Low-energy and net-zero buildings are set to become business as usual in Australia as the Building Ministers Forum has committed to investigating necessary changes to the National Construction Code.
The COAG Energy Council has also committed to the Trajectory for Low Energy Buildings.
What Defines a Low-Energy or Net-Zero Building?
So what is a low-energy or net-zero building, and do we have the tools to achieve them?
Tony Arnel, Deakin University Professor and Global Director of Norman Disney & Young [a Tetra Tech Company], tells Jobsite ANZ that the basic concept of a net-zero building is a simple one—to make what you use in terms of energy.
The focus of the process is on the installation of renewable energy capacity that will meet the energy needs of the building as measured over any 12-month period. In conventional, domestic housing, this generally means installing sufficient solar panels on the roof. In other sectors, such as industrial, retail and commercial, however, there are some exciting innovations happening, Arnel explains.
Particularly when it comes to large commercial buildings, the focus has been on energy efficiency for nearly two decades. For instance, Commercial Building Disclosure schemes that make National Built Environment Energy Rating System (NABERS) ratings mandatory for large buildings where those buildings are on the market for sale or are to be leased have driven this interest in efficiency.
Green Star, WELL, Living Building Challenge, and other rating systems have also contributed, as have policies like State or Federal government tenancy policies which mandate the leasing of office space meets a specific NABERS or Green Star benchmarks.
Going Beyond Solar
In addition to managing demand, the opportunity to make enough energy for an individual building to supply all its own power is now in the forefront. According to Arnel, this is seeing solutions that go beyond solar, such as the installation of small-scale wind power on some buildings or the installation of geothermal systems.
The new $35 million Plumbing Industry Climate Action Centre training campus, which is nearing completion, in Narre Warren in Victoria is a showcase example. It will be Victoria’s first Net Zero training facility and a working demonstration of how smart energy systems including geothermal and solar can be incorporated into a building. It will also deliver the training to equip the first generation of Net Zero plumbers.
The geothermal design uses deep bored screw piles, Arnel explains. The system will supply a substantial part of the facility’s energy requirements, with the balance being provided by a solar array.
There is one crucial difference in a construction program when deciding between solar PV and geothermal—the latter generally cannot be retrofitted. The works package involved, which includes the bores, the water reticulation, and the integration with the building energy systems needs to be commenced at the early stage—the same time when civil works, foundations and footings are being completed.
It also requires early engagement of appropriate engineering energy modelling expertise, both during the early design phase and throughout the detailed design and program planning.
Energy Standards Impact
In terms of how the Low Energy Trajectory will impact the broader industry, Arnel says that the supply side is already well-established to a high level. The skillset around solar PV is advanced, and the number of providers in the geothermal space has also been growing. They may be stimulated by exemplar projects like Frasers Property’s Fairwater residential development, which was at the time the largest residential geothermal installation in the Southern Hemisphere.
Arnel says that on the demand side, the push towards net zero has for the past decade been the focus of rating tool systems such as Green Star. Similarly, it has been crucial to standards, for instance, the Australian Government’s National Carbon Offset Standards (NCOS) for Buildings and Precincts, launched in conjunction with the Green Building Council of Australia in October 2017.
COAG and the BMF’s commitment to increase the stringency of building energy standards takes this one step further towards making net zero become business as usual in the medium-term future.
However, this is unlikely to prove a major disruption for industry participants, according to Arnel. The skills, methodologies and technologies have already been established.
A builder will need to pay attention to key elements that influence the energy demand of the finished building.
A builder will need to pay attention to key elements that influence the energy demand of the finished building. Optimal net-zero approaches partner an energy-efficient building with renewable energy, keeping it right-sized for the designed energy demand.
Arnel highlights the importance of ensuring insulation is installed correctly. Orientation and design should also utilise passive solar principles while thermally-efficient glazing is fundamental to achieving energy efficiency.
For non-residential projects, the use of sophisticated energy modelling plays a “very important part.”
For non-residential projects, the use of sophisticated energy modelling plays a “very important part.”
Discussing Narre Warren, Arnel explains energy modelling was undertaken during the design phase to simulate the amount of energy the finished building would require. The results of the modelling dictated the design of the renewable energy supply systems.
Verification Process
For many non-residential projects, there is also a mandatory measurement and verification process that assesses the energy use in the first 12 months of operation. If a project has made a pre-commitment to achieve a specific NABERS rating, this is where the proof emerges. Only then does the builder find out whether they achieved the design intent and specifications.
Arnel says that while there is some specialist knowledge required to achieve net-zero buildings, builders can rely on the expertise of designers, architects, and engineers with the knowledge base in energy modelling and demand management.
Builders can also direct a project architect to engage additional expertise in design and modelling if required. They can also benefit from engaging that expertise for post-construction measurement and verification.
It’s important for the building industry to realise “everybody is talking about net zero,” says Arnel, including the state and federal governments. Large property portfolios are also getting behind the concept, as the idea of resilience. In fact, “being in charge of your own power” is an attractive proposition for them at a time in Australia when consistency of supply, particularly in hot weather, is sometimes challenged.
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