rubble to make our own hardcore and stone from the existing buildings to build new boundary walls,” Kieran concludes.

Read about a future proofed home, a well-insulated home and a pioneering eco self-build in part one...

More green homes:

• An Energy-efficient Contemporary Self-build
• A Green House in the Garden
• An Eco-friendly Self-build with Sails

Further reading:

• How to Build a Sustainable Home
• How to Build a No-heat Home
• The New Standards, and How to Achieve Them