Green giants: Clever design needn't take a back seat when it comes to eco-friendly living

The Home, Co Leitrim, Ireland

This house in Cloone is constantly evolving. Designed by the architect Dominic Stevens and his wife, Mari-Aymone Djeribi, and built using local materials and affordable building methods, it is an unpretentious building that can adapt to their family's needs.

To exploit the natural benefits of the site, the couple began living there in tents with a makeshift outdoor kitchen, giving them the opportunity to observe sun and wind patterns, views and routes across the site. Forty-four days later they had constructed two weatherproof timber boxes – the backbones of the house – into which they moved first the kitchen and then slowly themselves. A straw-bale extension was then added to the north side of the boxes, linking them. Stevens and Djeribi say as their lives continue to alter, so too will their 200-square-metre home.

The two horizontal timber boxes, built at right angles to one another, are divided into simple rooms. Prefabricated on site in the couple's polytunnel workshop, the frames were inspired by the cheap, easily constructed housing pioneered by Walter Segal in Britain in the 1960s and 1970s. Their southern façades are almost entirely glazed. The exterior cladding is Sitka spruce, usually used as pallet wood; at the end of its lifespan of seven to 10 years, the spruce will be burnt in the house's stove and the building fitted with a fresh skin.

The L-shaped straw-bale structure that connects the two timber boxes has no official function, providing an ambiguous place to loiter undisturbed in the shelter of its thick, earthy walls. The roof was erected on concrete, load-bearing walls before the straw bales arrived, eliminating the need for a temporary shelter to keep the bales dry during construction. The bales act as non-structural screen walls strapped to the concrete blocks at intervals. They have been rendered inside and out with a thick lime plaster that gives the building a warm, homely feel. Inside, the floors follow the gradient of the ground, combining with the thick, irregular walls to create the ambience of an excavated cave.

The two different structures create a very energy-efficient building. In the summer, large openings on the west and east elevations admit breezes to cool the house. In winter, the extensive south-facing glazing admits sunlight that heats the north side of the building. Thick insulation in the walls of the timber structure and roof guards against heat loss; additional warmth is supplied by a wood-burning stove.

The couple have planted trees along existing hedgerows; they will coppice them (periodically cut them down to ground level and harvest the regenerating branches) and become self-sufficient in fuel within 10 years. They are also farming four acres of land around the house, raising chickens, ducks and goats for eggs, meat and milk. They grow vegetables and fruit, swapping what they do not consume for other goods with their neighbours.

Until recently, self-sufficiency and a strong community network would have been the norm in Ireland. Building a home was a tradition that called on local people to lend a hand. Through their home and lifestyle, Stevens and Djeribi follow these traditions, relying not only on local and renewable resources but also on the interdependence that brings communities together. The Home looks completely different from the hundreds of developer-built houses currently spoiling the Irish countryside. Designed as a home for life, not as a commodity to be bought and sold, it is a reminder that lessons from the past could hold the key to the future.

Focus House, London

An unashamedly modern building, Focus House uses progressive materials to create an energy-efficient family home. Frustrated with living in a high-maintenance and inflexible Victorian end-of-terrace house, the client commissioned Bere Architects to create an economical, easy-to-maintain and entirely separate home on the adjacent triangular plot. The resulting new property is a daring metallic building that uses its site to the maximum but minimises the occupants' demands on the earth's resources.

The house is constructed from stacked metal-clad blocks punctuated with sizeable glazed areas. This cascading box arrangement maximises light while neatly demarcating the internal spaces. The west elevation, which looks out on to the street, is a mere 2.8 metres wide and politely slots in next to its Victorian neighbour, but at the rear the building spreads out, reaching a width of 7 metres. On the ground floor an open-plan living, kitchen and dining area opens with sliding doors on to the garden. A short flight of stairs leads to the first floor, comprising two children's bedrooms, a bathroom and a study, which juts out dramatically over the front entrance. The second floor (only just visible from the front) has a master bedroom and bathroom with commanding views.

The basic building material is cross-laminated timber slabs that look like giant lengths of plywood. Strips of Austrian spruce are glued crosswise on top of one another to a thickness of 200mm using a solvent- and formaldehyde-free adhesive, producing incredibly strong panels that can span larger distances than conventional timber. Used for wall, floor and roof slabs, the panels were prefabricated in Austria with window and door openings factory cut, enabling the building to be constructed and fully fitted out in just six months.

The architects have estimated that during its lifetime the timber frame will have removed 42.37 tons of carbon dioxide from the atmosphere, where an ordinary Portland cement structure would add 32.42 tons of carbon dioxide to the atmosphere through the burning of fossil fuels during its manufacture. Transporting the wood by lorry from Austria caused 2.97 tons of carbon dioxide to be emitted, but the statistics are still impressive.

The design of the Focus House draws on many PassivHaus principles. As well as being extensively insulated, the house is airtight thanks to meticulous detailing and high-quality Scandinavian windows that are double-glazed and timber-framed. A heat recovery system channels fresh air into the building while helping to regulate the internal temperature and minimising the need for additional heating and cooling. Solar thermal panels on the south elevation generate on average 50-60 per cent of the house's hot water requirements, varying from 100 per cent in the peak summer months to 5 per cent in the depths of winter.

Despite its radical appearance, Focus House was submitted for planning permission with letters of support from neighbours, and met with no resistance from planning officers. It demonstrates how modern techniques can be used to create visually innovative buildings that use minimal energy both in construction and occupation. High-density urban centres are being seen as crucial, since they preserve precious green countryside and cut down on the distances people and goods have to travel. Such an inventive project, exploiting every last awkward scrap of redundant urban land to create spacious dwellings, will help make this a reality.

Rowe Lane House, London

Nestling down a small lane in the heart of Hackney is a timber house that challenges prevailing attitudes about how urban buildings should be constructed. The Rowe Lane House explores new methods of prefabrication. Built in just 16 weeks, it not only promotes a new architectural aesthetic but also provides a model for environmentally friendly residential projects that could be applied more broadly to help meet Britain's spiralling housing needs.

Designed by Marcus Lee of Flacq Architects for himself and his young family, the Rowe Lane House aimed to create a timber system that would ensure efficient, straightforward construction, as well as flexibility once complete. Working closely with the design consulting firm Arup, Flacq created a bespoke, prefabricated, modular, timber-frame kit. The structure has been developed with no internal load-bearing walls, allowing Lee to carve up the interior spaces with partition walls that can be reconfigured as the demands of his family evolve.

The main frame is constructed from glulam (glue-laminated) beams, comprising several layers of timber bonded to produce beams in a variety of shapes that are stronger than solid wood and able to span greater lengths. Because the frame is exposed both inside and outside the building, Flacq chose glulam made from Siberian larch, a highly durable species, which is grown in sustainably managed forests. The glulam elements are joined together by specially developed stainless-steel connections that are entirely hidden from view. The frame sits on a foundation made of strips of concrete set in 3-metre deep trenches, resting on the earth's gravel strata – this depth provides sufficient weight to anchor the lightweight house without disrupting the foundations of the adjacent property.

The walls and roof are lined with flax insulation – a natural, renewable and non-toxic product – overlaid with Pavatherm insulating fibreboards, a German product with no glue or wood preservatives. Externally the building is clad in cedar.

The house is arranged so that the ground floor is almost entirely open plan, with large glazed areas visually connecting the interiors to the courtyard in front and the garden behind, and glass doors at either end of the property opening in the summer to cross-ventilate the space. Over the kitchen, the roof is fully glazed, drawing natural light into the ground-floor areas. In the summer this glazing is partially shaded by trees: in winter, when the trees lose their leaves, the sun helps heat the home.

Throughout, walls and ceilings are finished with lime plaster and porous paints, non-toxic materials that allow the timber walls to breathe, preventing damp and rot. The floors in the living areas are laid with slate, which is hardwearing and natural. All the floors have underfloor heating, fuelled by a wood-pellet boiler. Solar hot-water panels on the south-west facing roof are used to heat water. As Lee's children grow, he can alter internal walls without additional materials or disruptive work, extending the life of the building. If the house is ever abandoned it can be dismantled and rebuilt or recycled.

It is rare to see timber buildings in an urban context, yet this house slips effortlessly into its surroundings. As the cedar cladding ages it will become even more at one with its garden setting. This project clearly demonstrates the advantages of timber as an economical and sustainable construction material.

'The Sustainable Home' (Merrell, £19.95)