Eco-homes – niche experiment or large scale solution?

As energy costs continue to be a source of financial pain for many and worries about climate change grow, energy efficiency has become an important selling point for new homes. Recent years have seen many home builders taking steps to appeal to both the environmental concerns and the wallets of potential buyers, including use of additional recycled insulation and higher quality glazing. This has had undeniable benefits, with new build properties using an average of 60% less energy than older counterparts.

While these steps towards energy efficiency are to be welcomed, some housing developments are demonstrating the benefits of design that has efficiency at its core, rather than treating it as something to be added on. The Lodestar for this type of development is the Hockerton Housing Project in Nottinghamshire. The homes here are built in an “earth-sheltered” style, with soil covering the rear slope of the house and providing exceptional insulation. Combined with the way the homes are oriented to absorb as much solar energy as possible throughout the year, this removes the need for a central heating system, with the building maintaining a constant temperature of 18-22 degrees C all year round. The icing on the cake is the community approach to electricity generation, with the development utilising its own onsite wind turbines and solar panels. This combination of excellent efficiency and self-generation means that energy costs for these homes are around £100 a year, a welcome idea for many.

The catch however is that you almost certainly won’t be able to actually buy one of these homes, although they do come up occasionally, as Hockerton is a community of five houses. Is it possible then to build homes to this incredibly sustainable and cheap to run standard at scale? The answer appears to be “not quite, but nearly”. While the “earth sheltered” concept will doubtless appeal to many, it remains at present the preserve of small-scale niche developments and individual “grand designs”. The central concept of making efficiency a core feature from the beginning of the design process has been popular for some time, with one of the earliest large scale examples being BedZED, in Sutton, South London. This mixed-use development featuring 100 homes was built around high levels of insulation, airtightness, and thermal mass. These homes also make maximum use of the sun’s warmth for space heating. The homes were all built to the Passivhaus standard, achieving extremely high levels of energy efficiency. This German building standard is met only by buildings which are so well constructed, insulated and ventilated that they retain heat from the sun and the activities of their occupants, requiring very little additional heating or cooling.

While BedZED has flaws as an environmental project, with the renewable power fuelled by biomass pellets imported from Spain and its location more or less necessitating car use, it was a pioneer of efficient construction. The technology used in it is now no longer the preserve of expensive lifestyle based developments, becoming more common among affordable and social housing.

When the Agar Road estate in the London Borough of Camden is complete, it will feature 493 homes, 80% of which will be to Passivhaus standard, the largest development of its kind in the UK. Similar projects can be seen around the country, with the Greenhaus development – a highly sustainable development of 96 homes, built on Chapel Street in Salford. Also built to Passivhaus standards, the 96 affordable properties include triple glazed windows, the latest insulation technology, improved ventilation and excellent airtightness pumps.

While it seems unlikely then that any mass developments will achieve the purity of energy efficiency that has been obtained by projects like Hockerton, they provide valuable lessons for architects and designers and an important proving ground for energy efficient technology. Although your next home is unlikely to be earth sheltered, the advances in technology and changes in mindset pioneered by small scale eco-developments mean it may very well be a Passivhaus, and that’s a big step in the right direction.