We all want to live well and enjoy life
Ordinary domestic life wastes finite resources, worsens climate change and pollution and can make enjoying life that bit harder.
The desire to do what ended up happening at Bellis in subtropical Brisbane in 2003 originated in England during the Oil Shocks of the 1970’s. For most Australians, the British experience of an oil-dependent economy without enough oil is quite literally unthinkable. If you are part of the majority of Australians who have no idea about the Arab-Israeli War of October 1973 (aka The October War) and its consequences, check out this link.
Much of our way of life depends on non-renewable fossil fuels, their availability and their cost. Australia is utterly dependent on imported oil for transport and defence and much of that oil comes from potential adversaries. Even the alcohol added to petrol comes from crops that depend on the use of fossil fuels.
Supermarket food depends on industrial food production run on fossil fuels, and while those fuels are plentiful and heavily subsidised by taxpayers, that food can be supplied at low prices. Cheap food production peaked alongside world oil production yet demand for fossil fuels keeps growing and so the price of food and the cost of living are not going anywhere but up.
It’s not just the price of non-renewable fossil fuels we have to concern ourselves with. Phosphorous is also non-renewable. All food producing gardens require inputs of phosphorous, it’s one of the three major nutrients required by crops however they are grown and a phosphorous is an essential element for a healthy human diet.
Phosphorous is mined. Australia imports around 60% of its phosphorous needs and a significant proportion comes from China. Global phosphorous production is finite and production will peak mid-century.
Food security, sustainable population, sustainable energy and resource use, affordable housing, pollution control, and global warming will not go away. Australia will become a conserver society. How will we make the change? In an ordered way by choice, or chaotically when there is no choice left?
Bellis has been adapted to reduce a household’s impact on the natural world: saving domestic water use, reducing sewage and stormwater pollution, conserving nutrients in the soil, generating a surplus of renewable energy whilst sequestering atmospheric carbon dioxide. Bellis helps to reduce peak demand for energy too.
On this water sensitive property, the back garden grows a surplus of fruit, vegetables, herbs and spices. The mostly ornamental front garden grows plants suited to natural rainfall and long-lived stock has been selected to cope with predicted climate change for Brisbane to 2050.
Plants are grown sustainably and special crops are being acclimatised to suit tougher growing conditions. Together the nursery and the seed bank act as a community gene bank for valuable and unusual crops and plants.
In 2003, the retrofit aimed to spend less than a new family four wheel drive car on the sustainability items. The only subsidy has been a rebate from the federal government for installing solar panels.
Michael Mobbs of Sustainable Projects is familiar with domestic sewage systems and he liaised with Brisbane City Council, smoothing the development application. Approval was quickly granted.
Rain Water Harvesting
A 21,000 litre, in-ground concrete rainwater tank was installed. When full, this theoretically provides a three month supply of water for the house, not the garden. Excavating the tank pit generated 37 cubic metres of soil. Aware of the problems of rapidly filling landfill sites this was spread and conditioned on site.
Leaf and mosquito excluding rain heads have been fitted, one atop each downpipe to prevent any leaf litter entering the tank. Each downpipe is fitted with a first flush device. The rainwater tank is gravity filled.
The tank is connected to mains water. A float valve prevents the water level falling below the output pipe. The capacity to collect rainwater is hardly affected but there is little need to worry about completely running out of water. A network of soakaway trenches around the property capture any rainwater tank overflow during very wet weather and any surplus is discharged into the stormwater infiltration well in the front garden.
A sediment and activated carbon filter on the mains supply to the tank remove chemical (chlorine, but not fluorine) and biological pollutants. A ceramic and carbon filter are fitted to the drinking water fountain in the kitchen.
All waste water feeds this system which digests solid waste. Water passes through a sand and gravel filter, enters a holding tank and then passes through an ultraviolet filter for chemical free disinfection and is then ready to flush the toilet or water the garden.
Excess waste water is used to hand water the food garden. Independent wastewater quality testing documented that no contaminants, including chloramines, remain in the wastewater.
The original photovoltaic system (2003-13) comprised six solar panels on the north facing side of the roof. Compared to the new panels, the original ones were very heavy and less efficient.
In 2014 a new system (pictured) comprising of two arrays of ten panels were installed. One array faces east, the other west. The old system supplied, during summer, up to 60% of household daily needs with the balance being purchased as certified renewable energy.
Solar systems supply 220 to 240 volt, 50 Hertz power, the Australian Standard, and plug into the power grid. During the day surplus power is directed into the grid, power is drawn from the grid as needed. At night the house effectively uses the grid as a battery, drawing back some of the surplus power generated during daylight. The new system produces three times as much energy as the house needs. Even on a cloudy winter day the house is more than self-sufficient in electricity.
As an early adopter, it was necessary to have a special contract with the energy supplier. The supplier pays the household (at a good rate) for the excess power Bellis supplies to the grid, a little perk. This evergreen contract ceases if the household changes energy supplier, or the house is sold.
Peak power output corresponds with the most intense period of sunshine, which coincides with Brisbane’s peak energy demand, the time when everone’s air-conditioning is working hardest.
Once the safety, cost and reliability of domestic batteries has been achieved, one will be installed to eliminate the need to draw on renewable power from the grid at night. This would then make a charging point for an electric vehicle a viable option.
The retrofitting budget included buying equipment. The old electric cooker was replaced with gas. The old electric water heater was replaced with an efficient instantaneous gas water heater – there wasn’t enough room on the roof for a solar hot water system plus photovoltaic panels.
The old washing machine died a week after moving here and had to be replaced with a water and energy efficient front loader. The ‘energy star’ and water efficiency ‘A’ ratings are helpful in making the most approriate choice, but the water ratings are not absolute. They compare like with like. For example a four ‘A’ top loader is not nearly as good a water saver as a four ‘A’ front-loader.
Compact fluorescent light globes are long lasting: they were brought here from Sydney.
Originally the plan was to have the rainwater tank under or alongside the house, but Brisbane City Council would not permit installation within ten metres of the sewage system – a hang over from the bad old days of leaky septics. So the tank is at the top of the garden. The resultant plumbing work cost twice as much as the cost of the tank, and more electricity is used for a pump to draw water to the house.
The energy supplier took three months to connect the solar panels to the grid (back in 2003 solar households were a novelty) so Bellis was unable to generate electricity during the first summer after installation.
I learned that it’s critical to use quality gravel suited to a wastewater filtration tank. The installer used cheap gravel that contained iron. This dissolved out, turning the water brown. A rusty deposit stained the toilet bowl and impeded efficient decontamination by the UV filter. The gravel was replaced, the sewage system carefully cleaned and put back into action.
Nick Walford-Smith, an award-winning Gold Coast-based landscape designer created a beautiful landscape plan to work from. The layout slightly changed as a result of inadequate funds to complete certain landscape features, like the summer house planned to sit above the rainwater tank. Instead of a solar pergola, a Screw Pine (Pandanus tectorius) was planted in the centre of the vegetable garden to shade outdoor meetings. The nursery area was found to have sufficient shade from neighbouring trees in summer to function as a propagation area without a constructed shadehouse.
Green Survival, Brisbane-based landscape contractors, installed the land drainage from the tank around the property, the stormwater infiltration well and the gravel-lined front garden path and driveway.
Soil conditioning was based on thorough laboratory testing and specialist advice from the National Measurement Institute, Sydney Environmental Soil & Laboratory and the President of the Australian Society of Soil Science, Queensland, (now Soil Science Australia).
A test crop of silverbeet was grown and laboratory tested for the presence of toxic metals (lead, mercury, cadmium, copper) and other persistent organic pollutants (POPS) that might prevent bioaccumulating crops, like turnip, radish, beetroot and silverbeet, from being eaten. Tests results proved the soil is safe for cropping.
Find out more about the changes faced by Brisbane gardeners in Sister Cities
2005 (edited July 2016)