Introduction

According to Du Plessis (2007), “Construction is the broad process/mechanism for the realization of human settlements and the creation of infrastructure that supports development. This includes the extraction and beneficiation of raw materials, the manufacturing of construction materials and components, the construction project cycle from feasibility to deconstruction, and the management and operation of the built environment”. Therefore, the construction industry is highly motivated to ensure the adoption of sustainability practices during the construction phase of a project (Srivastava et al., 2021). The construction industry contributes significantly to meeting the needs of society, improving the quality of life of the people, and strengthening the economic growth of a country (Albtoush et al., 2022; Khanzadi et al., 2020; Sedayu et al., 2020; Sharifi & Sharbatdar, 2021). It contributes effectively to encouraging internal and external investment (CBJ, 2018), which has become the backbone of the Jordanian economy (Albtoush et al., 2022). The general political climate and the safe investment environment are just two of the many factors that have influenced the growth of this industry in recent years (Albtoush et al., 2022; Anisurrahman & Alshuwaikhat, 2019). The gross domestic product (GDP) ascribed to construction in Jordan increased by approximately 21% during 2021 (Anisurrahman & Alshuwaikhat, 2019; Trade Economics, 2020), reaching JOD 249 million in the third quarter of 2021 compared to JOD 206 million in the second quarter of the same year (Trade Economics, 2020). The construction sector represents more than 60% of the investment projects in the region, or around 33% of GDP, and offers job opportunities for around 30% of the labor force (Jordan Times, 2019). Due to the geopolitical conditions in the region in recent years, the percentage of immigration has increased dramatically particularly for safety issues (DoS, 2016; GAN, 2020), which has led to an increased demand for public construction (MPWH, 2016). However, while Jordan has developed a successful and thriving construction sector, it has been strongly criticized for being a major contributor to carbon emissions, global warming, and environmental degradation (Alam et al., 2017). Globally, construction is responsible for 30–40% of total energy consumption (Lafargeholcim, 2015) and between 40 and 50% of greenhouse gas (GHG) emissions (MPIC, 2017). While construction creates facilities for human activities and social development, its impacts on the environment, society and economy, both negative and positive, are very profound (Alam et al., 2017; Durgam et al., 2022). In terms of environmental concerns, different types of negative impacts that the construction industry can create, related to social and economic issues, are considered serious problems, which have significant impacts on the country (Sharifi & Sharbatdar, 2021) and on our lives (Sedayu et al., 2020). For instance, the construction industry contributes to the increasing demands for natural resources, which is a particular problem for countries with inadequate resources (OGC, 2007).

Every day, sustainability as terminology is getting more widely spread. Sustainability, a term that is increasingly used as “A thought for long-term goals”, because it is a dynamic balance of three mutually interrelated elements: natural ecosystems, resource conservation and enhancement; economic production; and the provision of social infrastructure such as jobs, housing, education, medical care, and cultural opportunities (Bell & Morse, 2008; Sharifi & Sharbatdar, 2021). While Zakrzewska et al. (2022) define sustainability as a dynamic process that combines economic, social, institutional, and environmental dimensions, the concept of sustainability performance is more difficult to define due to its broad and subjective characteristics, especially with regard to its environmental dimension and the way in which this interacts with other economic and social dimensions. Thus, it is necessary to propose a common framework for measuring sustainability performance and sustainable practices that have positive impacts upon the industry (St Flour & Bokhoree, 2021). Jordan demonstrated its commitment to sustainable development when the Jordanian government signed the UN Agenda 2030 in 2015 (CSIS, 2018). However, there remains a lack of laws and regulations regarding sustainable construction, and an absence of penalties for those who build using unsustainable methods.

The construction industry has three main phases: design, construction, and operation. Sustainable construction is carried out throughout these three phases. Addressing sustainability into the design phase refers to the design process that integrates an environmentally friendly approach to reduce negative impacts on the environment and considers nature resources as part of the design, thereby improving building performance (Elmansy, 2014; U.S. GSA, 2021). It is about optimizing site projects, minimizing-renewable energy, using friendly materials and products, conserving water uses, and optimizing occupational practices (U.S. GSA, 2021). In contrast, sustainability in construction is the practice of creating a healthy built environment using recyclable materials in building and minimizing energy consumption and waste production during the construction of a project where possible and protecting the natural environment around the site (BigRentz, 2020; Jackson, 2021). Finally, sustainability in operation is about promoting sustainability practices during the occupation aiming to the achievements of the facility itself. It will encourage end-users to play their part in the evaluation to identify how satisfied people are with the building and to examine how the facility is meeting its environmental objectives throughout its operational life (OGC, 2007). The current study considers sustainability assessment only during the construction phase.

In fact, there is a lack of awareness of sustainable practices in the construction industry, and there continues to be a widespread use of traditional materials in construction, even those that are harmful to the environment, with little evident appetite for more environmentally friendly materials (CSIS, 2018). In addition, there is insufficient expertise among Jordanian contractors to implement sustainable projects. The authorities in Jordan have responded to the need for establishing environmental regulations that help reduce the negative impacts of the construction industry, partly to identify problems related to the environmental, social, and economic impacts of the industry, and to identify the most important measures to implement (CSIS, 2018; Raynsford, 2000). Thus, there is an urgent need to have authenticated construction firms to help develop the Jordanian economy while avoiding any obstacles that might impair the development of the construction industry.

Among the green management practices that are missing during the construction phase include reducing the waste of construction materials, minimizing energy and water use, and reducing pollution (Raynsford, 2000). As a result, highly competitive and profound changes in the construction industry are forcing contractors to continuously improve their performance. Construction contractors, who typically manage any interaction between construction activities and sustainability, play an important role in environmental protection (Fei et al., 2021; Kim & Huynh, 2008). Performance measurement is the heart of ceaseless improvement. Generally, improving contractors’ efficiency and effectiveness is the main objective of this research, to assist managers and members of an organization to improve the outcomes from delivering construction projects and for the purposes of identifying the strengths and weaknesses in their performance during construction (Khanzadi et al., 2020). Contractors do not recognize the importance of sustainability or how to apply sustainable practices during the construction phase. It is worth mentioning that some projects are specifically designed to be sustainable, but these efforts become nullified during the construction phase, because the practices of contractors are far from sustainable, which ultimately results in an unsustainable project (Sedayu et al., 2020).

In 2021, Jordan lacks qualified contractors with sufficient experience in implementing sustainable projects, a situation worsened by the lack of detailed studies on construction projects before construction begins, the lack of experience within the industry in dealing with complications that occur during construction. This is due to the relative ease with which a construction company can be established in Jordan, thereby allowing unqualified members to enter the contracting world, which can lead to serious problems during the construction of a project (Sedayu et al., 2020). It also means that it is common for the profit motive to take priority over quality, and no environmental, social, and economic impact studies are done before a project is initiated.

Supporting the construction sector to become more sustainable ensures the development of effective solutions to these problems over the long term, so that that the positive impacts might be noticed in the short term. Although many studies have covered several dimensions of sustainability, there is still a lack of experience in applying the principles of this science on the ground, which limits the impact of any theoretical benefits. Therefore, this research aims to develop a system for evaluating and qualifying contractors to enter the field of sustainable construction. This involves outlining the most important problems arising from the traditional methods of construction, clarifying the impact of the application of sustainability practices on this sector, and the issues that prevent its implementation, and explaining the need to move away from traditional methods of construction toward new strategies based on a more sustainable methodology. The current research study remains open to the possibility that rating systems developed elsewhere, may provide important information for the development of a rating system in Jordan (Sharifi & Sharbatdar, 2021). Ultimately, the current research study proposes an assessment of sustainability performance for the Jordanian construction industry, that is linked to rewards, the like of which has never before existed in the country.

The paper is structured as follows:

  • Section 2 provides a literature review on the topic;

  • Section 3 provides the methods of the current study;

  • Section 4 provides the techniques used in determining sustainability assessment indicators;

  • Section 5 presents the results, and the discussion of the results, including a comparison with the existing rating systems worldwide;

  • Section 6 present the conclusions.

Literature review

By reviewing previous literature related to the importance of sustainability and its dimensions, some researchers have touched on the importance of implementing sustainability in the construction phase as it is considered an important part of the project life cycle. Myers (2005) presents the initiatives that encourage sustainable construction in Britain and reviews the responsibility of large companies toward society and their attitudes toward sustainability, which were mostly negative. The study argues that the construction industry is overly complex already and it does not need the extra complication necessary to transform it into a sustainable industry. As a result, only a few companies changed their construction methods to fall in line with the concepts of sustainability. Sarkis et al. (2012) look at the Analytic Hierarchy Process (AHP), a model to help decision-makers in selecting sub-contractors, clarifying the benefits of this model on the sustainability of the built environment and discussing the economic, social, and environmental impacts when it is applied to projects. Vazquez et al. (2013) focus more on the importance of the project construction phase in shaping the relationship between humans and the environment, emphasizing the importance of meeting sustainability principles at the execution phase of hospital projects in Brazil.

It is estimated that 60% of the solid waste in urban centers is construction waste and reducing this and other environmental harms starts at the design phase of a project, using sustainability principles from the outset and continuing to applying them during the construction phase of the building. Controlling all aspects of a project requires a bird’s eye view over its entire life cycle (Khanzadi et al., 2020). This study concludes that the sustainability of a project cannot be limited to its operational phase only but must also be sustainable during the construction phase. Jiang et al. (2019) presented a comparison between the sustainable performance of prefabricated and traditional buildings. Their study focuses on studying the construction phase only. They generated 16 indicators from a literature review, questionnaire survey, and specialist interviews to conduct a sustainability evaluation of the buildings’ performance. Finally, Sedayu et al. (2020) conducted a study to propose measures required to improve construction project management performance using the green buildings concept in Indonesia. The study applies importance-performance analysis to measure user satisfaction and the performance of contractors. The results indicate that the technical factors affecting construction projects are dominant in measuring the constructor’s performance, so the use of the green buildings concept is important for construction projects in Indonesia.

There are relatively few studies discussing the importance of sustainable construction; most focus on the design phase, and none of them offer a clear and precise system or set of practices that could be applied by contractors during the construction phase to evaluate their sustainability performance, or even to determine the extent of their experience in implementing sustainable projects. However, the current situation in Jordan is that contractors are delivering either sustainable or traditional construction projects with no performance evaluation in place.

This research aims to develop a practical tool that includes sustainability assessment indicators that have been set and analyzed in scientific ways to assess the performance of contractors during the construction phase of projects in Jordan. This will ensure reducing the destructive effects of construction by delivering future construction projects in a more efficient and sustainable manner.

Research methodology

Worldwide, different methods are available for developing sustainability assessment indicators (Sharifi & Sharbatdar, 2021). However, the overall methods for how to develop a list of indicators to assess contractor performance are still lacking, and as shown in the literature review in the previous section, studies which are related to the current research are limited. Therefore, the current research aims to develop a list of indicators that measure the sustainability performance of construction contractors. This was developed through four phases, as shown in Fig. 1.

Fig. 1
figure 1

Research methodology summary (adapted by the authors)

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Phase I carries out a thorough review of the relevant literature for the study area. The importance of this phase is first to identify the research problem and formulate the research objective by reviewing and carefully studying the literature to identify the best sustainability practices worldwide. A gap was identified in the knowledge and references regarding the performance assessment of contractors when delivering construction projects. Consequently, the research problem is the absence of a precise assessment of the sustainability performance of contractors in Jordan, to enable them to be evaluated and classified, which currently impedes sustainability practices in Jordanian construction projects.

In Phase II, a list of indicators is identified by reviewing the literature as a technique for collecting data, conducting a questionnaire survey, and commencing interviews. The questionnaire was designed following a review of the relevant literature. Thus, a survey instrument that includes 42 indicators was conducted and distributed to 300 engineers and experts. Only 106 of them answered questionnaires in full, giving is a 35% response rate. The small sample size is indicative of the limited number of people in the industry who are nominated experts in the field of sustainability. This is followed by suggesting a type of creation method that uses the experts’ opinions to develop a set of sustainability assessment indicators. The reason is that a specific and rigorous data set is required, as well as a favorable environment for citizens to participate in the decision-making process, both of which are lacking in Jordan. Thus, a panel of experts is formed here to present their opinions on the proposed set of indicators. The panel included academics and experts who are currently working in the public and private sectors and are familiar with sustainability practices. By the end of this phase, 78 indicators were generated.

In Phase III, an analysis was conducted on the collected data using statistical techniques to determine the weight and importance of each indicator.

In Phase IV, the generated list of indicators was developed, along with their weightings, and the scoring system to be used when certifying contractors’ performance during the construction phase. Two additional categories were added to the list to make five main categories and 78 indicators.

Determining Sustainability Assessment Indicators

Researchers argue that many tools have been developed for the purposes of sustainability assessment that fail to consider all sustainability dimensions in a comprehensive way and, in most cases, these tools focus on only one of the three main sustainability dimensions, namely environmental, social, or economic (St Flour & Bokhoree, 2021). These methodologies often fail to address country-specific contexts and issues; since these can alter drastically between nations in terms of history, physical formation, economy, local customs, the significance of religion, political and institutional systems, and so on, such methodologies are often not generalizable to other parts of the world. As a result, the main objective of most existing assessment models is to discover the specific condition of the country through the chosen indicators. In many cases, the indicators do not provide the answer as to why the level of sustainability achievements differs from one place to another.

In the proposed model for the development of sustainability assessment indicators for measuring contractors’ performance, the limitations of the existing models are sought to be highlighted and overcome in the best possible way, with comprehensive coverage of the key issues that improve contractor performance and enhance the deliverables for construction projects in Jordan. Three major dimensions were identified following the review of a wide range of literature, namely the environmental, social, and economic dimensions, and then 14 sub-categories were identified within these. On this basis, this study then attempts to present a comprehensive and integrated model of sustainability assessment indicators that incorporates the link between existing theories and practices by overcoming the afore-mentioned limitations from previous studies in the best possible way.

Literature Review

A literature review is an approach used to review the existing knowledge from existing studies on the specific topic of the research to gain a full understanding of the current status. It can also reveal which areas require further investigation to enhance the work already done (Hart, 2018). Based on previous literature and through understanding the problems and limitations facing the application of sustainability practices in the construction sector, especially in Jordan, 42 indicators have been reached and data collected on the three dimensions of sustainability. These practices were allocated to either environmental, social, or economic, where the environmental dimension includes 21 indicators, and the economic and social dimensions include 11 and 10 indicators, respectively, as shown in Table 1.

Table 1 Sustainable assessment indicators during the construction phase
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Questionnaire preparation and conducting the survey

The sustainability concept varies from one region to another, and indicators should be precisely formulated based on location, the country under study, institutional and regulatory frameworks, available resources, and the national policies, programs, and plans that need to be followed (Yigitcanlar & Teriman, 2015). Consequently, to formulate specific indicators within the Jordanian context, a questionnaire survey was designed, using a 5-Point Likert Scale [strongly agree (5), agree, neutral, disagree to strongly disagree (1)] that covered the three dimensions of environmental, social, and economic. Multiple-choice questions were closed to make the questionnaire easy to answer. Respondents were asked to give each indicator related to each aspect of sustainability a score based on its importance. The questionnaire survey was sent via Google forms and a time limit was set of 2 weeks; any forms returned after this period were discarded. All those that were returned were used to rank the indicators and each one was given a weight of importance. The completed questionnaires that were returned and answered in full were considered valid to be analyzed using SPSS. The questionnaires were distributed to 300 participants in the field of sustainable construction, as shown in Table 2.

Table 2 The characteristics of the respondents to the questionnaires
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The response rate from the returned and valid questionnaires was 33%. For each item, a mean score of 3.5 or higher was used as a cutoff point, which produced a final set of 42 indicators, with rankings, as shown in Table 3.

Table 3 Main findings from conducting questionnaire survey
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Interviews

Following the questionnaire survey, a series of interviews was carried out to gain greater insights into the development of a list of indicators to assess contractor performance. The interviews were commenced with specialists from the Ministry of Public Works and Housing MPWH, university professors, as well as specialists in the field of sustainability from the Jordanian Engineers Association and the Jordanian Green Building Council. A total of eight respondents were contacted from the questionnaire survey for the purposes of conducting an interview. The interviewees were chosen based on their expertise and specialisms in the field of sustainable construction. The interviews were semi-structured, based on a list of questions related to developed categories, and covered the following aspects:

  1. 1.

    The development of such indicators related to the given categories.

  2. 2.

    Ranking the developed indicators and the need to extend the list.

  3. 3.

    Rate the developed indicators based on their importance.

  4. 4.

    Develop a scale of achievements for measuring contractor performance.

In line with the current COVID-19 restrictions in Jordan, three of the interviews were conducted over the telephone, and the remaining five over Skype. Their profiles are given in Table 4.

Table 4 The characteristics of the respondents to the interviews
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The interviews were all transcribed and analyzed using a qualitative analysis approach. The results from the analysis were applied to the list of indicators and grouped into new categories within the three dimensions of environmental, social, and economic. The interview questions enabled the interviewees to share their knowledge and experiences regarding developing a list of indicators for the purposes of sustainability assessment, and they offered their opinions and attitudes openly and broadly. The analysis, as mentioned earlier, used a thematic approach, coding similar data with an appropriate theme. The coded data were then used to developed and feed the developed list of sustainability assessment indicators more precisely and more broadly.

Results and discussion

Based on the literature review, an initial assessment was conducted which resulted in 42 indicators across the 3 main dimensions. The questionnaire was distributed to over 300 engineers and specialists. There were 106 fully completed questionnaires that were received back and statistically analyzed. It should be noted that, at the first phase of developing the list of sustainability assessment indicators, the literature review produced five main categories embedded into the three sustainability dimensions. Then, the initial list was tested by conducting the questionnaire survey. The completed questionnaires indicated the importance of each indicator. The indicators were then rated and given a weight to be used in measuring the performance of the contractors during the construction phase. In the final phase of developing the list, semi-structured interviews were conducted. As a result of these interviews, more indicators were added which were then grouped into new categories. This led to creating the final model that contains 78 indicators divided into five categories (environmental, social, economic, lean manufacturing, and cultural). The two new categories (lean manufacturing and cultural) were added, because they influenced the application of sustainability indicators during construction and led to the upgrading of the sustainable assessment guide. Specifically, lean manufacturing was defined by one interviewee P5 as a manufacturing approach that focuses on avoiding waste while concurrently optimizing productivity to save time and operating costs, while also increasing the level of quality and improving time management (Diann, 2020). The cultural category was added, because, in some research cases, it can be considered as the fourth dimension of sustainability. According to Hawkes (2001), the environmental, economic, and social issues in one country cannot be solved separately from the culture of the society in which these issues arise. Consequently, this category was added to the model with two sub-categories, namely heritage and human rights. Heritage was included as one of the sub-categories in this new dimension, because Jordan has a long history, and its cultural legacy deserves more attention. There are many archaeological sites in Jordan that are not listed by the Department of Antiquities (DOA); indeed, studies have shown that there are 870 archaeological sites in Jordan that have been destroyed, 390 were looted, and there are thought to be thousands of sites that remain undiscovered and/or undeclared (DOA, 2022). The second sub-category is human rights. Unfortunately, there are many violations of human rights in projects in all regions of the world, so we have added indicators that preserve the rights and dignity of the labor force and to eliminate all kinds of racism. The initial list of indicators is given in Fig. 2 refer to Table 1 and the final list of indicators is given in Fig. 3 refer to Table 5.

Fig. 2
figure 2

Categories and sub-categories before the interviews

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Fig. 3
figure 3

Categories and sub-categories after the interviews

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Table 5 Final list of main/sub-categories and indicators for sustainability assessment
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There are nine indicators that were added to the environmental dimension, six indicators to the economic dimension, and seven to the social dimension. The main five categories were chosen by taking the most frequently mentioned categories from the literature, the questionnaire survey, and the interviews, each of which was given a rating score. The rating output for the main categories was determined using SPSS software. The mean, standard deviation, rank, weight*100%, and rating (score) for each category are shown in Table 5. This assessment tool is a multi-dimensional method that covers different environmental, social, and economical issues. Therefore, the process of creating the weighting system for the categories and the indicators, within the context of the local community, is calculated by dividing the mean of each category, for example, on the summation of means for all categories and so on for indicators as shown in Eq. 1

$$\mathrm{weight}= \frac{\overline{X} }{\sum \overline{X} },$$
(1)

where x is the mean for (category/indicator).

Each indicator in each category has been given an award based on its weight and mean using Eq. 1.

Calculating the weighting score for each (category/indicator), the system can define the importance of each indicator according to the local context within which the tool is developed. The final score is 332 and contractors should be graded according to these awards. The list of developed categories, and the indicators, are given in Table 5.

The final list of indicators is shown in Table 5. The weight for each category and indicator were adjusted due to the additional sub-categories and indicators that were added. A new statistical analysis was prepared for the updated model; hence, the highest and lowest scores were changed as shown. To develop these sub-categories and indicators into a comprehensive model that can be adopted by the specialized authorities to evaluate contractor performance during the construction phase of a project, these were all discussed with specialists and experts in the field of sustainable construction. Their opinions and experiences helped to establish the final model, in which indicators among the three main dimensions were added. In the environmental dimension, the total number of indicators grew from 21 to 30, while six indicators were added to the economic dimension to become 17, and the total number of indicators within the social dimension is also 17. Moreover, two further sub-categories were added to the model, namely cultural and lean manufacturing, with combined indicators of 14. Therefore, the developed model contains a total of 78 indicators distributed across five categories. Figure 4 shows the weight of each category.

Fig. 4
figure 4

Weights of the categories

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As shown in Fig. 4, the environmental dimension has the highest weight at 39% and incorporates a total of 30 indicators across the 7 sub-categories which are safety, leadership, energy, quality control, waste management, well-being, and water. Following our studies, analysis, and discussions with the experts, this category became the one with the highest number of indicators to emphasize the importance of focusing on improving contractor behavior toward the environment during the construction phase. According to the experts, taking responsibility for their actions should be one of the top priorities and this is shown in the awards of the indicators. The maximum score which can be obtained to measure a contractor’s performance during the construction phase is given in Table 6, where the maximum score which can be obtained 332 is distributed, as shown in Table 6.

Table 6 Distribution of marks
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Performance indicators: environmental dimension (EnD)

The environmental dimension is about the ability to use natural resources without undermining the equilibrium and integrity of ecosystems, and reduce the burden on the environment (Bell & Morse, 2008; Sami & Farid, 2021; Sharifi & Sharbatdar, 2021; St Flour & Bokhoree, 2021; Zakrzewska et al., 2022). The environmental dimension was ranked first in importance, with a weight of 39% across the five categories. Subsequently, 7 sub-categories and 30 indicators were generated from this research, between which were assigned a total of 130 marks. The highest ranked indicator is E20, with a weight of 3.88, while the lowest ranked is E9, with a weight of 2.33.

Performance indicators: social dimension (SD)

The social dimension is about ensuring equality of opportunities for people, involving welfare, quality of life, and sustainable human development. It should liberate individual capacities and fulfill human needs, thus ending poverty and improving individual quality of life, offering security with full rights and liberties in the long term, and engendering social cohesion (Bell & Morse, 2008; Sami & Farid, 2021; Sharifi & Sharbatdar, 2021; St Flour & Bokhoree, 2021; Zakrzewska et al., 2022). The social dimension was ranked second in importance with a weight 24% across five categories. Subsequently, 4 sub-categories and 17 indicators were generated from doing this research, between which were assigned a total of 79 marks. Indicators S11 and S17 are the highest ranking, both with a weight of 6.72, while the lowest ranked indicator is S6, with a weight of 3.04.

Performance indicators: economical dimension (EcD)

The economic dimension is about the efficiency of economic and technological activities, fostering investment and productivity, economic growth, and economic output potential (Bell & Morse, 2008; Sami & Farid, 2021; Sharifi & Sharbatdar, 2021; St Flour & Bokhoree, 2021; Zakrzewska et al., 2022). The economic dimension was ranked third in importance with a weight of 19% across five categories. In total, 5 sub-categories and 17 indicators were generated from doing this research, between which were assigned a total of 64 marks. The EC13 indicator is ranked highest, with a weight of 7.21, while the lowest is EC7, with a weight of 3.03.

Performance indicators: cultural dimension (CD)

The cultural dimension is about creativity, heritage, knowledge, and diversity. These principles are essentially connected to human development and make up the cultural dimension of sustainable development (Wiktor-Mach, 2020). The cultural dimension was ranked fourth in terms of importance with a weight of 13% across five categories. Two sub-categories and 10 indicators were generated throughout this research, and the maximum rating assigned to this category is 42 marks. Indicators C7 and C10 are the highest ranking, both with a weight of 10.65, while C4 is ranked the lowest with a weight of 8.33.

Performance indicators: lean manufacturing

Lean manufacturing is a production philosophy that concentrates on customer value and targets to serve the customer as efficiently as possible by eliminating all unnecessary waste from the operation (Järvenpää & Lanz, 2020). Waste means all the actions that do not add value to the customer, and value is something that the customer is willing to pay for. It is an integrated socio-technical system whose main objective is to eliminate waste by concurrently reducing or minimizing supplier, customer, and internal variability (Resta et al., 2016). Lean emphasizes the efficient flow of products over the maximum utilization of resources (Järvenpää & Lanz, 2020). It is a multi-dimensional approach that encompasses a wide variety of management practices that work synergistically and are mutually reinforcing (Resta et al., 2016). The importance of lean production in this context is in satisfying the expectations of the end-users throughout the entire operational life of the building, from the start of the construction phase, during the years of building use, all the way through to demolition. This dimension ranked fifth in importance with a weight of 5% across the five categories. Only one sub-category was produced with four indicators and the maximum rating assigned to this category is 17 marks. L1 is the indicator ranked first with a weight of 27.38, while the lowest ranked is L2 with a weight of 22.62.

Certification criteria

The certification criteria are based on the summation of scores which were assigned to indicators on the assessment list. The score for each sub-category comes from the summation of all scores which are given to each indicator. Then, the total score for each category comes from the summation of the score for each sub-category. The formulas for these workings are given in Eqs. 2–5

$${\text{Indicator's result}} = {\text{ Indicators result's score }}*{\text{ weight of the indicator}},$$
(2)
$${\text{Sub-Category's result}} = \, \sum {\text{ Indicators result's score }}*{\text{ weight of the Sub-Category}},$$
(3)
$${\text{Category result}} = \, \sum {\text{ Sub-Category result's score }}*{\text{ weight of the Category}},$$
(4)
$${\text{Total assessment level }} = \, \sum {\text{ Category results}}.$$
(5)

The score results multiply by the specific weight for each category, sub-category, and indicator. The total sum of each parameter will appear on the indicator, and finally, the sum of indicator levels will be shown on the category level with their relative weights. The result of this awarding system can be driven by applying Eq. 4 that derives the contribution of each category and Eq. 5 that derives the summation of all weights to classify contractor performance. Five levels are considered to classify contractor performance including Class A, Class B, Class C, Class D, and finally not certified. The classification criteria of the contractor performance of the awarding system for sustainability assessment are shown in Table 7 which are based on proposed classes in the Jordan Green Building Guide (JGBG, 2013).

Table 7 Award system for sustainability assessment (JGBG, 2013)
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It is clear from the previous discussion that each category, sub-category, and indicator have a weight and a score. The summation of all results obtained from each one is inputted to the given equations to arrive at the final awarding scheme. For example, if a certain practice has achieved a mean equal to 4.6, it would be awarded a 5. Therefore, it could be recognized that the rating of many indicators is 5. In fact, 12 indicators have been rated to 5 and only 2 indicators are rated to 3. Moreover, the slight differences in the standard deviations and the weights between the indicators made it possible to rank them. Thus, PE 20 states “Establish a policy for waste management according to the sustainability criteria” and is ranked first, with a mean of 5, S.D 0, weight 3.88%, and it was rated according to its mean of 5. This rating is only achievable if the contractor establishes a sustainable system to manage both hazardous and non-hazardous waste during the construction phase, as well as recycling and reusing materials as much as possible; unsustainable methods of waste management will be awarded zero. It should be noticed that the zero deviation of this practice clarifies its importance. Subsequently, the practice that ranked last was (PE9) states, “A report must be prepared detailing gas emissions resulting from any burning operation” with a mean of 3, S.D 1.87083, weight 2.33, and a rating of 3. The total reward for this category is 130/332 with a percentage of 39%.

The findings from the study suggest that all the indicators were important in assessing contractor performance during the construction phase with respect to sustainability across the entire execution stage. These results indicate that environmental protection plays a crucial role in defining sustainability; the social category comes second in importance, while lean manufacturing is at the bottom of the list with a weight of 5%.

Implications of the assessment indicators in practice

The discussions with the experts proved that the list of indicators is comprehensive and are applicable to construction projects in Jordan. However, real differences will only be made when systemic changes are made at multiple levels. For example, with regard to national legislation, some governmental systems should be adjusted, and new instructions must be enacted. Serious steps should be considered in the education sector and in raising awareness, too, because the community needs to be more conscious and aware of their rights and duties toward the planet. Some specialists suggested that the Ministry of Public Works and Housing could collaborate with the Green Building Society to agree on this model. Then, the agreed list of actions could be added to all tender documents produced for each project, and all contractors must then commit to it as a condition of their involvement in the project. It is important for the assessment process to be objective and free from bias, so it should ideally be carried out by a third-party committee, assigned by the MPWH, and acting independently, during the construction phase.

Conclusions and future pathways

Sustainability as an approach to development is becoming an urgent requirement globally, and construction is no exception; in reality, it might be the most important industry with which to start, especially in Jordan. The literature to date lacks clear systems and codes for contractors to follow during the construction phase to execute a sustainable project; this was the motivation for this scientific paper.

The system of Sustainability Assessment Indicators for measuring contractor performance during the construction phase, developed herein, provides a blend of comprehensive and functional guidelines, based on sound sustainability research in Jordan. It also offers a set of achievable goals for local authorities and national policymakers who wish to deliver a project in a sustainable manner. The system contains five main categories, namely, environmental, social, economic, cultural, and lean manufacturing with 19 sub-categories and 78 indicators. The findings indicated that the most important category is the environmental one, though they all play a role. The experts who were interviewed all agreed that the proposed system is a unique strategy, providing a set of indicators that the contractor can follow during the construction phase, in cooperation with all involved parties. The proposed system has great potential to accelerate the understanding and implementation of sustainable construction.

The possible limitations of this proposed system are the willingness of the contractors to participate on a voluntary basis, and the ability of professional training organizations to raise the awareness of sustainability within the construction industry. We recognize the challenges of implementing this system in Jordan due to limited funding, technology, and infrastructure, and the lack of a comprehensive national plan to drive sustainability deeper into the construction industry. The country needs a higher level of awareness, appropriate planning, and a consideration of the proposed system as forming part of the tender documentation, so that contractors see the economic benefits of sustainability, in addition to protecting the environment and raising social awareness about sustainable construction and infrastructure development.

The findings from this study may help decision-makers and other stakeholders analyze the issues with the current strategy, especially in the construction phase, and implement the most realistic actions to encourage sustainable development in Jordan. Using a structured framework that provides logical steps, based on a problem-solving approach, will increase the potential of sustainable projects to be successful. This model is only a first step on the path toward sustainable construction; further studies and annual revisions will be necessary to continue moving forward.

Finally, this model creates a comprehensive and integrated sustainability assessment method, which may require further development, to measure the performance of contractors who are delivering both public and private projects in Jordan. In the end, this rating system, or a derivation of it, will require concerted effort from all involved authorities to ensure that it is properly applied and developed.