Sustainable Construction: Techniques and Trends

After 24 years building in Queensland, here's what actually makes a new home greener, and what's mostly marketing.

The good news is that a lot of the basics are now built into the rules. The better news is that the cheapest green features are design decisions, not expensive add-ons.

Start with what the rules require

Under the National Construction Code (NCC) 2022, most new homes need:

A 7-star NatHERS rating for the building shell (walls, roof, windows, insulation, orientation and shading), up from 6 stars.
A whole-of-home energy budget covering the main appliances: heating and cooling, hot water, lighting and pool or spa pumps. Rooftop solar can offset this.
Livable housing features, such as a step-free entry path and wider doorways and corridors, making homes easier to live in as you age.

Queensland has adopted these requirements. Your building designer and energy assessor handle the compliance, but ask to see your star rating and what's driving it. Going beyond the minimum is often cheap at design stage and expensive later.

If you want independent recognition beyond the code, the Green Building Council of Australia's Green Star Homes standard is the local option. You'll sometimes see the American LEED system mentioned online, but it's rarely used for Australian homes.

Design for our climate first

Passive design means using the sun, shade and breezes so you need less air conditioning. In Queensland, the priority is keeping heat out in summer.

Put living areas on the north side. It's the easiest side to shade in summer and lets in low winter sun.
Size eaves properly. Eaves of around 600 mm or more on north-facing walls block high summer sun.
Be careful with glass. Big unshaded windows, especially facing west, turn a house into an oven. Use shading, better glazing, or smaller windows on the west.
Catch the breeze. Place windows on opposite sides of rooms to allow cross-ventilation.
Choose a lighter roof colour. It absorbs less heat and helps your star rating.
Insulate and seal well. Good ceiling and wall insulation, installed without gaps, and a well-sealed building envelope make a big difference.

Materials

Recycled and recyclable materials

Steel framing and roofing are highly recyclable. Recycled timber, recycled-content concrete and plasterboard with recycled content are also options. Ask your builder what's available locally without adding cost or delay.

Natural and biodegradable materials

Plant-based materials such as hempcrete (hemp fibres with a lime binder) are lightweight, breathable and insulate well. A reality check: hempcrete is still a niche product in Queensland, mostly used by owner-builders and specialist builders. You'll need a builder and certifier who know how to detail and approve it.

Low-toxic finishes

Low-VOC paints, adhesives and sealants, and low-emission engineered timber products, improve indoor air quality at little or no extra cost.

Green roofs and walls

Plants on roofs and walls can cool buildings and manage stormwater, but they add weight, waterproofing risk and ongoing maintenance. On a typical house, I'd spend the money on shading and insulation first. If you want one, get it designed properly with the waterproofing and structure to suit.

Water saving

Rainwater tanks. Mandatory tanks were removed from the Queensland building rules years ago, but some councils still encourage them. A tank connected to toilets, laundry and garden taps cuts mains water use and keeps your garden alive in restrictions.
Greywater systems. Reusing water from showers, basins and the laundry on the garden is possible, but systems need plumbing approval through council. Check what's allowed before you plan one.
Water-efficient fixtures. Check the WELS star ratings on tapware, showers, toilets and appliances. It's the cheapest water saving there is.

Trends worth a look

Rooftop solar and batteries. Solar helps meet the whole-of-home energy budget and cuts power bills. Batteries are getting cheaper.
All-electric homes. Heat pump hot water, induction cooking and efficient air conditioning, ideally run on your own solar.
Smart controls. Timers and energy monitoring help you see where your power goes. They're useful, but they don't make up for a poorly designed house.
Prefabrication. Factory building can reduce site waste.
3D-printed construction. Interesting, but still early days for houses.

The bottom line

The greenest house is one designed well for its block and climate: oriented properly, well shaded, well insulated, well sealed and not bigger than you need. Get that right first, then add solar, tanks and better materials as your budget allows.

Building Green: What Actually Makes a New Queensland Home More Sustainable

Start with what the rules require

Design for our climate first