Value Creation Assessment Tool for Green Buildings: Development and Implementation

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Introduction
Green buildings are designed, consructed, and operated with minimum environmental impacts for long-term sustainability. In the recent past, the global construction industry has acknowledged the substantial benefts of value management without compromising the quality and function of sustainable green buildings, e.g., processes efciency, waste minimization, and premium price [1][2][3]. Lützkendorf and Lorenz [4] reported direct and indirect benefts of value created by the green buildings for investors and other stakeholders, including (i) operational cost reduction and improved marketability, (ii) longer useful lifespans, (iii) cash fows stability, (iv) minimal impact of changing environmental legislation stringency, and (v) improved occupant productivity and wellbeing. On the contrary, various types of operational (e.g., failure to consider desired increase in routine maintenance with time), functional (e.g., failure to consider construction implications during design), management (e.g., incorrect time estimate), environmental (e.g., failure to consider obsolescence of equipment impact), and fnancial (e.g., uncertainty in price increase) risks can potentially destruct the value created by green buildings [5].
Te development of green buildings is more complicated compared to conventional ones due to the involvement of multiple stakeholders with diferent interests, e.g., investors, engineers and design consultants, contractors, equipment and material suppliers, governmental institutions, and the general public [6]. Generally, the investor looks for high fnancial return and market value, the buyer is interested in comfort and aesthetics, and the designer wants to follow the green building regulations that might lead to high cost. Nevertheless, the investor should be aware of possible legislative changes in the future, which might afect their asset value and their income streams. In addition to defending the economic viability of green buildings, coordination amongst the involved stakeholders becomes challenging for the developer [7][8][9]. Value management tools improve stakeholders' coordination, develop mutual consent on objectives and defnitions, and eliminate redundant costs [10].
Value and risk management improve both of quality and cost of construction. Te concept of value appreciates the multitude of dimensions of a project through economic, cultural, and social interpretations [11]. Value management intends to attain the anticipated value with minimal cost without compromising the quality and functions, while risk management evaluates rational strategies to minimise uncertainties to maximise the organization's performance. Te indicator of perceived value in construction projects obtained success in the projects that ofer risk tolerance, reasonable cost, timely completion, and compliance with quality parameters [12]. Te whole life-cycle value exchange mechanisms are risky and complex, so a deeper investigation of the risks associated with value exchange is needed to develop value targets throughout the project's life cycle [13].
Vision 2030 of KSA focuses on the need for sustainable housing and targets related laws and regulations in the near future [14]. Tere is a need to set up a framework for improving the creation of value during the building development stage in Saudi Arabia by integrating value with project management. Te efciency in delivering value by integrated risk, value drivers, and corporate objectives has the potential to link a project's outcome to the company's strategic objectives. Value analysis and value management are increasingly becoming part of the construction industry's development in the country [15]. Terefore, the Saudi Arabian construction industry will obtain signifcant benefts from the application of value and risk management in all projects. Presently, there is no exclusive value creation assessment tool that can simultaneously assess the value creation and associated risks in the Saudi Arabian GB construction industry. A framework integrating value and risk has great potential for the application of green building development in order to manage investments in construction projects and ensure the positive contribution of value drivers to the particular business outcomes of products, services, and projects during the life cycle of building assets. Te present study specifcally aims to (i) develop an assessment tool for assessing value creation in GB development and (ii) apply (test) the assessment tool on real case studies.

Literature Review
Although a tangible value in GB might be hard to achieve [3], literature has reported tangible and intangible environmental values provided by GB, such as waste reduction and socioeconomic benefts. Alyami and Rezgui [16] emphasised the importance of social and cultural aspects in a building's design by using environmentally sustainable materials and evaluating their functionality, usability, durability, and reliability. A good building design responds to the site's microclimate and contributes to the environment, which can result in a range of wider socioeconomic [17]. Improving function longevity and productivity enhances the performance, reliability, quality, safety, and life-cycle cost of GB. Such improvements generate additional revenue for the building owner and efectively compensate the additional cost spent on value addition and make more GB initiatives worth the investment. Although GB has strategically attained attraction in most of the countries, a push is yet required from the governments' leadership to promote them at regional and national levels [18].
Te perceived value has a multidimensional concept that can be afected by the dynamic nature of risks or benefts [19]. It is important to connect value creation dimensions through the life-cycle stages and measure the impacts of perceived risk on perceived value [20]. A deeper investigation of the risks associated with value exchange is needed. In addition, a substantial disconnect does exist between the builders and investors on how to quantify and validate the value added by GB [8]. Both the value and risk analysis identify project development contextual issues and provide opportunities to optimise the design and operation of GB during the early stages of development. Te construction sector in Saudi Arabia did not consider risk management in development projects and identifed a need to set up a framework for improving project value by integrating value and risk in the development of construction projects [5].
A variety of assessment tools were used to assess the building design performance. As these tools were applied and used in diferent countries to meet their local requirements, some of them are not applicable in their original forms for achieving best practices in other regions [21][22][23]. Due to the importance of environmental sustainability in construction projects, environmental assessment procedures have been developed worldwide since the frst attempt by the UK building research establishment environmental assessment method (BREEAM) in 1990 [16,24]. Subsequent efforts developed tools to specify, predict, evaluate, and measure a building's performance. Te main tools for the environmental assessment of buildings are BREEAM, leadership in energy and environmental design (LEED), and the green building tool (GBTool), which can evaluate resource use, ecological impact, indoor environmental quality, and fnancial and management aspects. Te existing tools have some limitations, such as avoiding the fnancial aspects, complexity, regional variation, and the use of weighting mechanisms [24][25][26]. Te constructs of these tools signifcantly vary based on the interests of the involved parties. For instance, the owners are more interested in fnancial returns, while the occupants are concerned with health and safety and indoor environment [27]. Tese interests should be taken into consideration in the design of the assessment tool to ensure its success [25].
In general, an assessment tool consists of three main components, including assessment criteria and subcriteria, criteria scoring and weights estimation, and criteria aggregation to generate an overall sustainability score [24, [28][29][30][31]. Finally, the assessment tool has to be validated with a practical application [32]. Although similarities exist amongst diferent assessment tools in terms of their aims, structure, and approach, they difer as well in terms of scope, metrics, and standards [33]. Nevertheless, an assessment tool should be simple, practical, and fexible and covers all the required aspects in the context of the assessment.
To date, many versions of BREEAM have been developed for diferent regions, such as BREEAM Gulf/Middle East which is used in Saudi Arabia and HK-BEAM, which give the BREEAM tool a strong and mature system [16,24]. However, it has been criticised for its limited transparency [24,30]. Alyami and Rezgui [16] stated that there is a strong similarity between the criteria of BREEAM Gulf/Middle East and BREEAM-UK, with few modifcations due to the differences between the socioeconomic and environmental conditions of the two regions. In addition, the LEED system is based on ISO standards which are not aligned with European standards [24]. Zou [34] evaluated LEED and 3-Star rating systems based on their potential for GB assessment and found LEED more appropriate for commercial and industrial buildings, while 3-Star was found to be a more suitable choice for residential buildings. Terefore, it can be said that the region, culture, and type of building should be considered in the development of a new assessment tool.
Although there are some similarities in the assessed categories, each assessment system has its speciality in the weighting mechanisms and the rating scales. For instance, some diferences and similarities between BREEM and LEED are as follows [24, 30]: (i) BREEAM: the evaluation categories are management, health and wellbeing, energy, transport, water, materials, land use, ecology, pollution, and innovation. It uses a percentage score for rating: <30% Unclassifed, ≥30% Pass, ≥45% Good, ≥55% Very good, ≥70% Excellent, and ≥85% Outstanding. (ii) LEED: the evaluation categories are sustainable sites, water efciency, energy and atmosphere, indoor quality, materials and resources, innovation, and regional priority. It uses a point score for rating: 40-49 points Certifed, 50-59 points Silver, 60-79 points Gold, and 80 points and above Platinum.
Te GBTool is one of the most comprehensive evaluation tools. As it covers most of the evaluation categories that are either ignored or poorly mentioned in other assessment tools, including resource consumption, loadings, indoor environmental quality, quality of service, economics, management, and commuting transport, the tool can be applied in diferent regions, with some adjustments [35]. However, users may face difculties in using GBTool due to the inherent complexities of its framework. CASBEE, developed in Japan, distinguishes between the building environmental loading and building environmental quality and performance [26]. CASBEE consists of four main aspects, energy and resources efciency, and local and indoor environment, which are categorised into two groups, loading and quality [16]. Determining the building's environmental efciency by scoring the groups separately and then calculating the ratio of environmental quality to building environmental performance diferentiate this tool from others. CASBEE's weakness is related to its specifc regional character, i.e., it is for Japan and its national standards [24].
Te design quality indicator (DQI) supported by the construction industry council in the UK has been used as a complementary system for measuring performance in construction and aims to capture the perceptions of design quality associated with buildings. Te DQI consisting of three main building assessment categories, including function, build quality, and impact, enables the client to defne their aspirations that obtain the project's success and then measures the project success against these aspirations [25,26,31,36]. Te DQI assesses a wider range of considerations than other building environmental assessment tools, so it can be considered one of the most useful tools to improve the design, functionality, and sustainability of a building [31].
Te following theoretical and practical gaps still exist to assess the GB design in the existing assessment tools [21]. Te gaps in available tools are (i) dimensionality of performance value drivers, (ii) no consideration of the risks impacting value creation, and (iii) no integration between the value creation drivers and the associated risk factors. Most of the existing building performance assessment tools, such as DQI, use a hierarchical framework consisting of criteria at the top of the hierarchy, subcriteria in the middle, and indicators as the main building blocks. Te value assessment tool developed in the present research also adapts points and percentages as a rate to assess the performance of value creation aspects, similar to BREEM and LEED.
Recognizing the research gap, authors [37] in their previous study identifed 98 performance value drivers (PVDs) from the literature, evaluated them through a handdelivered questionnaire survey and statistical analysis, and fnally selected 51 most important PVDs to cover the fve primary value creation drivers (VCDs), including fnancial, functional, operational, environmental, and management of a green building. In the subsequent research, Alattyih et al. [5] examined various risks that may lead to GB value destruction in KSA. In this research, they identifed 66 potential risk factors from the reported literature and conducted a hand-delivered questionnaire survey to 300 practitioners (managers, engineers, and architects) having knowledge of value engineering in the construction industry. Te SAVE International reported over 1,350 people in KSA with value engineering certifcates [38]. It was also found that out of around 8800 certifed professionals worldwide, around 16% were from KSA at the time of the study. For the confdence interval and confdence level of 10% and 95%, respectively, the research demanded at least 76 respondents from the population of 1,356. To overcome the problem of Advances in Civil Engineering nonresponsiveness, the questionnaire was sent to 300 professionals (sample size) serving the KSA construction industry. Based on an overall response rate of 29.7%, the 35 most signifcant risk factors were fnally grouped into 5 clusters, i.e., 8 in functional risk, 13 in fnancial risk, 3 in operational risk, 3 in environmental risk, and 8 in management risk cluster. Te study enhanced the understanding of the importance of the risk factors' impact on value creation in KSA. Readers interested in the detailed selection process of PVDs and risk factors are referred to Alattyih et al. [37] and Alattyih et al. [5].
Te present research developed a tool for assessing value creation in green building development and associated risks. For evaluating pragmatism, the tool has been applied to three real case studies (buildings) in Saudi Arabia. Te assessment tool can provide a unifed platform for all the stakeholders for the development and application of value management of green buildings in KSA. Figure 1 presents the methodological framework developed in the present study. Te assessment tool for value created by green building design was developed and integrated based on a critical literature review, extracting value attributes, refning them, and comparing the methodology of existing tools. Five primary VCDs were developed to cover the fnancial, functional, operational, environmental, and management aspects of a green building. Based on a questionnaire survey followed by detailed statistical analysis, the 51 most important performance value drivers (PVDs) were selected for GB design in KSA. PVDs were also grouped into ten subcriteria (two under each VCD), including capital expenditure cost (CAPEX) and operating expenditure cost (OPEX), longevity, reliability, manageability, energy and efciency, ecoresources, adaptability, control, and planning. Likewise, the 35 most signifcant risk factors that can destruct the value of GB were selected for the same (as VCDs) fve risk categories from the response of experts in the country. Te questionnaire consisting of the list of identifed PVDs and risk factors was hand-delivered to 300 practitioners (managers, engineers, and architects) having knowledge of value engineering in KSA. An overall response rate of around 30% was obtained [5,37].

Methodological Framework.
Te weights of all the PVDs (and VCDs as a whole) and the risk factors were established using the DQI weighting mechanism. Subsequently, the assessment tool was applied to three GB in KSA. Professional responded to the following two questions, related to the selected PVDs and the risk factors, using the Likert scale from "0" corresponds to "not implemented" and "5" to "highly implemented": (i) To what extent are the following indicators (PVDs) considered and implemented in this design? and (ii) To what extent is the value creation in the design of this project impacted by the following risk factors? For the second question, "0" corresponded to "not impacted" and "5" to "highly impacted." Finally, the scores and weights were aggregated to estimate the total gained score for each subcriteria and risk category and the weighted mean scores. Details for all the steps are given in the following subsections.

Selection of Indicators.
First of all, lists of controllable value attributes were extracted in each one of the fve VCDs. A questionnaire survey is a fast and efective technique for collecting statistical data and opinions [39]. Terefore, the most important attributes were examined by sending a questionnaire to the relevant professionals possessing knowledge and experience of value engineering applications in the KSA's construction industry to rate the level of importance of each value attribute to value created by green building design. After that, the most efective value indicators were extracted through statistical analysis followed by data ranking, factor analysis, and data reduction techniques. Te value creation indicators were identifed in each component, and then the components were grouped into clusters based on their relation to each other. Te data reduction technique analysed the value attributes and removed the redundant data in order to reduce the number of attributes. Te most efective indicators for value creation were 10 fnancial indicators distributed into two clusters (OPEX and CAPEX); 18 functional indicators distributed into two clusters (longevity and reliability); nine operational indicators distributed into two clusters (manageability, energy, and efciency); eight environmental indicators distributed into two clusters (ecoresources and adaptability); and six management indicators distributed into two clusters (control and planning). Details can be seen in Alattyih et al. [37]. Later, Alattyih et al. [5] identifed the most efective risk factors that can impact the value created by GB. Tese include 13 fnancial risk factors, eight functional risk factors, three operational risk factors, three environmental risk factors, and eight management risk factors.
Authors in their past studies used analysis of variance (ANOVA) to statistically diferentiate the responses of the respondents. Te Statistical Package for the Social Sciences (SPSS) software examined the importance of PVDs defned by diferent groups. Te following anticipated hypothesis for a signifcance level of 0.05 was established for PVDs selection [37]: Tere is no signifcant diference among the respondents' ratings for the importance of the PVDs (ii) H 1 : p < 0.05. Tere is a signifcant diference among the respondents' ratings for the importance of the PVDs (at least one of the groups is signifcantly diferent from other groups) Te following hypothesis for the selection process of risk factors was adopted [5]:

Weighting
System. Te weighting system was applied to estimate the weighting value for each indicator based on its impacts or importance within each group. Te weighting factors obtained the priorities of each factor to fnd out performance scores at diferent levels of the hierarchy [40]. Te main value groups in the tool are fnancial performance, functional performance, operational performance, environmental performance, and management performance. Te clusters are OPEX, CAPEX, longevity, reliability, manageability, energy and efciency, ecoresources, adaptability, control, and planning. Te main risk groups are fnancial, functional, operational, environmental, and management risks.
A simple and easily understandable questionnaire was developed for the participants in the design process. Te questionnaire structure encompassed three main aspects of the framework, including VCDSs (groups), clusters, and Financial (10) Functional (18) Operational (9) Environmental (8) Management (6) Selection of risk factors (Alattyih et al. 2020) Financial (8) Functional (13) Operational (3) Environmental ( Advances in Civil Engineering controllable attributes (PVDs and risk factors). Te questionnaire hierarchy consisted of statements assessed by using a scale, from strongly disagree to strongly agree or not applicable. Te participants' scores obtained the weights for each group, cluster, and attribute. Te weighting system estimated the weighting value for each attribute based on its impacts or importance within each group. Te weighting factors helped to obtain the priorities of each attribute and to fnd out an accurate rating for the overall performance [40]. Te most important part of the assessment process was the weighting coefcients, which were determined through a questionnaire survey in order to gain opinions from users who are suitable for the specifc regional conditions. Te weighting system used in this assessment made the total summation of all indicators equal to 100%. Details on the selection of professionals and the methodology used to develop and validate the questionnaire survey can be seen in Alattyih et al. [37].
Supplementary materials 1 and 2 show the overall weight for each indicator. Based on the results of the questionnaire survey and the scientifc approach of statistical analysis of data ranking, factor analysis, and data reduction, the optimum value created green building design consists of 19.07% fnancial performance, 35.49% functional performance, 17.66% operational performance, 15.66% environmental performance, and 12.12% management performance. Te risk factors that might destroy the value created by green building design consist of 37.09% fnancial risks, 23.19% functional risks, 8.50% operational risks, 8.00% environmental risks, and 23.23% management risks. Te weighted values were calculated through the average weighted mean for each indicator based on its value performance criteria. Ten, the overall weight for each indicator was calculated so that the total summation of all indicators is equal to 100%, as shown in the following equations: criteria weight � indi cator average weighted means criteria indi cators average weighted means , overall weight � criteria weight × criteria percentage.
Equations (1) and (2) help the designer and the value engineering team to evaluate the level of design performance and value created by a green building design throughout the design process.

Scales and Scores.
In the present study, the scoring system for the value created by the green building design assessment tool was developed and was similar to the scales used by BREEAM and LEED. Moreover, a similar 5-Likert scale has been frequently used in several past studies on the sustainability of green buildings [41,42]. Te value created by the green building design assessment tool was tested by asking value engineering professionals to evaluate the building design related to one of the value engineering projects designed by their practice by asking them to what extent the selected indicators were considered and implemented in this design. Te scale adopted for the value indicators goes from 0 not implemented to 5 high implemented, with 3 being considered, whilst the scale adopted for the risk factors goes from 0 no impact to 5 highly impacted, with 3 being moderately impacted.
Te score computing method is initiated by giving each value creation scale separately; these are called indicator scales (ISs) and should be identifed based on the respondents' rating for each indicator. Ten, the score was calculated by multiplying each IS by the given overall weight (Ws) for the same indicator, and then all gained scores were summed together to obtain the total gained score, as shown in the following equation: (3) Ten, the result of Ts is divided by the total weight multiplied by 5, which is the highest scale for each indicator. Finally, the result was multiplied by 100 in order to obtain a percentage result for each cluster and for all performance criteria, i.e., weighted mean score (Wms), as illustrated in the following equation: 3.5. Plotting the Results. Te assessment tool for value created by green building design developed visualisation of the outputs of the tools by graphical representation of the results to be easy to read and interpret. A spider diagram represents the scores scaled between 0 and 100. Tis graph displays the selected participants' answers to each section. A result further shows out a higher weighted mean score, which gives the client and the design team a better overview of the evaluation of the design and enables them to check the achieved added value for the building's s performance. Te idea of the graph is to assess how well a building or design is thought to have performed in relation to value creation in each section and look at the risks associated with each group. Tis assessment tool shows three graphs for data sets of main groups and subgroups, i.e., clusters.

Results and Discussion
4.1. Results. As part of the development process testing, the assessment tool needs to be tested through pilot studies in order to refne it if required. Terefore, the tool was tested on three buildings in KSA to evaluate the pragmatism of the proposed assessment tool. Tree buildings were selected where value engineering had been applied during project development. Te assessment tool was sent to the members (participants) of the value engineering team for scoring each value creation indicator. Tey were then asked to assess the level of consideration or implementation of each indicator. Te design quality indicator equation was adopted to calculate the gained scores. Each value creation group was given a code as follows: fnancial value creation indicator VFI, functional value creation indicator VFU, operational value creation indicator VOP, environmental value creation indicator VEN, and management value creation indicator VMA. Te highest points can be obtained from VFI + VFU + VOP + VEN + VMA � 500 points.
Te value creation assessment tool � (VFI + VFU + VOP + VEN + VMA)÷500 × 100, and it can calculate each value creation group and cluster separately as required. Table 1 presents the value creation and risk impact rating results, which are adapted based on the BREEAM and LEED rating systems. Tis table evaluated the total value created by green building design. Te value engineering team and the client can fnd out to what extent the design has brought value to the project. Te following subsections apply this assessment tool to some projects and check the value obtained.

Building 1: A Multistorey Hotel.
Te frst building was a hotel in Riyadh City. Tis multistorey commercial building has two basements, one ground foor, four upper foors, and a parking facility. In addition, it has lounges, a women's banqueting hall, cafeteria, courtyard and landscaping, wet area, restaurant, spa, swimming pool, sauna, meeting rooms, business centre, suites and studio suites, studios, and family apartments. Te total cost of the project was estimated to be SAR. 167 million (44.5 million USD). Te purpose of the study was to defne the functions of diferent facilities to generate other alternative solutions and recommendations to optimise the project's total cost, and the VE team identifed the following objectives during the introduction process: Te assessment tool was applied to all three buildings. Te results for Building 1 are presented in Tables 2 and 3. Figures 2(a)-2(c) illustrate the scores in the form of spider diagrams scaled between 0 and 100. Te results in Figure 2 present the value groups plots value, clusters plot results, and risk group plot results. Figure 2(a) illustrates that the PVDs under the subcriteria OPEX, longevity, reliability, manageability, and control were considered in the design process more (>70%) than CAPEX (68.13%), energy and efciency (65.14%), and ecoresources (63.9%). Adaptability and planning were given the least importance in the design performance with Wms less than 50%. Te results presented in Figure 2(b) fnally yield a low overall performance of environmental and management drivers. Figure 2(c) presents the results of the risk assessment tool for building 1. Te fgure depicts that environmental risks impacted the value creation most (80%) during the design process, followed by functional risks (69.7%). Table 4 shows that the overall rating result for the value created by Building 1 would be an added value with a neutral risk impact.

Building 2: An Ofce
Building. Te second building was an ofce building in Riyadh that comprised three basement foors with car parking area for 168 cars, two water tanks, and fltration and treatment units. Tere were eight foors above ground: ground foor (entrance/technical/ control), three foors of rentable spaces, four foors for offces, and the last foor for socialising. Te VE results grant signifcant cost saving in various disciplines as well as adding some extra costs to improve the project value. Since frequently the VE savings are not cumulative, as some ideas are alternatives, therefore, it is estimated that the best implementation will yield an initial net saving of SR 47,535,939, which represents 34% of the total project cost, which is estimated to be SR 139,100,888, in addition to life-cycle cost saving of SR 499,120 per year. Tables 5 and 6 present the value and risk assessment results. Figures 3(a)-3(c) illustrate spider diagrams to represent the assessment scores scaled between 0 and 100. In this project, only the PVDs for functional performance were given desired importance during the design process, i.e., Wms � 80%. Operational performance was also considered that obtained a Wms of around 70%. Te planning PVDs were not considered in the design process at all, which yielded "zero" Wms for this subcriteria. Based on the overall Wms, the fnancial performance is low (36.53%). Similar to Building 1, environmental and management VCDs obtained the least performance scores less than 30%. Te risk assessment tools revealed that the value creation in Building 2 during the design process was mostly impacted by management (60.6%), functional (50.23%), and fnancial (47.97%) risks. Te overall rating result for the value created by this project would be moderate value with a neutral risk impact, as shown in Table 7.

Building 3: A Commercial
Plaza. Te third building project was remodelling an existing residential suites system into a fve-star hotel in the northern area of the central area of Al Madinah. Te project covered a total land area of 2300 square metres, which was owned by a local real estate development, which is a shareholding company with a capital of three billion riyals and a branch of one of the leading real estate companies in KSA.
Before development, the status of the building was a commercial and residential centre with a system of residential suites consisting of 14 typical foors, which constitute 182 residential apartments and one ground and commercial foor and four basements that were used as parking and services. Te project was designed to transform the centre into a fve-star hotel consisting of 598 rooms. Te study took place to transform 13 typical foors from a residential apartment system into a hotel room system. After development, the frst foor was transformed into a restaurant with the addition of a kitchen to the fourth basement foor. New entrances have been added to the ground foor towards the two main streets with the expansion of the reception. Tables 8 and 9 present the value and risk assessment results.
Te value engineering focuses on architectural, structural, mechanical, and electrical disciplines and transmitting and developing the function of the building from the furnished apartments system into a 5-star hotel room system. Figures 4(a)-4(c) illustrate the spider diagrams showing the results of the assessment tool for Building 3. As the building intends to serve the customers with a high level of service, the functional performance obtained the highest Wms of 96.2%, followed by operational (79.89%), management (76.78%), and fnancial (73.8%). Although the environmental performance was not given sufcient (42.87%) importance, it is higher than the other two buildings. Te results of the risk assessment tool in Figure 4(c) describe management risks at the top (62.79%), followed by environmental (47.57%) and operational (46.76%). Functional risks relatively less (20.39%) impacted the value creation in the design process. Te overall rating scores given in Table 10 show that this project adds value with neutral risk impacts.

Discussion.
Te proposed tool's potential for valuecreating assessment of GB has been demonstrated in the three case studies. Te assessment tool was created based on a combination of features reported in the literature. Te adopted method uses scores and weights (most of the existing tools do not use weights) to compute indicators for value creation and risks. An excellent project that includes most of the features that contribute to value creation should have a 100% score in each of the fve value creation indicators. At the same time, such a project should have the lowest risk scores for each of the fve categories so that the value created is preserved. For example, the testing carried out on building one showed that the project performed well in functional performance as compared to other value creation indicators. Furthermore, the project performed very well in relation to mitigating environmental risks but not well in including strategies to mitigate possible fnancial risks. By using this type of information, designers and consultants would be able to optimise the design to improve the building's performance, leading to value creation and preservation. It is well accepted that every building project has opportunities to improve the value, and the proposed tool has the objective of identifying those opportunities. Value is improved and optimised by taking into consideration the value creation indicators while reducing or mitigating the risks that can destroy value creation. Tere were numerous options and opportunities for implementing value creation during the evolution of the green building development process. Te developed tool is based on a DQI methodology which was tested widely in the UK construction industry sector. Te study results demonstrated how some aspects of value creation were not taken into consideration during the design of the test buildings. With further development and refnements, the tool can be used to assist in optimising value creation during the early stages of green building development projects.
Te majority of existing tools are concerned with the assessment of the environmental performance of a building design in the early design phase of building development. Te underlying theme of these assessment tools is assessing how a building performs throughout its life cycle in relation to its environmental impacts. It has been pointed out that these assessment tools aim to answer the following questions [43]: (i) What was the basis for environmental design decisions?
(ii) What was the method of assessment?
(iii) Have the environmental impacts of the consumption of materials, energy, water, and other resources been considered?  Advances in Civil Engineering 9  10 Advances in Civil Engineering Advances in Civil Engineering (iv) Will the energy embodied in the building be ofset by savings in operational energy over the building's lifetime?
(v) What quantity of greenhouse gas emissions will be generated?
As can be seen from the above list, the scope of the existing tools in relation to value analysis is limited. Tese tools neither analyse the required functions of the project from a value perspective nor do they aim to evaluate and test the ideas that are most promising for value creation. Tat is why cost-conscious developers are turning to value engineering analysis as a method to minimise waste and maximise functionality and proftability from building asset development [44]. Value engineering has been used to study and optimise the development of products and services for decades and has been applied successfully in construction project development. However, all project development is associated with several risks. Tus, it seems logical and obvious that a "combination of efcient value management practices and risk management is one possibility to try to avoid the most dangerous risks to realise for planned value" [45]. Tus, this research attempted to elicit VCDs that can be used to aid value engineering analysis become a useable tool    Advances in Civil Engineering 13  Advances in Civil Engineering Advances in Civil Engineering 15 that assists in unlocking value in the development of GB. Te risks that challenge the destruction of value were also considered for adoption into a practical tool. Tis was achieved in part by defning the drivers that contribute to value creation and in part by defning the risks that may have an impact on realising the identifed value. Te proposed value assessment tool consists of fve main performance aspects, including fnancial, functional, operational, environmental, and management. Financial performance concerns with project value creation parameters to examine how to reduce the required CAPEX and OPEX in order to optimise the value of the proposed investment in green building assets. Ten value generation drivers listed in Table 2 with a cummulative weight of 19.07% contribute to the fnancial performance of green assets. Functional performance assessed the required functions of the asset being designed. Te stakeholders need to identify what functions are important and which performance characteristics are required for these functions. Te asset function is viewed as consisting of "longevity" and "reliability" value drivers. Eighteen value-generation drivers with a total weight contribution of 35.49% (see Table 2) assessed the functional performance of green assets.
Te continuous increase in energy consumption has increased the need for building energy analysis worldwide [46]. Operational performance evaluated how operational value generators related to maintaining, energy use in, operating, and cleaning the green building asset once it is in use are considered and optimised in relation to other value generators during the VE analysis stages. Te asset operation performance was viewed to consist of "manageability" and "energy and efciency" value drivers. Nine value-generation drivers are used to assess the operational performance of green assets; their total weight contributes 17.66% to the overall profle of the assessed project. Environmental performance measures how to minimise the impact on the natural environment. Te green building asset's environmental performance is viewed to consist of "ecoresources" and "adaptability" value drivers. In Tables 2 and 8, value creation drivers assessed the environmental performance of green assets with their total weight contributing 15.66% to the overall profle of the assessed project. Finally, management performance dealt with the management processes used and the selection of an integrated project team working throughout the life cycle of the proposed development. Te management performance is viewed to consist of "control"    and "planning" value drivers. Six VCDs assessed the management performance of green assets. Teir total weight contributes 12.12% to the overall profle of the assessed project. Figure 5 presents a comparison of the overall results of the assessment tool for the three buildings evaluated in the present study. Te commercial building is the best performer with the highest percentage of value addition and lowest risk impacts during the design process. Te multistorey hotel performance can be considered moderate as it obtained around 70% score for value addition but around 60% risk impact simultaneously during its design phase. Ofce building attained the lowest performance scores in value addition; however, the risk impacted the value was also low. Tese results clearly show that the concept of value creation has been more implemented in high-value projects (i.e., B1 and B3) as compared to conventional buildings (B2). Nevertheless, the design process is susceptible to being impacted by various types of risks if not adequately addressed during the design process.
Te results from the assessment tool in the form of aggregated scores (ranging between 0 and 100) for each main VCD and risk categories are based on the evaluation of the project design parameters by concerned stakeholders. Te spider charts display and inform stakeholders about which of the value drivers need to be optimised to add value to the  Advances in Civil Engineering green asset. However, the assessment tool's ability to capture data and results of each assessment needs to be further enhanced. Tese should then be used as feedback for learning purposes. In order to take into account of the variability, the following challenges will need to be considered: (i) Representation of the sensitivity associated with evaluator opinions with highly subjective scoring of value drivers (ii) Te need to improve the range of value drivers to refect diferent contexts (iii) Te need to integrate and synchronise the assessment with value engineering processes In general, the tool will assist the value engineering studies to deal with the following issues concerning green building development: (i) Understanding project criteria (ii) Identifying appropriate project scope (iii) Validating project initial cost and budget (iv) Ascertaining best value alternatives (v) Evaluating life-cycle costs   Te proposed assessment tool can be globally used in green building development, providing the scoring system can be changed to refect the context of a specifc regional application outside KSA.
Tere is an increasing endeavour in the industry to maximise value from investment in green development.
Hence, further knowledge about value creation and risks will consolidate the theory of value creation in the development of GB. Further work needs to be carried out to refne the extracted value drivers and risks. If this can be performed according to building type, it will increase the accuracy of the tools. Additional research can test the proposed framework on case studies to verify the correlation between risks and the value creation drivers and to demonstrate the implementation and use of the prosed tools and gather feedback from the users for further improvements. Uncertainties associated with the vagueness of expert opinion while using subjective rating can also be addressed in the future [47,48].

Conclusion
Te developed value creation and associated risk assessment tool is useable at the early stages of preparing a business case and design for developing GB. Te overall framework, including the selection of PVDs and risk factors, and the tool presented in the present study can be used to assist in sustainability and value-for-money analysis. Te value generated from investment in GB will hinge on the level of value-creation strategies inducted into the project brief and on the perceived risks from not including some of the valuegenerating strategies. In addition, the proposed approach provides appropriate opportunities for the stakeholders to assess value and risk impacts before the actual construction starts. It will provide a cheap alternative simulation environment for testing what-if scenarios. Although value drivers and risks are mainly derived from green building assets, as commonalities across similar building projects exist, this will provide appropriate opportunities for this study to be utilised in other building types as well.
Although the developed tool is based on specifc population data collected from the KSA context, the framework is robust enough to be applied anywhere with diferent conditions and associated feedbacks. Although the number of respondents is comparable to other studies, it is not possible to claim that their views represent the views of the majority of value experts in KSA. Due to the lack of professional databases in KSA, it was an impossible task to defne the exact population. Consequently, the extraction of value drivers and risk factors was not from a specifc type of building.
Te proposed tool's in this research potential for use in value-creating assessment are demonstrated in the three case studies in KSA. Te test results demonstrated how some aspects of value creation were not taken into consideration during the design of the test buildings. Tis was carried out based on the work of three projects, including multistorey hotel, ofce building, and commercial plaza. Each of these projects was scored by the value engineering professionals (who were involved in the value engineering of these buildings) and then calculations were carried out to obtain the fnal results. An excellent project that includes most of the features that contribute to value creation should have a 100% score in each of the fve VCDs. Te results of the assessment tool revealed that the environmental driver was given less importance in the design process with Wms of less than 60% for all three types of buildings. All the buildings gave the highest importance to functional performance driver with Wms of 80% or more.
At the same time, such a project should have the lowest risk scores for each of the fve categories so that the value created is preserved. Overall, all the buildings showed moderate fnancial risks ranging between 40 and 50% and a higher potential of management risks with scores around 60% or higher. A wide variation between 20 and 60% was observed for operational risks. Interestingly, the largest commercial building reported the lowest functional risk with Wms of around 20%.
By using this type of information, designers and consultants would be able to optimise the design to improve the building's performance, leading to value creation and Weighted respondent score (%) Figure 5: Comparison of three diferent types of buildings in terms of value-added and risk impacts in the design process.