Reorienting Green Ratings Towards the Big Problems Rather than Business as Usual: A Review of Pragmatic Issues

Abstract

With expanding urban sprawl and the characterization of Australian housing as little more than glorified tents, there is a clear need for expert-informed tools—such as the Green Building Council of Australia’s Communities ratings. But what lessons can be learned from the ratings of recent housing developments? A review of existing cases and supporting materials found low rates of engagement for some criteria and few projects meeting the criteria, with the most direct links being with sustainability. The patterns of scores obtained and criteria addressed appear to reflect many developers placing emphasis on compliance with the minimum standards rather than best practice in sustainability. Notable areas with poor performance include greenhouse gas mitigation strategies, the use of environmentally friendly materials and the sustainability of buildings. Strong, comprehensive education campaigns regarding up-front costs relative to long-term benefits, perhaps more heavily focused on end consumers, may help address some of the hesitancy developers have in engaging with key criteria. However, current rating frameworks fail to account for the pressing need for infill development to address the ‘missing middle’. Perhaps an evolution is needed in sustainability-oriented ratings, such as a mandatory sustainability assessment, that would crystallize the green premium of sustainable housing, thereby harnessing the demand from consumers’ for better quality.

1. Introduction

Australia is currently going through a housing crisis characterized by a shortage of housing and a lack of housing affordability [1]. Lower-income earners seeking affordable housing end up having increasingly large commutes to city centers and their jobs, resulting in an infrastructure growth pattern known as urban sprawl [2], due to the physical expansion of urban areas [3].

Urban sprawl is a complex phenomenon that has the potential to cause ongoing detrimental effects on the environment, as well as the economy, social wellbeing and the sustainability of cities [4]. Urban sprawl is costly to local councils and governments, as well as the general population, particularly due to the cost of additional infrastructure and the increased reliance on cars [5].

Urban sprawl leads to challenges in energy sourcing, transport congestion, water and air pollution, natural resource availability and environmental quality [6]. Essential infrastructure may cost 2.5 times as much as inner city infrastructure [5] and lower-density housing consumes 83% more energy [7]. Exacerbating these sustainability issues, urban sprawl often results in urban heat island effects [8], among other problems that sustainable cities would wish to avoid.

The causes of the growth of urban sprawl may be symptomatic of, among other issues, a phenomenon known as the ‘missing middle’. The missing middle is a middle range of housing that can act as a transition area between single-household housing suburbs and neighborhoods with taller apartment buildings [9]. Building the missing middle often entails infill and redevelopment to provide housing that may be attractive to smaller households seeking a lifestyle with high levels of walkability, such as empty nesters, or others wanting to downsize. [10].

More thoughtful infill of the missing middle can be achieved with form-based building (i.e., specifying the shape, size and design of buildings, such as in terms of setbacks, building height and façades), as well as zoning and regulations based on building types [11]. The missing middle is not about density, per se, but rather, has a thoughtful focus on the esthetics of form and building type in context.

The word “middle” in the term “missing middle” refers mainly to the middle scale of buildings, but also refers to being affordable for the middle-income market [11]. However, note that although infill that attempts to address the missing middle will often be of higher density than suburban houses, the emphasis is on allowing a range of types of housing appropriate for a particular neighborhood, not density.

The push to address the missing middle is one consequence of demographic changes, where the majority of new households created over the next 15 years will be households without children, a large portion of which will be single-person households [10]. These demographic changes are occurring in the context of a unmet preferences, particularly for households without children, in communities where the vast majority of services are available within easy walking distance [10]. A key component of the solution to this situation is argued to be planned neighborhoods with multi-unit, house-scale buildings that are walkable and available at affordable prices.

The types of missing-middle housing that are needed are house-scale buildings with multiple homes within them, ranging from duplexes to mansion apartments [9]. The focus of the missing middle is on the scale (i.e., being of house scale) and the forms of buildings, with calls to avoid certain types of middle-density buildings in certain contexts, requiring a more complex approach to guidelines and regulations. More specifically, although the houses that make up the missing middle vary from city to city and region to region, the characteristics they share include the following:

• Being in a walkable setting;
• Having lower perceived density (where perceived density is largely a function of form, scale and building types), but enough objective density to support services and amenities, including transportation options;
• Small-to-medium-sized building footprints (with a body width, depth and height no larger than those of a single family home);
• Smaller but very livable homes, bearing in mind that these smaller homes are very attractive to large portions of the market, although this then leads to the challenge of creating small spaces that are well designed and comfortable;
• Functioning like a family home, perhaps the most important characteristic in terms of market viability, which entails providing a similar living experience to living in a standard suburban single-family home (e.g., entering via a private door on a front porch), which should be much less of a change than moving to a high-rise apartment [11].

The consequences of the substantial and increasing urban sprawl arising from the missing middle are exacerbated by the low standards of buildings in Australia. Housing in Australia is so flimsy that the most populous state capital cities in Australia have surprisingly high relative rates of death from cold weather, which are eight to twelve times the mortality rates due to heat [12], leading to Australian houses being called ‘glorified tents’ [13]. The far higher rates of mortality from cold than heat are particularly surprising, because the three Australian state capital cities analyzed in [12] are all temperate, being either temperate humid subtropical or temperate oceanic in terms of Koppen climate types [14]. These three cities (Brisbane, Sydney and Melbourne) often have heat waves and repeatedly achieve temperatures over 40 degrees Celsius every year recently, and have either not had snow or only had snow a maximum of three times in the last hundred years. The implication is that the unexpectedly high mortality rates from cold are a function of the poor thermal performance of houses in Australia (per [13]), especially in terms of air-tightness (which currently has no minimum standard at all for residential housing), as well as insufficient insulation (which has quite a low minimum in building codes).

There has also been growing recognition, from a productivity perspective, that there is a need to improve building quality, among many other issues [15]. Therefore, whether in terms of the residents’ health or the productivity that drives affordability, stronger guidelines with higher standards may help builders and developers better address urban sprawl and the consequences of focusing so heavily on the minimum standards when building housing.

In Australia, there are multiple programs available to developers to assess and measure sustainability initiatives in the construction industry and to provide benchmarks for best practice in sustainable urban growth. Possibly the most widely known sustainable housing rating program in Australia is the Green Building Council of Australia’s (GBCA) Green Star rating system [16]. Therefore, the following sections will briefly introduce some international approaches to the rating of sustainable development and then explore the GBCA’s community assessment tool (arguably the most applicable tool for addressing the missing middle), and explore how the approaches used by certified projects reveal the issues that the developers focus upon, resulting in the suggestion of some specific areas for consideration in future revisions of the tool and the associated lobbying and influence processes of the GBCA.

1.1. Rating Sustainable Urban Development

The increase in demand for sustainable development has been reflected by an increase in the creation of building-related sustainable rating schemes. A rating system creates a performance driver for industry, where the competitive environment reinforces the goal of producing global best practice guidelines through a quantifiable assessment that allows direct comparisons within the industry, and encourages participation in improving them. These programs can also encourage the development of relevant technologies in industry, contributing to the overall improvement of the built environment and sustainability of areas through innovation.

One of the first broadly recognized rating schemes for sustainable urban development was the UK-based Building Research Establishment’s Environmental Assessment Method (BREEAM) established in 1990. The rating systems started with a simpler focus, directing ratings towards specific issues such as toxicity, its impact on health and the quality of indoor spaces [17]. By 2017, an increase in assessment systems led to approximately 600 rating systems worldwide [18]. Some leading sustainability rating systems in use are shown in

Table 1. A summary of select sustainability rating programs (adapted from [18,19]).

Program Name	Country of Origin
Building Research Establishment’s Environmental Assessment Method (BREEAM)	United Kingdom
Leadership in Energy and Environmental Design (LEED)	United States of America
Leadership in Energy and Environmental Design Canada (LEED)	Canada
High Environmental Quality (HEQ)	France
Green Sustainable Building Council (DGNV eV)	Germany
Green Star Program	Australia
Green Star Rating	New Zealand
Building Environmental Assessment Method (BEAM)	Hong Kong
Building and Construction Authority (BCA)	Singapore
CEEQUAL	United Kingdom
Comprehensive Assessment System for Building Environment Efficiency (CASBEE)	Japan

. Many of these programs operate through an optional participation model, with incentives provided in some cases, but not all.

Programs have moved further towards overall environmental and sustainability performance as climate change and environmental impacts have become more prominent, working alongside initiatives to develop technologies to improve practice in such areas [17]. The systems vary in terms of their criteria, overall focus, breadth of the scope of the rating, and claims of potential improvements [20]. For example, one of the criterion differences by geographical area is the seismic considerations included in the CASBEE rating system, a program operating in Japan, one of the most earthquake-prone areas in the world [21].

These rating systems have found different roles in their respective development areas across the world, with differing areas of focus across industries but many common trends between them. The broad areas of sustainability assessment for four of the leading rating tools and that of the GBCA are shown in

Table 2. Summary of areas contributing to assessment scores (adapted from [21,22]).

Criteria	CASBEE	Green Star	BREEAM	LEED
Ecological Aspects	X	X	X	X
Local Characteristics	X	X	X	X
Hazards		X	X
Water
Water Uses and Monitoring	X	X	X	X
Water Recycling Systems	X	X	X	X
Energy
Thermal Load Control	X	X	X	X
Energy Monitoring	X	X	X	X
Renewable Energy Production	X	X	X	X
Materials
Eco-Friendly Material Use	X	X	X	X
Life Cycle Assessment		X	X
Construction and Demolition Waste Management		X	X	X
Seismic and Security Aspects	X
Outdoor quality
Global Warming	X		X
Heat Island Effect	X	X		X
Pollutant Emissions	X	X	X
Noise Pollution	X		X
Light Pollution	X	X
Operational Waste Management	X	X	X
Sustainable Transport and Mobility	X	X	X	X

. Although these categories of criteria represent only elements of the overall assessment process, the pattern of similarities and differences begins to illustrate the nature of the programs [21].

With many of these programs built with a similar concept in mind, some, including the Green Star ratings, have drawn inspiration from more developed programs such as BREEAM [21]. BREEAM has also seen numerous revisions to its program that aimed to create a well-rounded assessment, and this has led to its reputation as a leader in the industry, having completed assessments of over 250,000 buildings and over 15,000 projects [19,23].

In Australia, the Green Star rating system is run by the GBCA and is recognized as the largest assessment tool of its kind in Australia, and one of the most detailed assessment systems [24]. Additional rating systems in Australia focusing on sustainable and environmental goals include the Building Energy Efficiency Certificate (BEEC), National Australian Built Environment Ratings System (NABERS), TNationwide House Energy Rating Scheme (NatHERS), Living Building Challenge, building sustainability Index (BASIX) and Enviro Development [25]. Each of these systems has the potential to assist in the ultimate goal of encouraging sustainable practice and providing overall measurable assessments of performance. BASIX and NABERS are the only mandatory systems among these, but they are only applied in limited situations such as new dwellings and alterations in the state of New South Wales or 1000-square-meter-plus offices, respectively [24]. Key differences that set apart the GBCA rating system are the broader range and larger size of projects that it can be applied to, with tools developed for assessing communities, individual buildings and, in some cases, custom projects [26].

1.2. The Green Star Rating System Used in Australia

The GBCA is an organization established in 2002, directed towards driving sustainable development in the built environment [16]. The organization aims to address this issue through several avenues, including rating current projects, educating industries in the area, advocating through government, and collaboration [16]. Their rating tools originated as tools to be used for buildings only, focusing on the elements of each structure, but a new, broader edition was released in 2015 to cover communities [26]. The rating tool is called Green Star, with ratings ranging from 1 to 6. The lowest score reflects minimum practice, and the highest score of 6 indicates world leadership status. Certified Green Star projects that attain a six-star rating are becoming more prevalent within Australia, but there is still room for improvement, with many projects still scoring in the lower categories.

There have been a total of 2827 certifications issued, including 456 certifications in the 2020 financial year alone, reflecting the rapidly growing use of systems to assist with sustainable development [26]. The Green Star rating system can be split into four key categories: Communities; Design and As Built; Interiors; and Legacy and Performance [26]. The most prominent of these categories is Performance assessments, which include 1438 of the 2827 certifications, followed by 1030 Design and As Built certifications [26]. The least utilized category is the Communities tool, with only 68 certified projects as of November 2021 [27], despite the need to address the missing middle.

The Communities tool was added to the program in 2015 and is still being improved [26]. The Green Star—Communities tool assesses the design and development of large-scale projects at a precinct, neighborhood and/or community scale. The Green Star—Communities program has five key areas that are assessed, including Governance (28 points), Liveability (22 points), Economic prosperity (21 points), Environment (29 points) and Innovation (10 points) [28], as detailed in

Table 3. Criteria and weightings of GBCA Green Star—Communities Version 1.1 (adapted from [28]).

Index	Criteria	Points Available	Percent Category	Percent Overall
	GOVERNANCE	28	100%	25.5%
1	Green Star-Accredited Professional	1	3.57%	0.91%
1.1	Green Star-Accredited Professional	(1)
2	Design Review	8	28.57%	7.27%
2.1	Site Planning and Layout	(4)
2.2	Urban Design	(4)
3	Engagement	6	21.43%	5.45%
3.1	Stakeholder Engagement Strategy	(3)
3.2	Strategy Implementation	(3)
4	Adaptation and Resilience	4	14.29%	3.64%
4.1	Climate Adaptation	(2)
4.2	Community Resilience	(2)
5	Corporate Responsibility	3	10.71%	2.73%
5.1	Corporate Responsibility	(1)
5.2A	Sustainability Reporting—Core	(1)
5.2B	Sustainability Reporting—Comprehensive	(2)
6	Sustainability Awareness	2	7.14%	1.82%
6.1	Community Users Guide	(1)
6.2	Sustainability Education Facilities	(1)
7	Community Participation and Governance	2	7.14%	1.82%
7.1	Community Facility Management	(1)
7.2	Community Program Management	(1)
8	Environmental Management	2	7.14%	1.82%
8.1	Environmental Management System	(1)
8.2	Environmental Management Plan	(1)
	LIVABILITY	22	100%	20.0%
9	Health and Active Living	5	22.73%	4.55%
9.0	Minimum Requirement—Footpaths	(-)
9.1	Active Lifestyle	(2)
9.2	Recreational Facilities	(2)
9.3	Healthy Places	(1)
10	Community Development	4	18.18%	3.64%
10.0	Minimum Requirement—Community Development Plan	(-)
10.1	Community Development Officer	(1)
10.2	Community Group	(1)
10.3	Community Events	(1)
10.4	Community Information	(1)
11	Sustainable Buildings	4	18.18%	3.64%
11.1	Certified Non-Residential Buildings	(4)
11.2	NatHERS and Livable Housing Australia	(4)
12	Culture, Heritage and Identity	3	13.64%	2.73%
12.1	Understanding Culture, Heritage and Identity	(1)
12.2	Enhancing Community Culture, Heritage and Identity	(2)
13	Walkable Access to Amenities	2	9.09%	1.82%
13.1	Walkable Access to Amenities	(2)
14	Access to Fresh Food	2	9.09%	1.82%
14.1	Access to Fresh Food	(1)
14.2	Local Food Production	(1)
15	Safe Spaces	2	9.09%	1.82%
15.0	Minimum Requirement—Visibility	(-)
15.1	Design for Safety	(2)
	ECONOMIC PROSPERITY	21	100%	19.1%
16	Community Investment	4	19.05%	3.64%
16.1	Community Infrastructure Investment	(4)
17	Affordability	4	19.05%	3.64%
17.1	Residential Affordability Strategies	(2)
17.2	Non-Residential Affordability Strategies	(2)
18	Employment and Economic Resilience	2	9.52%	1.82%
18.1	Increase in Local Jobs	(1)
18.2A	Diverse Local Employment—Performance Pathway	(1)
18.2B	Proximity to Major City—Prescriptive Pathway	(1)
18.2C	NCC Class Mix—Prescriptive Pathway	(1)
19	Education and Skills Development	3	14.29%	2.73%
19.1	Higher-Education Facilities	(1)
19.2	Skills Development Programs	(1)
19.3	Industry Capacity Development	(1)
20	Return on Investment	2	9.52%	1.82%
20.1	Analysis of Direct Costs and Benefits	(1)
20.2	Analysis of Indirect Costs and Benefits	(1)
21	Incentive Programs	2	9.52%	1.82%
21.1	Residential Incentives	(1)
21.2	Non-Residential Incentives	(1)
22	Digital Infrastructure	2	9.52%	1.82%
22.1	High-Speed Broadband	(1)
22.2	Wireless Local Area Network	(1)
23	Peak Electricity Demand Reduction	2	9.52%	1.82%
23A	Reduced Peak Electricity Demand—Performance Pathway	(2)
23B	On-Site Generation—Prescriptive Pathway	(2)
23C	Energy Storage—Prescriptive Pathway	(2)
	ENVIRONMENT	29	100%	26.4%
24	Integrated Water Cycle	7	24.14%	6.36%
24A	Integrated Water Cycle Performance Pathway	(7)
24B	Integrated Water Cycle Prescriptive Pathway	(5)
25	Greenhouse Gas Strategy	6	20.69%	5.45%
25A	Greenhouse Gas Strategy—Performance Pathway	(6)
25B	Greenhouse Gas Strategy—Perspective Pathway	(4)
26	Materials	5	17.24%	4.55%
26A	Life Cycle Assessment (LCA)—Performance Pathway	(5)
26B	Life Cycle Assessment (LCA)—Prescriptive Pathway	(3)
27	Sustainable Transport and Movement	3	10.34%	2.73%
27A	Sustainable Transport and Movement: Performance Pathway	(3)
27B	Sustainable Transport and Movement: Prescriptive Pathway	(2)
28	Sustainable Sites	2	6.90%	1.82%
28	Conditional Requirement	(-)
28.1	Previously Developed Land	(1)
28.2	Best Practice Site Decontamination	(1)
29	Ecological Value	2	6.90%	1.82%
29.1	Change in Ecological Value	(1)
29.2	Biodiversity Enhancement	(1)
30	Waste Management	2	6.90%	1.82%
30.1	Construction and Demolition Waste	(1)
30.2	Operational Waste	(1)
31	Heat Island Effect	1	3.45%	0.91%
31.1	Heat Island Effect	(1)
32	Light Pollution	1	3.45%	0.91%
32.1	Light Pollution	(1)
	INNOVATION
33	Innovation	10	100%	9.09%

Note: NatHERS = Nationwide House Energy Rating Scheme; NCC = National Construction Code. Where an Index code includes a letter, the lettered indices within a set represent the alternatives that could be chosen, and the numbers in parentheses represent the maximum number of points available for any given pathway.

. To achieve a six-star rating, a total of 75 points or higher must be attained.

Each of these areas contributes to the overall sustainability rating of a community, with higher weighting placed on items that would apparently have a larger impact on the sustainability of the community [28]. The overall goal is to provide a holistic assessment of all elements of a sustainable project through a well-developed set of criteria.

Some criteria have alternative pathways for assessment, as indicated by letters in the Index column of Table 3. For example, criterion 26, Materials, presents the applicant with two options. The applicant can either pursue option 26A for a maximum of five points, or option 26B for a maximum of three points.

Nonetheless, only a few projects have received a rating over 90 out of a possible 110 in the Green Star—Communities scheme. Completing an item to a higher level is likely to have additional benefits, including greater exposure in industry and a competitive edge over competitors. There has been market engagement with the Green Star—Communities rating tool; however, the developers that have utilized the tool still have difficulty achieving a score over 90 points or have deemed having a higher score not worthwhile.

Importantly, the GBCA notes that their rating tools continue to evolve through industry and government consultation. Consequently, this paper reviews the approaches to the Green Star—Communities rating tool to raise some practical and pragmatic issues that may help the rating scheme achieve its goal of informing and encouraging sustainable property development. Furthermore, the review will also highlight other lessons that can be learned from the ratings of housing developments to improve the sustainability of urban housing.

2. How Are Developers Using the GBCA Communities Tool?

The project started by collating the data available in the GBCA Communities project directory. The collected data were then entered into an Excel spreadsheet for processing. The initial data set was filtered to focus only on projects that had been certified, leaving 68 cases that had been certified under the Green Star—Communities rating tool and excluding 20 cases that had been registered but not yet certified by mid-2021.

Australia had strict lockdowns during the peak of the COVID-19 pandemic, with a variety of policies implemented that impacted building industries; these policies were often changed during that period. Consequently, to reduce the potential impact of the disruptions to supply chains and the many and varying policies that impacted housing construction during the main COVID-19 lockdown periods, the main focus for the analyses is on projects that were concluded or mostly completed before the main lockdowns. The data are used as indicative results for this review, and are not focused on in detail. Checks of the key patterns of results on more recent data led to the results presented below. Notably, the housing industry is still suffering the consequences of the COVID-19 pandemic period, including many companies failing, dramatic changes in immigration and substantial concerns about workforce shortages [15].

From the data provided in the directory and in the list of criteria, each criterion can essentially be ranked in terms of weighting, and preferences can be revealed to determine which elements of a green community are valued most by the GBCA and which are addressed by the developers. The GBCA builds their criteria based on a determined set of factors that, when combined, are the elements required for a sustainable community. They develop the categories and corresponding criteria based on consultation with a wide range of advisors, industry members and developers [26]. The highest-weighted criterion may belong to the Governance category; however, the highest-weighted category is Environmental, with a total of 29 points allocated compared to Livability (22 points), Economic Prosperity (21 points) and Governance (28 points).

The review summarized here explores the patterns in certified cases and the criteria themselves, and their weightings, to highlight patterns regarding their likely impact on urban sustainability. There were some difficulties with the reversal of the rating system, not least of which was that the sustainable buildings category within the Livability category was not as detailed as desired. The details of the criteria and the issues underpinning key criteria, such as supply chain providers, were reviewed. Several sets of concerns emerged and are the focus of the results presented below.

3. Some Notable Patterns Across Certified Developments

This review began with an examination of the pattern of scores obtained, as an indicator of how developers approach the use of the GBCA tool. Further investigation explored which criteria the projects focused on to obtain their points and found notable concerns with the criteria that are the most direct reflections of a house being sustainable—the materials used (under the Livability and Life Cycle criteria)— and the classic sustainability metrics most directly associated with greenhouse gases; furthermore, a review was conducted of more complex, system-level issues.

The points required for a four-star rating range from 45 to 59, the points required for a five-star rating range from 60 to 74 and the number of points required for a six-star rating range from 75 to 110, the maximum obtainable. Overall, of the 68 cases, 4 had achieved a four-star rating, 22 had achieved a five-star rating and 38 had achieved a six-star rating. That is, there were significantly more six-star projects than five- or four-star projects that have been certified under the Green Star—Communities scheme, suggesting that developers self-select whether to go to the effort of obtaining a Green Star—Communities rating, only attempting to obtain a rating if they believe they could score highly, or at least higher than others may expect.

The next step involved looking at the scores achieved by certified cases within each star rating. Figure 1 shows the number of cases, grouped by whether the scores the cases achieved were in the upper or lower half of the points required for each star rating. Within each level of star rating, there is a notable pattern in the scores, where the majority of scores within a band, especially for the cases scoring six stars, are at the lower end of the range of points required to achieve that star rating.

The number of cases seen in the upper half of each band contains a much smaller number of projects than the lower half. The scores for the projects appear to indicate that the developers are either targeting the bottom half of each band (e.g., adding characteristics to just meet the threshold for a star rating) and/or are having difficulties achieving higher scores within a score band.

The cases were reviewed for the notable areas of improvement and challenges faced by many projects. In particular, the review highlighted pragmatic areas for improvement with the Green Star—Communities rating tool.

Some areas seemed to be relatively easy to obtain points for and did not cost much, especially on a per house basis. Other patterns of results were more concerning across the cases, especially the sub-criterion of sustainable buildings within the area of Livability and related areas for improvement such as materials and greenhouse gas strategies. Areas such as sustainable buildings, materials and the management of greenhouse gas impacts would be expected to be central to achieving sustainable development and, yet, were often not addressed or only weakly addressed. Furthermore, the criteria appeared to give little attention to other key sustainability criteria in housing regarding how the houses are considered as a whole, particularly in terms of air-tightness, a pre-condition for energy efficiency and the reduction in energy use (e.g., per [29]).

Some criteria, such as Community Investment, the highest-weighted within the Economic Prosperity category with an allocation of four points, appear to be areas prone to scoring well. This criterion is worth almost 20% of the category and 3.6% of the entire rating system. Project teams can be awarded four points if they can successfully demonstrate that the facilities, programs and services claimed to warrant credit are optional investment items provided within the local area. For example, Lendlease and Landcorp’s six-star-rated Alkimos Beach development in Western Australia, completed in 2018, demonstrates how this can work. The developers contributed AUD 4000 per dwelling to help build community facilities, which was double the required investment to achieve full points for the criterion at that time [30]. Alkimos Beach also demonstrates the up-front costs involved with the Digital Infrastructure criterion. To enable Fiber-to-the-premises internet, the main national providers’ actual costs equate to AUD 3058 per dwelling [31].

There are also other areas of the rating system that appear to have complex demands that may need addressing, such as renewable energy production, a development-wide criterion that can have substantial up-front costs. However, it may be that there is a need for more information and more education about the costs relative to the benefits. In particular, the benefits of more sustainable buildings, including their lower ongoing running costs, can contribute to a green price premium for housing owners [32], and consequently, they would be valued by the end consumer. To highlight the pragmatic opportunities in this space, the section below pragmatically reviews some of the key criteria that are under-engaged by certified cases.

One of the key criteria that demonstrates how key sustainability issues are not being engaged by developers is that of Livability—sustainable buildings. It is unclear, in physical terms, why the criteria associated with materials in buildings are not being addressed. There does not appear to be a lack of available sustainable materials. For example,

Table 4. Energy saving elements for single-story buildings (adapted from [33]).

	NatHERS 6-Star		NatHERS 7-Star
Energy Saving Element	Energy Rating Type	Energy Saving (%)	Energy Rating Type	Energy Saving (%)
Ceiling Insulation	R = 1	46.2	R = 4	56.5
Wall Insulation	R = 1	11.1	R = 3	15.4
Window Glazing	Single Glaze	0	Double Glaze	4
Roof Color	Light Color	8.3	Light Color	8.3
Wall Color	Light Color	13	Light Color	13
Window Covering	R = 0.03	7.9	R = 0.03	7.9
Air infiltration	<1 cycle per Hour	24.5	<1 cycle per hour	24.5
Total Energy Saving		73.45%		80.4%
Annual Energy Consumption		110.16 MJ/m2		81.35 MJ/m2

Note: NatHERS = Nationwide House Energy Rating Scheme.

provides a high-level cost analysis of implementing the sustainable buildings category under the residential Nationwide House Energy Rating Scheme (NatHERS), outlining the minimum requirements of various construction elements to achieve a six-star and then seven-star NatHERS rating for a typical single-story detached dwelling. To upgrade a residential single-story detached dwelling from a six- to a seven-star NatHERS rating, wall insulation can be upgraded from an R1 rating to an R3 rating to provide an additional 4.3 percent energy saving. Ceiling insulation can be upgraded from an R1 rating to an R4 rating to provide an additional 10.3 percent energy reduction. Finally, by changing all windows from single to double glaze, an additional 4 percent energy reduction can be obtained. Overall, these elements would improve the total energy saving of the dwelling by 6.95 percent, lowering the annual energy consumption by 28.81 MJ/m² and moving the NatHERS rating into the seven-star band [33].

A related constraint that may explain why developers have not been more widely and thoroughly using sustainable materials, even among developers applying for a Green Star rating, may be to do with perceptions about increased costs.

Table 5. Additional cost of seven-star NatHERS rating (adapted from [33,34]).

Energy Saving Element	Delta Cost (AUD/m2)	Average Area in Dwelling (m2)	Additional Cost per Dwelling (AUD)
Ceiling Insulation	3.16	179.5	567.42
Wall Insulation	1.51	161.17	242.61
Window Glazing	51.85	37.7	1954.81
Total Cost Difference			2764.84

summarizes a cost analysis to improve a dwelling from a six- to seven-star NatHERS rating, calculated using the average dimensions of single dwellings in Melbourne [32]. The cost difference between a NatHERS six- versus seven-star rating appears to be as little as AUD 2,765 and comes with potentially huge benefits, environmentally and financially, for future residents. However, developers may be seeing that extra cost as a cost to them, which consumers may not be aware of or appreciate.

Countering this increased upfront cost are the ongoing savings over time, although these benefits are specifically for the consumer purchasing the house. The difference in annual energy consumption between the six- and seven-star results (calculated from Table 4) is 28.8 MJ/m² (being 110.16-81.35), which, for an average single-story house in Melbourne, would be 8.004 kWh/m², for an average floor area of 179.5 m² and a cost of electricity of 0.1946 AUD/kWh; this comes to an annual electricity saving of AUD 279.58.

Concerningly, the materials criterion (worth up to five points) appears to be one of the least addressed of the Environmental categories among the currently certified projects. The materials criterion is split into two alternative options, including the Life Cycle Assessment (LCA)—Performance Pathway and Life Cycle Impacts—Perspective Pathway.

To qualify for any points for either of the criteria, the project must first source materials from ISO14001 accredited facilities for at least 80% of tonnage for reinforcing steel, asphalt and concrete [35]. Accreditation bodies require that steel producers comply with the World Steel Association’s Climate Action Program (CAP). In addition, timber utilized on the project must be from sources certified by a forest certification scheme or be from a recycled source, with a minimum of 95% of project timber by cost being certified. Upon an initial assessment of these requirements, most of these criteria look to be achievable, with some requirement for selectivity as to the primary suppliers.

Table 6. An indicative summary of Australian supplier compliance (as of September 2021).

Supplier Name	ISO14001		Materials’ Compliance Requirements	Green Star-Compliant
	Compliance	Original Registration Date
Steel			World Steel Association’s CAP
BlueScope [37]	✔	2013	✔	✔
Liberty OneSteel [38]	✔	2001	✔	✔
Infrabuild [39]	✔	2005	✔	✔
Asphalt			Warm-Mix Product
Boral [40]	✔	Unclear	✔	✔
Fulton Hogan [41]	✔	Unclear	✔	✔
Downer [42]	✔	Unclear	✔	✔
Concrete			Fly Ash Mixes
Holcim [43]	✔	Unclear	✔	✔
Boral [40]	✔	Unclear	✔	✔
Hanson [44]	✗— Not Listed			✗
Cement Australia [45]	✔	Unclear	✔	✔
Barro Group [46]	✗— Not Listed			✗
Timber			Forest Certification Scheme
Big River [47]	Not Applicable		Yes—Australian Forestry Standard for 85% of materials	✔
Boral [48]	Not Applicable		Yes—Australian Forestry Standard, not for all products	✔/✗
Britton Timbers [49]	Not Applicable		Yes—Scientific Certification Systems and Tasmanian Forestry Agreement	✔
Weathertex [50]	Not Applicable		Unclear—Global Green Tag-Certified	?
Austral Plywoods [51]	Not Applicable		Yes—Responsible Wood Program	✔

Note: ✔ indicates compliance, ✗ indicates not compliant, ? indicates uncertainty about whether compliance has been achieved

provides a summary of some major suppliers and their compliance. The details in Table 6 are indicative and were produced based on publicly available information from leading suppliers in each area of the market. There may be organizations that achieved compliance after the product review in mid-late 2021, so compliant-material availability may have increased since the snapshot summarized in Table 6. Over time, as the market develops, compliance should become clearer or more prominent as organizations meet the requirements [36]. The main conclusion from Table 6 is that there should be plenty of availability of compliant materials.

Once each of the above qualification requirements is met, the Life Cycle Assessment—Performance Pathway then requires environmental impact assessments across six general environmental areas (e.g., climate change, ozone formation or depletion, and acidification), with an additional option of performing five further life cycle analyses in more specific areas (e.g., human toxicity, ionizing radiation and particulates) in order to achieve maximum points. An issue for developers following the Life Cycle Assessment path may be a lack of understanding of the tools, making it a more difficult criterion than using product supplier information and certification alone. Though assessment tools to assist with rating have been identified, their requirements are not easy to locate or create [52]. These specific issues may also have the effect of holding back the adoption of newer sustainability-enhancing materials such as mass timber (e.g., per [53]), which have far better life cycle analysis results than standard building materials [54] and have increasingly been found to have positive livability impacts in community-level situations (e.g., see [55]).

Thus, pre-approved products offer a much simpler method for achieving points. The difficulties that are presented due to the more complex requirements are consistent with past studies, highlighting the importance of pre-approval for materials to simplify the process [52].

3.1. Issues Arising from the Consideration of Life Cycle Impacts—Prescriptive Pathway

For the alternative prescriptive pathway, a project can achieve points by meeting the sustainability requirements for concrete, steel, asphalt, and polyvinyl chloride (PVC). Based on their achievements, there is potential for three points to be awarded for the area, considering the percentage of materials meeting project requirements by cost. The compliance requirements for concrete include Portland cement reductions by 40% of mass across the project. For steel materials, the product must be high-strength 500 Mpa steel for all structural applications. Asphalt is required to be a warm-mix asphalt as opposed to the traditional hot-mix product. PVC must meet the PVC best practice guidelines or use alternatives for applications that would normally require PVC, while also being certified to be sufficient for points to be attributed.

There are some caveats to the information summarized in Table 6. For concrete, fly ash products are available to reduce the Portland cement content, but specialty applications, such as projects including early high-strength mixes and high-slump mixes for piling, may have more difficulty meeting the 40% requirement, although it should still be achievable. Further, some suppliers note that they cannot guarantee the availability of fly ash for use, although it is unclear how long this has been an issue, or whether it has since been resolved [40,43].

Appropriate high-strength steel appears to be available, with BlueScope and Infrabuild both noting acceptable materials in their product information [37,39], although there may be a potential cost differential. The installation of warm-mix asphalt has been increasing in popularity in recent years, despite costing AUD 3 to AUD 5 per tonne more than standard materials [56]. Trials were carried out by the majority of the Australian state and territory road authorities between 2006 and 2012, with the materials used now largely having approval for use [57]. Thus, warm-mix materials were available by 2014 for the commencement of the Green Star—Communities program. A more prominent limitation may be the number of mixes available in warm mixes in comparison to hot mixes, although more warm mixes have been made available since the trial periods, with large producers in the Australian market, such as Boral, Downer and Fulton Hogan, now offering products at their respective plants [40,41,42].

When assessing PVC products, the number of alternatives and the feasibility of their use are limited. Upon reviewing the Vinyl Council of Australia website, there is a readily available list of suppliers of approved products, with the majority of major PVC conduit and pipe providers certified, including Australian Plastic profiles, iPlex pipelines, Marley, Pipemakers Australia, TechPlas and Vinidex [58]. These checks suggest that although alternative materials may take effort to find, depending on the application, finding compliant PVC products should not be a concern. As such, the barriers appear to currently be resistance to change and additional costs [59]. In some cases, difficulties may arise due to being in remote locations, unless contractors are willing to accept additional transport costs to bring products to these areas.

For the specific application of green materials in green communities, the more prominent issues appear to be cost, product awareness and resistance to change [59]. To assist in mitigating these issues, educational initiatives and approved supplier lists are suggested, easing the process for developers [60]. Programs such as GBCA Green Star could assist in resolving any issues associated with awareness of the requirements of the criteria and having contacts to source the correct materials. There is potential for improvement if the program was to provide a list of approved suppliers in each region for each material type. Some of the approved products may have higher costs, although those higher costs may also be partly due to the current lower demand and could be reduced over time.

Alternatively, there is also potential for a decrease in opposition to the additional cost if the lifecycle impacts and value of these materials are understood. Initiatives to increase awareness of costs and lifecycle impacts could be directed to both consumers and developers, to arrive at the point where the increase in cost is seen as justified by both parties. The ultimate goal here is to add perceived value in order to provide clarity about the benefits of sustainable practices [60].

3.2. The Environment, Greenhouse Gas Strategies and Energy Efficiency

The Greenhouse Gas (GHG) Strategy—Performance Pathways is the broadest of the criteria, essentially looking to encompass the projects’ overall improvement in GHG emissions relative to a reference project. This criterion requires calculations of the project factors, including on-site energy usage, power generation abilities and export power, with score assignment based on the percentage improvement attributed to the project. The most likely difficulty here is not having access to the appropriate professionals to perform these calculations at the correct stage in the project. Recommendations for improvements in this category could include the development of a list of reference projects and potentially the development of a tool to calculate the required factors. Further, the importance of early involvement from accredited professionals could be explicitly raised up front. Alternatively, a list of organizations capable of calculating such factors could also be developed to simplify the process for developers.

Energy efficiency is assessed in two forms, with infrastructure lighting being the most easily achievable of the two aspects. To meet the criteria, traffic lights and streetlights must use light-emitting diodes (LEDs) or infrastructure lighting with a minimum of a 15% reduction below a benchmark level. However, this criterion has received little attention from certified projects.

One of the difficulties in addressing this criterion could be due to the requirement to also manage light pollution. Many LED lights are not of an acceptable light temperature (Kelvin) rating to allow them to simultaneously pass the infrastructure lighting and light pollution criteria. The challenges associated with addressing both reductions in community lighting and reducing light pollution are nuanced, but are surmountable (for a detailed review of the LED paradox, please see [61]). Cost should not pose a barrier here, with the lifetime cost of LED lights being lower due to LEDs’ greater life span and lower energy consumption, although the higher upfront cost of LEDs could be a deterrent, as could the need for those LEDs to be warm colored. Reticence to address the lighting criterion could arise from a lack of developer knowledge of life cycle cost reductions, a common issue with energy efficiency improvements [62]. To assist with raising awareness, technical advice sessions could be run for Green Star professionals with the potential to create a shortlist of products that meet both efficiency and light pollution requirements. These education sessions could be coupled with the use of publications to demonstrate the lower life cycle cost of LED systems despite the marginally higher upfront cost.

The second aspect impeding energy efficiency is that all upgrades to existing buildings need to meet best practice requirements, including requirements for heating and cooling, lighting and water heating. Difficulties with implementing energy-efficient buildings can depend on the nature of the project, particularly the lack of control in existing buildings. That is, although many projects involve a master plan, control of existing privately owned locations can be limited.

Cost-efficient improvement methods commonly provide three to four times their initial cost in savings throughout their lifetime, further supporting the life cycle cost benefits [63]. The behavior of avoiding the upfront costs of energy-efficient buildings, then effectively paying more over the life of the building, is a barrier that has been argued to be due to a lack of understanding [62]. This pattern of behavior further reinforces the need for initiatives to address knowledge gaps, to emphasize the value of initiatives and incentivize improvements.

3.3. More Complex Concerns Across the Rating Categories

There were a few criteria that highlight other complexities regarding their rating, in particular, renewable energy production across the community, ecological value and the heat island effect. Renewable energy production is the criterion focusing on the utilization of renewables to produce energy on site for at least 5% of the precinct’s projected annual thermal and electrical demand [28]. Renewable energy production has seen significant development in recent years, and mainstream systems are available that should easily meet this criterion. To increase rates of utilization, government subsidies could be considered for items such as solar panels [64]. There are also other contemporary funding sources that may be helpful in addressing renewable energy generation costs. For example, within Australia, there is the possibility of staged payments for solar panels using buy-now pay-later systems such as Brighte [65]. From a developer’s point of view, solar panels or a renewable energy source could be mandated as part of the project master plan, rather than being considered to be an add-on to the development.

In terms of ecological value, although there may be significant investment required to improve the local environment, savings will come from energy reductions, pollution removal, stormwater runoff reduction and carbon storage [66]. Cost difficulties may be particularly challenging in lower socio-economic areas, where there may not be funds available for initial installation or maintenance [67]. Ecological value may be an area of the criteria that would benefit from information being published to the GBCA community to illustrate the long-term benefits to developers and reduce the resistance to initial spending. Assisting with cost justification could help address a key barrier—both for initial outlay and maintenance requirements [66].

An additional issue is in integrating ecological value into an existing built environment. Adding ecological value could be particularly difficult if the areas being developed never considered ecological value in the initial design, and, depending on development levels, it may be difficult to retroactively carry out improvements [68]. However, the GBCA data suggest that many of the projects seeing improvements are in highly developed areas. The improvements in developed areas could reflect new methods that have been utilized in recent years. Case studies on past projects and innovative methods could be useful for assisting developers, as well as increasing publicity benefits and improving the perception of a development.

In the area related to ecological value, potential barriers to biodiversity in community projects may be a lack of awareness and contradicting requirements with built-environment standards. Biodiversity is often the ‘lowest totem’ in green or sustainable rating systems, with historic performance in programs such as BREAAM and LEED (Leadership in Energy and Environmental Design) showing lower levels of consideration for their criteria [69]. This situation may be compounded by the low value attributed to this category in rating systems, where developers may be able to ignore biodiversity requirements and still reach their desired outcome. The issues common across both ecological improvements and biodiversity requirements for communities could once again be a need for education to reduce barriers and increasing recognition that ecological issues need to be considered early in the planning process.

Possible barriers to addressing the heat island effect criterion may include additional expenditure, and addressing this issue may be avoided because there is a lack of awareness regarding the possible benefits of doing so. Issues surrounding control of the existing environment and land control concerns have been found to be a key hurdle, even in locations that are largely not master-planned areas [70]. The use of master-planned communities should assist in mitigating these heat island issues, along with assistance in terms of planning or policy from governing bodies to encourage landowners to allow improvement measures.

The Innovation category recognizes pioneering initiatives in sustainable design, process or advocacy, but is rarely used by certified developments. The sub-categories within the Innovation category include projects that use an innovative technology or process is world-leading and not recognized under other criteria, contributes substantially to the broader market transformation toward sustainability, has achieved beyond the maximum number of points in Green Star benchmarks, addresses a sustainability issue not in any of the other criteria, and/or engages a criterion from a similar international green building rating tool that is not currently included in the Green Star tools [71]. Up to 10 initiatives can be submitted in an application, with each initiative potentially receiving one point. Very few certified developments had any points for innovation. New avenues for improving innovation may be needed.

4. Discussion

The overall goal of sustainable development rating tools is to provide an assessment of all elements of a sustainable project through a well-developed set of criteria. A review of these criteria and projects leads us to suggest, in terms of immediate, practical improvements, that extra resources should be made available as part of an expanded education effort, especially in terms of how to consider the up-front costs relative to lifetime benefits. Furthermore, possible changes to the rating system could include identifying a list of critical credits; introducing (more) minimum requirements to the critical list; increasing the weighting for some of the more expensive or neglected credits that have large sustainability impacts; restructuring the star bands, especially by increasing the minimum score for a six-star rating; and customizing processes for certain classes of projects, such as infill projects relative to greenfield projects on the urban fringe. This discussion will briefly summarize the more specific business-as-usual activities, but then focus on contributions that could be made that would address key strategic drivers of urban sustainability.

Overall, the GHG performance of the majority of Green Star projects was lower than expected for an initiative focused on sustainability, with none of the sub-criteria consistently addressed by the projects. A variety of activities could help more projects address more of the criteria. Specific education activities (e.g., how to conduct life cycle cost analyses) could improve sustainability efforts, a recommendation that has also been suggested by a review of similar rating systems in other countries [23]. Further, having technical advice sessions run by specialists in the field (e.g., on the best ways of performing life cycle analyses) could assist GBCA-accredited individuals and developers alike.

The costs of improvements have been noted to be a concern for many green community projects [70]. Concerns about the cost of improvements pertain to not only the initial installation, but also the ability of the local government or managing body to maintain public additions, which is why cost issues are particularly problematic in areas of lower socio-economic status [72]. In Australia specifically, there have been calls for government incentives, in a report by the Victorian Environmental Assessment Council, to encourage these improvements, which could assist with issues over land control [70].

Similarly, a common problem is the resistance that emerges from a lack of understanding about the benefits that can emerge, on a lifetime cost basis, from more sustainable technologies, materials and approaches that have higher initial costs, where the focus is on value improvement. To address this resistance, the GBCA could reinvigorate one of its key activities, education, for members of the public and for developers.

Education initiatives could focus on both the consumer and developer, illustrating both the cost and environmental benefits to broaden and deepen people’s understanding. Education could lead to a decrease in the resistance to change that seems to impact some categories, such as materials, and other factors that reduce greenhouse gas emissions [59]. Education and awareness regarding how freshwater and stormwater are consumed and harvested also need attention. Resources to educate the public about the benefits of more sustainable housing and more sustainable development could be provided in the form of information sessions.

From a business perspective, education programs could also emphasize the point that green changes often no longer incur a cost and are becoming more of an opportunity [73]. Increasing people’s understanding of the benefits of sustainable communities, specifically in terms of the criteria of the rating systems, may assist in addressing some of the hesitancy about more sustainable building. The above points are just some of the issues associated with considering the benefits of green communities. There are many more studies in the literature that could not be summarized here but that could also be more widely disseminated as part of an awareness and education program supporting the Green Star rating system.

4.1. Changing the Green Star Rating System

In terms of specific changes to the ratings, the above review leads to some direct suggestions. The GBCA may want to set more of the higher-weighted criteria within their assessment categories as minimum requirements, due to decreased engagement with criteria that hold significant benefits and value, such as the Affordability criterion. The possible change in the weighting of criteria is generally in alignment with feedback the GBCA has received previously from project contacts as part of their “Have Your Say” feedback system.

In some areas, categories that require particularly high expenditure may need their points reviewed, an example being district heating and cooling under greenhouse gas strategies. Similarly, the criterion of sustainable buildings represents 18 percent of the livability criterion’s points, but other credits, such as creating a community development plan and incorporating cultural heritage, are relatively cheaper to achieve. The potential undervaluing of some areas sees them commonly become the ‘lowest peg’ in many different systems [69], but this is often not the case, at least at the level of broad criteria, with the Green Rating system. For example, livability is the highest scoring amongst the five GBCA Green Community categories, although costly criteria or criteria worth fewer points, such as sustainable buildings, safe spaces, and walkable access to amenities, are sometimes ignored.

A further concern with the Green Star rating system was the breadth of the star rating bands, especially the breadth of the six-star band. Restructuring the bands may help the rating system achieve its goals. Such a broad six-star score band enables developers to build sub-standard ‘cookie cutter’ communities and claim them as a sustainable six-star neighborhood. Although the proposed change may make it more difficult for communities to achieve six-star ratings, the overall quality of the infrastructure produced will likely improve.

The process of the rating system may also need to become more customized to the community being assessed. In particular, greenfield sites face different issues and challenges to infill sites. At a broad, strategic level, the need for more of the ‘missing middle’ to be put in place suggests that sustainability assessments should tend to favor infill communities, but the differences in considerations and, thus, criteria between infill and greenfield scenarios may need specific consideration. Infill developments are disadvantaged in terms of being able to obtain a high score because they are less likely to be able to meet many of the criteria. For example, master planning is sometimes not feasible in higher-density, already developed areas, especially for criteria such as the heat island effect, biodiversity, GHG strategies, energy efficiency in existing buildings, and renewable infrastructure, to name a few. Yet, there is a need for thoughtful consideration of form and place when building the missing middle, which would be far more sustainable than greenfield sites in car-dependent areas of urban sprawl. Perhaps a separate assessment scheme is needed for infill development of the missing middle.

One of the few criteria in favor of the missing middle or other higher-density sites over greenfield sites was the walkability sub-criterion within livability. Yet, the walkability criterion has some specifics that are unclear. Walkable access to amenities is defined as being within a 400 m radius to primary services and an 800 m radius to secondary services from the habitable building. However, it is unclear at this stage what the detailed definitions are of primary and secondary amenities. Moreover, a strict radius approach, when dealing with walkability, can hide difficulties in access to facilities due to poor walking infrastructure and obstructions that require much longer walking paths than the radius can account for. In contrast, the missing middle considers walkability in terms of being able to walk to a destination such as work, cafes, restaurants and other amenities [11], which is much more of a neighborhood-oriented approach.

In summary, the current rating criteria have quite a few constraints and limitations in engaging the need for more infill of the missing middle and broader system-level sustainability considerations, such as needing to add infrastructure at greenfield sites. To help facilitate further discussion of those broader issues, especially in terms of addressing the missing middle and improving the quality of housing, there may be mechanisms that can build on expertise in sustainability ratings, particularly by surfacing sustainability benefits, rather than being held back by up-front costs.

4.2. Harnessing Latent Pull Forces from Consumers

Rating schemes have the potential to benefit several key parties involved. Developers can increase the sale price of properties based on high ratings and, in some cases, gain access to sustainability grants. Owners can reap the benefits of higher resale values and decreased direct running costs, known as a green price premium [32]. Those in the surrounding environment are commonly left with a more socially beneficial end product. The overall impact can be quantified through the performance data of communities and buildings that have been part of the schemes [23].

Common benefits for developers of accrediting housing sustainability could include improved brand perceptions, which could provide a competitive advantage, with an increasing number of clients seeking out Green Building characteristics [26]. For businesses and communities looking to build, there is a long-term benefit of participating in sustainability rating programs. The long-term resale value of their buildings will increase or remain higher than those in areas that are not of the same sustainability standards, while the running costs of a held asset will also be lower, with the initial investment paid back in 6.5–8 years on most projects.

The benefits of rating schemes include energy usage, water consumption and emissions efficiencies, with many organizations claiming measurable decreases in energy usage ranging between 6% and 40% from initiatives such as the LEED and BREEAM schemes [18]. The Green Building Council of Australia has noted that they have managed to achieve a reduction of 920 million kg of CO₂ each year from their Green Star-Certified buildings alone [26].

Specifically considering the social benefits to a community, a green building environment can improve the physical and physiological state of health of those occupying the building [74]. Green community infrastructure in a part of New York, including bioswales, tree pits, community gardens and permeable pavements, was found to provide local social value, with over 35% of immediate residents indicating that the program improved their quality of life through green infrastructure [75]. From an efficiency point of view an increase in energy performance will lead to a decrease in long-term running costs, important for both individual residents and utility management, and can also decrease financial stress, thereby helping to relieve social pressures [76].

The water-sensitive design of urban buildings and installation of water-saving appliances help reduce the overall water usage in green buildings. Examples of this can include rainwater-harvesting systems such as rainwater tanks, water-efficient showerheads and toilets, and increased green spaces in residential and commercial areas to harvest stormwater runoff and reduce urban heat island effects. The water usage rates of 1307 green-certified buildings in Taiwan over a 10-year period had an overall water use 37.6% lower than the baseline water usage rate for all buildings in the country [77].

Waste management is a key lever in sustaining a future that is not stifled by non-recyclable and single-use materials. Solid waste is expected to rise by 200% by 2050 due to rapid population growth, urbanization and single-use consumerism [78]. Municipal waste often gets transferred to either recycling stations or landfill, with few alternatives. However, practices can impact waste management. A case study of the city of Adelaide’s diversion rate, for which a value of 82% was achieved in 2020, may provide some ideas, although stakeholders suggested that there were considerable barriers to reaching 100% waste diversion [78].

Common items included in rating programs that are directly associated with environmental impacts include eco-friendly material use, improvements in water use and recycling, renewable energy consumption, pollutant emissions, operational waste management and sustainable transport and mobility [21]. The aims in each of these areas are set to differing standards based on each rating scheme, regardless of the rating systems, as drivers to ensure improvements and strong performance [19]. The impacts of a strongly rated project can include a reduction in energy consumption by 66% for an average building when using the Green Star program [26].

Adopting the refuse, reduce, reuse, recycle and repair methodology assists in minimizing the impact of these actions. Alternatives such as using recycled concrete and asphalt mixes, substituting fly ash with Portland cement where possible and using sustainably produced products, can lead to a decrease of over 40% in greenhouse gas production [79]. Past projects such as the Aura community in Queensland also demonstrate that an effective integrated water system can be very beneficial. Using a broad range of measures, the project minimized runoff and prevented impacts on surrounding waterways, with over 43% of their water requirements provided through recycling and reuse systems [27,80]. Improvements in each of these areas can drastically reduce the overall initial and ongoing impacts on the environment, and larger changes could improve sustainability even further.

The mandatory energy ratings for commercial buildings have been found to lead to a green price premium, reflecting decreased direct running costs that lead to higher resale value [32]. Extending the mandatory building energy rating policies for commercial buildings and adapting them to new housing would harness the demand from consumers for better-quality, more sustainable housing, accelerating sustainability improvements in the housing industry.

Mandating a sustainability assessment across multiple criteria for residential buildings and developments would likely receive substantial push back from the industry, especially if the processes were not clear and simple. However, once the details, weightings and calculations underpinning the sustainability assessment have been developed (the GBCA, NatHERS and others would play a role in this, using their expertise), with easy-to-use resources such as software plug-ins for builders, a comprehensive sustainability assessment for new residential buildings could be implemented. To make the effort of learning the new processes worthwhile for builders, perhaps the sustainability assessments could be, at least initially, limited to housing expected to sell for more than 1.5 times the median house price in that city, or developments where the final houses would be expected to sell for a combined total of over 10 times the median house price. Such a mandatory assessment system would help to crystallize the green premium of those houses and would indicate that the houses are likely to be cheaper and more sustainable to live in over the long term.

5. Conclusions

A rating system acts as a performance driver for industry by creating a competitive environment that reinforces the goal of achieving global best practice outcomes. It does this through quantifiable assessments that enable direct comparisons within industry, and encourage broader participation in improving standards. When investigating the GBCA schemes, especially the scheme best aligned with one of the most critical areas to address—the missing middle—there were some concerning trends identified, including low rates of engagement for some criteria and a number of projects not completing several aspects of the largest criteria. The pattern of criteria addressed in these cases appears to reflect developers placing emphasis on compliance rather than performance, although the criteria themselves may need changing. The criteria and their weightings often do not reflect the needs or costs of more sustainability-enhancing elements. For example, using sustainable materials should be worth many times more than merely having a plan to address one facet of sustainability; energy efficiency attracts surprisingly little attention, and renewable energy (particularly solar panels) receives very little attention. Some of the key criteria may be changed to minimum ‘hurdle’ requirements, or have their weighting changed to reflect their contribution to sustainability and the costs associated with addressing their respective criteria.

For the current criteria, a more comprehensive and strongly championed education campaign regarding the considerations of up-front costs relative to long-term benefits in sustainable communities may help to address some of the hesitancy many developers have in engaging with many of the key criteria. Further, educational support for some of the more technical elements, such as the cost–benefit and life cycle analysis tools, could be intensively promoted within the GBCA and to developers, not only serving as a means of educational development for green community developers, but also facilitating the engagement of more of the rating systems’ criteria.

However, the key issues highlighted in this review are those associated with the need to engage system-level sustainability issues, such as addressing the missing middle and lifting minimum standards. Engaging these system-level issues could and—we would argue—should facilitate the building of sustainable housing and development that does not contribute to urban sprawl. Doing so may require a separate set of criteria customized to the infill of the missing middle, because to address this need successfully requires a thoughtful approach to building that reflects the desired forms and types best suited to their context. There are a growing set of examples of ways to approach form-based zoning (e.g., see [9,81]) and housing types that facilitate the infill of the missing middle (e.g., [11,82]), and ratings could be derived to reflect these.

Then, there is the need to lift minimum standards. The current suite of GBCA rating systems has had the effect of lifting standards in the industry, but this review suggests that there is a lot further to go, and lives depend on it. Australian buildings are so flimsy that they deserve the moniker of glorified tents. Building standards need to be lifted not only in terms of using better materials, per the detailed tables above, but also in terms of facilitating the adoption of new materials such as mass timber, which has been shown to be viable and positive in a community-sized context [55]. Further, the green ratings criteria, and, in turn, lobbying for changes to the minimum standards and building codes, could place much more emphasis on key sustainability drivers arising from the investigation of how buildings can be assessed as a whole, particularly in terms of air-tightness (e.g., per [29]). Increasing the standards in the rating systems, continuing to lobby to change basic standards and facilitating or informing the general standards could potentially be enacted as a means of improving and then unifying (called for by [15]) the national building codes.

One of the key issues impacting the declining productivity and, thus, affordability of the housing industry in Australia is the complexity of the national building codes [15]. Instead of simplifying these standards and building codes downwards, they could be streamlined and raised. These efforts to lift minimum standards could also be facilitated by educational efforts, especially for end consumers, as noted above. Extending the mandatory building energy rating policies for commercial buildings that have led to a green price premium [32] to new housing would harness the demand from consumers for better-quality, more sustainable housing, accelerating sustainability improvements in the housing industry.

Missing-middle developments, often aimed at middle-income customers, are likely to also benefit from a well-designed green assessment system. The net result would be housing that has desired esthetic values and is more sustainable directly, in terms of the materials and design of the housing, as well as being more sustainable for the urban system by supporting existing transport infrastructure and not requiring the expansion of infrastructure at the urban fringes.

This review encourages a multi-stakeholder approach to increasing education within the building industry and improving people’s understanding that the costs associated with community projects are key to ratings systems facilitating sustainable building and development. With a focus on practical tips, as well as providing summary guides of appropriate products, this pragmatic review aims to help developers and the GBCA take the Green Star rating system for communities from strength to strength in the future.

These suggestions are not intended to merely enable continuous improvement of the rating systems, but also to ensure that the rating systems consider the bigger picture. Addressing issues such as the missing middle and simpler but higher minimum standards could help to address the housing shortage and affordability crisis in Australia, while also improving the health of the housing’s residents. At the very least, such changes would help society more cost-effectively maintain a high standard of living by, for example, avoiding the need to extend transport infrastructure to greenfield sites on the urban fringe. The issues raised here could prompt the evolution of sustainability-oriented ratings of housing and developments to engage broader sustainability issues and make cities truly more livable.