Few other sectors have such a great impact on sustainability as the construction industry, in which concerns over the environmental dimension have been growing for some time. The sustainability assessment methodology presented in this paper is an AHP (Analytic Hierarchy Process) based on Multicriteria Decision Making (MCDM) and includes the main sustainability factors for consideration in the construction of an industrial building (environmental, economic, and social), as well as other factors that greatly influence the conceptual design of the building (employee safety, corporate image). Its simplicity is well adapted to its main objective, to serve as a sustainability-related decision making tool in industrial building projects, during the design stage. Accompanied by an economic valuation of the actions to be undertaken, this tool means that the most cost-effective solution may be selected from among the various options.
The environmental footprint of construction activity is immense. The building sector in the developed countries of the European Union consumes 40% of their total energy consumption [
The “ICLEI-Annual Sustainability Report 2011-2012” affirmed once again that sustainable development should be high on the agenda [
These tools may be described as follows: Life Cycle Analysis (LCA): tools that process complex data sets such as ECOQUANTUM and ENVEST [ Scientific standards: less complex but also accurate tools, such as DGNB, LEED, and BREEAM [ Checklists: very simple tools based on best practice, such as IHOBE Guides [
Specific modules that are part of LEED, BREEAM, and DGNB, for example, exist for the evaluation of industrial buildings.
The methodology advanced in this paper sets a sustainability value for industrial buildings, by applying a limited number of easily quantifiable evaluation criteria, so as to assist decision making in relation to sustainability during the design stage of industrial building projects.
The Integrated Value Model for Sustainable Assessment (Modelo Integrado de Valor para una Evaluación Sostenible, MIVES), a Multicriteria Decision Making (MCDM) tool based on AHP (Analytic Hierarchy Process), is central to this assessment process. MIVES is applied in the Spanish structural concrete standards [
Our definition of a factory or an industrial building is as follows: “an area in which industrial production takes place as well as storage. The term factory as an alternative to industrial building covers generic aspects of industrial production. Nevertheless, both terms imply the existence of constructions, that is, areas of human design completed with the use of natural and artificial products, elements and construction systems within a controlled environment” [
In the past, the design of an industrial building was limited to its envelope, four walls, and a roof, under which productive activities took place. Today, their sustainable aspects refer mainly to the production processes that take place inside it. Attention centres on aspects such as pollution from the productive activity at all stages of the building life cycle (air, noise, water, etc.), as well as waste disposal and recycling, while very few resources are dedicated to research on the actual building [
Factories may be perceived in terms of architectural elements interacting with sustainability requirements [
In conventional terms, three basic, interrelated pillars constitute sustainability: the environment, the economy, and the society [
A total of six scopes of study or requirements are therefore defined around these 3 basic pillars for the sustainability assessment of a factory. Further 3 requirements were separately defined, due to their relevance to industrial production, as shown in Table
Criteria in relation to the different requirements according to their stage of its life cycle.
Study scope | Life cycle | |||
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Conception | Materialization | Use | Reintegration | |
Safety | CrSC1 | CrSM1 | CrSU1 | CrSR1 |
CrSC2 | CrSM2 | CrSU2 | CrSR2 | |
⋮ | ⋮ | ⋮ | ⋮ | |
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Society | CrSoC1 | CrSoM1 | CrSoU1 | CrSoR1 |
CrSoC2 | CrSoM2 | CrSoU2 | CrSoR2 | |
⋮ | ⋮ | ⋮ | ⋮ | |
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Environment | CrEC1 | CrEM1 | CrEU1 | CrER1 |
CrEC2 | CrEM2 | CrEU2 | CrER2 | |
⋮ | ⋮ | ⋮ | ⋮ | |
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Economy | CrEcC1 | CrEcM1 | CrEcU1 | CrEcR1 |
CrEcC2 | CrEcM2 | CrEcU2 | CrEcR2 | |
⋮ | ⋮ | ⋮ | ⋮ | |
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Functionality | CrFC1 | CrFM1 | CrFU1 | CrFR1 |
CrFC2 | CrFM2 | CrFU2 | CrFR2 | |
⋮ | ⋮ | ⋮ | ⋮ | |
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Corporate image | CrCIC1 | CrCIM1 | CrCIU1 | CrCIR1 |
CrCIC2 | CrCIM2 | CrCIU2 | CrCIR2 | |
⋮ | ⋮ | ⋮ | ⋮ |
Each of the headings set out below relate to one of the various requirements.
All of these sustainable requirements have clear roles in the different phases of the building life cycle, from the design and throughout its useful life to its demolition and the management of any waste products. A list of 31 study criteria was composed, connected to the 6 requirements described above for sustainability evaluation in industrial buildings.
The MIVES [
The hierarchical structure of the requirement tree defines the assessment object, scopes of study, criteria, and indicators. Following the definition of this requirement tree, the methodology is used to calculate the Industrial Building Sustainability Index (IBSI), as shown in (Figure
Hierarchical structure of the requirement tree.
The following requirements are also known as the scopes of study (SS): safety, society, environment, economy, functionality, and corporate image. These can be divided into more specific criteria (CR): external mobility, safety measures in the construction process, use of ecological materials, cost of supplies, durability, brand image of the firm, and so forth. In turn, each criterion can be subdivided into indicators (ID), estimated with quantifiable values.
The key aspect in the definition of the indicators is that, apart from allowing quantification and simplification of the study phenomena, they must reflect the changes that occur in the system. Moreover, the utility of the indicators varies greatly with the context, which suggests that they have to be very carefully selected. The available information on the processes, functions, and study factors is a further key point in the selection of the indicators. All these points have an effect on the indicators, on their development, and on the development of their defining variables.
The following steps have to be completed, to prepare the sustainability assessment.
Prepare an evaluation tree consisting of scopes of study, criteria, and indicators. A requirement tree that has a balanced number of criteria is of great importance.
Calculate the weights to attach to each different stage in the evaluation; each criterion with its indicators, the requirement with its set of criteria, and the requirements that comprise the “Industrial Building Sustainability Index” are all assigned to different levels of the evaluation tree.
The value function of each indicator between a minimum value of “0” (the worst solution) and the maximum value of “1” (the best solution) offers a range of possible solutions, a set score or an output register.
The requirements yield partial results, as well as the value of the “Industrial Building Sustainability Index,” when the set of output registers are added, on the basis of the proposed system of weighting at each stage. All these values are in turn defined at some point between 0 and 1.
The most important criteria were selected using the Delphi method. This method addresses a complex problem through a group of individuals (Expert Panel) [
In the first phase, the Expert Panel obtained a total of 185 criteria, through an open-ended questionnaire. Following the initial collection of the criteria, the Expert Panel ranked these criteria, in the course of several successive meetings, and allocated a relative weight to each one, grouped under the requirements. These results were unified in the final phase, eliminating those with a relative weight of less than 5%. A total of 154 criteria were filtered out with this process, to arrive at 31 final evaluation criteria.
The Delphi method was selected for this study, because it offers the following advantages [ Group knowledge will always be superior to the knowledge of an individual participant who is better prepared than others, as the knowledge of each of the participants is complementary. The opinions of each of its members may be contrasted. The number of factors under study is higher, as each expert contributes a general idea of the topic from their specific knowledge domain to the discussion.
Using this method, it is necessary to avoid the dominant influence of any member of the group over the rest, in order to achieve an effective communication process. Many authors have pointed out that the Delphi method can minimize this aspect [
An essential key to carry this process through successfully is the appropriate selection of panel members, selected for their skills, knowledge, and independence. The members of the Expert Panel comprised construction sector professionals (experts in raw materials, construction products, construction, engineering, and health and safety as well as researchers at technology centres and universities). Various panel member selection methods can be used. The criteria defined by Hallowell and Gambatese [
Table
Breakdown of the scopes of study.
Industrial Building Sustainability Index (IBSI) | ||||
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Scope of study | Weight | Criterion | Designation | Weight |
SS1 Safety | 16.67% | CR1.1 | Structural safety against fire | 19% |
CR1.2 | Safety and health in the execution procedure | 37% | ||
CR1.3 | Safety measures in the construction process | 19% | ||
CR1.4 | Maintenance and conservation of the industrial plant | 10% | ||
CR1.5 | Safety against intruders | 5% | ||
CR1.6 | Safety and health during deconstruction | 10% | ||
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SS2 Society | 16.67% | CR2.1 | External mobility | 43% |
CR2.2 | Respect for the urban environment | 14% | ||
CR2.3 | Auxiliary services for personnel | 43% | ||
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SS3 Environment | 16.67% | CR3.1 | Integration in the natural environment | 6% |
CR3.2 | Environmental impact during construction | 17% | ||
CR3.3 | Use of ecological materials | 10% | ||
CR3.4 | Environmental impact during utilization | 34% | ||
CR3.5 | Waste management during utilization | 10% | ||
CR3.6 | Impact of materials from demolition | 23% | ||
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SS4 economy | 16.67% | CR4.1 | Cost of executing the work | 17% |
CR4.2 | Construction timeframe | 12% | ||
CR4.3 | Cost of supplies | 32% | ||
CR4.4 | Cost of maintenance | 32% | ||
CR4.5 | Cost of building demolition | 7% | ||
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SS5 Functionality | 16.67% | CR5.1 | Performance of the building in use | 6% |
CR5.2 | Constructability of ease of construction | 11% | ||
CR5.3 | Quality of internal environment | 23% | ||
CR5.4 | Durability | 16% | ||
CR5.5 | Flexibility | 23% | ||
CR5.6 | Ease of maintenance | 11% | ||
CR5.7 | Auxiliary production services | 4% | ||
CR5.8 | Deconstructibility | 6% | ||
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SS6 corporate image | 16.67% | CR6.1 | Integration in the urban environment | 20% |
CR6.2 | Brand image of the firm | 60% | ||
CR6.3 | Aesthetic maintenance of the building | 20% |
Certain tangible and therefore directly measurable criteria were selected. Other more subjective and intangible criteria as in the case of “quality of internal environment” had also to be considered. In these cases, quantifiable indicators were used to assess the criteria. Measurement of the “quality of internal environment” was quantified through an evaluation of the following 5 indicators: “light level,” “interior ventilation,” “temperature in the work area,” “noise present in the building,” and “electromagnetic pollution.” The relevant weights were attached to the indicators that constituted each criterion for its quantification.
Initially, sustainability priorities or weights have to be attached to the respective hierarchical levels of the assessment model (
In recent years, various studies have examined the preferential assignment of some criteria in relation to others, based on attributes wherever complete information is missing [
Following this method, the relative priority of each alternative is placed on a quantifiable scale. It thereby emphasizes the intuitive criteria of the decision-makers and the reliability of their comparisons when rating different options. The methodology incorporates the principle that knowledge and experience guide the judgments of decision-makers. It also organizes both tangible and intangible factors in a systematic manner, to arrive at a simple structured solution. As explained, this methodology constitutes a numerical assessment of alternatives based on the systematic assessment of a set of decision alternatives [
The addition of each dimensionless value (
The addition of the specific dimensionless values (
Each of the dimensionless values (
The value functions (
By entering different values in the 5 variables of the expression, we can get different modes of adaptation to the nature of the study variable (indicator). Thus, the obtained values can vary from a linear response (ascending or descending), to concave shaped responses, convex shaped responses, or even “S” shaped responses, as seen in Figure
Modes of adaptation to the nature of the indicator.
In the following section, only the example of the evaluation of the indicator associated to “safety measures in the construction process (CR 1.3)” criterion will be described, due to limitations on the length of the paper.
The input values that are taken into account to assess this specific indicator are shown in Table
Input values of the indicator associated with criterion CR1.3.
Number | Input value | Satisfied | Not satisfied | Case Study 1 |
---|---|---|---|---|
1 | Strict compliance with the safety rules in force | 0 | Evaluation is not allowed | 0 |
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2 | Existence of a health and safety coordinator, which has to belong to the construction company and must not be outsourced | 30 points | 0 points | 0 |
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3 | In the technical specifications, the existence of the requirement that all personal and collective protection systems must have the CE marking | 30 points | 0 points | 0 |
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4 | Promotion of the use of collective protection measures, rather than individual protective equipment, which are only used when it is essential | 40 points | 0 points | 40 points |
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As an evaluation example, Case Study 1 (oil mill housing) has been selected, which is described in more detail in the next section (Section
Breakdown of “safety” study scope at its different hierarchical levels.
Study scope | Criterion (CR) | Oil mill housing |
Slag pit housing |
Storage depot |
---|---|---|---|---|
Safety (SS1) | Structural safety against fire (CR1.1) | 0.000 | 0.000 | 0.087 |
Safety and health in the execution procedure (CR1.2) | 0.037 | 0.257 | 0.184 | |
Safety measures in the construction process (CR1.3) | 0.077 | 0.193 | 0.135 | |
Maintenance and conservation of the industrial plant (CR1.4) | 0.036 | 0.051 | 0.068 | |
Safety against intruders (CR1.5) | 0.051 | 0.051 | 0.051 | |
Safety and health during deconstruction (CR1.6) | 0.098 | 0.098 | 0.065 |
Value function of the indicator associated with criterion CR1.3.
Three case studies of industrial buildings were performed with the methodology: a building housing an oil mill, another housing slag pits at a steel plant, and a construction materials storage depot and showroom. The three examples have very different characteristics, so as to test the responsiveness of the proposed methodology and its behaviour. These characteristics reflect different locations, from rural to highly urbanized zones with large-scale public communications infrastructure. Steel and precast concrete were the main construction materials found in the buildings. The various agents who intervened in the construction held different quality and environmental certifications. The processes that take place inside them differ and, in consequence, so do their environmental requirements. The proposed sustainability assessment methodology is applied to the different practical case studies in the following sections.
The manufacturing process of pressing olive oil takes place regularly at the same time of year in this building. Throughout the rest of the year the building remains open to sell and to distribute the product. The oil mill is near a rural agglomeration of 4,000 inhabitants, without any public transport links. The building occupies an area of 1,092
This industrial building houses one part of the steel coil production process. Its industrial site is nearby two large urban areas, with reliable public transport links via interurban train and bus networks. The built area of the building is 3,175
The firm carries out an unpleasant, unhealthy, or dangerous activity under Spanish legislation that involves a risk of explosions. Moreover, slag vapours can involve short-term damage to the metal sheeting on the walls and roof and the metallic structure. All parts of the roof are accessible for inspection purposes, to ensure good repair that will reduce the dangers associated with explosions.
This building stores construction material for retail and wholesale business. It is located in an urban area with widespread business and industrial activity. Public transport links the industrial zone to the rest of the city with frequent services. The building is not precisely an industrial one, as its serves as a storage depot for the retail sale of construction material to the general public and the building trade, so it is usually clean and well arranged. Its built area occupies 1,584
Tables
Breakdown of “social” study scope at its different hierarchical levels.
Study scope (SS) | Criterion (CR) | Oil mill housing |
Slag pit housing |
Storage depot |
---|---|---|---|---|
Society (SS2) | External mobility (CR2.1) | 0.080 | 0.428 | 0.428 |
Respect for the urban environment (CR2.2) | 0.057 | 0.057 | 0.028 | |
Auxiliary services for personnel (CR2.3) | 0.172 | 0.086 | 0.258 |
Breakdown of “environment” study scope at its different hierarchical levels.
Study scope (SS) | Criterion (CR) | Oil mill housing |
Slag pit housing |
Storage depot |
---|---|---|---|---|
Environment (SS3) | Integration in the natural environment (CR3.1) | 0.017 | 0.033 | 0.025 |
Environmental impact during construction (CR3.2) | 0.087 | 0.066 | 0.167 | |
Use of ecological materials (CR3.3) | 0.000 | 0.000 | 0.000 | |
Environmental impact during utilization (CR3.4) | 0.127 | 0.042 | 0.212 | |
Waste management during utilization (CR3.5) | 0.000 | 0.099 | 0.099 | |
Impact of materials from demolition (CR3.6) | 0.000 | 0.000 | 0.235 |
Breakdown of “economic” study scope at its different hierarchical levels.
Study scope (SS) | Criterion (CR) | Oil mill housing |
Slag pit housing |
Storage depot |
---|---|---|---|---|
Economy (SS4) | Cost of executing the work (CR4.1) | 0.117 | 0.089 | 0.121 |
Construction timeframe (CR4.2) | 0.076 | 0.098 | 0.092 | |
Cost of supplies (CR4.3) | 0.054 | 0.051 | 0.065 | |
Cost of maintenance (CR4.4) | 0.116 | 0.198 | 0.234 | |
Cost of building demolition (CR4.5) | 0.075 | 0.075 | 0.000 |
Breakdown of “functionality” study scope at its different hierarchical levels.
Study scope (SS) | Criterion (CR) | Oil mill housing |
Slag pit housing |
Storage depot |
---|---|---|---|---|
Functionality (SS5) | Performance of the building in use (CR5.1) | 0.064 | 0.064 | 0.064 |
Constructability of ease of construction (CR5.2) | 0.098 | 0.078 | 0.101 | |
Quality of internal environment (CR5.3) | 0.085 | 0.103 | 0.194 | |
Durability (CR5.4) | 0.049 | 0.098 | 0.131 | |
Flexibility (CR5.5) | 0.153 | 0.076 | 0.153 | |
Ease of maintenance (CR5.5) | 0.000 | 0.080 | 0.053 | |
Auxiliary production services (CR5.6) | 0.038 | 0.017 | 0.033 | |
Deconstructibility (CR5.7) | 0.059 | 0.050 | 0.045 |
Breakdown of “corporate image” study scope at its different hierarchical levels.
Study scope (SS) | Criterion (CR) | Oil mill housing |
Slag pit housing |
Storage depot |
---|---|---|---|---|
Corporate image (SS6) | Integration in the urban environment (CR6.1) | 0.066 | 0.033 | 0.000 |
Brand image of the firm (CR6.2) | 0.000 | 0.451 | 0.451 | |
Esthetic maintenance of the building (CR6.3) | 0.147 | 0.100 | 0.196 |
Table
Values of the different requirements and IBSI values.
Study scope (SS) | Oil mill housing |
Slag pit housing |
Storage depot |
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Safety (SS1) | 0.298 | 0.650 | 0.590 |
Society (SS2) | 0.308 | 0.571 | 0.714 |
Environment (SS3) | 0.231 | 0.240 | 0.737 |
Economy (SS4) | 0.439 | 0.510 | 0.513 |
Functionality (SS5) | 0.545 | 0.566 | 0.773 |
Corporate image (SS6) | 0.213 | 0.584 | 0.647 |
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These results can be represented in a bar diagram, for better observation of the strong and the weak points in each case study, so as to facilitate decision making regarding the selection of the best improvement measures to take, as shown in Figure
Results of the 3 case studies.
The proposed methodology is capable of improving the sustainability level of a construction project during the design stage. Its application incorporates features of interest: it gives aggregated global and partial indexes as a result and quantifies each indicator, criteria, requirements, and results and it has been configured and specially adapted for this area of study. Thus, the proposed modifications at the design stage may be studied to see how they would affect the different requirements. Therefore, at this stage, the proposed solution may be improved in terms of its sustainability, because the changes at the design stage have less economic impact than the changes at the construction phase and in subsequent phases.
This section describes how the methodology can help decision making in relation to the sustainability value of a construction project. Consequently, we may see how the decisions taken at the design phase modify the final sustainability values of the construction project. Case Study 1 has been selected for this purpose because it has the lowest IBSI rate. In Table
Improvement proposals.
Previous value | Improved value | ||
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SS1: safety | |||
CR 1.1 | The introduction of fire detection systems and alarms |
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CR 1.2 | The existence of a health & safety coordinator |
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CR 1.3 | The health & safety coordinator must belong to the construction company and must not be outsourced |
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CR 1.4 | Placing anchoring systems and lifelines, in order to facilitate maintenance and cleaning under safe conditions, throughout the life of the building |
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SSS2: Society | |||
CR 2.1 | Changes to the planned location of the plant to an industrial estate closer to the town centre, with access to public transport lines, improving worker access to the plant |
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CR 2.2 | The introduction of a budget heading on water spraying systems to reduce the generation of dust in the environment |
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CR 2.3 | An increased level of hygiene above the legal minimum, because the plant has an area dedicated to the sale of olive oil products to the public |
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SS3: environment | |||
CR 3.1 | The installation of solar photovoltaic panels on the roof, with the aim of reducing external energy consumption and therefore CO2 emissions |
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SS4: economy | |||
CR 4.2 | The imposition of clauses threatening economic sanctions, in case of delays, in order to ensure compliance with deadlines |
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CR 4.3 | Rain water collection tanks for subsequent reuse of rainwater in other applications, thereby reducing resource consumption |
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SS5: functionality | |||
CR 5.3 | The implementation of a system to regulate the use of lighting, to reduce energy consumption |
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CR 5.4 | The requirement that quality accreditation must be held by the engineering company that bids for the design of the project |
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CR 5.6 | The implementation of security systems, in order to facilitate access to the roof and in consequence, to enable operators to perform maintenance work safely |
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SS6: corporate image | |||
CR 6.1 | Reduction of the visual impact of the parking of the factory, considering the trees growing on the plot where it is located |
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CR 6.2 | The requirement that the company should hold quality and environmental management accreditations |
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With this set of actions taken in the case study of the oil mill, the IBSI rose from an initial value of 0.339 to a final value of 0.581.
Figure
Initial results and improved results.
The advanced vision of the sustainable construction concept that has been described in this paper focuses on the following requirements in the context of industrial building: safety and industrial health, functionality, and corporate image. These requirements may be added to generic ones—environmental, economic, and social requirements—which are standard in all construction work. The noncommercial MIVES methodology that we have proposed has been used to calculate a global sustainability index and partial indicators of an industrial building. It has meant that we can now ascertain the strengths and weaknesses of a project, at the design stage, identifying those indicators and criteria in need of improvement, and facilitating sustainability-related decision making.
In the 3 case studies that were contrasted, the storage and sale of construction materials, which is not strictly a productive process, obtained the highest scores for the environmental, economic, societal, functional, and corporate image requirements. The presence of this firm in the tertiary or service sector influenced this assessment, where there is greater contact with the general public. New and improved images are sought to improve sales, along with better communications systems and proximity to significant residential areas, as it is a nonpolluting process.
Functional and economic requirements were given greater priority in the two specifically industrial processes. As firm size grows, concerns for other requirements also grow such as security and the social factor, above all when the firm has a brand image, which also leads to increased environmental awareness. From this comparison, it may also be seen that the scores of the smallest firm are lower than the scores of the larger firms, principally due to their having fewer available economic resources. A number of improvement proposals have been proposed for the case study of the oil mill, which has the lowest sustainability index. In this way, the IBSI has increased from an initial value of 0.339 to a final value of 0.581.
The development of this methodology was made possible thanks to the work of the Expert Panel, comprising qualified professionals in the construction sector, who defined the evaluation tree, identifying criteria, indicators, and the specific weights for each one, following Delphi methodology guidelines, which has proved itself suitable in these types of problems.
The authors declare that there is no conflict of interests regarding the publication of this paper.
The authors of the paper gratefully acknowledge funding from the Basque Regional Government through IT781-13 and from the UPV/EHU under Program UFI 11/29. They also acknowledge the Ph.D. Grant received from the Vice-Rectorate of Basque Language of the University of the Basque Country (UPV/EHU).