Buildings
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Buildings
Earthsong houses are built to last! Well-designed for site and climate, using sturdy, simple materials, these houses are great to live in and will age gracefully. The strong, simple shapes and materials used throughout allow variations and individuality within an overall coherence. Rammed earth and natural timber give the houses a solid and timeless feel, with plenty of sun warming the coloured concrete floors for passive solar design. The character and variability of natural materials enlivens the interiors.
Residents live in healthy, warm, low-allergy houses, and people with severe chemical sensitivities report much better health since living at Earthsong. Houses have very low running costs, and are naturally much warmer in winter and cooler in summer than the lightweight housing that is standard in New Zealand. Solar water heaters, rainwater collection, non-toxic materials, natural oils and paints all add up to low-energy and healthy houses.
Design
Earthsong members were intensively involved in the design of our neighbourhood, in collaboration with our architect Bill Algie. Before the design process commenced, members developed a comprehensive Design Brief, setting out our goals for style, materials, accommodation and layout. While this continued to evolve and some details changed over the design and construction period, the Design Brief continually proved its worth and the finished neighbourhood fulfills those articulated expectations with distinction!
When considering eco-building, small really is beautiful. Even a house designed to the highest principles of sustainability still consumes enormous resources in its construction, and an important principle of eco-building that is often forgotten is "only build as much as you need". At Earthsong we have built both self-contained dwellings and extensive common facilities. The compact but well-designed houses include open plan living, dining and kitchen areas, bedrooms, bathroom and lofts, allowing a range of internal uses. Building small homes freed up capital to be pooled to build a large, beautiful common house that we all share, with large spaces for entertaining and meetings, a guest room, children's play areas and shared laundry, thus reducing the need to accommodate these within individual homes. Collectively we have available to us a much wider range of facilities than any one household could provide for themselves.
A key aspect of the design brief was that all buildings be oriented and designed for energy efficiency and natural climate control using passive solar design. Passive solar design takes advantage of the desirable aspects of a location and avoids the undesirable aspects by designing the building correctly for the climate and latitude of the particular site. In the Auckland climate, allowing the sun inside in winter is desirable, but in summer is less welcome. Winter winds are best avoided, while a light breeze through the house in summer can be a relief from the muggy heat. Achieving this through orientation and design means that houses are naturally comfortable while using far less energy. Read our introduction to passive solar design.
Monitoring results show that the thermal performance and water and energy efficiency of Earthsong houses is significantly better than for standard construction. Home Energy Rating Scheme (HERS) assessments in 2008 gave Earthsong homes an '8' rating, the highest in New Zealand at that time. The houses achieved a Green Home Scheme "Excellent" rating from the Building Research Association of NZ in 2001.
Materials
Non-toxic, low energy materials from sustainable sources reduce the environmental cost of the buildings, and provide a healthy comfortable living environment. When choosing building materials, Earthsong members weighed up many aspects of each product and chose those that best fitted the following criteria:
- Renewable or sustainable source, with low environmental impact in its extraction
- Low embodied energy - the energy required to extract, manufacture and transport the material to site
- Low toxicity to manufacturers, builders and occupiers
- Reusable or recyclable at the end of the building life
- Durability
- Cost and availability
Using these criteria, most building materials used at Earthsong are simple, locally-sourced materials used close to their natural state. Solid timber was used in preference to re-constituted timber products (e.g. particle board and MDF) to avoid toxic glues, and naturally-durable timber has been used instead of treated timber.
Concrete, though with a relatively high embodied energy, is the perfect durable material for ground level floor slabs and post footings, avoiding any need for in-ground (and thus treated) timber, and providing thermal mass for the houses. A concrete mid-floor between separate upstairs and downstairs apartments gives excellent acoustic and fire separation, and allowed rammed earth to be used for the upper apartments.
350m and 400mm thick rammed earth walls form the core of each house, providing great strength and solidity, thermal mass, and excellent acoustic and fire separation between houses.
Timber species used at Earthsong have varied over the 6 years of construction as availability and building codes changed, although macrocarpa has remained our timber of choice for all joinery. All timber was sourced from around the North Island. Macrocarpa, lawsons cypress and western red cedar have all been used for the cladding. Pine, douglas fir or heart lawsons cypress were used for framing, and macrocarpa, poplar and lawsons cypress line some areas of the interiors. Internally all the timber is finished with tung oil (tung tree oil) and citrus thinners, giving the houses a beautiful and healthy smell. Externally we have used CD50, a copper quinolinate oil that, while unfriendly in high concentrations to aquatic organisms, was the best option we could find that is otherwise relatively benign but still provided reasonable protection to the timber.
One of the unusual building materials we used was "mill flooring" for the terrace house upper floors. Manufactured off site, these used short lengths of otherwise waste macrocarpa timber glued together with non-toxic allopathic glue to create 300mm wide x 50mm thick solid timber boards. Joined together by tongues and grooves, they span heavy timber beams to form both the upstairs floor and the ceiling to the downstairs. Timber that would otherwise be considered too short to be useful has been turned into a strong and beautiful floor/ceiling.
It is important to us that our houses "breathe", i.e. that any moisture in the air can move into and through the fabric of the house, rather than condense on cold surfaces or be trapped by plastic paint. This gives a much healthier and drier indoor environment and avoids mould or accumulation of toxins from furnishings or chemical products. The timber framed side rooms and upstairs rooms are lined with gibralter (plaster) board and finished with eco-paints, and with the timber board and batten cladding, give fully breatheable walls that also avoid any "leaky house" problems of trapped moisture in the framing.
Building materials that are considered toxic either to inhabitants or the environment were avoided, including CCA-treated ('tanalised') timber, VOC paints and most glues and sealants. Polypropylene downpipes were used in preference to PVC, though standard PVC waste pipes, electrical cables and conduits were still used due to the high cost of alternatives.
Light-weight corrugated zincalume roofs fit the vernacular aesthetic of New Zealand homes, and are excellent for collecting rainwater. A problem that has become apparent however, due to materials incompatibility, is rapid corrosion where copper-rich water from the solar water heaters discharges onto the metal roof, requiring regular maintenance and painting of the roof under the panels. When incorporating a range of non-standard construction techniques there will always be some areas where lessons are learnt through overlooking some of the issues!
Our philosophy favours choosing the right materials for the situation and honestly expressing those materials, not covering them up or pretending they are something else. Thus the earth walls are as naked as the day the formwork came off, with all the patterns and variability of a 'living' wall. The structure is expressed in the concrete bond beam visible around the tops of the earth walls, and the oiled grain of the timbers is much more beautiful than painted timber could ever be.
The use of simple robust materials meant that the skills of the builders were visible and valued, and the construction methods encouraged the builders to refine their skills and take pride in their work. This proved to be much more satisfying than the standard high-volume low-skill technology that relies on fossil energy use and manufactured products. There is skill and time required to make beautiful joins in solid timber, but the results are timeless, beautiful and don't require paints or filler to cover up the joins and give a seamless result.
House Types
Our aim was to encourage a diverse community, with singles, families, owners and renters, old and young, able-bodied and less mobile, so we've built a range of dwelling types and sizes from 1-bedroom studios to 4 bedroom houses. House areas range from 56 m2 to 122 m2. All ground floor entries have low thresholds and all paths within Earthsong have a gentle gradient for easy accessibility.
The two-storey terrace houses come with 2, 3 or 4 bedrooms. The main house cube has open plan living, dining and kitchen downstairs opening onto private terraces and garden areas, and two bedrooms, bathroom and loft area upstairs. The larger houses have another 1 or 2 extra bedrooms at ground level, often used as studies or to extend the living area.
Seven ground floor 1 or 2-bedroom apartments are ideal for those older or less mobile, although they are also popular with the able-bodied. The single-level homes have open plan living, dining and kitchen areas, bathrooms with level-entry showers, and 1 or 2 separate bedrooms. One home also has an extra small bedroom or study. Like the terrace houses, each ground-floor apartment opens onto a private garden area. The apartments are generally located closer to the carparks and common house and the gentle gradients on the paths make access to all parts of the neighbourhood easy.
Accessed from a shared internal stairway and open-air landing, the 1 and 2-bedroom upstairs apartments are light and airy. The high vaulted ceilings give an open and spacious feel to the open plan living, dining and kitchen areas. A large loft area to one side serves as the bedroom of the smaller unit, while for the larger units with 2 separate bedrooms it essentially becomes a third bedroom or study. Living areas open onto a small sunny deck. Though there is no area of garden specifically for these apartments, there are plenty of common garden areas nearby to satisfy keen gardeners.
Common House
At the heart of the neighbourhood is the common house, the much-loved community building owned jointly by all the householders as an extension of their homes. The 340 m2 building provides shared spaces including the large dining/meeting hall, sitting room, large kitchen, childrens' and teens' rooms, guest room, smaller quiet room and shared laundry.
The large dining room or main hall has a high cathedral ceiling with spaced timber battens over acoustic insulation, giving a very comfortable acoustic environment even when 60 people sit down to dinner. Large doors and windows line the north wall letting the sun flood onto the coloured concrete floor. For cold winter nights, the efficient wood fire is a favourite place for residents to gather before dinner. The adjoining kitchen is roomy and efficient, and though it maintains a welcoming domestic feel with timber benchtops and cupboards, it is an easy place for 4 or 5 cooks to work together turning out meals for up to 100 people.
