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Environmentally sustainable design and building is for everyone

In Business and Environment, Environment, Ethical and Eco Agriculture by LivingNowLeave a Comment

As conscious people we all know that everything we do makes a difference to the world around us. This is particularly so when we change the built environment. In the developed world our buildings, services and infrastructure are resource-hungry organisms that seem to have an insatiable appetite. The problems that our built environment create for the natural environment are the result of resource harvesting and waste production in all its forms: solid, liquid and gases.

To make a positive difference to the planet by the way we build is a huge challenge. Turning the resource-hungry tanker of the developed world’s building industry takes time. It is difficult to predict whether the damage we have already caused has gone past the threshold of sustainability for the ecosystems on the planet because the effect can take 50 years to be measurable. However most intelligent people agree that we are now seeing the measurable effect of the damage we have caused as a species.

While there are no simple solutions, every choice we make every day can make a positive difference. Really we need strong leadership from government, industry and big business to make the biggest difference. Environmentally sustainable policy, legislation and pricing will shift human behaviour en masse very quickly.

Clearly we would like a planet that our children and our children’s children can live on, in terms of habitability for humans and in terms of equitable distribution of resources to everyone on the planet.

For years environmentally sustainable design (ESD) was an idea that people liked the sound of, but, when it came to the crunch, very few would put their money where their mouth were. Right now many clients are asking for the real deal and realise ESD building and infrastructure is worth investing in. An environmentally sustainable design home is not about sacrifice but rather about exceptional levels of building occupant comfort, savings in ongoing running and maintenance costs and a user-friendly interface with modern fittings and appliances. Environmentally sustainable design homes are a pleasure to live in. To avoid the tokenism of adding a small water tank or some solar panels to an overly large, resource-and energy-hungry home, we need to work to a set of priorities:

1) Location, location, location
2) Designing for thermal efficiency
3) Select materials for lowest environmental impact
4) Rainwater harvesting for 100% domestic supply
5) Solar hot water and heating
6) Waste water harvesting for 100% reuse
7) Solar power generation when everything else works

1) Location

Live within a sensible transport network, preferably walking distance to public transport, work, schools and services. Domestic consumption of energy, resources and water is tiny compared to transport, industry and agriculture. So a large part of how we live and build our homes needs to be focused on local sustainable systems, materials and labour wherever possible. Everything is not always as it seems. For example if you build, for a ‘sustainable image’, a new house in the bushy hinterland with huge timbers and a wood fire and commute 50 kilometres to work in a car every day you will have a much bigger environmental footprint than someone who lives modestly in an existing small inner urban flat and catches public transport everywhere. Living simply is good, but technology is also good, enabling telecommuting and more resource-efficient systems and products.

2) Designing for thermal efficiency

Thermal efficiency often called ‘passive solar design’ is all about your home being an efficient shelter from the elements, working with the natural environment. For instance in Melbourne it is possible to design and build a home that needs no cooling or heating. The correct combination of orientation, insulation, glass and internal thermal mass will give you a home that is comfortable all year round and a pleasure to live in. A well-designed passive solar home will have a natural temperature range of 18 to 26 degrees without heating or cooling. This range is well within human comfort levels, when we wear appropriate clothing for the seasons. Such a home would be rated better than 6 stars on the SEAV home energy rating system.

An incredible amount of energy is used all over the world in air-conditioned buildings keeping building temperatures between 20 and 22 degrees Celsius. Often in air-conditioned buildings both the heating and cooling will be activated within the same day! The reason for these huge internal temperature swings is usually bad design.

An important part of passive solar design is the connection with the earth below. Because the temperature of the sub soil is constant all year, in winter, the soil below a slab is a source of base temperature supplemented by direct solar gain. In summer the soil below the slab becomes a source of cold, drawing heat into the ground below. Dense products such as concrete and masonry, which are not good at insulation, are good for storing heat within an insulated building, creating ‘thermal mass’. Good internal thermal mass moderates the internal temperature all year round.

Thermal efficiency is a pretty simple principle. Heat travels to the surface or air that is at a lower temperature. The resistivity or R value (insulating ability) of the material between will moderate that flow of heat. Double-glazing does that with ambient air temperature. High-energy direct sunlight will penetrate through glass (even double glass) and turn to low energy heat inside the building. The more square to the glass the rays are, the more effective the penetration – this is why in the Southern Hemisphere, north-facing glazing works for positive heat gain in winter and why west-facing glass turns your home into an oven in summer. North-facing vertical glass with correctly proportioned eaves will allow full sun penetration in winter and full shade to the glass in summer. Well-sealed windows and doors keep the heat inside in winter and outside in summer. Good cross flow ventilation capacity helps to air and cool your home naturally. In winter keep your home well sealed generally and then open windows to ventilate at the warmest time in the afternoon. In summer seal during the day and ventilate in the coolest times at night.

3) Select materials for lowest environmental impact

Smaller homes use less material. Design space efficiently for what you really need to live in. Consider whether you really need three living spaces and three bathrooms, or perhaps one of each would do? Compare the housing we expect in the wealthy developed world to that in which the majority of the planet’s population live due to poverty and lack of opportunity. Imagine if everyone in the world expected to use resources in the same way that we do to build a home.

Wherever possible select materials that are harvested, produced and manufactured as close to the building site as possible. The heavier that a product is and further it travels, the more transport energy is used and greenhouse gas produced. The energy used to harvest, extract, manufacture, transport and install products is called the material’s ‘embodied energy’. Mud bricks have a very low embodied energy as does recycled timber; whereas new aluminium has a very high embodied energy per cubic metre. Sometimes a higher embodied energy material may be appropriate to use in the right way, for example a concrete slab on ground. Also while structural steel has a higher embodied energy than timber per cubic metre, a highly efficient lightweight hollow steel section may do the same job as a heavy timber post many times its weight.

Selecting local materials gives you a chance to visit the source of the product and assess how responsibly the resources are harvested. It is more responsible to harvest our own resources and make good any damage than to shift that burden elsewhere.

Toxicity during manufacture of materials or during the life of a building is an important consideration. Always use physical termite barriers over chemical ones, consider using poly pipes in lieu of UPVC, and consider using other products than those with urea formaldehyde glues.

4) Rainwater harvesting for 100% domestic supply

It is possible on an average domestic block with an average roof to install rainwater tanks that will give you 100% domestic supply if your tank is big enough and your water use highly efficient. At least 80,000 litres is ideal. With longer dry spells and then dumping rain events more common, large capacity is essential. Install a first flush settling pit or device before the tank. After the pump install a pressure tank, grit filter, carbon filter and UV steriliser unit. With this set-up your water will be cleaner and fresher than any town water and free from bacteria and viruses.

5) Solar hot water and heating

Solar hot water panels generally pass water or another heat exchange liquid through dark tubes to absorb heat from direct sunshine. The more efficient panels now use well-designed reflectors and evacuated glass tubes to maximise the heat gain. With a solar boiler or tank, the heat can be exchanged with the domestic hot water supply pipes. If you are building a new home, the ideal system is solar hydronic slab heating. A second coil in the solar boiler can be pumped via a control manifold through embedded hydronic heating pipe coils in the slab. Both the domestic hot water and hydronic heating water can be backed up with a high efficiency instantaneous gas booster. This set-up is the lowest carbon producing form of hot water and space heating. If the slab is an exposed aggregate finish (the most resource efficient) or other masonry finish such as stone or tiles, inside north-facing windows, then the direct passive solar gain does most of the heating.

6) Waste water harvesting and treatment for 100% re-use

More than 90% of what goes down the sewer is water. There are many good EPA approved wastewater treatment systems available now. If possible, especially in a new home, capture treat and re-use all wastewater, grey and black. A wastewater treatment system can be cut into the sewer drain between the home and the sewer point in sewered area. The treated water can then be pumped in underground dripper systems to the whole garden. Reverse osmosis filtering and UV treatment will make recycled water drinkable again, if rainfall diminishes.

7) Solar power generation when everything else works

The light converting photovoltaic panels look great on a roof as a badge of environmental responsibility. The electricity generated by a 1.5 KW solar PV array may be 10 KW hours a day depending on your latitude and season. If you have a home and lifestyle that uses 50 KW hours per day, then the solar panels are for show. It is far more efficient to reduce consumption of energy than to produce it. Once you have a thermally efficient home, install high efficiency lighting and appliances. Get your average daily consumption down to 10 to 20 KW hours a day and then install grid interactive solar PV panel system. The grid interactive systems mean that you do not need battery back-up; the electricity grid becomes the back-up with a two-way meter. The electricity supply authorities will credit any excess electricity sold back to the grid against your usage.

Living now in an environmentally sustainable design-conscious home

Do what you can right now to make your existing home more environmentally sustainable. If you are one of the privileged few who has the opportunity to build a new home, don’t blow the opportunity. Whatever your circumstances pick one thing that will make the biggest difference to your home’s environmental footprint and act now.

 

Llewellyn Pritchard, Director of Conscious Homes, is an ESD consultant, registered Architect, a registered Builder (Domestic Unlimited and Commercial Unlimited), an SEAV Home Energy Rater, an HIA Greensmart Builder and writer. Conscious Homes won the 2006 National HIA Greensmart Resource Efficiency Housing Award.

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