Building Design

Pre-design strategies

The owner, John Smith, has always been interested in an 'ecologically-sustainable' design. He had conducted his own research to find out the best ways to build an 'ecologically-sustainable' house for his family. With this background knowledge he approached architect John Maitland who specialises in energy-efficient design.

Design strategies

The design process started with several site visits by the owners and architect to establish the location of the house. The design was formulated by the architect in consultation with the owner. The owner requested that used building materials, which had been collected over the years, as well as rammed earth walls, be used in the building. The architect was involved until the building process began.

Post-design and construction strategies

The owner was involved in the construction of the house which occupied 2 tradesmen and 2 labourers for 6 months. Since the construction was completed, the owner has also been improving the house performance, for example by making a 'double-glazing effect' on the north-facing windows (by installing a plastic shrink-wrap), adding fly screens, ponds, and a sliding insulated door (polycarbonate) in the hallway to the back entry. A trombe wall with black CaCl2 panels which change phase at 28°C facing north was also installed at the kitchen end, which was monitored by the University of South Australia. A tracking set of 12 BP Saturn photovoltaic panels have also been installed and the owners keep track of how much electricity is produced through a monitoring device. In 2000 internal comfort (temperature and humidity) was measured / monitored in half-hour intervals by researchers from Adelaide University.

Since its completion the building is also open for general public (by appointment) who are interested in building an environmentally-friendly home for themselves. Schools and young couples are amongst the people who often visit the house though tours for seniors have also been popular.

Detail of kitchen entrance showing trombe wall

Design strategies

This section addresses strategies to reduce building energy consumption and adverse environmental, social and cultural impacts.

Energy and Greenhouse gas emissions

1. Operational Energy

a. Passive and Active Systems

i. Lighting: natural light during the day, compact fluorescent (16W, 24W, 26W and 36W) at night. Average lighting load is 2W/sqm in the living / dining block and 2.6W/sqm in the sleeping / bathroom block.
ii. Heating: Passive solar heat gain and a slow combustion heater (9.1kW, 71% efficiency) in the living space, with home grown wood. A radiator is sometimes used in the study room.
iii. Cooling: no mechanical cooling equipment
iv. Ventilation: Cross / natural ventilation. No fans installed.
v. Hot water: 6sqm solar collector with 380 litre water tank, connected to the slow combustion heater and an instant gas booster for the kitchen.
vi. Appliances and equipment: 378W dishwasher, 640W refrigerator, 237W washing machine (no electric clothes dryer), and a gas stove / oven.
vii. Power generation: 1kW photoivoltaic panels, connected to the grid and to the house. The house is also connected to the electricity grid.
viii. Energy source: gas (LPG) for cooking and backup for water heating, electricity for lights and appliances, wood for space heating.

Interior of Living Room

b. Comfort issues

i. Thermal comfort: Summer comfort is maintained through natural ventilation (opening the doors / windows to let warm air out and bring cool air in) and ceiling fans, some external and internal shading, and thermal mass effect. Winter comfort is maintained through passive solar heating and space heater at night. In other seasons the building is comfortable without any further 'efforts'. Winds are reduced by earth dunes and vegetation.
ii. Visual comfort: glare is not a problem aithough internal blinds are also installed (rarely used). The views to the east, north and west are quite spectacular.

2. Embodied energy and life-cycle energy

Building materials were selected for their environmental, thermal, aesthetic as well as economical performance. External walls are constructed of stabilised rammed earth (400mm thick for the east and west walls, 200mm thick for the north and south walls), and 90 mm concrete blocks for the south wall of the sleeping block and east wall of the kitchen, all of which are insulated with R2.5 fibreglass insulation on the outside and clad with corrugated metal cladding (colorbond). Stabilised rammed earth was chosen by the owner as it provides a compromise between mud brick, a low embodied energy material but has a natural look, and concrete, a more modern looking material but has a much higher embodied energy and a 'cold' look. A 1m bluestone wall snakes through the house from east to west which adds thermal mass and separates the two levels. The bluestone coloured earth came from John Smith's boyhood home which had been sold 25 years ago but was being demolished in 1998.

The 100mm polished concrete floors provide thermal mass and do not need tiles or other finishes. The north wall and roof structures are of used Oregon timber (except for the roof purlins) which had been collected by the owner for a number of years. The door and window frames, however, are of new Western Red Cedar. Aluminium frames were consciously avoided because of their high embodied energy and conductivity. R-4 roof insulation was installed above the plasterboard ceiling. First, wool insulation and insulation made of recycled paper were considered, but they could not be applied due to bushfire restrictions. Fibreglass insulation and reflective foil was finally used.

Detail of building exterior showing corrugated metal cladding

Environmental

1. Water and waste management

a. Water collection: Sole water source is rain, collected in 2 @ 27,000 litre tanks. Water from a nearby dam may be used in case of fires.
b. Grey water and black water: liquid wastes from kitchen and bathroom sinks as well as solid wastes from the toilet are collected in an earthworm run Dowmus Biolytic Filter (3000 litre). Organic kitchen and garden scraps and some cardboard are also disposed of this way. The liquid wastes are discharged into a 37m horizontal trench set underground according to the Health Department regulations.
c. Appliances: dual flush toilet (6/3 flush currently, but looking to test 3/2 flush in 2001), low water use dishwasher and washing machine.
d. Landscaping: native vegetation (plants and grass), two ponds.

2. Health

a. Air quality: minimum toxic materials used, no mechanical heating / cooling equipment.
b. Building cleaning: Trinature cleaning products (made from citrus rather than petrochemicals) and Ha Ra cloths are used.

3. Biodiversity

a. All of the natural habitat is maintained as much as possible. The rest of the site grazed with Eucalyptus over storey is being revegetated to return the natural habitat that used to be there.

b. Building materials: recycled oregon for roof structures, western red cedar for window / door frames, recycled jarrah for bench top, steps and entry floor.

4. Resources

a. Waste products collected in the Dowmus Biolytic Filter can be used as fertiliser.
b. Waste minimisation: All building materials used are from places not too far from the building site or made on the site; thus the energy and cost for transporting the materials were reduced. Fittings are from recycled elements wherever possible. Waste steel, plastics and cardboard from the building process were recycled via the local council, collected or taken into the waste recyclers.
c. Design for a long building life: Basically, the building is designed and built to be occupied as long as possible.
d. All labour and machinery used were locally sourced.

Detail of corner of house showing Western red cedar window/door frames

Social and cultural

1. Security: The area is quite safe and security is not a main concern. What is more important to the occupants is the openness of the space which enables them to have a feeling as if they were living 'amongst the trees and the birds'.

2. Community: The house is open for general public (by appointment) to learn about the efforts to achieve environmentally -friendly design and landscaping.

3. Cultural identity: The building design is not for a particular ethnic group, rather it is a result of an effort to try to 'sit nicely' within the environment. The colours of the house (green, blue and earth colour) were chosen to reflect the colours of the site. The interior decoration gently reflects Jillian's Aboriginal cultural identity.

Floor plan

Financial

The construction cost of the house can be considered as low to moderate. To reduce construction costs, the materials are finished in a simple way (for example, the concrete floor is only polished and not tiled) and many of the materials are from the owner's 'repository' of recycled materials. The relatively higher capital costs are mostly for the environmental systems (solar collector, photovoltaic panels, water and waste management system). Extra costs were also added to improve the thermal performance of the house, such as to add fly screens, rubber seals around the doors / windows, and plastic shrinkwrap. The latter is to create a double-glazing effect to the glass windows, and it is quite inexpensive.