Sustainability, what does it really mean to the potential design and subsequent construction of your vision? Not to be confused with energy efficiency or “going green”, all these concepts can overlap one another, and each deserve their own space and explanation when applied to building science. The basic premise behind sustainability is to identify or describe the ability for something to continue on providing its purpose at a certain level. So how can a building be sustainable? There are plenty of old buildings around that seem to be carrying on their purpose just fine, in a manner these have sustained their existing over all the ones that have been demolished to make way for new ones. But sustainable building means so much more!
Now before we jump down this rabbit hole, it is important to remember that sustainability can mean different things to different people as applied to their particular circumstance. Whilst there are no strict rules when individually considering something sustainable, there are guidelines, limitations and ideals that help us assess whether we have achieved some level of sustainability or not. In Australia the government has already begun and is continuing to develop new sustainable housing laws for the building industry to abide by. Ready to jump? Lets go! I promise there is light at the other end and no its not a train!
Part of the sustainable concept is to consider how suitable a particular building is for both its proposed, current and future occupants. A sad reality is we are all getting older every minute of every day and as we get older our needs change. In order to fulfill that basic requirement, that in order to be sustainable the building must be able to continue providing its purpose at a certain level, we should consider both how our ability to use the building and the buildings ability to be used, may change. Lets look at some key areas, remembering again that different people have different circumstances and that circumstances can not only change, but are inevitable, though maybe not yet.
Getting accessibility right from the start is one of the most impactful sustainable design decisions you can make. Retrofitting later is almost always more expensive and disruptive.
Doors should have a clear opening of minimum 870mm to allow mobility aids throughout the building. The vast majority of existing housing has standard “820 doors” which, once door stops are accounted for, leave less than 800mm clear. Wheelchairs require 850mm minimum. By building with a larger opening in the first place, the building can be used by a wider range of people now or in the future. Changing doorways later is expensive and creates knock-on problems, for instance floor coverings will have gaps that need dealing with too.
Entry thresholds should be no greater than 10mm. This is the “step”, or difference to the ground level, or floor of the door frame at external doorways. They are there to prevent rainwater from flowing into your house (at least that’s what was intended) and are commonly much greater than 10mm when measured on the path of travel (think the step from the path or driveway or patio floor). When reducing this threshold to less than 10mm we need to consider not only how to deal with rainwater, but also maintain integrity of termite barriers. If you think about the house you live in now, how high is this step or bump, would it be difficult to take on if you were less mobile or disabled in some manner, could a wheelchair or stretcher cross it easily?
Hallways should be 1200mm in width, short or not at all. Most houses have hallways of 900mm or even less. Wider hallways provide greater levels of access, light and airflow. Its not only straight line access that we are considering, think of wheelchairs, walking aids, stretchers or even moving furniture when turning into and out of doorways.
Garages should be a minimum of 3.8m width for a single car. Ever parked in a standard single car garage that’s only 3m wide? Not great accessibility, but that is the historic standard single car garage width.
Bedrooms should be at least 3.9m x 3.5m minimum for the main bedroom. This supports both accessibility and general well-being.
Door handles and catches should be positioned between 900mm and 1100mm from the floor. Some may find it difficult to unlatch or latch a door when the catch is in its usual place just off the floor. “D or Bow” style door and cupboard handles are easier to open and close if your grabbing ability is compromised.
Showers should have no hob (the step over often seen in many houses to get into the shower). A hobless or level-entry shower is safer and more accessible for everyone.
Power points should be a minimum of 600mm from the floor rather than the 250-300mm commonly used. This makes them easier to access if mobility is compromised. Preferably use larger rocker switches.
Light switches should be large rocker types, positioned away from corners and 900-1100mm from the floor. Sensor lights to commonly accessed areas such as toilets, hallways and bathrooms add both convenience and safety.
Switchboards and sub-boards should be located in an accessible position internally to the house.
Bathroom windows should not be located above the bath where they are harder to reach and operate.
Stairs should be wide enough to allow for a stair lift, with continuous handrails that extend beyond the first and last steps.
Footpaths and access to the house should be minimum 1200mm wide with maximum 1:40 cross slopes and 1:14 path of travel slope. They should be slip resistant and lead to a covered entryway. Ramps in place of steps where possible.
A well-ventilated home with good thermal performance reduces the need for mechanical heating and cooling. On the Gold Coast, where we deal with warm humid summers and mild winters, getting ventilation right is especially important.
Openings and ventilation should be placed to make maximum use of prevailing breezes. Openings need to be adequate on both sides of the building to allow air to enter and escape. Ventilated roof spaces and eave vents help release trapped heat. Extraction fans should be ducted to the outside in bathrooms, toilets and laundries. Draft seals to doors and windows reduce unwanted air infiltration when you want to keep conditioned air in.
Ceiling heights of preferably 2700mm improve light, spaciousness, airflow and atmosphere. They also allow for safer ceiling fan installation, keeping blades well above head height.
Thermal mass should be used appropriately. The right use of materials with high thermal mass and low thermal mass in construction can make a significant difference to comfort and energy ratings. In our subtropical Gold Coast climate, getting the balance right between thermal mass and insulation is critical.
The materials you choose and how they are used play a major role in the overall sustainability of your home.
Building materials should be constructed with readily available, local where possible and renewable resources. Low maintenance and highly durable materials reduce the long-term environmental and financial cost of ownership.
Colours should be appropriate to local climatic conditions. Light colours for warm areas like the Gold Coast help reflect heat, while darker colours suit cooler climates where heat absorption is beneficial.
Hot water systems should be solar, gas or heat pump. Five star instant systems offer excellent efficiency and reduce standby energy losses.
Range hoods should be ducted externally, not into the roof space. Ducting into the roof space introduces moisture and cooking residue where it can cause damage over time.
Safety and security are often overlooked when people think about sustainability, but a building that keeps its occupants safe and secure is fundamental to it continuing to serve its purpose.
Key safety features include slip resistant flooring, childproof storage for dangerous items, insect and security screens, garden fences with self-closing gates, and driveways separated from walkways and play areas. High strength soap holders, shower shelves and towel rails can double as grab rails. Smoke alarms, hot water thermostats, protected relief valves and safety switches are essential.
For security, consider solid external doors with peepholes or cameras, window locks, sensor lights, lockable mailboxes and locked meter boxes with internal sub-boards.
Energy and water efficiency tie closely into sustainable building. The less energy and water a building consumes, the longer it can sustain its purpose without placing undue strain on resources or your wallet.
Ceiling fans should be installed to all rooms practical and outdoor entertaining areas. On the Gold Coast, a good ceiling fan can reduce air conditioning use significantly.
Windows should have extended eaves of minimum 900mm to shade glazing from direct summer sun. Window awnings, tinted or low-e type glazing, external shading devices or shutters, and skylights all contribute to better thermal performance and natural lighting.
Power and water efficiency measures include LED light fittings, smarter meters, water restriction devices, dual flush toilets, rainwater tanks and energy efficient appliances. These are relatively low-cost inclusions that deliver ongoing savings.
One of the most important aspects of sustainable design is thinking ahead. Where and how could you extend if required? What are your current and future family needs (think about the current generation of children living at home longer)? How much maintenance is required for property upkeep? A sustainable home considers adaptability to changes in circumstance, so that it continues to serve you well no matter what the future holds.
| Feature | Standard Practice | Sustainable Approach | Typical Cost Impact |
|---|---|---|---|
| Doorway Width | 820mm door (~790mm clear) | 870mm+ clear opening | Minimal at build stage |
| Hallway Width | 900mm | 1200mm minimum | Moderate (extra floor area) |
| Ceiling Height | 2400mm | 2700mm | Low-moderate increase |
| Hot Water System | Electric storage | Solar, heat pump or gas instant | Higher upfront, lower running |
| Power Point Height | 250-300mm from floor | 600mm+ from floor | Nil (labour only) |
| Window Shading | Minimal eaves | 900mm+ eaves, awnings, low-e glazing | Moderate upfront, energy savings |
| Shower Entry | Raised hob | Level entry (hobless) | Minimal at build stage |
| Ventilation | Limited openings, recirculating fans | Cross-ventilation, externally ducted extraction | Low, better design placement |
Made it this far? Congratulations, it was a bit to get through and I have minimised it as best I can. As we can now appreciate, sustainability can encompass a wide variety of elements and design concepts. Whilst intended as a guide only, many of the concepts listed here have, or are proposed to become part of building laws in Australia, as has occurred within different regions around the world. To summarise, we need to think about how our building designs are used not just now or in the past, but their potential uses by occupants in the future. We are seeking buildings and designs that work and can carry on working into the future and are constructed from materials and in a manner that is renewable as well as fit for purpose.
Quite the subject. At Design Science we understand that a lot of these concepts may not be circulating within your current visions. You may also not wish to integrate some of these within your designs. What we do set out to achieve is to highlight, educate and offer the opportunity to encompass smarter science within your design. For more information on Design and Building feel free to check our other blogs and resource pages.
Thanks for your time and we hope it has been time well spent.
Many sustainable features add little or no extra cost when included at the design stage. Wider doorways, higher power points and better window placement are about smarter design rather than expensive materials. Some features like heat pumps have a higher upfront cost but deliver savings that typically pay for themselves within a few years. The key is integrating sustainability from the beginning rather than retrofitting later.
Gold Coast homes must comply with the National Construction Code (NCC), which includes requirements for energy efficiency, accessibility (the Livable Housing Design standard) and condensation management. The NCC 2022 updates raised the minimum energy rating to 7 stars for new homes. Queensland also has specific requirements around termite management and cyclone ratings that influence how sustainable features are implemented.
Yes. Adding ceiling fans, LED lighting, water-saving fixtures, solar hot water and rainwater tanks are all straightforward upgrades. Widening doorways, adding eaves or improving ventilation may require more involved building work but are well worth considering during a renovation. A building designer can help you prioritise which improvements give the best return for your home.
Homes with sustainable and accessible features are increasingly sought after, particularly on the Gold Coast where our ageing population and climate make these features genuinely practical. Better energy ratings, accessible layouts, quality ventilation and durable materials all contribute to wider buyer appeal. Features like solar hot water and good natural ventilation are especially valued in our subtropical climate.
Energy efficiency is one component of sustainable building, but sustainability is much broader. Energy efficiency focuses on reducing energy use for heating, cooling, lighting and appliances. Sustainable building also considers accessibility, material selection, durability, future adaptability, water efficiency, safety, and how well the home serves its occupants over its entire lifespan.
At Design Science, we integrate sustainable design principles into every project — from passive solar orientation to NCC 2022 energy compliance. As a dual-licensed builder and building designer, David understands how to make sustainable features practical and cost-effective. Learn more about our sustainable home design services or book a consultation to discuss your project.
Related: Custom home designs | Renovation design | Our design process
David Steadman
Licensed Builder & Building Designer
David Steadman is the founder of Design Science, a Gold Coast building design practice backed by over 30 years of hands-on construction experience. One of few Australians holding both a QBCC Builder's Licence and Building Designer licence, David brings a rare combination of design thinking and practical building knowledge to every project.
