There has been a call for the construction industry to become more energy efficient in its planning and activities, to reduce greenhouse gas emissions to help combat climate change. The Australian Building Codes Board has implemented ‘Energy Efficiency’ standards through the National Construction Codes to direct the industry towards net zero emissions goals. However, the Board has maintained a focus on operational flows considerations despite this only being a part of the total expenditure in a building lifecycle. Embodied flows, the energy output, and emissions from harvesting, manufacturing, transporting, and manufacturing materials for a building have not been included as a part of the current standards despite their growing share in the outputs of construction.
1. Introduction
Sustainable production and consumption have become a necessity and a priority, globally and within Australia, as humans are confronted with climate change and associated natural crises in modern-day society
[1][2]. Most industries and sectors are evolving and adopting environmentally responsive materials, methods, and processes to mitigate anthropogenic greenhouse gas (GHG) emissions globally, to preserve the environment and prevent catastrophic societal failure
[3][4][5]. As one of the largest global GHG emitters, the construction industry is also changing its conventional practices through policy changes and other legislative frameworks to help mitigate climate change
[6][7][8]. Currently, most construction industries in developed and developing countries have their sustainability policies and practices established aiming at emissions reductions and preserving the environment
[3][9][10][11][12][13]. Many of the existing policies developed for construction industries emphasize reducing operational energy and emissions in buildings during the use phase, although its only part of the energy used and emissions generated from buildings during their life cycles
[14][15][16][17][18].
As one such measure to enforce change within its policies, the Australian Building Codes Board (ABCB) has adopted ‘Energy Efficiency’ standards as a part of the ‘National Construction Code’ (NCC)
[19]. The ABCB is a government representative involved in developing and maintaining a safe and high-standard building industry and has outlined sustainability as a high-level goal for the Building Codes of Australia (BCA) in 2006
[19]. Since then, the BCA and the Plumbing Code of Australia (PCA) have combined to create the NCC, which provides the minimum requirements for Australian states and territories.
Volume One and Two of the NCC have a set of ‘Energy Efficiency’ minimum standards that have adopted tools such as Green Star Rating Tool, Nationwide House Energy Rating System (NABERS) energy for offices, and GHG emissions modelling as a way of verifying compliance to these standards
[19].
The current standards on ‘Energy Efficiency’ sections have an impact on the operational flows of a building project, which typically comes from the building’s design, including energy and emissions from heating, lighting, ventilation, and cooling
[20][21][22][23]. The energy and emission flows associated with building materials and construction practices used for construction of buildings have been neglected from the NCC volumes
[10][24].
This continuous emphasis and commitment on operational flows over the years has made significant contributions towards reducing its share in the total energy and emission flows of a building, leading to the rise in embodied energies’ share in this total output
[25][26][27][28]. Hence, in the recent decade, the emphasis has been shifted to embodied flows associated with building design and construction phases
[9][25][26][29][30][31][32][33][34].
Globally the construction industry contributes 30 to 50 percent of raw materials
[35][36] and 18 percent of worldwide carbon (CO
2) emissions, with electricity, water, waste, and materials being the most significant sources of CO
2 output from the sector
[37][38][39]. As the built environment in Australia grows and thrives in economic performances contributing up to 9 percent of the country’s gross domestic product (GDP) as of 2021, the efforts to reduce these embodied flows should parallel
[25][37][40].
Embodied flows are generated from building design and the construction stage and are associated with materials and methods used. When considering building materials used, raw material acquisition and manufacturing stages contribute significantly to embodied flows as the processes use fossil-fuel operated heavy machinery and other operations
[21][30][31][41][42][43]. These exploitations of raw materials have extreme negative effects on the natural environment, causing land degradation and erosion, creating toxic waste, and emitting excessive amounts of GHG
[44][45]. Transportation also accounts for a significant share of embodied flows associated with these materials
[46][47]. It has been suggested that the construction sector might tackle these emissions by optimizing supplier and client logistics, ensuring maximum efficiency in each load of resources delivered, resulting in minimal capacity wasted and less unnecessary travel to and from sites
[48][49]. Hence, the need for regulatory policies and support for builders to improve their material supply management has been recognised in the current literature
[50][51][52].
The erection of a building during the construction process typically uses energy sourcing from machinery, equipment, generators, electricity, and fuel consumption
[13]. The daily site activities can include mechanical plants such as excavators, compactors, cranes, pilers, and drillers, which typically use different types of fossil fuel, including diesel, petrol, gas, crude oil, and electricity
[53][54][55]. Use of these fossil fuels during building erection leads to significant contributions of GHG emissions, which are considered as embodied flows of the building itself
[33][54][55]. The erection stage of the project is also generally the creator of waste, which has been seen as an indirect embodied flow creator
[50][56]. If not appropriately managed through environmentally responsive approaches, waste can lead to further energy use and emissions generation
[13][25][44][56][57][58][59][60].
There were early discussions in 2003 and 2017 surrounding a potential widening of the NCC’s scope to include manufacturing policy to improve the industries’ reuse and recycling
[61][62]. However, still no changes have been made as of the 2022 amendment of the codes
[2]. The growing market can outline the opportunity for the industry to promote use of environmentally responsive materials
[63].
The modern emphasis on creating green cities and suburbs has been increasing in Australia as government incentives and policies have encouraged builders to adopt more environmentally responsive materials and methods to mitigate embodied flows
[2][64][65]. While Australia is trending in the right direction, some research cites further motivation as a required incentive for builders to become more active participants in working towards sustainability goals
[47].
Australia’s researched transition into sustainability has been challenged by some examiners, with the belief that a ‘passive government’ has permitted builders to have a lack of accountability regarding the energy efficiency and sustainability of their design and construction. This is due to regulations not being audited, being too lenient, and not considering the total life cycle of the building’s energy use
[65]. Cost and time factors can also affect a builder’s decisions regarding efficient design and building. The client’s needs may not prioritize sustainable design if it can negatively impact their budget or timeline requirements
[25][66][67].
The Australian government has committed to the international treaty on climate change, the 2016 Paris Agreement, which is legally binding and aims to limit global warming by reducing GHG emissions
[2][68]. The Paris agreement is a worldwide arrangement by each nation to keep the world’s average temperature from rising above two degrees Celsius over the pre-industrial levels
[69]. Each nation is expected to set its own goals with the treaty and Australia is committing to having net zero emissions by the year 2050
[24][69]. This has been the incentive for many industries, including construction globally and within Australia, to influence change that can have positive impacts on mitigating climate change
[70][71].
Energy efficiency frameworks, codes, and regulations are among the most efficient measures to minimize carbon emissions from the construction industry
[3][10][11]. While the policy is viewed as the base for initiating change, the code’s implementation and effectiveness are pivotal in continuing the push toward a more sustainable future in the construction industry
[72]. Currently, there is the NCC, a performance-based code from the ABCB in Australia. It sets the minimum performance and general requirements for construction designs and activities in many categories. The states and territories in Australia each individually provide the NCC legislative effect as the framework for the construction industry
[19].
In overall, few studies have been conducted with a focus on the Australian codes and regulatory framework surrounding embodied energy output
[2][10]. In Europe
[32][73][74] and in India
[75][76][77][78], there has been much more academic discussion around the topic. These studies have suggested the inclusion of embodied energy requirements in efficiency policies for the nations within their case studies.
2. Embodied Policy and Built Environment Practices
The policy has been significant in guiding the industry towards more efficient practices, as the inclusion of embodied energy within these codes and standards has been expected to reduce greenhouse gas emissions and energy usage that comes throughout the often-overlooked stages of a construction project.
All the studied nations have implemented their strategies for carbon reduction in response to the Paris Agreements
[10][79] and aim to be net-zero carbon by 2050, as many of them share similar aims and timeframes as their intended target.
As discussed, many nations have attempted to combat the rise in embodied emission share within their construction industries with policy and planning
[80][81]. Yet, there is an expectation that their built environments will be impacted due to these process changes, new considerations, and innovation to meet new market demands resulting from the mandates.
The influence on the Netherlands’ physical environment will be strongly emphasized, as the building act changes are one of the primary measures that have been implemented to make a 100% circular economy by 2050. A circular construction economy is a concept identified by the Dutch government’s national environment database to improve their built environment by having the materials within the industry receive high recycling and reuse rates, along with reduced wastage and manufacturing of new materials for buildings. The goal of the Dutch government in their Coalition Agreement is for the economy (including construction) to be 50% circular by 2030, assuming that their principal resource use will be cut in half in the same timeframe. Along with carbon caps, the general goal of a circular economy can produce a future for the Netherlands in which material harvesting, manufacturing, and transportation can be decreased significantly, reducing embodied energy and emissions from these activities.
The built environment changes expected or hoped for by the French government include the need for buildings to have a reduced impact on climate change, improve energy performance, and guarantee they will have a better ability to combat heatwaves, which they expect will become more frequent due to rising temperatures. The thermal designs of these new buildings will be more of a focus, with building envelope and insulation measures also a big part of the new standards expected from construction. The embodied outputs are also likely to be reduced through material selection as envisioned by the International Energy Agency, as the sector’s decarbonization seems destined to result in a more significant number of eco-friendly materials being used. The E+/C- labels will help create better decision-making for designers to create buildings that comply with the RE2020 and are certified.
Denmark’s National Strategy outlines the expected changes to the built environment, as their five focus areas are to create more climate friendly construction, durable and high-quality buildings, resource efficient buildings, energy efficient/healthy buildings, and look to aid this with digitally supported construction. These focuses aim to balance the environment, social needs, and financial quality of buildings to improve the country’s constructed landscape further.
The New Zealand strategy expects that there will be an estimated 0.9 to 1.7 metric tonnes of carbon dioxide equivalent (Mt CO2-e) that can be reduced using their plan for the construction industry. The sector created 7.4 Mt CO2-e in 2018 results, so a reduction of up to 22% would be a drastic change as part of an early plan, which they aim to further reduce to 3.9 Mt CO2-e over time as they navigate policy implementation. The government wants to encourage more timber use in buildings by supporting smaller construction businesses. The government is also exploring ways to provide specialists to the companies so that they can be advised on creating more low-emission builds that use sustainable materials.
3. Australian Built Environment and Embodied Policies
Australia has well-established operational flow efficiency design standards currently being enforced in the construction industry. These have generated a market for green building designs and sustainable considerations that have benefitted Australia’s built environment. Additionally, more consideration towards occupant health and emission reduction has occurred as there have been improvements in energy efficiency since the 1990s
[19]. Despite this, the proportion of embodied flows associated with the harvesting raw material acquisition, manufacturing, transportation, and construction phases of building projects are increasing due to the lack of emphasis and attention.
However, some indications of policy changes to mitigate embodied flows of the built environment have been observed in recent years. The Green Star Buildings (GSB) rating tool introduced by the GBCA has incorporated embodied emissions as part of the minimum requirement for rating buildings. It further establishes that a building requiring a rating should have a reduction of 10% embodied emissions compared with a reference building, which is targeted to increase to 20% in 2030
[10]. It also allows buildings to offset emissions using carbon credits to rate as net-zero buildings. The developed GSB acting as a mandatory tool to reduce embodied flows in the Australian built environment is a positive signal of industry-level change. In addition, there is a significant demand for change advocated by the industry stakeholders, requiring more stringent control and regulation of embodied flows in the near future
[10][38]. Nonetheless, Australia is yet to take strong actions on establishing and enforcing effective policies and regulations and incentive schemes to direct the industry towards embodied flow reduction targets fast.
Clean energy finance corporation (CEFC) demonstrates that Australia has great potential to reduce embodied flows in the building sector
[82]. It quantifies the decarbonization challenges and recognizes Australia’s opportunities to mitigate embodied flows through optimizing material usage, utilizing low-carbon materials and construction technologies. Alternative material solutions, including geopolymer concrete, environmentally responsive concrete admixtures, and recycled materials, are proposed to substantially lower embodied flows
[9][25][83]. Switching to renewable energy sources for material manufacturing and building construction is also one of the most effective methods of achieving embodied emissions reductions
[82][84].
However, these potential solutions are not with their inherent risks and challenges
[55]. Additional costs, supply chain issues, unawareness, and fear of change associated with green materials and technologies are perceived as the most significant challenges in adopting sustainable materials and technologies in the Australian built environment
[85][86][87]. Although many research studies have established that embodied flow reduction does not lead to additional costs, low and medium-industry practitioners are yet reluctant to believe that truth
[25][67][88][89]. Therefore, the regulatory bodies need to establish effective policies and frameworks and introduce incentive schemes to drive industry practitioners towards sustainable alternative solutions. If effective policies and strategies are not enforced soon, “Australia will fail to meet its 2030 Paris emissions reduction target”
[2].