After a smoke-filled summer and now a pandemic, we’re all spending a lot more time at home.

You might be thinking of ways you can reduce your home’s carbon footprint, and be less expensive to run. Or quieter. Or cleaner. Or use the fall of sunlight better. 

In fact, you might be wondering how you can produce all your own energy or break even with what you produce and consume.

Welcome to the Carbon Net-Zero Revolution! 


What is a carbon net-zero home?

A carbon net-zero home is one in which the home is able to produce all the energy it requires over a given year. How? Through good design, energy-efficient appliances, and a renewable system such as solar PV.

Carbon neutral and carbon zero mean a similar thing. Often companies use the term Carbon Neutral when they have reduced energy consumption and increased recycling, but cannot claim to be carbon zero. They will offset the remaining energy they consume by purchasing carbon offsets (or carbon credits) to compensate for the power consumption. 

Similar to net zero, a carbon positive home produces more energy than it uses. This can be sold to the electricity grid with the proceeds sent to you as a payment, or deducted from your existing bill.

Carbon zero homes are healthy, quiet, sustainable, and are low-cost to run.

The Australian Government Your Home website says that carbon net-zero homes are today’s benchmark of best practice“. 

Benefits of a Carbon Net-Zero Home

Fewer Emissions

Obviously, the first benefit is contributing fewer emissions to our warming planet.

Households contribute around 12% of Australia’s carbon emissions, according to the Department of Industry, Science, Energy, and Resources.

Energy Cost Savings

When households reduce their reliance on fossil fuels for the heating, cooling, air conditioning and lighting of their homes, the savings are significant for them and can pay for the retrofit after a few years.

The typical Sydney home uses around 5,000kWh of electricity per year. With solar PV panels and passive design changes, as well as the use of efficient appliances, running costs can be significantly reduced.  

Healthier Household

When we stop using gas heaters, air conditioners and other equipment to heat, cool, and light our home, we are breathing cleaner air. When they get older,  some of these machines that we rely on can become leaky. That includes gas heaters and air-conditioners which can also leaky a refrigerant that vaporises into gas. Air-cons can also suffer from frozen coils and leak water that requires servicing.

All in all, the cost of such heating and cooling equipment including servicing can, in some cases, be avoided with good passive solar design.

And another thing. Without the hum and purr of machinery, it’s also quieter.

Can I Retrofit my House to be Carbon Net-Zero?

It is one thing to design and build a brand new carbon-neutral house, but quite another to retrofit an existing place.  It is a challenge, but maybe not impossible.

In the UK, government targets mean that 26 million homes will need to be retrofitted by 2050. Many of them are draughty Victorian and Edwardian dwellings. There, the leading engineering and design philosophy behind this elaborate exercise is to use “only natural materials and to retain as much of the original structure of the building as possible.”

In Manchester, the Zetland Project claims to be the greenest retrofit in the UK. It also stands as “proof that Victorian housing can not only be made zero-carbon but can actually generate energy.”

Professor David Ness of Architecture AU supports retrofitting rather than knockdown/rebuilds.

Ness cites Paris 2024 Olympics has embraced a “build less strategy” and 95% of venues already exist. Similarly, Los Angeles which will host the games in 2028,  plans not to have any new permanent structures but will ‘radically reuse’ what is created in a circular economy. 

Another benefit of retrofitting or remodelling your home — rather than knocking it down — mean it will generally incur lower construction costs.

If a full carbon net-zero goal is too hard to achieve all at once, you can also look for the small changes that will gradually improve your energy efficiency and comfort.

You might be able to make your home greener without going all the way to net-zero. 

You can also change energy suppliers to renewables companies like Red Energy (powered by the Snowy Hydro Scheme) and Powershop and become effectively carbon neutral that way.

Principles and Features of Carbon Zero Homes

Good design.  Houses need to meet a minimum score of 6 out of 10 on Australia’s National House Energy Rating Scheme (NatHERS). A good building designer (like the team at Design Plus Drafting) will examine the strengths and weaknesses of a site, including the orientation and air flows.

Use the sun as a heating source. PV panels often on the north and western sides of homes. In areas outside Sydney, it is more common to see wind turbines, but solar is generally much more popular as an energy source.

Insulation is a key factor. Make sure the windows and doors, and any gaps are airtight through seals, crack and floor gap fillings. It sounds obvious but external doors and internal doors have different composite materials. We need to make sure we have selected well-insulated doors, including the frames, as well as windows.

Consider window heights, and shading from the eaves. These can stop the harsh western sun penetrating a home.

Materials Consider “embodied carbon” when choosing materials. “Embodied carbon is those emissions created in the creation of building materials, during the building process and at the end of a building’s life.” There are a range of natural, sustainable building products that are just as versatile as concrete. 

For example, you could consider hempCrete, Ferrock, AshCrete, Bamboo, Wood, Recycled plastics, or — can you believe — Mycelium!

Highly efficient heating and cooling systems. Many of the newer models reverse-cycle airconditioners can cut bills, especially when used in conjunction with solar panels. The right temperature settings for your home can create a pleasant environment without much drain on energy.

Appliances are responsible for around 30% of energy bills. Use quality appliances that will stand the test of time and carry a high star rating

CanStarBlue can show you the ratings of your appliances and help you select efficient choices.

Sydney Examples of Carbon Neutral Buildings

Australia has 12 buildings that are carbon neutral.

Winner of the Best tall Building in the world award for its sustainable design, One Central on Broadway is a gobsmacking presence covered in greenery. With an internal water recycling system and trigeneration power plant, it is a 5 Green Star award winner as well.

The city of Sydney committed to being carbon neutral by 2040 (instead of 2050). Thanks to a proactive Sydney Council, Barangaroo is the first net-zero precinct.

Legion House on Castlereagh Street is an historic office building that is set to become carbon neutral. 

Even the iconic Sydney Opera House has become certified carbon neutral. This, however, has been achieved through a combination of energy efficiency, reduced waste and the purchase of carbon offsets (carbon credits).

According to the Fifth Estate,  Workplace 6 in Pyrmont (home of Google), recently achieved entry into the elite circle of carbon-neutral buildings. This has been achieved similarly to the Opera House, by reducing wastes, improving energy efficiency and then switching to a 100% renewable electricity provider.

Further afield, a housing estate development in Melbourne suburb, Altone North, is set to be net-zero.


More Information & Resources

For more information on sustainable home renovations, CHOICE has this article to help.

Right now, Australia has the lowest interest rates in history and the economy needs stimulation. It’s a good time to renovate.

If you would like help with your renovation design plus drafting in Sydney, please give us a call on 02 9565 2265.