Projects> Emerald> Architects comments
This house will help show how living sustainably in Emerald can be done easily, without much extra effort. You can have a lot less impact on the environment without extra cost and without your house being unusual and demanding to live in. In fact, the house will be more pleasant to live in and less costly to own over a few years. At the same time it will use less energy, thereby reducing 'greenhouse' gas emissions, use less water and be healthier to live in.
It will also be a friendlier house in the sense that it will allow you to see and speak to people in the street – but keep your privacy if you want to. It will encourage use of the street for views and for walking. These sorts of casual interactions, as planners like to call them, mean that sustainable housing has the potential to provide stronger and safer neighbourhoods.
It is often forgotten that sustainability is not just about land, energy, water, resources and waste. It is also about people and communities. An important point is that sustainable houses don’t make you use less energy or water and so on, they just make it very easy.
Concerns like access for people with disabilities, comfort, livability, improving people's lives, being safe and secure, the look of a house and garden and so on, are all sustainability issues. The emphasis on technology has often put people off the idea of living in a sustainable home.
The Emerald house will have four bedrooms including a master bedroom with its own ensuite and walk-in robe. It will also have a sitting area and a kitchenette, allowing it to be semi-self contained. It might be a 'parents retreat', but it mostly provides some flexibility in the use of the house. Emerald is unusual, with a partly temporary population of workers. It may be that a small family can share the house, using rental to help pay for the house.
The house also has some clever design features that allow spaces for a range of activities to be provided without the expense of a bigger floor area. Uses for spaces can be overlapped. For example, in the latest proposals a wider hallway can be used for study or as a library. Childrens' bedrooms can open out to the hall to make a play area but be closed off for privacy. Another example is the car port area that can become a covered patio in the central courtyard.
The house design is based around courtyards, one large central one and a smaller one between bedroom wings. There are also small private courtyards off bathrooms. These provide cool, shaded, private 'oases' and help generate a pleasant micro-climate around and in the house. This is an important strategy in Emerald's climate.
The general approach of the house design is 20% of the effort gives 80% of the result. This means doing fairly simple things provide big reductions in environmental impacts. These might be called the 'low hanging fruit'.
Avoiding the need for heating and cooling is one of these. After extensive research, the Australian Greenhouse Office has found that shading, insulation and ventilation are the most important factors in making a house comfortable in the more northern parts of Australia.
The house uses the mass of its slab, insulation and roof overhangs to passively control the inside temperature. The right width of eaves allows the sun in, to a reasonable extent, in winter and keeps it out in summer. The slab's mass can be used to even out temperature variation over a day and over the seasons. Natural ventilation is also important, especially at night, and at cooler times of the day. Ceiling fans and ventilation of hot air from the rooms, using roof-mounted ventilators, adds further to comfort.
The biggest area of energy consumption and green house gas emissions in Queensland is hot water. It accounts for over 30% (50% in some areas) of household energy use. Therefore, the use of a solar hot water system will greatly reduce energy use. Using a good instantaneous gas system will also reduce energy use because only the needed amount of water is heated. It will greatly reduce 'greenhouse' gas emissions.
The use a daylight and energy-efficient lighting and appliances will help reduce energy use by a smaller amount.
Water is a big issue in Emerald, as it is everywhere. Household water consumption in Emerald is very high, more than twice that of a typical Queensland house. This is expensive for the local government but, most importantly, it may restrict the growth of the town and therefore, the economy.
Most water consumed by households in Emerald is used for maintaining lawns and gardens and for washing vehicles. This accounts for about 70% of the water supply. In Queensland this figure is between 30% and 50%. Residents in Emerald use a lot of water on the garden because this is a semi-arid area.
In Emerald, the collection and storage of roof water for watering gardens and lawns and washing cars will greatly reduce the amount of water used as well as reducing costs. It avoids the expense and complexity of making roof water suitable for drinking (to local authority standards) and installing duel plumbing systems. The sustainable house will provide a very simple solution of a series of tanks for seepage or trickle irrigation of particular areas and a large main storage for backup. A portable pressure pump can be connected for extra pressure for car washing.
The use of water-efficient taps and shower heads, very low flush toilet (2/4L) and water-efficient appliances will further reduce water use.
Careful plantings, using mostly local species that require less water, will help provide cool, moister areas, especially in the courtyards, and improve the soil moisture balance. They will also provide good shading for the house.
Another important issue is the use of less materials. There are two simple strategies for this: the first is to build a house that is as small as possible for what must be accommodated, but still have it flexible in use, balance individuals' needs (like privacy, family interaction, and so on) and provide all the functions people need. The overlapping of spaces and good design of rooms, etc., as mentioned above, will ensure that the house is a good fit and will in fact enhance its livability.
The second strategy, related to the first, is to minimise waste of materials. A significant amount of material is wasted through on-site cutting. The house uses a simple geometry of standard dimensions so that most can be made out of standard-length materials. This also facilitates pre-cutting or prefabrication of elements like wall frames, etc., which is more material efficient.
Waste generated by people living in the house will consist of sewage, grey water (from laundry, kitchen and bathrooms), organic materials like food scraps and garden waste, and dry solid wastes like paper, cardboard, plastics and metals.
It will be very difficult to deal with sewage on site given the location, the size of the site and the expectations of people who will most likely live there. The site is sewered. The water-efficient toilets and other fittings will reduce the volume load on that system.
An option worth exploring is on-site recycling of grey water from the house. This will require a treatment system to meet health standards, requiring increased energy consumption. Grey water recycling also requires duel plumbing to the toilet and any other fixtures that might be able to make use of the lower quality water.
Recycled grey water can be used to water gardens. It does have a high nutrient content, however, which would increase the nutrient input to the site. Composting organic waste would also increase the amount of nutrients going into the site. This increase in nutrient load could be a problem because the soils are generally of 'low nutrient status' and easily contaminated. This can be avoided if there is a substantial area of plants, such as a vegetable patch, that can quickly take up the excess nutrients. Such plantings require good maintenance.
Grey water recycling will increase construction cost and energy cost for a house of this type. The potential reduction in water use is not large compared to that from simply using rainwater tanks as previously discussed.
This sustainable house project provides an opportunity for the Council to review its waste recycling program. Generally, householders are willing to sort dry waste and facilitate recycling if it is reasonably easy.
It may be possible to explore options with private companies, as recycling is feasible for them if most sorting is done before collection and if volumes are sufficient. The sustainable house may be a catalyst by showing how dry waste can be sorted and easily recycled, but there will be 'start-up' costs, but those costs would reduce as the scale of the recycling system increases.
The house site is somewhat unusual in that it lies between two streets. To its west is a large, higher speed, road that does not provide access to the site. There is a large, 20 metre-wide buffer between the road and the house site. So far, making use of the wide buffer as a pleasant, shaded public space for walking and playing has been explored. The 'front' street, which provides access to the house, is socially important. Being able to see and speak to neighbours as they walk by: to be encouraged to walk around the streets safely are all important to sustainability. These are very effective methods of maintaining security. They can all be facilitated by good house design, good landscape design of front yards and good landscape design of streets. A high level of street tree plantings is an important part of this in Emerald where walking around the streets can be uncomfortable in the heat.
If you wish to discuss the above, contact Scott Riley of the Emerald Shire Council or Jim Gall of Gall & Medek Architects.
Last updated April 2006
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