A Guide to Sustainable Heating in Australia

Before starting any construction or retrofitting project, you need to define your project goals clearly. What do you want your heating system to achieve? These may include objectives such as compliance with building codes and standards, attaining your desired comfort and performance levels, and achieving the required sustainability benchmarks set by independent accreditation bodies.

By law, any building project should adhere to the National Construction Code which sets the required minimum standards for the safety, health, amenity, accessibility, and sustainability of all buildings in Australia. When designing your heating system, provisions in this code must be considered in addition to the comfort and performance requirements of your property. These comfort and performance requirements may include temperature, humidity, response time, and efficiency requirements, as well as the functionalities that you want your heating system to have. Identifying these requirements requires involvement and coordination with all stakeholders— tenants, engineers, management, and all concerned government authorities.

However, just complying with these mandatory and performance requirements wouldn’t necessarily make your project sustainable and carbon-neutral. To ensure that your project meets both the national and global standards for sustainability, you can voluntarily apply to have it certified by independent sustainability accreditation bodies. In Australia, we currently have two sustainability rating systems: Green Star and NABERS.

Green Star is a sustainability rating system being administered by the Green Building Council of Australia. It is composed of four rating tools: Green Star – Design and As Built for the design and construction of a building, Green Star – Communities for the planning and delivery of projects at the neighbourhood, precinct, or community scale, Green Star – Interiors for new interior fit-outs in a building, and Green Star – Performance for the operational performance of an existing building. These tools assess projects against various environmental impact categories including indoor environment quality, energy, emissions, water, transport, land use and ecology, materials, innovation, and management. In this scale, projects with the best sustainability practices are given the maximum 6-star rating.

On the other hand, NABERS, which stands for the National Australian Built Environment Rating System, is focused on assessing a building’s operational efficiency across four key aspects: energy, water, waste, and indoor environments. Just like Green Star, the NABERS rating scale ranges from 1 to 6. They have also partnered with Climate Active to provide a Carbon Neutral certification.

These targeted plans should be defined as early as possible in order to maximise resources and avoid unexpected changes along the way.

Once you have a clear picture of your project requirements and heating demand, the next thing to do is research and find out which technology suits your application best. There are a lot of available heating technologies in the market. However, not all technologies are created equal. When looking into the different options, it is important to evaluate and consider factors like cost, available fuel, equipment efficiency, warranty, the complexity of installation, supplier reputation, and environmental impact, among others.

Traditionally, boilers (or water heaters) have been the most popular technology used in commercial heating. The concept of its operation is simple— by burning gas, diesel, or some sort of biomass, a flame is produced which is then used to heat water via heat exchangers. However, as a technology that involves burning fossil fuels, boilers produce exhaust that contains greenhouse gases including carbon dioxide. Modern boilers use condensing technology to minimise these gases and increase efficiency, however, they still do not completely get rid of on-site emissions.

In hopes of solving this problem, the use of renewable hydrogen gas as an alternative fuel for boilers is being explored. Unlike fossil fuels, burning hydrogen gas emits no carbon dioxide; instead, it yields water— making it the most environmentally-friendly combustion fuel available emissions-wise.

In Australia, the Future Fuels Cooperative Research Centre is studying the feasibility of using hydrogen gas or hydrogen blends with existing gas appliances and industrial equipment. Some states have also started to blend at least 5% hydrogen with natural gas into their gas distribution networks, and the country is poised to blend more in the coming years. However, the production of hydrogen gas through electrolysis is expensive and requires a huge amount of electrical energy. Even though we can use renewable energy to keep the process carbon-neutral, a technological breakthrough is needed to make it cheaper. At its present state, it is more cost-effective and practical to use alternative heating technologies like heat pumps.

The future of the sustainable built environment is electrification. In the heating sector, this means shifting to electric-powered green heating technologies like heat pumps. A heat pump is an appliance that manipulates a confined refrigerant to extract thermal energy from the environment and produce heat.

Although ambient air is the most common thermal source for a heat pump, there are also other renewable options including the ground, water bodies, and wastewater, among others. (See: Types of Electric Heat Pumps) Two or more thermal sources can even be integrated to allow redundancy and improve system efficiency.

Since a heat pump essentially only uses electricity to facilitate heat transfer between the thermal source and the circulating water, it can reach net efficiencies of up to 450% with respect to the electrical power input. This is much higher than typical boiler efficiencies which can reach around 95%. In addition, since it runs on electricity, it eliminates on-site carbon emissions.

There are several heat pump models available on the market. The most common ones use HFC refrigerants. However, an emerging technology that is becoming popular among sustainable developments is the CO2 heat pump. As the name suggests, a CO2 heat pump uses supercritical carbon dioxide as a refrigerant operating under a transcritical cycle. This means that carbon dioxide is compressed beyond its critical pressure, allowing a much higher heat rejection through sensible cooling and increasing the overall heat pump efficiency. Carbon dioxide is also known to have the lowest global warming potential (GWP) and ozone depletion potential (ODP) among all common refrigerants today. With a 1.0 GWP and zero ODP, CO2 heat pumps are undoubtedly the best option for sustainable and carbon-neutral buildings.

Ultimately, your budget and required payback period will dictate which sustainable heating technology to use. In general, heat pumps have a higher upfront cost than boilers. However, because heat pumps have much higher efficiency, their potential energy savings could prove to be more beneficial in the long run. It is important to get quotations, conduct a benefit-cost analysis, and compare ROIs in order to select the best heating option and configuration for your property.

It is also important to note that the government provides incentives for sustainable businesses that choose to go green. An example of this is the Emissions Reductions Fund which gives businesses that adopt green practices and technologies from select sectors the opportunity to earn Australian carbon credit units for every tonne of carbon dioxide equivalent they store or avoid emitting.