Environmentally sustainable design: Green returns

By Nila Sweeney

 “If you have good passive solar design with awnings or eaves on the north and west aspects of your house, you can reduce solar heat gain”

Heating and cooling our homes accounts for up to 40% of our energy bills.

“If you’re not renovating, the most cost-effective things you can add include a good hot water system and energy efficient lighting”

Make your home up to 5 C warmer in winter and 10 C cooler in summer

Unless you’ve been living in a cave, you would have felt the green movement gradually creep its way into daily household life. Starting with dual-flush toilets and efficient tap ware, the use of sustainable products now encompasses everything from the choice of building materials to rainwater tanks and solar hot water systems.

As more Australians become aware of the impact of fossil fuel consumption on greenhouse gas emissions, and the increasing scarcity of water, the desire to conserve our precious resources has never been stronger. Joining the green building revolution isn’t merely about conservation – it can also save you a pretty penny.

And you don’t have to turn into a hardcore greenie to enjoy the benefits of an energy efficient home. In fact, even the budget conscious can make a few minor adjustments that will quickly pay for themselves.

Moreover, experts agree that it’s simply more comfortable to live in an environmentally sustainable home. Incorporating passive design features such as cleverly placed awnings and other shading devices, sealing doors and windows and insulating floors and ceilings, could make your home up to 5 C warmer in winter and 10 C cooler in summer.

Passive Comfort

Heating and cooling our homes accounts for up to 40% of our energy bills, according to figures from the Australian Greenhouse Office. With the increasing strain this places on electricity supply, particularly in peak periods, governments and architects alike now seek to promote efficient house design which maximises cross-ventilation, absorbs heat in summer and prevents heat loss in winter.

Passive solar or thermal design techniques work on the principle that direct sunlight can generate as much heat as a single bar radiator of each square metre of a surface. In winter, the aim is to trap radiant heat and circulate it around the house, while in summer it is optimal to block or shade the heat.

Thermal mass is used to store heat from the sun during the day, and re-release when it is required. “It’s lifestyle and comfort rather than energy conservation,” says Tone Wheeler, an architect at Environa Studios. “It’s how you feel, and enjoy yourself in your home. A passive solar house with higher thermal mass is more comfortable to live in than one relying constantly on airconditioning and heating.”

Five stars

Star ratings denoting energy efficiency on electrical appliances, notably whitegoods, have been around for years. The same principles have been applied to housing via the Australian Building Code Board, which has developed energy efficiency standards for new dwellings.

Last November, the ABCB implemented a five star standard for new houses and apartments, which has been adopted by most states. Complying with the standard involves increasing the level of insulation, draught-proofing, glazing and orienting the home so that living spaces sit on the northerly aspect. Installation of energy efficient appliances, water efficient tap ware and solar hot water systems are other integral components of the standard.

In Victoria, which has implemented the five star system, Geoff Mabbett, chief executive, Sustainability Victoria says that: “Under current prices, homeowners will save around $200 a year on electricity and gas costs for heating and cooling their homes, and $50 a year on water bills.”

Covering the BASIX

New South Wales follows a slightly different system. The Building and Sustainability Index (BASIX), sets energy and water reduction targets for new homes, achieved through both passive solar design and energy efficient installations.

Stringent targets under BASIX have been gradually introduced over the past two years, and on 1 July the energy reduction targets for new homes will increase to 40% from 25%.

“In practical terms, currently one in four homes has a solar hot water system, but with the new legislation this will probably increase to three in four. [The changes] will also lead to better design choices, including more use of glazing and shading,” says Bruce Taper, director of sustainability, Department of Planning.

BASIX-compliant households in NSW will save around $300–600 per year on energy bills. If you were to plough these savings back into your mortgage each year, this could save you upwards of $10,000 in interest payments over its lifespan.

Start simple

You don’t necessarily have to renovate to save energy. While it is obviously easier to access the roof space to lay down insulation batts if you are putting on a second storey, you can install a range of other fittings yourself.

“Insulation is not just fluffy batts,” says Kristin Tomkins, Housing Industry Association deputy director residential development. “Think of your house as a box. You should be able to properly close it up and seal it so you can heat it effectively in winter. You can buy door and window seals from Bunning’s and put them in on a Saturday afternoon.”

Installing water saving devices need not cost you an arm and a leg either, Tomkins says. “You can install flow regulators in taps and showers. They are a small plastic disc, and cost around $3. You don’t need a new shower or tap head, you just unscrew your existing tap, and place the disc in between the tap and the wall.”

Lighting, which accounts for 10% of household energy use, can also be cheaply converted, Taper says. “If you’re not renovating, the most cost-effective things you can add include a good hot water system and energy efficient lighting – this will save you 10–15% off your power bill alone.”

Getting serious

If you’re able to wear higher up-front costs and want to make savings on your utility bills over the longer term, Tomkins says that you should first assess your hot water source. “Is your hot water service efficient? You could look at installing a solar hot water system. Although there is a slightly higher up-front cost, running costs are greatly reduced so it should pay for itself after a few years. If you have airconditioning, you could look at zoning the areas in your house, so you can effectively cool just the zone you are living in.”

Rainwater tanks, which collect run-off from your roof, are an ideal source of water to use in the garden or swimming pool. Given that 60% of our water is used for outdoor purposes, and with the rebates that many water authorities now offer, rainwater tanks can bring your water bills right down.

Adding shading devices will not only save you money on heating and cooling, but will also improve the comfort of your home, Tomkins says. “If you have good passive solar design with awnings or eaves on the north and west aspects of your house, you can reduce solar heat gain. If you place them at the correct angle, it’s possible to attract the winter sun, while blocking out summer sun.”

What if I’m renovating?

For any major alteration or addition, it’s a good idea to initially consult the experts. “If you’re renovating, get some design advice from a recognised architect who’s had some experience in environmentally sustainable design. What features you decide to go with will depend on your home’s orientation,” Taper says.

“The placement of new rooms can improve thermal comfort of the existing house, by providing shading to the adjacent rooms,” Tomkins adds. “New external walls should have insulation, and any new water rooms can include water efficient tap ware or toilets.” If you’re in NSW, BASIX will apply to those renovating or extending an existing home from 1 July.

Options abound for improving the comfort of your home, reducing reliance on artificial heating and cooling. You needn’t rip apart walls, or shell out thousands of dollars to enjoy energy and water savings, and a temperate internal climate. What’s more, reinvesting the money you save back into your mortgage will enable you to own your green-friendly home that much sooner!