a House built in Australia today Not suitable for a net-zero world in the year 2050.
Australian homes are hot in the summer, and freezers in the winter. Air conditioning and heating systems can make us comfortable. But with rising energy costs, a cost-of-living crisis, and the climate emergency, we need to radically rethink how we build and thermally regulate our homes. Technology to make our homes carbon neutral, and we have examples: In 1973 the oil crisis prompted the development of energy building standards across Europe.
A primary focus of the legislation has been insulation, says Roberto Lullini, professor of building physics and research leader in energy-efficient buildings at Eurac Research in Bolzano, Italy.
Double glazing and roof insulation became the minimum for all new buildings. But Lollini says making a home carbon neutral isn’t just about insulation. Over the decades, European legislation has added more requirements, and in 2010, it became mandatory for new homes to have at least a portion of energy consumption covered by renewables.
Minimum insulation requirements did not appear in Australia until the 1990s, and it was only in 2003 that the Australian Building Code established national standards for housing energy efficiency. However, Australian legislation falls far short of the minimum building standards in many other countries for energy efficiency.
“Building a very energy-efficient home is very easy,” says Associate Professor Philip Oldfield, Chair of the School of the Built Environment at UNSW and a researcher in sustainable and low-carbon architecture. “You provide optimal insulation and ventilation, recover heat in the winter, provide shade in the summer and generate energy from the roofs.”
But he says Australian housing building regulations are 20 years behind many other developed countries, and even a home built today falls short of the 2050 net-zero target. “We need to make a commitment that what we build now is suitable for our carbon-neutral future.”
From net zero to positive carbon
The Energy Performance in Buildings Directive 2010 requires European countries to ensure that all new buildings are virtually energy-neutral by the end of 2020. A nearly zero-emission building (NZEB) has a very high energy performance, with almost zero or zero emissions. Very low energy required, which is largely covered by energy from renewable sources.
The Germans led the way with their Passivhaus – an ultra-efficient, highly insulated, airtight building with excellent ventilation and heat recovery systems. Heating and cooling are almost unnecessary at the Passivhaus. “Ideally, people should not need an active heating or cooling system,” says Lullini.
The almost zero energy house is oriented and shaded in such a way as to maximize sun exposure in the winter and decrease it in the summer. It is airtight and has excellent thermal insulation in the ceiling, walls and between floors to prevent unwanted heat dissipation; It has air filtration systems in addition to natural and mechanical ventilation systems. High-performance windows, such as triple glazing, allow plenty of natural light in while keeping the interior temperature stable. Artificial lighting and efficient appliances reduce the required energy produced by solar panels.
In 2021, the European Commission proposed revising the Directive and moving from NZEB to Zero Emission Buildings (ZEB) by 2030 to drive decarbonization. Households still account for 27% of final energy consumption in Europe in 2020, according to Eurostat, the European Union’s statistical office.
Emission-free homes do not release net carbon dioxide into the atmosphere while they operate. This means that each year the home generates as much energy as it needs for heating, cooling, hot water, lighting, and appliances.
But Lulini believes that to achieve our climate goals, we must go beyond the zero-carbon standard by making homes able to make additional “positive energy contributions.” A carbon positive home produces more renewable energy on site than the home requires and returns that excess to the grid. “We’re starting to see buildings as an active part of the urban environment,” he says. “As such, they can produce, store and exchange energy with other buildings, infrastructure and the e-mobility system.”
How to make your home more energy efficient
The technology is there for that. From popcorn-based waterproof building insulation as an alternative to petroleum-based materials to smart windows and 3D-printed insulating facades, the field of energy-efficient building has seen some impressive innovations.
But if the idea of retrofitting our home to make it zero-emissions or even carbon-positive seems unattainable, there are steps we can take to improve our home’s energy efficiency and make it more comfortable, says Oldfield. “Upgrading a poorly performing home can be challenging, but there are some small things you can do to make it better.”
He says there are three main issues with Australian homes. “We still depend on single glazing; our homes are sufficiently insulated and very leaky.”
Roof insulation is a fairly simple job, he says, that doesn’t require you to go out and can be done on a relatively modest budget. “The best thing you can do is insulate the ceiling because that’s where the heat goes.”
Another simple and inexpensive way to upgrade your home is to improve air tightness by applying mastic around windows or gaps in building fabric.
To achieve zero emission standards, most Australian homes will need deep modifications, which involve a much more significant investment. “You can’t count on the private sector to rehabilitate all these homes,” Oldfield says. “There must be government support.”
Loans, tax cuts, and grant schemes triggered a wave of renewal in Europe.
In Germany, incentives are offered to self-builders, developers, and first-time homebuyers. Homeowners who want to upgrade their properties can deduct 20% of the costs of certified technologies, such as improved windows and exterior doors, from their tax liability to make their home more sustainable. In Italy, the Super Bonus scheme allows homeowners a tax credit of up to 110% of the cost of remodeling their homes.
Oldfield says Australia should also devise ways to encourage homeowners to upgrade their homes and invest in retrofitting public buildings such as schools, hospitals and offices. “It’s not cheap, it’s not cheap, but you’re going to get an amazing buyback.”
One of the obvious benefits of investing in building energy efficiency is a significantly lower energy bill. But there are also indirect benefits, says Oldfield. “We will be more comfortable at home. We will get sick less. Our physical and mental health will improve. Absenteeism will decrease and productivity will increase.”