Environ Dev Sustain (2013) 15:1573–1591 DOI 10.1007/s10668-013-9462-0

Sustainability assessment of urban communities through rating systems Umberto Berardi

Received: 5 January 2013 / Accepted: 6 May 2013 / Published online: 11 May 2013  Springer Science+Business Media Dordrecht 2013

Abstract This paper focuses on the sustainability assessment of urban communities through multi-criterion rating systems. Recent interpretations of the concepts of sustainability, assessment and community are discussed before reviewing existing assessment systems. In particular, the systems BREEAM for Communities, LEED for Neighbourhood Development and CASBEE for Urban Development are presented and compared. Each one of these systems bases the assessment on the summation of rates for different criteria often similar to those considered in sustainability assessments of buildings. The comparison shows that existing systems often accept a weak sustainability where natural resources may be subsidized by other priorities. Missing assessment criteria are proposed mainly within the social and economic dimensions of sustainability. This paper also shows that the dynamicity of a community suggests considering the sustainability assessment systems as tools to monitor the evolution of communities. Finally, it shows that an increase in citizen engagement in the selection of assessment criteria is necessary to share priorities and customize sustainability goals for each community. Keywords Sustainability assessment
Rating systems
Urban community
Urban sustainability
Triple bottom line 1 Introduction Climate change has raised concerns over the rapid depletion of the environment and its resources. International programs and policies have indicated that the built environment is the most promising sector for a rapid transition to sustainability (IPCC 2007; GhaffarianHoseini et al. 2013). This attention to the built environment is due to energy consumption and greenhouse gas emissions, which, in developed countries, represent 30 and 40 % of the total quantities, respectively (IPCC 2007). In this scenario, many examples of sustainable communities are showing the advantages of sustainability applied at the U. Berardi (&) Worcester Polytechnic Institute, 100 Institute Road, Worcester, MA 01609-2280, USA e-mail: [email protected]

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community scale. Meanwhile, an increasing request for tools to assess their sustainability is recorded worldwide. The sustainability assessment of the built environment was addressed with rating tools for buildings more than two decades ago (Ha¨kkinen 2007). Sustainability assessment systems for buildings were first developed in Europe and North America, before diffusing worldwide (Sev 2011; Berardi 2012). Although there is a high demand and attention to green buildings, these have demonstrated insufficient to guarantee the sustainability of the built environment (Ha¨kkinen 2007; Cole 2010). Recent literature has discussed the importance to go beyond the sustainability assessment of single buildings and to enlarge the assessment scale to communities and cities (Berardi 2011; Turcu 2012). Cole (2011) stated that a significant achievement in sustainability assessments has been the introduction of rating systems for communities and urban design. The increase in the scale allows the consideration of aspects not accounted for when simply focusing on the building scale. Examples of some aspects are the flows and the synergies between initiatives within the built environment and consequent results for sustainability (Berardi 2011). Sustainability assessments at the community or city level are proving to be much more than the summation of individual green buildings and infrastructures (Haapio 2012; Mori and Christodoulou 2012). The switch to a larger scale cannot be considered simply as the aggregation of sustainable objects, as scaling up results in complex interactions. These interactions may significantly alter the results which may have been valid on the building scale (Bourdic and Salat 2012). Requests to go beyond the building-centric approach in the sustainability assessments have led to discussions of new possible areas of sustainability within the built environment (Conte and Monno 2012; Berardi 2013; GhaffarianHoseini et al. 2012). One of the main critiques of sustainability assessment on the building scale has been its inability to capture what makes a built environment sustainable for its citizens (Rees and Wackernagel 1996). The rare consideration of criteria related to social and economic aspects of sustainability has often been underlined, but many other limits of current sustainability assessment tools exist (Berardi 2011; Conte and Monno 2012). Previous considerations show that communities are nowadays considered as a proper scale to assess sustainability of the built environment. In fact, the urban environment plays a prime role in the social and economic sustainability, and it has a huge impact on the environmental sustainability (Mori and Christodoulou 2012). Over 50 % of the world’s population currently lives in urban areas, a figure expected to rise to 70 % by 2050 (UN 2008): In Europe, 75 % of the population lives in urban areas, and by 2020, the number is expected to reach 80 % (EEA 2006). The importance of urban areas is also confirmed by the diffusion of megacities of more than 20 million people which are gaining ground in Asia, Latin America and Africa (UN 2008). As a result, most resources are nowadays consumed in urban environments worldwide. This fact contributes to the economic and social importance of urban communities, but also to their poor environmental sustainability. Their metabolism generally consists of the input of goods and the output of wastes with unavoidable and consistent externalities (Turcu 2012). Urban sustainability has attracted much criticism, as urban areas rely on too many external resources. As a matter of fact, urban areas are (and probably will always be) net consumers of resources. Promoting sustainability of urban communities has been interpreted through the promotion of natural capital stocks, such as local foods or fisheries. Other interpretations of urban sustainability have promoted a more anthropocentric approach, according to which urban areas should respond to demand based on people’s needs. This last approach interprets sustainability as a long-term measurement of the quality of life and focuses on the social aspects of sustainability (Turcu 2012).

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Large and mega urban areas increase the difficulties in promoting sustainability and their consequent request of tools for sustainability assessments. New assessment systems have hence been created in last few years to answer such requests (Ha¨kkinen 2007; Sharifi and Murayama 2013). Pope et al. (2004) and Tanguay et al. (2010) have offered a review of available indicators for measuring sustainability. They showed that most of the currently used indicators are characterized by a strong environmental approach. This is evident considering indices such as the Ecological Footprint, the Water Footprint, the Environmental Sustainability, and the Environmental Vulnerability. The preservation of natural resources is a key component in ensuring sustainability, and as a matter of fact, the environmental quality is a key dimension of people’s well-being. Furthermore, people also directly benefit from environmental assets and services as these allow them to satisfy basic needs and to enjoy leisure time (OECD 2011a). Thus, it is commonly accepted that environmental sustainability has an effect on the social dimension of well-being (Vallance et al. 2011). This paper is based on the belief that direct measures of social and economic aspects should be explicitly considered in sustainability assessment of urban communities. Consequently, systems only related to environmental and ecological assessments are not considered. The attention is focused on sustainability rating systems which adopt a multicriterion approach in order to consider the different dimensions of sustainability using the triple bottom line approach (Pope et al. 2004): The systems are BREEAM Communities, CASBEE for Urban Development and LEED for Neighborhood Development. In the systems considered below, sustainability is generally evaluated by the summation of the results of different performances related to environmental, social and economic aspects (Scerri and James 2010). Multi-criterion systems are gaining increasing attention as they are easily understood and allow a step implementation for each criterion (Berardi 2012). However, one of the limitations of multi-criterion systems is their additional structure, basing the overall result of the assessment on the sum of different evaluations. This limitation has been extensively discussed in assessment systems for buildings (Devuyst 2000; Berardi 2012); therefore, it will not be further considered in this paper. This paper is focused on the scale of urban communities, also referred to as the neighborhood or district scale. The systems considered below have been created in the last few years in Europe, the USA and Japan. Based on a critical comparison, this paper aims to answer to the following questions: • Are existing systems able to assess the different dimensions of sustainability of urban communities? • Which criteria are most widely adopted among existing sustainability assessment systems of communities? This paper is composed of five sections. Section 2 clarifies the possible meanings of a process of sustainability assessment at the urban level. Section 3 presents three systems for sustainability assessment and compares them according to their criteria and weights. The results of a sample of assessed communities are also described and commented. Section 4 outlines the limitations of existing systems for sustainability assessment systems for communities. Finally, conclusions are summarized in Sect. 5.

2 Framework of sustainability assessment of urban communities In order to compare existing sustainability assessment systems of urban communities, it is helpful to clarify what is meant by sustainability, assessment and community. In fact, lack

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of consensus on the definitions of these terms would lead to difficulty in the comparison of the rating systems. Sustainability is not a single and well-defined concept. At least one hundred definitions have been given to this term (Hopwood et al. 2005). New definitions are continually added, often clouding its concept. Sustainability has also been accused of being indefinable as every time a definition has been formulated, it has always left out some of the possible meanings (Robinson 2004). The concept of sustainability dates back to the 1970s. Its theoretical framework evolved after the publication of ‘‘The Limits to Growth’’ and led to the most famous definition by the Brundtland Commission (WCED 1987). In the 1990s, an intensive debate about different definitions and models of sustainability occurred. This also marked the beginning of the relationship between sustainability and policies, and the development of sustainability indicators for modeling urban sustainability (Spiekermann and Wegener 2003). However, the recent multitude of interpretations that sustainability has received indicates a resistance in the acceptance of an official definition. There is a preference to contextualize and adapt this term to the context in which it is considered anytime (Martens 2006). Paradoxically, the Sustainable Buildings and Climate Initiative (SBCI) of UNEP has declared that sustainability requires all the different interpretations that are often given to the term because the concept of sustainability represents the synthesis of all of them (UNEP-SBCI 2009). The wide meaning of sustainability opens several options to the considerable criteria in sustainability assessments. Sustainability is time and socially dependent, and it has different interpretations for different people, being partially dependent from the point of view of assessment (Martens 2006; Dempsey et al. 2011; Turcu 2012). These sources of uncertainty have contributed to creating the belief that several levels of sustainability exist and that it is more useful to consider sustainability as a relative concept (Martens 2006). The introduction of the concepts of strong and weak sustainability increased this belief: Strong sustainability states that it is not possible to accept an exchange between environment and economy, whereas weak sustainability accepts their substitutability (Mori and Christodoulou 2012). The resilience to anthropogenic disturbances over temporal and spatial cross-scales has more and more been used as a relative measure of sustainability (Mayer 2008; Barr and Devine-Wright 2012). If the definition of sustainability suffers from ambiguity, so does its assessment. A sustainability assessment can be defined as the process of identifying, measuring and evaluating the potential impacts of alternatives for sustainability (Devuyst 2000). Several sets of sustainability indicators have been developed so far, but none have emerged as a universal measure (Mitchell 1996; Pope et al. 2004). Multi-criterion rating systems have often been used by focusing on environmental indicators (Berardi 2012). However, as an increasing attention on sustainability assessments is recorded among sociologists, economists, politicians and planners, new assessment systems and indicators have been promoted. Sustainability indicators have raised the debate about the way in which they were developed and used: from the top, initiated primarily by governments and based on expert input (expert-led), or from the bottom (citizen-led) drawing on local networks and involving citizens (Turcu 2012). These tensions between expert-led versus citizen-led systems of sustainability assessment seemed to be solved through the integration of the two approaches (Reed et al. 2006). Finally, previous research has also shown that the assessor, his/her point of view and time of assessment often play a prime role in the assessment results because they influence the criteria and benchmarks that are considered (Devuyst 2000; Martens 2006). Consequently, a transparent, objective and plural (or promoted in a multi-agent contest) assessment has recently been considered necessary.

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The difficulties in the sustainability assessment of urban communities are greater because the object of the assessment is not a bounded entity. An urban community can be identified in different ways in terms of land use, infrastructure or people density (UN-Habitat 2006): These criteria raise ambiguity about urban boundaries. For example, evaluations of transportation generally cover several communities, whereas population density may consider residents or workers. Different criteria have been used to define the boundaries of communities among which administrative criterion, population density and economic characteristics are the most common (UN-Habitat 2006). Urban sprawl is also increasing the confusion in establishing exact boundaries. Consequently, during sustainability assessment, attention must be given to external impacts (leakage effects) on areas beyond the assessed boundaries (Bithas and Christofakis 2006). Considering the scale of urban communities, a high uncertainty exists regarding their dimensions. In the Haussmannian fabric, an approximate 200 9 200 m represented the dimensions of a neighborhood; in South America, the grid is generally larger and it often reaches the dimensions of 400 9 400 m, whereas in cities such New York, it is generally rectangular (100 9 200 m). A part from geometrically planned cities, the boundaries of a community are generally difficult to establish. As a consequence, during sustainability assessments, they are often established only considering the area object of assessment. This criterion is often meaningless in sustainability terms. The importance of the interactions between different parts of the built environment has been recognized as an unavoidable aspect of sustainability and has increased the request for assessments at scales larger than buildings (Berardi 2011; Conte and Monno 2012). However, it is widely recognized that instruments of countries and regions are often far from capturing, influencing and assessing sustainability of the daily practices of people (Mori and Christodoulou 2012). Urban areas are therefore considered the institutional and geographical level closer to citizens where sustainability can efficiently be promoted and assessed. As a matter of fact, a community represents the nearest natural environment, social network and economic market around a citizen. Urban areas are the lowest level where problems can be meaningfully resolved in an integrated, holistic and sustainable way (Aalborg Charter 1994). International policies are often focusing on sustainability assessment in urban areas, and therefore, the number of communities experimenting sustainability assessment is increasing. This increase shows that sustainability assessments are recognized as tools for monitoring urban dynamics and land promotion. Many communities have developed their own sustainability assessment system (AtKisson 1996; Cartwright 2000; Corbie´re-Nicollier et al. 2003; Turcu 2012). Several frameworks of sustainability assessment indicators were examined (Bentivegna et al. 2002; Xing et al. 2009; Mori and Christodoulou 2012), and, finally, the list of indicators reported in Fig. 1 were selected as reference. Although these indicators are common in many available systems for sustainability assessment systems and can be considered a reference framework, a specific urban setting may require alterations in the frameworks (adding other site-specific indicators or removing some of those in Fig. 1). For example, environmental sustainability has often been conceptualized in many indicators related to land use and biodiversity preservation. Finally, the framework in Fig. 1 should be considered as a reference which leaves the opportunity to contextualize different visions of sustainability also by assigning different (relative) importance to each criterion. In this sense, using an adaptive set of sustainability assessment indicators for specific local situations developed by the Reed et al. (2006), many recent processes of local contextualization have generated a multitude of different systems. The request for their comparability is among the scope of this paper. In particular, this paper aims to compare

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Fig. 1 Lists of indicators for the assessment of sustainable communities (Turcu 2012)

the most diffused multi-criterion systems for sustainability assessment of communities. The main questions examined in the comparison among the systems are: • What balance among environmental, social and economic parameters is assumed? • Through which criteria is sustainability made operative and is it adapted to a community?

3 Systems for sustainability assessment of urban communities In this section, the most internationally well-known systems for sustainability assessment of urban communities through multi-criterion ratings are described and compared. The reader should note that many other systems for sustainability assessment of urban

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communities exist worldwide (for example, a new version of the Green Star Communities system has recently been launched). The considered systems were selected for their established worldwide diffusion and resonance, thanks to institutions and organizations actively involved in promoting their use. This criterion resulted in neglecting the systems which have been developed for specific cases and communities (AtKisson 1996; Cartwright 2000) or the indicators developed within research projects (Xing et al. 2009). However, these last references were considered for the framework of comparison and for the discussion about the critical aspects of the selected systems. 3.1 Description of the systems The selected systems were developed within the last 5 years from building sustainability assessments systems. They maintain the logic and structure of the analogous building assessment systems, but they have gone beyond the building scale by redefining the assessment criteria. The three systems are BREEAM Communities (Com), CASBEE for Urban Development (UD) and LEED for Neighborhood Development (ND). Aside from their worldwide adoption, they were selected because BREEAM, CASBEE and LEED protocols have already reached a significant diffusion for sustainability assessments of buildings, and they promise to diffuse also to communities. The British Building Research Establishment Environmental Assessment Method (BREEAM) was planned at the beginning of the 1990s and was the first multi-criterion system for sustainability assessment. In 2009, BREEAM Com was developed to assess the sustainability of a community (BREEAM 2009). This system received an updated in 2012. BREEAM Com applies the BREEAM methodology to the community level and can be used for both new and regeneration development projects. BREEAM Com assesses the environmental, social and economic impacts of a community. The assessment criteria are divided into eight categories: Climate & Energy, Resources, Place Shaping, Transport & Movement, Ecology & Biodiversity, Buildings, Business & Economy and Community (BREEAM 2009). At this time, BREEAM Com has been experimentally applied to Media City in Manchester (UK) and to Masthusen and Varvsstaden in Malmo¨ (Sweden). CASBEE (Comprehensive Assessment System for Building Environmental Efficiency) is a Japanese rating system, recently made available in English. CASBEE assessment systems are based on life-cycle evaluations and consider two main kinds of criteria: performances and environmental loads. The performance criteria consider aspects as the natural environment, quality of services and the contribution to the local environment, whereas the environmental load covers aspects related to the impact on local environment, social infrastructure, and energy and material consumptions. CASBEE results are presented as a measure of eco-efficiency on a graph with loads on one axis and quality on the other, so that sustainability for CASBEE corresponds to the lowest environmental loads and the highest quality. The system CASBEE UD has been developed in 2007 to assess urban areas (CASBEE 2007). CASBEE UD partially promotes local stakeholders’ engagement in the choice of the weighting coefficients assigned to different criteria. Doing this, it often uses a qualitative assessment. This system has officially been applied in one project, but it has been used as a self-assessment tool for developers in many other projects. LEED (Leadership in Energy and Environmental Design) for Neighbourhood Development (ND) is a system developed by the US Green Building Council (USGBC) in partnership with Congress for the New Urbanism (CNU) and the Natural Resources Defense Council (NRDC). It was developed in 2009 for the USA, and then it has been

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applied in Canada and China; versions for other countries are currently being developed too (LEED 2009). LEED ND places emphasis on the site selection, design and construction elements that bring buildings and infrastructure together into a neighborhood, and relates this last to its landscape and regional context. Smart location, neighborhood pattern, ecodesign, green infrastructure and buildings are the main categories considered by LEED ND (LEED 2009). Moreover, LEED ND rates innovative practices and regional priorities as the sustainable features of a community. 3.2 Comparison between the systems The systems described in the previous section are compared below. First of all, it is important to clarify the dimensions of an urban community in the different systems. BREEAM allows considering sizes from 10 units (small projects) to 6,000 units (large projects) as an urban community; however, it also considers bespoke projects of more than 6,000 units, after confirmation by the British Research Establishment. LEED suggests considering communities with an extension below 1.3 km2 and suggests dividing the project if the surface exceeds this value (LEED 2009). For example, the pilot projects which have been assessed with LEED ND have an average project size of 1.2 km2, with a median size of 0.12 km2. In particular, the smallest size was 687 m2, while the largest was approximately 51.8 km2 (USGBC 2007). No indication about the dimensions of an urban community is presented in CASBEE UD. These data confirm that the dimension of a community has been particularly heterogeneous, ranging from a single building to almost a medium-size city. Each sustainability assessment system bases its evaluation on several parameters whose rates are generally obtained comparing real performances with referenced ones (benchmarks). However, a few criteria are just evaluated looking at the presence of an element. For example, LEED ND enables to earn one point for the presence of a bicycle network, without going into the assessment of its characteristics and relationships with the urban transportation grids. Points earned in this simple way are rare in the other systems. In multi-criterion systems, each criterion has a certain weight over the total assessment, and the overall sustainability evaluation comes out by the weighted sum of the results for all the criteria. A fundamental aspect in multi-criterion systems is hence the selection of the criteria. Unfortunately, reasons behind the choice of the criteria are not explicitly discussed by any of the responsible agencies (Haapio 2012). Table 1 reports the main categories of the assessment criteria which are used by the three systems considered in this paper. Similarities between the main categories of the different systems in Table 1 exist. For example, all the systems consider the sustainability of the land in terms of ecology and natural environments. However, other sustainability aspects are considered only in some systems. BREEAM Com, for example, gives a relatively larger importance to the business opportunities, whereas social aspects such as the history, tradition and culture preservation are only considered in CASBEE UD. Using the respective manuals, the assessment criteria of each system were divided into seven main categories. These categories were chosen according to both the structure of the systems and the requirements of a sustainable urban community (Kellett 2009; Haapio 2012). The following were the selected categories: sustainable land (sustainable planning, design and buildings, microclimates), location (previous land use, reduction of sprawl), transportation (pedestrian, bicycle or public transportation), resource and energy (use and selection of materials, waste management, energy production and efficiency), ecology (biodiversity), economy and business (employment and new opportunities) and well-being (quality of life).

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Table 1 Main categories in the three sustainability assessment systems considered in this paper BREEAM Communities

Climate and energy: reducing the contribution to climate change through energy efficiency and passive design Resources: It emphasizes sustainable and efficient use of resources also through construction management Place shaping: provides a framework for the design and layout of local area Transportation: focuses on sustainable public transportations, walking and cycling Community: encourages to integrate the community with surrounding areas and emphasizes mixed use Ecology and biodiversity: aims at conserving the site ecological value by reducing pollution Business: aims at providing opportunities for local businesses Buildings: focuses on the sustainability performance of buildings

CASBEE for Urban Development Performance

Load

Natural environment, microclimates and ecosystems Service functions for the designated area Contribution to the local community: history, culture, scenery and revitalization

Environmental impact on microclimates, fac¸ades and landscape Social infrastructure Management of the local environment

LEED for Neighborhood Development Smart location and linkage: emphasizes development of preferred urban areas, Brownfield redevelopment, bicycle network or housing and jobs proximity, and wetlands and water bodies conservation Neighborhood pattern and design: focuses on walkable streets, public transportation access, reduction in cardependency compact development, but also mixed-use neighborhoods center and mixed-income communities. Green infrastructure and buildings: decreasing environmental impact caused by construction and maintenance of buildings and infrastructure. Energy and water efficiencies are emphasized mainly; some attention to waste management. Innovation and design process Regional priority

Content analysis was used to attribute the criteria of each system into the previous categories. However, the organization of assessment criteria into the previous seven categories resulted in some difficulties as the systems were not easily and fully accessible and criteria among systems did not perfectly overlap. For example, the distinction of criteria for sustainable land and ecology was not always straightforward, and several uncertainties in the attribution of assessment parameters in each one of these two categories existed. Finally, after having completed the attribution, this was repeated by two sustainability experts to check coherence of assigning the criteria in the seven categories. Figure 2 depicts the categories with a high frequency of occurrence in the varied systems. The results show that a large importance is assigned to the sustainable use of the land, ecological measures and sustainable transportations. On the contrary, economic themes are scarcely considered in the analyzed systems. The average weights among systems for each category were 33 % for sustainable land, 9 % for location, 13 % for transportation, 16 % for resources and energy, 21 % for ecology, 3 % for business and economy, and 5 % for well-being. Surprisingly, existing systems assign a low weight to energy- and resource-related topics. This result is significantly different from the sustainability assessment of buildings

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BREEAM Com

45

CASBEE UD

Percentage (%)

40

LEED ND

35 30 25 20 15 10 5 0 sustainable land

location

trasportation

energy and resources

ecology

economy opportunity

well -being

Assessment categories Fig. 2 Percentages of points given by the three sustainability assessment systems for urban communities grouping the assessment criteria in seven categories, and average values among the systems

where energy-related criteria represent the most influencing category (Berardi 2012). For example, the weight assigned to the criteria related to building energy efficiency, solar orientation, on-site renewable energy sources, and district heating and cooling was only eight points over the possible 110 in LEED ND. Together with the attribution of criteria in the seven categories, the analysis showed the level of detail and the difference among criteria in each system. The number of criteria used by each system is particularly different. For example, transportation is assessed through 11 criteria within BREEAM Com (over the 51 parameters used by this system), whereas fewer criteria are considered in the other two systems. This also corresponds to different weights that transportation criteria have: 22 % of total weight in BREEAM Com, 8 % in CASBEE UD and 15 % in LEED ND. In particular, LEED ND is more focused on the promotion of a compact design of the community, favoring walkable streets. This reminds us the different status and kinds of public transportation in the UK and USA where previous systems have been developed respectively. As a consequence, US communities are firstly interested in increasing compactness to accommodate walkable streets, and only secondly, they consider the (often inefficient) public urban transportation. This result is confirmed by the high weight of the location category in LEED ND as compared to the two other systems. The different weights given to the location category are probably influenced by the different scopes and applications of the systems. LEED ND aims to be applied in new urban communities, whereas BREEAM Com is mainly focused on interventions of rehabilitation. This different field of application has probably discouraged assigning a high weight to location in BREEAM Com, because this assessment category is generally satisfied in rehabilitation projects. The well-being category has received a low average weight in the categorization shown in Fig. 2. This is also related to the fact that only assessment parameters which exclusively referred to social aspects of the quality of life have been considered in this category. However, it is undoubted that other parameters, such as bike transportation or urban microclimate, play a fundamental role for the quality of life and that by considering these, both BREEAM Com and LEED ND indirectly assess the well-being in the community.

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However, Fig. 2 shows that the criteria of well-being contribute with a low percentage to the overall assessment. 3.3 Characteristics of certified communities The LEED ND system is here used as a reference for a detailed examination of the characteristics of a sample of certified communities. According to the author, the results of assessed communities can be useful in understanding practices and trends of certified communities. LEED ND system was chosen as there are a large number of assessed communities versus other rating systems. A sample of 42 communities located in the USA was selected. Table 2 shows the percentage of total and mean earned points of each assessment criteria. This allows considering the frequency of successfully achieved points and the most influential criteria on the final rate. The resulting data suggest several considerations. In the smart location and linkage category, the selection of a sustainable site was often difficult as it was influenced by property possibilities and municipal policies. Moreover, the selection of a Brownfield redevelopment was uncommon, whereas many communities preferred to pursue the preferred locations and reduced automobile dependence categories. The neighborhood pattern and design category had the largest number of points within LEED ND. Criteria in this category showed significant differences in their success rates: Criteria such as the diversity of uses or the presence of walkable streets were commonly satisfied in assessed projects, whereas other criteria, such as the affordability of rental housing, the restoration of habitat or wetlands and water bodies, were uncommon. The green construction and technology category showed that sampled communities were able to minimize site disturbance, reduce the water use and plan a storm water management. However, they became particularly unsuccessful with criteria such as building reuse and adaptive reuse, solar orientation, on-site energy generation, wastewater management, contaminant reduction, and district heating and cooling. This suggests that energy and resource efficiency is still difficult to achieve at the community scale, and also communities that aimed at sustainability certification do not rigorously pursue solutions within this category. Moreover, results in Table 2 suggest that sustainable communities are generally able to reduce the impact of their material uses, although this ability is shown by selecting new virgin materials more than by using recycled or low-energy-embodied ones. Obviously, the choice to use the LEED ND system and to consider US communities limited the value of the results. In fact, these were influenced by the system structure as well as by its criteria. Further analysis should test the previous findings in different samples of communities and with other rating systems in order to obtain a larger validity in certified communities. It is also worthy to note the potential application of sustainability assessment systems in other countries (especially in developing countries) may represent a key opportunity for sustainability assessment systems of communities. This last opportunity was not explored in this study; however, it is an area of great promise given the rapid urbanization rates in these countries.

4 Limits of existing sustainability assessment systems In this section, the limits of sustainability assessment systems described in Sect. 3 are discussed. In particular, the following limitations are examined: assessment of a weak

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Table 2 Criteria of LEED ND, percentages of total and mean earned points over the total possible points among the assessment categories, in a sample of assessed communities Max available points Smart location and linkage Smart location

% Of communities which earned points

27

Mean earned points 16.8

Prerequisite

Imperiled species and ecological communities

Prerequisite

Wetland and water body conservation

Prerequisite

Agricultural land conservation

Prerequisite

Floodplain avoidance

Prerequisite

Preferred locations

10

96

6.9

Brownfield redevelopment

2

45

0.9

Locations with reduced automobile dependence

7

92

4.0

Bicycle network and storage

1

77

0.8

Housing and jobs proximity

3

85

2.3

Steep slope protection

1

66

0.7

Site design for habitat or wetlands and water body cons

1

56

0.6

Restoration of habitat or wetlands and water bodies

1

36

0.3

Long-term conservation management of habitat

1

34

Neighborhood pattern and design criteria

44

Walkable Streets

Prerequisite

Compact development

Prerequisite

0.3 25.6

Connected and open community

Prerequisite

Walkable streets

12

96

6.1

Compact development

6

87

2.9

Mixed-use neighborhood centers

4

99

3.3

Mixed-income diverse communities

7

80

5.3

Reduced parking footprint

1

73

0.7

Street network

2

80

1.3

Transit facilities

1

63

0.6

Transportation demand management

2

55

0.8

Access to civic and public spaces

1

89

0.9

Access to recreation facilities

1

88

0.9

Visitability and universal design

1

63

0.6

Community outreach and involvement

2

90

0.9

Local food production

1

27

0.4

Tree-lined and shaded streets

2

40

0.4

Neighborhood schools

1

40

0.3

Green construction and technology Certified green building

29

13.3

Prerequisite

Minimum building energy efficiency

Prerequisite

Minimum building water efficiency

Prerequisite

Construction activity pollution prevention

Prerequisite

Certified green buildings

5

86

Building energy efficiency

2

73

1.5

Building water efficiency

1

40

0.6

Water-efficient landscaping

1

40

0.6

Existing building reuse

1

18

0.2

Historic resource preservation and adaptive use

1

18

0.2

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2.9

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Table 2 continued Max available points

% Of communities which earned points

Mean earned points

Minimize site disturbance during construction

1

82

0.8

Storm water management

4

86

2.9

Heat island reduction

1

75

0.8

Solar orientation

1

32

0.3

On-site renewable energy sources

3

30

0.3

District heating and cooling

2

15

0.2

Infrastructure energy efficiency

1

22

0.2

Wastewater management

1

22

0.2

Recycled content in infrastructure

1

53

0.5

Solid waste management infrastructure

1

53

0.5

Light pollution reduction

1

64

0.6

sustainability, lack of an appropriate assessment of social, environmental and economic sustainability, static sustainability assessment, and adaptability and stakeholders’ engagement. 4.1 Assessment of a weak sustainability Although the number of criteria which are considered is generally high (51 criteria in BREEAM Com, 80 in CASBEE UD and 53 in LEED ND), every system is fundamentally dominated by an environmentally based approach. The comparison has revealed that every system is characterized by a difficult integration among different criteria; this aspect may lead to the promotion of weak sustainability. Bourdic and Salat (2012) criticized existing systems because they only assess the different criteria by comparison with benchmark values, and stated that there is no quantitative evidence that a high-rated community emits less carbon than a lower-rated one. Considering the unscientific selection of the criteria, their weights and the benchmarks, this critic is difficult to overcome. Moreover, the aggregated level of assessment, which synthesizes the evaluation in one single rate, reduces the ability to deliver a robust and transparent output (Mori and Christodoulou 2012). In fact, the use of aggregated rates as outcome of the assessment allows different choices, without being able to map them. This may also favor a weak sustainability within the community. 4.1.1 Lack of an appropriate assessment of social sustainability An important leakage in existing systems regards the social features of sustainability. Although it is unavoidable that a sustainable city should promote social relationships and well-being of citizens, the analyzed systems poorly assess the importance of social life and the sense of citizenship. Doing this, they misrepresent one of the main reasons for urban life. The low importance toward social aspects is caused by the adoption of an approach which considers almost exclusively the physical and material properties of the built environment. On the contrary, the new interpretations of sustainability and the increasing awareness that the built environment is more than the physical space should lead to consider social criteria in sustainability assessment systems (Bond and Morrison-Saunders 2011; Dempsey et al. 2011; Berardi 2013).

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Vallance et al. (2011) discussed the importance for the built environment to assume the status of the locus of a community and emphasized the importance to assess the sense of community. This suggests that other criteria have to be considered in sustainability assessments of communities. A proposal for a set of social indicators has been given by Albino and Dangelico (2012). Based on a review of country-relevant well-being indicators, they proposed three main domains of well-being criteria: material well-being, quality of life and social inclusion. Moreover, they indicated ten relevant dimensions with 45 indicators in three main area of social sustainability: • Material well-being: income and wealth, employment, and housing; • Quality of life: health, education, work–life balance, political well-being and safety; • Social inclusion: social cohesion and equity. Previous dimensions well apply to the scale of urban community. Several of these indicators have been introduced in a recently proposed tool for city sustainability assessment which considers crime prevention and quality of housing for the living environment, educational, cultural, medical and child care services for social services, and information pressure for social vitality (Murakami et al. 2011). Obviously, the application of previous criteria on a community scale raises difficulties such as the lack of benchmarking data to which to refer. A possible solution may be represented by parameters which compose The Better Index Life indicator, for which national open source values are available (OECD 2011b). However, further studies are necessary to evaluate social sustainability parameters at the community scale. 4.1.2 Lack of an appropriate assessment of economic sustainability Another limitation in existing systems regards the misrepresentation of economic sustainability. Figure 1 shows that a low importance is given in current systems to the ability to promote business and economic opportunities within a sustainable development. Reasons for this can be related to the strong attention which has historically been given to the economic aspects in the evaluations of development and to the consequent request to reduce the weight of economic criteria. However, local businesses and new economic activities are critical for sustainable communities. Consequently, sustainability assessment systems should be able to take into account these, decouple and promote both economic growth and environment protection. Among the dimensions of social sustainability assessment proposed by Albino and Dangelico (2012), few also referred to economic sustainability. For example, in the category of material well-being, they consider the household net income, the employment rate and the percentage of homeless people. Moreover, criteria referring to socioeconomic aspects within an urban community have to be taken into account to prevent a decoupling between these two aspects. Other missing criteria to assess the economic sustainability of an urban community are the industrial vitality (change in number of employees), the amount of economic exchanges and the financial viability in the community (Murakami et al. 2011). 4.1.3 Lack of an appropriate assessment of the environmental sustainability A limit in the current sustainability assessment systems for urban communities refers to environmental protection measurements. Given the high consumption of resources in urban environments, sustainable communities should increase their focus on reusing materials

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and their circulation in closed-loop cycles of production, recovery and re-manufacture (Mang and Reed 2012). This would result in an evolution from the current rating system advocacy in the use of virgin materials to more eco-friendly practices. Moreover, sustainable assessment systems rarely focus on a lifestyle in harmony with nature. Criteria aiming to integrate physical, functional and emotional properties of a community in a holistic perspective would help promoting a more integrated idea of sustainability and would overcome the eco-technocratic trend which can be seen in Tables 1 and 2. 4.2 Limits of static sustainability assessment Another limitation of existing systems is the adoption of a static perspective. In these systems, the assessment is a process realized once at the beginning of the urban community development. However, recent definitions of sustainability have encouraged looking at this as a moving target, showing that assessments done at a single time are not sufficient (Brandon and Lombardi 2005). Unfortunately, existing systems are seldom influential in the life of the community (Innes and Booher 2000), especially because the sustainability assessments of communities are often promoted by developers alone. This means that it is particularly important to monitor progress through a reality result check (Innes and Booher 2000). The static assessment prevents to look at the trends in the evolution and performance of a community (Berardi 2011). Instead, continuous evaluations should be incentivized, in a way that sustainability assessments become an interactive process, which could be used to map the evolution of the urban development (Bentivegna et al. 2002; Lowe 2008). This corresponds to the use of assessment systems as diagnostic tools for in-progress programs. The importance of dynamic evaluation is also related to the time dependence of sustainability and to changes of the requisites and the benchmarks that sustainability may require (Martens 2006; Berardi 2011). Criteria that consider the evolution of a community should finally be introduced in the assessments. 4.3 Limits of adaptability and stakeholders’ engagement (institutional sustainability) The analysis of existing systems has shown a link between the assessment systems and the context in which they have been developed. This relationship limits the use of these systems in other countries, unless the criteria are modified to consider the culture and laws of those countries (Haapio 2012). According to this limitation, BREEAM has recently made available different regional weightings in order to account the different priorities among the regions of the UK. Similarly, the Canadian Green Building Council has developed Canadian Alternative Compliance Paths in order to apply the LEED ND rating system (LEED 2009). This process of adaptation of the assessment systems has recently started and aims to be fundamental to contextualize new assessment criteria. A larger adaptability of the systems should be encouraged in order to use the systems in countries besides those for which they have been formulated, especially considering the rapid urbanization processes in act in developing countries. An important opportunity for adapting the systems is offered by stakeholders’ engagement. Mathur et al. (2008) and Mascarenhas et al. (2009) have conceptualized the importance of stakeholders’ engagement in the development of sustainability assessment systems. Earlier in this paper, it was discussed how different interpretations are possible for sustainability and its criteria.

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All the systems compared in this paper, although they accept some local adaptations, do not promote communities’ engagement adequately. A new definition of the methodology and steps of the implementation of these sustainability assessment systems is hence necessary to enforce a participative context which stimulates citizens and increases their awareness of the sustainability measures in their community (Berardi 2011). The existing systems are mainly based on criteria defined by the agencies which developed them. Although these systems have often been developed through extensive experts surveys, they have also been accused of lack of scientific consensus. However, citizen-led experiences of sustainability assessment of communities have shown to be able to measure indicators that are better suited to the individual happiness within the community (Hardi and Zdan 1997; Morse and Fraser 2005). In fact, indicators developed from the bottom have often been proven to be successful for measuring the level of community activity, satisfaction with local area and perception of community spirit (Hardi and Zdan 1997). Research in this sense has emphasized the importance of sharing knowledge through a transparent process of citizens’ involvement in order to define and prioritize indicators (Thomson et al. 2010). Stakeholder engagement may lead to the discovery of human relationships within the community, including the interweaving of the objective and the subjective parameters that create a sustainable community (Scerri and James 2010). As Reed et al. (2006) found, the local context only becomes visible when the indicators are checked through the lens of local communities, because these are needed to unpack area-specific and hidden local conditions which shape local sustainability. However, as a high emphasis on citizen engagement has also resulted in problems of leadership and the ability to foster change toward sustainability, integration between expert- and citizen-led indicators and assessment criteria is necessary to synthesize different aspects (Turcu 2012). Finally, the reader should not forget that the systems compared in this paper are often promoted by an urban developer whose final scope does not fully correspond with the construction of a sustainable urban area, also because his power is time limited. This consideration enforces the importance of adopting sustainability assessment systems as program tools that, after having been contextualized and used for a community in the development stages, serve as continuous evaluations for shaping sustainable communities.

5 Conclusions The paper has presented and discussed current systems for the sustainability assessment of urban communities. A clarification of the concepts behind the sustainability assessment has been done by looking at the possible meanings of sustainability, assessment and community. Three systems—BREEAM Com, CASBEE UD and LEED ND—have been considered. These represent the most internationally known systems, especially because their corresponding versions for assessment of buildings have already reached a significant adoption. The previous systems have been compared considering their assessment criteria mainly. This paper has shown several limits of the available systems, as they lack appropriate assessment of social, economic and environmental sustainability. The comparison among systems has revealed that they generally promote a weak sustainability and accept that economic development can reduce natural capitals. This choice reduces their capability to measure sustainability in the long term. The discussion has helped to show that assessment of urban communities should support sustainable business as well as people’s well-being and environmental protection goals. Besides, the dynamicity of a community discourages a static approach to the assessment and suggests using these

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sustainability assessment systems as tools for monitoring urban transition toward sustainable communities. The limits of adaptability of existing systems to different countries have been considered, and the need to redefine and adapt the assessment criteria through citizens’ engagement has been discussed. Finally, statistical data of assessed communities have been reported to understand a few limits and difficulties actually encountered in communities aiming for sustainability. A lot of research still remains. In particular, an in-depth analysis of the application of existing systems in a few case studies would help to understand the limits of these systems. Moreover, the definition of systems and criteria for assessing urban communities in developing countries represents an unavoidable goal. Acknowledgments The author would like to thank the anonymous reviewers for their valuable comments.

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