Net zero heroes Buildings without emissions.

PRINT POST APPROVAL NUMBER PP352532/00001

SEPTEMBER 2018 · VOLUME 17.8RRP $14.95

Ecolibrium

ECOLIBRIUM • SEPTEMBER 201834

Eco: What is the definition of a net zero carbon building?

Cooper: Defining net zero carbon is potentially complex, and even controversial, because the long-term or short-term targets for this concept become relevant. At the less ambitious end of the spectrum of desirable sustainability outcomes is the goal of

implementing net zero energy buildings – i.e., those that, over the course of a typical year, export more onsite renewable energy to the grid than is imported from fossil-fuel sources.

At the most ambitious end of the spectrum one can define a zero carbon building taking into account embodied

carbon (or energy) – that is, the emissions involved in the sourcing, manufacture and transport of all materials used to construct the building. The issue of embodied environmental impacts, including carbon emissions, is becoming ever more important as we move towards net zero carbon buildings with no operational emissions, since operational energy requirements are met fully by renewable energy resources, leaving only embodied impacts to mitigate.

The World Green Building Council’s (WGBC) description that “a net zero carbon building is a building that is highly energy-efficient and fully powered from on-site and/or off-site renewable energy sources”, is a good definition for operational purposes, but misses the elephant in the room of embodied carbon impacts of manufacturing and transport.

The zero effect

C O V E R F E A T U R E

The term “net zero carbon” has been around for a while, but what does it really mean, and are many buildings pursuing it? Sean McGowan explores the concept of net zero carbon with Professor Paul Cooper, M.AIRAH, director of Sustainable Buildings Research Centre (SBRC) at the University of Wollongong; Clare Parry, M.AIRAH, director at Grün Consulting; and Tony Arnel, global director of sustainability at NDY and Industry Professor at Deakin University.

35SEPTEMBER 2018 • ECOLIBRIUM

C O V E R F E A T U R E

Image supplied by NDY.

We need to have a much greater focus on this embodied carbon issue now, not just at some point in the future. And this includes guidance in relevant building codes and standards.

Parry: Any robust net zero definition must include an “efficiency first” requirement. I like the World Green Building Council’s definition: “A net zero carbon building is a building that is highly energy-efficient and fully powered from on-site and/or off-site renewable energy sources.”

The Australian NCOS definition is similar. (see breakout)

Arnel: There are many terms for buildings that use renewable energy

sources to reduce or eliminate emissions, including low-carbon, carbon-neutral, zero energy, zero emissions and carbon zero.

However, ASBEC defines zero carbon as a building with no net annual greenhouse gas emissions resulting from on-site energy or energy procurement (Scope 1 and Scope 2) from its operation.

Eco: How many of these buildings exist in Australia, and what types of buildings are they?

Arnel: We are not aware of any comprehensive database of net zero buildings. There are examples overseas of such databases (for example, the US New Buildings Institute’s “Getting to Zero Database”), and developing one for Australia may be a useful exercise.

The Green Building Council of Australia says, in its recent “Carbon Positive Roadmap”, that there are a dozen Green Star rated buildings that meet its criteria for net zero, in that they are fully powered through on-site renewables. These are in the education sector, and at least one shopping centre is in the pipeline.

NDY is delivering Australia’s first net zero energy education facility at Narre Warren north of Melbourne. It features a unique mix of geothermal and solar applications, and has attracted a $500,000 grant from ARENA to be used as a future demonstration project.

Cooper: I am not aware of a comprehensive study or database that could answer this important question, but there are probably relatively few Australian buildings that meet the WGBC definition of net zero carbon.

There will be far more existing Australian buildings that are net zero energy, which will more than offset their import of fossil fuel-generated energy from the grid by onsite renewable energy export. Our own Sustainable Buildings Research Centre (SBRC) and the Illawarra Flame and Desert Rose Solar Decathlon houses are three such net zero energy buildings.

Parry: I’m sure there are some we don’t know about, and some that said they were and didn’t perform, but those I am aware of tend to be office buildings.

I worked on the Pixel Building, a net zero energy, net zero water and carbon-neutral building. There is a commercial building in West Melbourne, and Monash is leading the way in building efficiency into their project with Passivhaus, and offsetting with renewables. They also have a firm commitment to net zero carbon by 2030, and many universities have targets. I think there’ll be a rise in the numbers.

Eco: How is a net zero carbon result generally achieved?

Cooper: Ideally we should be increasing the energy efficiency of the building first, and then working to provide renewable energy generation, onsite and/or off-site.

Parry: Often with plenty of offsets, although a minimum amount of efficiency measures are required. To meet the Australian government’s Carbon Neutral certification, a minimum NABERS Energy rating of 4 stars is required (without Green Power), implying this efficiency.

Arnel: Zero carbon is generally achieved through a combination of design measures – including orientation, shading and cross-ventilation – building fabric

Clare Parry, M.AIRAH Tony Arnel

A net zero carbon future is possible, achievable and economically beneficial

Professor Paul Cooper, M.AIRAH, in front of the net zero energy

Sustainable Buildings Research Centre.

ECOLIBRIUM • SEPTEMBER 201836

C O V E R F E A T U R E

measures – such as an air-tight building envelope to reduce leakage, as well as insulation and double-glazing – switching away from gas and other non-electricity fuels, as well as rooftop solar and more efficient air conditioning and lighting.

For buildings where there is limited opportunity for on-site generation, such as tall, skinny buildings, procurement of offsite zero-emissions electricity may be required.

Eco: What are the issues and tensions around net zero carbon? Will it always be too expensive to be a mainstream objective?

Parry: The issues are more around education and established pathways to deliver, and a focus on up-front construction cost has played a big part. Although the knowledge base has existed for a long time, there has been limited appetite to use it. We’re seeing a new focus on whole-of-life impacts of building design.

There has been a lot of work done historically by organisations such as BZE, and more recently, in particular by ASBEC and ClimateWorks, to show that a net zero carbon future is possible, achievable and economically beneficial.

Arnel: Cost is a factor, but it’s not the whole story.

ASBEC’s report finds a range of persistent barriers and market failures have prevented broader uptake of better practices across the building sector. These include lack of appropriate data, information and skill, particularly when making decisions to buy or rent. Split incentives – where the landlord invests in energy efficiency measures but the tenant reaps the benefits – also play a role. In addition, energy requirements in the Code have not shifted substantially in a decade, contributing to the widening gap between industry leaders and minimum Code requirements.

Cooper: These issues and tensions vary from one type of building sector to another. An obvious example is the case of net zero carbon detached houses versus apartments. Houses have a much greater roof area available for PV per unit floor area as compared to apartments, so apartments would need to purchase a much greater fraction of off-site renewable energy per household.

The good news is that the falling price of solar photovoltaic systems is making on-site generation an increasingly cost beneficial option for many building types. However, to be truly net-zero carbon, operationally one must either purchase all of one’s imported energy from the grid from renewable sources, or go off-grid with batteries.

The SBRC research team recently completed all the energy modelling for the residential sector component of the Built to Perform final report for ASBEC’s NCC Trajectory Project. This project set out to determine how best to cost-effectively develop an Australian net zero energy building stock in the coming years.

Eco: Who in our industry is championing a net zero carbon future?

Cooper: One of the key champions of the goal of a net zero carbon future nationally is ASBEC and its many members. They are doing a terrific job in advocacy and in funding key activities aimed at providing a rigorous evidence base to inform policy makers, such as the NCC Trajectories Project.

Arnel: ASBEC and its members are championing this through its Low Carbon, High Performance roadmap to a zero carbon built environment by 2050 and the Built to Perform report on the National Construction Code (NCC).

The Green Building Council is also pushing for zero carbon through its Carbon Positive Roadmap.

Parry: There are government initiatives, such as the National Carbon Offset Standard (NCOS) that have made it

Melbourne’s Pixel building is a net zero energy, net zero water and carbon neutral building.

37SEPTEMBER 2018 • ECOLIBRIUM

C O V E R F E A T U R E

possible to get a recognised certification, and organisations like Architecture 2030 (the Zero Code) and the GBCA are helping not just to promote the opportunities but set minimum standards for what we see as sustainable buildings.

Eco: What role do mechanical services engineers have in striving toward more net zero carbon buildings?

Parry: Their engaged involvement is paramount to achieving buildings that have operational performance. Architects and engineers must work closely to optimise the building envelope and streamline building services; the whole package must become more robust.

The final frontier is then the construction side – can it be delivered onsite?

Cooper: To deliver a net zero carbon or net zero energy building cost-effectively, the ESD and mechanical services engineers need to work extremely hard at the design stage to develop a highly energy-efficient building and efficient building services, to drive down the energy and carbon footprints of the building. This takes effort and expertise. In the case of our own net zero energy SBRC Building, the building services design team initially estimated that we would need a 320kWp solar PV array to meet our net-zero energy goal. But after careful and innovative design changes to the HVAC, lighting and ventilation systems, the array came in at 160kWp.

Even with an array half the original size, the SBRC is significantly energy-positive in practice.

Arnel: Making buildings more airtight will be central to any efforts to reduce energy consumption, but that will

demand improved ventilation and indoor air quality. Mechanical engineers will be absolutely essential as we avoid unintended consequences of more airtight buildings such as condensation and mould issues or trapping of harmful airborne pollutants inside.

BUILT TO PERFORMBuilt to Perform: An Industry Led Pathway to a Zero Carbon Ready Building Code, prepared by the Australian Sustainable Built Environment Council (ASBEC) and ClimateWorks Australia, calls for a zero-carbon-ready building code.

“Improved energy performance of buildings presents a win-win-win opportunity, reducing stress on the electricity network, offering bill savings, supporting a least-cost pathway to a zero carbon built environment, and improving health and resilience outcomes for households and businesses” says ASBEC.

“The National Construction Code is a ready-made policy instrument to influence the operational energy use of new buildings and major renovations. The Code regulates the building

‘envelope’ and fixed equipment, including heating and cooling equipment, lighting and hot water.”

Built to Perform shows that setting strong energy standards for new buildings in the Code could, between now and 2050, reduce energy bills by up to $27 billion, cut energy network costs by up to $7 billion and deliver at least 78 million tonnes of cumulative emissions savings.

The report was produced with the support of the Cooperative Research Centre for Low Carbon Living, the RACV and dozens of building industry and government partners.

The project has been delivered in partnership with CSIRO, Energy Action (EA), Strategy. Policy. Research. (SPR) and the Sustainable Buildings Research Centre at the University of Wollongong (UOW).

AIRAH is a foundation member of ASBEC.

The Built to Perform report can be accessed at www.asbec.asn.au

Mechanical engineers are essential to the design of net zero carbon buildings, such as this one in Hong Kong.

C O V E R F E A T U R E

We encourage mechanical engineers to start educating themselves now. ASBEC recommends a phased introduction of quantified mandatory air-tightness requirements in the Deemed to Satisfy requirements of the Code.

Mechanical services engineers also have a crucial role to play in delivering innovative and more energy-efficient heating and cooling systems that will help with the transition towards zero carbon buildings.

Eco: What HVAC systems or designs provide the best opportunity for net zero carbon outcomes?

Cooper: The question should really start with, “What passive ESD features can the building designers and builders employ to minimise the active heating and cooling needed from any HVAC systems?”

To this end, all those well-established passive design techniques should be the starting point: good solar control, thermal mass inside excellent insulation, good airtightness and moisture control,

great natural ventilation, and the means for occupants to take an active part in controlling their indoor environment. Then a climate-sensitive HVAC system can be implemented, if required, with high CoP (coefficient of performance) and low environmental impact overall.

Parry: Simplicity seems to be the key to the exemplar projects. First principles in the fundamental systems, such as ventilation with heat recovery, and from there conditioning systems can be delivered far more flexibly.

Arnel: High-performing HVAC systems are a central plank in energy efficient buildings. The Built to Perform report demonstrates that significant improvements are possible through increased HVAC efficiency, in line with trends in increased efficiency observed over the past several years.

ASBEC also recommends phasing out gas HVAC in buildings, but further work is required to assess the best approach to this transition. We recommend this

because phasing out gas in buildings is likely to be needed over the long term to meet Australia’s commitments under the Paris Agreement. In a net zero world, gas use in buildings will need to be offset – something that will become increasingly difficult as offset prices increase in the future. In the short term, retail prices for gas have made gas increasingly unaffordable, and as electricity generation transitions towards renewable sources, electricity will be less emissions-intensive and potentially more cost-effective than gas.

Eco: Do we know the effect net zero carbon buildings have on occupants? Does net zero carbon compromise indoor environment quality and comfort in any way?

Arnel: On the contrary, low-energy buildings that are well designed enhance the health, wellbeing and comfort of building occupants. A raft of research makes the connection between energy efficiency and greater comfort.

C O V E R F E A T U R E

A “fabric first” approach to energy efficiency and comfort – through insulation, air-tightness and passive design – can maintain a comfortable ambient temperature, but also reduce condensation and mould by eliminating dampness and improving ventilation. This in itself could have a tremendous impact on Australians’ wellbeing as our asthma rates are among the highest in the world. Researchers at the University of Melbourne’s Centre for Epidemiology and Biostatistics, for instance, have found the risk of active asthma increases by 26 per cent when people live in homes with visible mould.

Cooper: Our own experience, as occupants of the net zero energy SBRC Building, is that a net zero energy building is likely to be one that has excellent IEQ, comfort and amenity.

Using the University of Sydney’s BOSSA post-occupancy evaluation tool to determine occupants’ perceptions, the SBRC building came out extremely well

– scoring top of all the approximately90 buildings in the BOSSA database forspatial comfort, and was on the 95 percent percentile for overall performance,health and productivity and at 96 per centfor IAQ.

Parry: Historically, there may have been (compromises). But there absolutely shouldn’t be, and some building standards utilise the pursuit of optimal IEQ and comfort to actually get the best outcomes for energy efficiency.

Passivhaus, for example, does this really well, focusing on the building envelope but at the same time having recommendations and criteria around natural ventilation, daylight, radiant comfort and air filtration that aim to capture the complete package. Something that is being found by researchers and practitioners, though, is that comfort and IEQ is complex, and what might be the intuitive or established understanding of a particular issue might not be reflected by occupant surveys.

Eco: Is the success of net zero carbon buildings tied to the climate or location in which they reside in?

Cooper: The ideal climate is a relatively benign climate (mild winters and summers) with high availability of onsite renewable energy. Many Australian cities qualify as having the best opportunity! But a net zero carbon building can potentially be built anywhere.

Parry: They’re suited to any climate; the restrictions on delivering net zero depend on the local potential for renewables, but as this could be solar, wind, tidal, etc., then the climate might not be the limiting factor. I expect buildings in locations with limited solar gains would be toughest.

There is one particular amazing office building in Dubai. Despite the climate, they have managed to stay off-grid by first applying the Passivhaus standard for optimised efficiency, then renewables and storage to deal with the office demands and inevitable cooling load.

ECOLIBRIUM • SEPTEMBER 201840

C O V E R F E A T U R E

Arnel: Net zero can be achieved in every Australian climate through a combination of efficiency, on-site renewable energy and off-site procurement of zero emissions electricity. The respective contribution of these varies across different climate zones.

In Built to Perform, ASBEC and ClimateWorks analysed eight building “archetypes” across four climate zones, each of which was modelled in four orientations. Many of the energy efficiency measures were found to be cost-effective for all the climate zones analysed. However, in milder and cooler climates, wall, under-slab and slab-edge insulation, as well as increased thermal mass improved residential building performance, and there were stronger requirements for heat exchangers in some non-residential buildings. In warmer climates, ceiling fans and larger eaves improved performance in residential buildings. Lighter outside wall colour boosted the performance of commercial buildings.

These are only a selection of the measures that could be pursued to achieve net zero carbon buildings. Improving the design of a building through orientation and careful selection of window sizes and locations, for example, is often the lowest-cost option to improve energy performance. Leading designers have shown that with close attention

to building design, very high energy performance can be delivered at low cost.

Eco: Which of the many rating systems are most aligned with achieving a net zero carbon outcome?

Cooper: The Living Building Challenge (LBC) framework is particularly well suited to this purpose, although it is widely regarded as probably the toughest building sustainability performance tool on the planet.

Here I speak from experience, as we are still making our way through the final stages of LBC accreditation. The LBC requires buildings to be net zero energy. In addition, the version we designed SBRC to deals with embodied environmental impacts by requiring developers to pay for an accredited carbon offset to counter the embodied carbon of the building, which is an excellent way to encourage dematerialised building designs, in the sense of using fewer materials generally and also the use of low-impact and recycled/reused materials.

Parry: The Living Building Challenge is great, and actually requires onsite offset of 105 per cent of energy and no combustion, and so is net zero carbon by default. All of these tools can be used to deliver the baseline efficiency, and Green Star is moving to require increasing

levels of efficiency. Unfortunately, the residential space is not well covered by efficiency standards, despite accounting for a significant proportion of the built environment.

Arnel: All credible rating systems could help to deliver outcomes aligned with a net zero future. For example, the GBCA has recently released its Carbon Positive Roadmap, outlining a pathway for Green Star certification to require net zero carbon outcomes.

Eco: What does the future hold for net zero carbon building in Australia?

Parry: Unfortunately there is much resistance to improving building standards, using cost as an immovable barrier, but much of this has to do with education. Thankfully, there is a bigger imperative and a push that will eventually see this type of standard become the norm. It might be a long and convoluted path, though!

Cooper: The concept of net zero carbon buildings becoming mainstream in Australia is achievable in the coming decade. We already have many exemplary net zero energy buildings operating, and recent research such as the ASBEC NCC Trajectories project has shown that the net zero energy goal is economically viable for a range of building types, including detached and attached housing, in the near term.

However, one of the big challenges, particularly for buildings with limited opportunities for onsite renewable energy generation such as apartments, is to decarbonise the Australian grid quickly so that we can power all buildings from renewable energy sources, and therefore massively reduce our national greenhouse gas emissions.

Arnel: We are optimistic that COAG’s energy ministers will commit to a set of forward targets for minimum building energy standards – and this will mean that the whole industry will benefit from the learnings of those that are already leading on zero carbon buildings. And that will mean eliminating emissions and reducing costs, while creating buildings that are more comfortable and healthy places for people.

In the meantime, market leaders are continuing to demonstrate the benefits and feasibility of moving rapidly towards zero carbon buildings. ❚

The National Carbon Offset Standard (NCOS) is a voluntary standard to manage greenhouse gas emissions and to achieve carbon neutrality. It provides best-practice guidance on how to measure, reduce, offset, report and audit emissions for organisations, products and services, events, precincts and buildings.

The NCOS can be used in a number of ways.

Organisations can use the standard to better understand and manage their carbon emissions, to credibly claim carbon neutrality and to seek carbon neutral certification.

To achieve and maintain a valid and credible carbon neutral claim against the Building Standard, the responsible entity and/or approved certifier must:

➦ MeasurePrepare a carbon account

➦ ReduceReduce emissions where possible

➦ OffsetCancel eligible offset units tocompensate for remaining emissions

➦ ReportPrepare a public report

➦ AuditArrange independent audit orquality assurance of the carbonaccount and offsets cancelled.

THE NATIONAL CARBON OFFSET STANDARD (NCOS)