With generous rebates available, it’s time to tap into efficient hot water.

“To save money on your bills, solar hot water is the best investment you can make – after you’ve done simple things like changing light bulbs,” says Nick Brass from renewable energy supplier Energy Matters. “You can save 75 per cent of the energy you need to heat your water.”

According to Mr Brass, households that now have electric water heaters stand to gain the most. Replacing a system that runs on peak-rate electricity can mean savings of up to $1000 per year. “If you’ve got an electric hot water unit you should go solar right now, without even considering it for a second longer,” he says.

Efficient hot water units cost more up front, but will cut your carbon footprint and save you money in the long term. To encourage you to switch, there’s a generous (but highly complex) set of state and federal rebates on offer.

The Federal Government will stump up $1600 for householders who replace electric systems. If you’re not eligible for the national scheme, the Victorian Government will pay up to $1500 in metropolitan Melbourne and $2350 in the regions – the most efficient units attract the highest rebates. Including extra dollars for Renewable Energy Certificates and Victorian Energy Efficiency Certificates, the total cash-back can be well over $3000. For more detailed guidelines, visit the Sustainability Victoria website.

Three kinds of hot water systems are eligible for the rebates. Flat-plate solar collectors have water pipes set inside a clear-fronted, airtight box, with a storage tank perched above. Evacuated tube systems use a row of glass tubes, each with a water pipe inside (in a vacuum), and no rooftop tank. Electric heat pumps work like a refrigerator in reverse, using warmth in the air to heat water. They’re not solar powered, but they’re highly efficient.

Which one is right for you?

Prices vary with rebates and installation costs, but Energy Matters estimates that the grand total will range from $2000 to $3500 installed, depending on the system. Heat pumps are cheapest upfront, followed by flat-plate, then evacuated tube. For ongoing costs, the systems rank in the reverse order.

“We recommend that if you’ve got a roof with solar access, you should use solar,” Mr Brass says. “If you don’t, then you should use a heat pump.”

Of the two solar systems, Mr Brass promotes evacuated tube. “The technology is very good. It’s easy to install, inherently frost-protected, and requires very little maintenance,” he says. “It’s more efficient. Because the tubes are curved, they passively track the sun all day. Flat-plate systems generate the greatest heat in the middle of the day.”

You’ll also need to back up your solar heaters for the times when sunlight isn’t enough. “Instantaneous gas is best,” Mr Brass says. “The only time the water gets boosted is when it passes into the home, so there’s no waste.”

With a low eco-footprint and high fire resistance, earth building is an old medium with modern appeal. 

Homes made from unfired earth – methods such as adobe, cob, pressed brick and rammed earth – now house up to half the world’s people, according to the Earth Building Association of Australia. And Victoria isn’t out in the cold: we have a long-standing tradition of earth building, especially in Melbourne’s north-eastern suburbs.

The association’s annual conference is being held in Eltham from Friday 14 to Sunday 16 August. It will focus on themes of sustainability, energy efficiency and bushfire resistance, and include tours of existing homes.

“Very few building techniques can match earth for low embodied energy,” says vice president Ray Trappel, an architect from NSW. It’s even possible for mudbrick walls to have negative embodied energy – to save energy overall – he says, if they’re made from intercepted excavation waste (which avoids trucking the material to landfill).

The potential for extra fire resistance is another benefit. A 250-millimetre thick mudbrick wall can achieve a high, four-hour fire rating. “A lot of people are considering using earth in their rebuilding (after the January bushfires),” Mr Trappel says.

If you build yourself, earth walls can also save you money. “It’s quite realistic to save up to $50,000 by not buying your bricks and not getting a bricklayer to lay them,” he says. He acknowledges that it will take hard work, but says there are many courses and resources available to guide your toil. “The association helps people share knowledge on all sorts of issues, like the most efficient ways to make bricks and the connecting and finishing details.”

But this kind of building is not just for the DIY set. There’s also an established professional industry. “A mudbrick house can be built cheaply using prefabricated technologies, or it can be a hand-crafted, top-end product,” says Greg Slingsby, a Melbourne builder and president of the Nillumbik Mudbrick Association. “Contemporary building styles have changed the image of mudbrick housing.

“We attract people who want to spend money on a craftsman-built, quality home. We’ve got a huge portfolio of modern houses that are architecturally exciting, with every state-of-the-art convenience,” Mr Slingsby says.

Earthen dwellings have a lot of thermal mass – the heavy walls absorb and store heat, which helps to curb the extremes of summer and winter – but they don’t record high insulation ratings. When the five-star regulations were introduced in Victoria, the earth building industry questioned the rules for failing to fully consider the benefits of thermal mass in external walls.

Mr Slingsby says that while the rating program has improved, it still doesn’t reflect the high comfort levels and low energy needs of residents living in mudbrick homes.

“Earth building, to my mind, is the most eco-friendly building medium there is,” he says. “The internal environment is healthy, low in humidity and comfortable all year round. These homes embody the very notion of green building.”

There are smart and inexpensive tricks to trapping heat indoors.

When the weather’s cold, ten times more heat escapes through standard windows than through insulated walls. That means your mid-year heating bill is vanishing through the glass.

But there are quick and simple fixes to help block the cold, says Amber Chamberlain from environmental consultancy Ecovantage. “Just covering up your windows in winter helps stop heat loss.”

When it’s cold outside, warm air turns into a chilly draught as it draws near exposed glass. To cut the heat flow, you need to trap a layer of still air next to the window pane.

“Curtains and blinds need to fit snugly and to be heavy – the heavier the better,” she says. “A good rule of thumb is that the more light coming through, the more heat that’s also being transferred.” Go for curtains that stretch below and beyond the sides of the frame, touching the wall or floor, and install pelmets (seals above the curtain or blind) to stop air at the top. You can fashion temporary pelmets from anything that fits – try cardboard or a thick scarf.

If heavy drapes aren’t to your taste, Ms Chamberlain suggests honeycomb or cellular blinds as a good alternative. “They trap a small amount of air within the blind itself, which acts as an insulating layer, and they still allow light into the home.” It’s wise to avoid gappy vertical and Venetian blinds.

Kirsten Johnstone, from Eco Edge Architecture + Interior Design, maintains that with careful thought, window coverings can be attractive as well as functional. If you’re building your home, she recommends designing window frames to fit recessed blinds. “You can create a channel that holds the sides of the blind within the frame,” Ms Johnstone says. “I think that’s a good solution, rather than the voluminous curtains that remind me of my Grandma’s house.”

She also says that, for homebuilders and retrofitters alike, pelmets need not be eyesores. “A minimal approach would be a small, painted box above the window or within a frame recess, painted out so it matches the wall. Try not to attract attention to it.”

Another way to improve your windows’ performance is by retrofitting double-glazing. Ecovantage suggests that DIYers try Clear Comfort, a membrane taped to the frame and made taut by shrinking with a hairdryer. “It’s virtually invisible and traps a layer of air in between the film and window, á la double-glazing,” Ms Chamberlain says. A 10-metre kit costs only $180.

For the less handy, companies such as Magnetite and MagicSeal sell secondary acrylic panes that attach to your window frame using magnets. “This solution is much more permanent and durable than DIY film. It’s more expensive, but still a fraction of [the cost of] double-glazing,” says Ms Chamberlain. The cheapest option of all is recycled bubble wrap, stuck on with the smooth side facing the room. “The little bubbles are perfect mini double-glazing cells, so why not use it on your windows?”

See related article: Windows