Design Matters true zero carbon challenge 07 July 2022

Design Matters true zero carbon challenge

Designing homes for zero emissions – because the built environment doesn’t need offsets

Written by Julianne Tice, Senior Project Officer, Energy Efficiency Council

Isn’t the built environment exciting? As we look to a net zero future, it’s becoming clearer by the day that we can achieve early and substantial emissions reductions from buildings. Not only can ‘net zero’ be reached in all buildings, but what if buildings could be energy-positive, and pay back their ‘carbon debt’ over time? This is the idea behind Design Matters’ “True zero” design challenge. We think that ‘true zero’is achievable for the entire building stock, particularly new buildings.

We’ve known for a while what we need to do to remove emissions from buildings – now we just need to do it. But how do buildings really become ‘true zero’ homes?

A true zero home is one that produces more power than it uses over the year through energy-efficient design, careful appliance selection, and photovoltaic integration. It also considers embodied carbon in material selection.

A true zero home doesn’t use offsets, and may not use any energy for heating and cooling at all. It is truly possible for a home to be fully operational and comfortable with no energy for heating and cooling: the thermal power of the sun can be harnessed, plus the thermal mass of building materials such as concrete, and the shading power of trees.

For ‘true zero’ to be achieved, efforts are much better placed at the design stage. Retrofitting an existing home to reduce its operational emissions is wholly feasible, and one of the areas of focus for the EEC’s advocacy. This is particularly important given that more than 10 million of the 17 million homes that will be needed in 2050 have already been built[JT1] [ASJ2] .

But it’s more difficult to take advantage of things like orientation, thermal mass and shading once a home has already been built, meaning reducing energy consumption has its limits (this is where electrification and solar PV can play a huge role).

Digging a little deeper, we can also think about the embodied carbon of the materials used to build a home. Timber is one great example of a low-embodied carbon material for housing construction, as trees sequester carbon as they grow, and then this carbon is ‘locked in’ to a home’s structure.

Unfortunately, if embodied carbon wasn’t front of mind during the design stage, those emissions are locked in once a home has been built. This makes emphasis on the design stage of new homes all the more important.

All of this is why the EEC is supporting Design Matters National’s True Zero Carbon Challenge. While the EEC is concerned first and foremost with existing buildings within the built environment, designing new homes to absolutely minimise their energy consumption – and to become energy positive – is relatively low-hanging fruit for reducing emissions now and far into the future.

However, it’s only low-hanging fruit if we have the people with the knowledge and drive to make sure homes are built this way. We need building designers, architects and builders who know how to design and build true zero buildings, and who are willing to do it.

The True Zero Carbon Challenge provides an opportunity for entrants to hone the skills necessary to design the homes we need right now. It also shows that entrants are ready, willing, and able to meet the challenges of the low carbon future, starting today.

Building ministers are soon to decide whether the energy efficiency requirements in the National Construction Code (NCC) will be increased from 6 to 7 stars through the National Energy House Rating Scheme (NatHERS). This is an important decision, considering that the NCC’s energy efficiency provisions have not been strengthened in over a decade. From an efficiency perspective, this seems like a no-brainer: homes with higher star ratings consume less energy, which saves occupants money.

But increasing requirements to 7 stars means we’re still far beyond other countries: new buildings in the European Union are now required to be nearly zero emissions buildings, and legislation is poised to increase this requirement to zero emissions buildings by 2030.

The True Zero Carbon Challenge competition helps continue to drive the discussion in the direction of low- to zero-emissions buildings in Australia, which is the direction in which we rapidly need to head.

If you’re an architect, building designer, thermal assessor or other Design Matters National member, you can help drive the conversation by designing your own true zero home and entering the True Zero Carbon Challenge by 15 August.