1. Introduction and Background
Sustainability has been a contested concept with many definitions since Brundtland report and hardly any consensus over a single term that can facilitate an easy measurement of the concept [
1,
2]. Consequently, the concept has been expanded with various disciplinary scopes [
3,
4]. In this paper, neighborhood sustainability is defined as the process of developing a neighborhood level urban form or built environment that meets the needs of its residents whilst avoiding unacceptable social and environmental impacts both locally and in a broader context [
5]. By urban form, we refer to the spatial distributions of different land uses connected together with physical infrastructures and associated transport networks [
6]. The way these features are distributed within a neighborhood has profound impact on sustainability both locally and globally. For example, research has shown that the availability of goods and services (e.g., diverse land uses) within local areas enables residents to participate fully in society (
i.e., meets the local needs for jobs, recreation, social, health activities), and in turn, contributes to economic and social sustainability locally [
7]. In contrast, a lack of local opportunities encourages motorized travel and thereby affects the environmental sustainability both locally (e.g., noise, habitat fragmentation, increased impervious surface and consequent damages in water quality and the formation of urban heat island) and globally (e.g., air pollution and climate change) [
8,
9]. Therefore, different urban forms contribute differently to sustainability and research studies around the globe have indicated that the built environment is the most promising sector for a rapid transition to sustainability [
10].
The need for a sustainable urban form at the local level has long been advocated by the United Nations [
11] through its “Local Agenda 21” programs. Neighborhoods are considered as the building blocks of cities where most development (e.g., new buildings) takes place, and therefore, the overall sustainability of a city depends on the sustainability of its neighborhood [
12]. However, past studies on sustainability assessment have focused on either the city level e.g., [
13,
14] or building level e.g., [
15]; whereas the assessment of neighborhood sustainability, an intermediate level, has received very little attention in general and in the context of developing countries in particular [
10,
16].
Limited research to-date suggests that sustainable neighborhoods have a significant positive impact on property prices [
17], and that people living in sustainable neighborhoods are happier [
18] and enjoy a better quality of life and place [
13]. Consequently, neighborhoods are increasingly gaining attention as planning units of great potential for contribution to sustainable urban development [
19]. At the same time, an increasing urge for tools to assess their sustainability is recorded worldwide [
10]. Neighborhood sustainability assessment (NSA) tools are defined as a set of criteria and themes; and are used to: (a) Evaluate and rate the performance of a given neighborhood; (b) Assess the neighborhoods’ position on the way towards sustainability, and; (c) Specify the extent of neighborhoods’ success in approaching sustainability goals [
16].
NSA tools have conveniently been used to benchmark the sustainable efficiency of neighborhood developments [
20]. For example, Han
et al. [
21] estimated sustainability level of an eco-community (
i.e., Xihe in China), and found that it achieved only a moderate sustainability level despite the community was built to become a sustainable neighborhood. NSA tools have also been used to provide greenness certificates of neighborhoods by respective authorities [
17,
22]. Using a NSA tool, Li
et al. [
23] compared the sustainability levels of 52 mining communities and found that four of them have reached a strong level of sustainability, 11 have achieved a satisfactory level, and the remaining 37 are still weak in their sustainability endeavors. More importantly, the availability of a NSA tool helps authorities to focus development towards sustainable outcomes. For example, after analyzing 19 housing developments throughout England, Smith
et al. [
22] found that in the absence of appropriate NSA tools, even where there is a desire to create a more sustainable solution, many schemes are falling short of their potential.
A number of NSA tools are currently operational around the world. The well-known ones include but not limited to the followings: LEED ND, UK; BREEAM for Communities, UK; CASBEE-UD, Japan; ECC, USA; HQE2R, European Union; Ecocity, European Union; SCR, Australia; QSAS, Qatar; Green Mark for Districts, Singapore; NSF, New Zealand; HK-BEAM, Hong Kong; EcoEffect, Sweden; EcoProfile, Norway, and; Escale, France (see, [
10,
16,
20,
22] for a review). These tools have broadly been categorized into: (a) Third-party assessment tools, which are spin-offs of building assessment tools and assess the sustainability beyond a single building (see, [
22]), and; (b) Tools, which are embedded into neighborhood-scale plans and sustainability initiatives to assess their sustainability performance [
16]. After critical reviews of these tools, researchers have raised several concerns about their methodology, applicability and transferability to another context. Sharifi and Murayama [
16] found that most of them are weak in taking into account the different dimensions of sustainability (e.g., economic, social, environmental, and institutional). They have also noted that most of these tools possess ambiguities in terms of criteria weighting, scoring, and rating system with no mechanism for local adaptability and participation.
Furthermore, the transferability of NSA tools has been questioned particularly with respect to the selection of sustainability assessment criteria [
24]. This is particularly true in case of new residential development. For example, Säynäjoki
et al. [
20] assessed the applicability of the LEED-ND, BREEAM for Communities, and CASBEE-UD tools in the context of new residential development in Finland and found that the consideration of some of the suggested mandatory criteria of the tools are not feasible and relevant in the local context. In addition, many internationally available NSA tools do not sufficiently explain how and why the criteria were chosen, and the methodology used to determine the requirements is also not clear [
20]. For example, Smith
et al. [
22] have identified that the inclusion of landscape related criteria are often ignored in these tools. The issue of transferability exacerbates due to the complexity associated with defining a neighborhood in different contexts [
10]. These findings imply that any realistic and reliable assessment should take account of the specificities of local context and varying needs of different stakeholders [
19].
The quest for sustainability of residential neighborhoods is more than a century old [
25], and mostly relates to integrating land use, transport systems and the environment [
26,
27,
28]. The Garden City movement led by Sir Ebenezer Howard is considered as an early initiative and emerged as a response to unsustainable condition of the then residential neighborhoods; and consequently, the concept of the three magnets was developed to combine the nature and environment with economic and social life [
29]. Since then various neighborhood development models have emerged and practiced in different contexts and branded as, for example, cohousing, the common interest development, the gated community, the smart community, traditional neighborhoods, neo-traditional neighborhoods, conventional suburban neighborhood, eco-community, ranchette development, subdivision development, piecemeal development, and master-planned development [
21,
25,
30,
31,
32]. Although the main purpose of all these models is to provide housing, their urban forms differ significantly, particularly in terms of layout design (e.g., density, street network, pedestrian access to transit and commercial stores, land use mix, gardens, parks and other attributes that characterizes spaces between homes) [
30,
33]. Relatively recent research has shown that these features significantly contribute to sustainable urban development [
34,
35]. Although a residential neighborhood is an outcome of the synergy and combination of these individual features, scant evidence was found in the literature investigating the overall impacts of these residential models on sustainability. Rather research studies to date have focused on analyzing the sustainability of two broad classes of urban forms—
i.e., compact and sprawling developments. As a result, a growing interest is evident in the literature on the increased importance of identifying various urban form typologies and their inter- and intra-urban scale interactions [
36].
Against the backdrop of above urgencies, Frame and Vale [
35] (p. 287) have stated that “there is a dearth of design and assessment tools for the residential built environment and of indicators to monitor progress towards sustainable development”. House building industries have already been criticized for their “build and walk away” trading ethos where the emphasis is predominantly on manufacturing rather than design and planning, and thereby, very little response to the sustainability agenda [
25]. The problem is even more severe in the context of developing countries where most of the residential development models are borrowed from the developed nation and are being implemented and marketed as sustainable model without being assessed their sustainability outcome in a local setting [
37,
38]. A World Bank report shows that some 90% of global urban growth now takes place in developing countries—and between the years 2000 and 2030, developing countries are projected to triple their entire built-up urban areas [
39]. This unprecedented urban growth possesses great concerns for policymakers on how to steer growth in a sustainable way in future, because urban growth is attractive as it leads economic growth of cities [
14,
40]. Despite some similarities in sustainability principles of neighborhoods between developed and developing countries, the differences are even larger and the resources to deal with them are considerably scarce in developing countries. Nevertheless, the urbanization can provide an opportunity for developing countries by practicing sustainability principles in their residential developments and thereby avoiding problems that experienced by the developed nations [
41].
The research reported in this paper aims to contribute to the efforts in bridging the sustainability assessment knowledge gap by investigating the sustainability outcomes of three popular residential development models (
i.e., subdivision, piecemeal, and master-planned developments) from an exemplar developing country context—
i.e., Malaysia. This way the paper contributes to the sustainability assessment literature in the mostly neglected geographic lacuna of developing countries. Malaysia is a representative case study from the developing country context as it has been suffering from high population increase, rural to urban migration, and deforestation with major causes from large-scale land development, mining and dam construction and logging. Much like the rest of the developing countries, these have caused loss of biodiversity, erosion, wildlife being threatened, siltation of rivers and water pollution. As stated by Sumiani
et al. [
42], “Malaysia, being one of the Asian countries that is rapidly developing, increasingly facing the tension between the economic incentives and the claim for ethical consciousness with regard to accounting for the environment” (p. 897).
The study develops a NSA tool to assess and/or compare sustainability levels of abovementioned residential development models. The main rationale behind developing a new assessment tool is to factor in local characteristics most appropriately—by involving a mixture of local and international experts in the formation of the tool—in sustainability evaluation, and thus provide a more reliable output to inform decision makers for effective and efficient actions and solutions. The tool is not only helpful in assessing the sustainability of current practices, but also potentially can act as an integrated residential design and development guide and expedites a fundamental shift in where and how people live in developing countries.
5. Discussion and Concluding Remarks
The literature findings revealed that rapid urbanization has brought environmentally, socially, and economically great challenges to cities and societies. To build a sustainable neighborhood, these challenges need to be faced efficiently and successfully. In this regard the first step of action is to determine the sustainability levels of neighborhoods [
84]. From this perspective the literature points to a number of NSA tools. However, as the critique of these tools suggests they have limitations in their indicator systems and adaptation in the developing country context is challenging.
This research contributes to the literature in two ways. A primary contribution of this research is the development of a NSA tool with an intention to be applied in the context of developing countries. Although there are quite a few NSA tools available in practice, these are built focusing on developed countries. As a result, their direct applications were found to be difficult in this research (i.e., developing country context) where the meaning and definition of sustainability vary substantially. For example, an affordable house in a developed country might be extremely unaffordable in this research. Similarly, a 1% reduction in car-based travel might be a significant shift towards sustainability in a developed country whereas this makes no difference in a developing country context where car is not the main mode of transport. In addition, currently available NSA tools often comprise of numerous indicators that requires the availability of extensive database to process and operationalize, which are rarely available to the researchers and/or planning authorities in developing countries. Moreover, research has highlighted several methodological weaknesses of the existing NSA tools as discussed earlier in the paper. These issues necessitate the development of a NSA tool suitable to operationalize in the context of this research.
The NSA tool was developed focusing on the assessment of certain aspect of a neighborhood in this research—namely the urban form of differential residential models/types in developing countries. As a result, the assessment focused only on the design aspects of residential neighborhood types (e.g., layout, road network, buildings, and community facilities). Consequently, some important themes that might be important for other type of assessment were ignored in this research—such as building energy and water efficiency, water and waste management. The NSA tools developed for this research contains only 18 criteria/indicators. They were selected based on a 3 round Delphi study involving both local and international experts. Therefore, although limited in scope, these 18 indicators consist of the most relevant factors associated with sustainability assessment in the context of this research as accepted by both local and international communities. This joined-up process thereby reduces the tensions between expert-led
versus citizen-led processes of sustainability assessment in this research. In addition, the Delphi method reduces the subjectivity of the criteria weighting in this research by involving both experts and local citizens [
21]. The robustness of the applied method was evident in the sensitivity analysis with no changes in the final results when various combinations of weightings were tested (e.g., weighting from local expert only, weighting from international expert only, and a combination of both—not reported in the paper though). Although these findings justify an initial validity, further research should seek to apply the developed NSA tool in another developing country context, or perhaps using a different weighting system (e.g., AHP), to investigate its wider validity.
The second major contribution of this research is to assess the sustainability of three prominent residential development models (
i.e., master-planned, subdivision, and piecemeal developments) that are being adopted in an accelerated rate within the urban fabric of developing countries. Although residential sustainability is a century old concept and various residential models have been developed over the years aiming for sustainable outcome, any systematic method to assess an overall residential sustainability level is almost non-existent in the literature [
35]. Unlike this research that incorporates an overarching framework of assessment, prior studies focuses only on a (or few) specific element of neighborhood feature (e.g., density) and its influence on certain outcome (e.g., car-ownership). The findings from this research robustly identified that master-planned communities provide option for more sustainable living in the context of this research over sub-division and piecemeal developments. Although these findings are in line with the scant evidence reported in the literature on this topic, which also justifies the validity of the developed tool, a more rigorous validation process by applying the tool against a gold standard (e.g., brown/green field development) is warranted. Note also that despite the results are presented in a quantifiable manner in this research, they represent sustainable utility/rating of a neighborhood, and therefore, cannot be mathematically traded-off (e.g., type A is two times better than type B). For example, although the experts rated the availability of open spaces highly (e.g., 6.02) compared to traffic calming measures (e.g., 5.14), this does not necessarily mean that one hectare of open spaces can be replaced by adding two traffic calming measure.
Despite master-planned communities out-performed in this research, local practitioners and policymakers must pay attention to make this neighborhood type more accessible to the wider communities (e.g., through provisioning of rapid transit system) in order to avoid social exclusion and car-dependency. Although the performance of piecemeal development was found to be poor, this research identified that ample opportunities exist to improve the sustainability performance of this neighborhood type if a focused policy is in place (e.g., in-fill development policy) through, which the development can be regulated or oriented towards important facilities.
This research develops a NSA tool and provides a comparison of sustainability performance of three residential neighborhood types. However, it neither provides an assessment of the neighborhoods’ position on the way towards sustainability nor specifies the extent of the neighborhoods’ success in approaching and achieving sustainability goals. Such assessment requires to set-up benchmark strategies to assure the achievement of a certain level of performance and the responsibility lies to the local planning authorities. However, the NSA tool developed in this research can be useful to serve as an integrated residential design and development guide and expedites a fundamental shift in where and how people live in developing countries—which was found to be a third policy related contribution of this research.
The findings, within Malaysia as a representative context for developing countries, demonstrated that master-planned development is the most sustainable residential development form followed by subdivision and piecemeal development models. This provides justification for policymakers and built environment (planning and development) agencies to encourage future residential neighborhoods to be developed based on the master-planned concept. The finding substantiates the claims by planners that such comprehensive development of master-planned estates or communities by a single agent has the advantages of providing greater design flexibility, better neighborhood environments, exclusive open spaces, various sustainable development practices, and community facilities for the residents [
85]. Unlike many of the developed nations, the concept of master-planned development in Malaysia is still at its infancy, but the continuing national economic growth has encouraged its conception and wider practice. Although in our study master-planned development scores a high overall sustainability ranking in comparison to other two development types, there is surely room for improvement to increase the sustainability levels further. For example, master-planned development practices can learn from subdivision development experiences especially with regard to the provision of external connectivity, crime prevention and safety, and access to emergency services. With regards to the development of residential neighborhoods in a piecemeal approach, a new innovative strategy is needed to improve its sustainability level. The findings indicate that this development type is not seen as a desirable development form in Malaysia and attention needs to be given to the issue of lacking in overall planning of the neighborhood that supports sustainability.
In terms of research limitations, we highlight some of the critical issues as follows: (a) Sustainable urban development surely contains more features than of the physical neighborhood features and layouts that we mainly investigated in this research—especially energy consumption and pollution generated from each buildings; (b) Although the potential correlation between selected indicators may not have a significant impact on the results—due to the nature of investigation being a purely comparative one—it is still important to run appropriate statistical checks; (c) The weighting assignment is mainly based on Delphi expert suggestions, and alternative methods such as Factor Analysis can provide alternates; (d) Malaysia may not be a perfect representation for all of the developing countries—perhaps more suitable case for the developing countries from the Southeast Asia; (e) Based on three case study investigations, it is not possible to reach to a conclusion and claim that master-planned developments provide a more sustainable urban development form, and; (f) Direct replicability of the tool in a different context may be problematic—as the tool requires local experts contribution along international experts in the development of the indicator base. To address some of these research limitations and challenges, we are planning to expand our investigation including more case studies from different cities in Malaysia and other developing countries, incorporating various other aspects of sustainability in the analysis, such as building energy and water use, transport mode preferences of residents, recycling, air pollution and other socioeconomic dimensions of sustainability, and run a number of statistical tests to make sure of the reliability of the results.
Lastly, we underline that sustainability and development are contradicting terms or more correctly an oxymoron. However, this does not diminish the importance of efforts in minimizing the negative effects of urbanization in a rapidly developing world. Therefore, as a concluding remark of the paper we stress the following set of recommendations that are broad, but clearly describe the fundamental steps of an effective process in making a move towards a more sustainable urban neighborhood development also see [
86]:
- (a)
Looking for the big picture;
- (b)
Understanding the sustainability phenomena clearly;
- (c)
Understanding the drivers of urban sustainability, and determining key factors and indicators;
- (d)
Collecting and accessing to the relevant data;
- (e)
Adopting tools and models and modeling the data;
- (f)
Defining quality targets for sustainable urban development;
- (g)
Facilitating the creation of relevant knowledge in the area of sustainable urban development;
- (h)
Formulating the urbanization policy from a sustainable development perspective;
- (i)
Changing behaviors and including stakeholder and community views;
- (j)
Forming collective efforts to develop sustainable urban neighborhoods;
- (k)
Planning dynamically for sustainable urban development;
- (l)
Translating the sustainability agenda into a number of strategic initiatives for implementation;
- (m)
Enhancing the control and monitoring mechanisms, and;
- (n)
Enabling an iterative policy and plan making process.