Using the OKR Method and Fuzzy Logic to Determine the Level of Sustainability in Restaurants

Abstract

Restaurants are one of the main sources of wealth in the tourism sector and have significant potential in the fight against poverty reduction and the lack of development of local communities. However, in relation to the emission of greenhouse gases and the generation of waste, they are seen as two of the less sustainable sectors of the world. This study has the objective of providing a method to determine the level of sustainability in restaurants by means of modeling the OKR method and fuzzy logic. For this, 100 key results from the environmental, social, and economic dimensions were selected, using the fuzzy direct rating method to validate and weight the key results. The method is shown in advance, noting how and at what intensity the key results are inserted in the restaurant, indicating the strong and weak points of each restaurant in regard to sustainability. The results of this study contribute by providing a method that measures the level of sustainability in restaurants, identifies the current panorama and existing challenges, and allows for a complete mapping for the elaboration of strategies for improvements in organizational sustainability.

1. Introduction

Population growth, the accelerated consumption of non-renewable resources, global trade, and the increasingly complex demands of consumption chains contribute to the significant reduction in natural resources, threatening the human species in the long term [1]. This panorama reminds us of the need for development that meets the needs of the present without compromising the ability of future generations to meet their needs [2].

Based on the principles that each individual has a particular responsibility and that companies are considered most responsible for environmental degradation [3], there are advantages for companies to adhere to sustainable programs, such as the reduction of waste and associated costs [4], improving corporate image [4,5,6,7], improving employee well-being and customer satisfaction [8], increasing stakeholder satisfaction, increasing competitiveness, and improving financial performance [5,6,7], and other improvements in all dimensions of sustainability [4].

Although companies are recognized as being largely responsible for environmental degradation, they are also potential providers of long-term solutions and innovations, capable of remedying the imbalance that involves the sustainability triangle [3]. In this way, the adoption of sustainable practices is something that afflicts all types of companies, including the restaurant sector [9], since it is one of the sectors that consume the most energy and water, produce waste, and harm the environment [10].

Although restaurants are not considered major polluters such as the metallurgical or chemical industries, they do considerably affect the environment [3,11]. Some examples: include the guarantee of food security [12], the high rate of production of solid and food waste [13,14,15,16], large greenhouse gas emissions [13,17,18], and the exacerbated consumption of fossil fuels [12], water, and energy [3,12,13,19,20].

The restaurant industry, unlike the hotel and tourism industries as a whole, depends less on the natural environment that surrounds it for success, resulting in fewer studies focused on environmental issues in this sector [21]. The advent of environmental regulations demanding business standards that minimize negative environmental effects [22,23], and increased demand for environmentally friendly foods [21,24], expands the quest to become a sustainable restaurant. However, it faces barriers such as the fear of excessive costs [25] and low awareness of effective methods [26].

Restaurants are the main source of wealth in the tourism sector, along with hotels [5], and have significant potential in the fight against poverty reduction and in the development of the local community as they offer a vast number of jobs, directly and indirectly generating prospects for low-skilled manual workers and disadvantaged groups such as migrants and ethnic and cultural minorities [27]. However, in relation to the emission of greenhouse gases and the generation of waste, it is seen as one of the least sustainable sectors in the world [23].

Certain international organizations such as the Sustainable Restaurant Association (SRA) and the Green Restaurant Association (GRA) have already developed guidelines on sustainability, aiming to help restaurants that seek this path. However, these guidelines do not allow for the broad measurement and determination of a restaurant’s sustainable performance. A company’s image is essential as it reflects how an organization can be differentiated from another, and by focusing on the restaurant sector, this becomes more expressive since the intangible characteristics of a restaurant cannot be qualified before the gastronomic experience, evidencing the dependence on the image and tangible aspects of the restaurants [28].

The restaurant sector is a virtually unexplored sector in relation to sustainable practices and guidelines regarding the creation, maintenance, and operation of a sustainable business [3]. This neglect intensifies in the context of small companies [29]. Another relevant fact is that most studies referring to sustainability in restaurants present data solely from the perspective of customers or consumers, and to a large extent, they focus only on the topic of energy consumption, thus providing inaccurate or incomplete information on the level of sustainable engagement in restaurants [12,30,31].

The implementation of sustainable practices is weak in the restaurant sector due to the lack of a green supply chain, the low demand from customers, the small community of restaurants that implement green practices, and certain barriers such as environmental laws and regulations [25]. According to Legrand et al. [3], the real challenge lies in the development of an effective and practical measurement process of sustainability and the relative weighting that each sustainable practice has since some factors comprise a greater weight in relation to their impacts on sustainability in restaurants than others.

Within this context, this study aims to propose a method to determine the level of sustainability in restaurants through the key results adopted in the environmental, social, and economic scope, using the OKR Method and fuzzy logic modeling. This study contributes to greater implementation of sustainability in the restaurant sector by simplifying the implementation of these practices through an elaborated method. To achieve this objective, we present the methodological procedures (Section 2) below, which include the survey of sustainability OKRs for restaurants (Section 2.1), assessment of importance weights (Section 2.2), and determining the sustainability level of restaurants (Section 2.3). Section 3 presents the results and discussion, containing weights assigned by experts to dimensions and key results (Section 3.1), the restaurants (Section 3.2), a synthesis (Section 3.3), and conclusions (Section 4).

2. Method

Assuming that knowledge of a restaurant’s sustainability level can help improve its practices and processes, this study was subdivided into three stages (Figure 1), the use of the objective and key results (OKR) tool to obtain the objectives to be achieved from the key results [32,33], the assessment of the weights of importance of each key result, and the determination of the level of sustainability in restaurants.

2.1. Survey of Sustainability OKRs for Restaurants

In short, OKR is a business management tool that proposes facilitating the planning and execution of strategies through the deployment of objectives aligned with key indicators that quantitatively measure the achievement of each objective; that is, it tries to answer two questions: Where do the organizations want to arrive? (objectives), and how does one identify that the organizations arrived where they wanted to arrive? (key results) [32,33]. Here is a significant lacuna in seeking to achieve sustainability: There are many proposals about what should be performed, but very little is known about how to check it and check the effectiveness of the actions in a methodologically integrated way.

In order to be perceived as sustainable, Munck and Tomiotto [34] warn that companies must develop their decision-making processes, both respecting and adjusting their value systems and organizational arrangements. When companies select a sustainability approach that most conforms to their objectives, purposes, and strategies and begin adapting it to their particular social circumstances, it is natural to review the dominant values of the approach. However, in addition to the definition of new visions, the challenge is to integrate traditional concepts of eco-efficiency and environmental management with those of sustainability and to incorporate the latter into current administrative practice.

When looking for the main theoretical background of sustainability aspects related to OKR in the context of a restaurant, no previous research was found, demonstrating originality in measuring the levels of sustainability using the OKR methodology to improve the practices of sustainability in restaurants. The key results came from the main sustainability actions established for restaurants, which are listed below. Thus, the OKR’s objectives and key results to measure the level of sustainability in a restaurant are the measurement of each of the dimensions that make up sustainability at the environmental, social, and economic levels.

To obtain the OKR key results, a bibliographic survey was conducted with the theme “sustainability in restaurants” using the following databases: Web of Science, ScienceDirect, Scopus, SciELO, and Google Scholar. The keywords searched were “restaurant”; “sustainability”; “sustainable”; “environmental”; “green”; “performance”; “indicator”; “guidelines”; “variables”; “measures”; and “practices”, which were combined in different ways, resulting in creating a database of 151 works in the global context.

The inclusion and exclusion criteria to select the articles relevant to the study were the presence of possible key results to measure dimensions that make up the pillars of sustainability for restaurants. There were 26 articles remaining, of which 100 key results were selected, of which 46 belong to the environmental dimension, 34 to the social dimension, and 20 to the economic dimension.

In the environmental dimension (Table 1), the main focuses are waste reduction, energy consumption, and the use of renewable energy, carbon dioxide emissions, and water conservation [35]. However, there are other factors that influence the sustainability of a restaurant; for example, the generation of organic waste can be minimized with other attitudes such as the use of local, fresh, and quality foods, limiting the number of items on the menu, and ensuring adequate portion sizes [36]. Composting and donation are also highlighted to help combat the generation of food waste, although some restaurants are afraid to donate due to legal responsibility [3,37].

Another relevant fact is the concern with health as a result of food production methods in general, arousing the interest of individuals in the search for ecologically correct foods [38], intensifying the search for organic foods [28], increased vegetable intake and reduced consumption of red meat [16], nutritional awareness, including dietary and allergenic aspects [39], food and menu labeling [40], respect to seasonal rhythms, and production or purchase of renewable energy [3].

There are also key results associated with construction and materials in general, such as furniture, equipment, utensils, and accessories, such as opting for those that save energy and water and can be applied in various areas of a restaurant, such as flow restrictors in faucets, low-flow toilets, LED lamps, and motion detectors for bathroom lights [28]. As far as building construction is concerned, focus on green construction, as, according to the International Hotel & Restaurant Association [41], green construction reduces operating and maintenance costs, improves comfort and health, and significantly restricts negative environmental impacts [41]. Maintaining a sustainable design and owning your own garden are also crucial elements [3].

Table 1. Key results of the environmental dimension.

Code	Key Results	Authors
ENV1	Portion size: avoid waste and the accumulation of organic residues	[42]
ENV2	Menu diversity: options for vegetarian, vegan, and protein substitutes	[23,39,42]
ENV3	Labeled menu: with “carbon footprint”, calories, nutritional content, low fat, gluten free, etc.	[3,42]
ENV4	Organic food: buys and uses organic food and drinks	[3,7,16,28,42,43,44,45,46,47,48]
ENV5	Local food: buys and uses locally produced food	[3,12,16,28,39,42,43,44,46,47,48,49,50]
ENV6	Certifications: opting for foods with certifications.	[3,28,42,44]
ENV7	Seasonal foods: buy and use seasonal foods	[3,16,39,46,50]
ENV8	Dietary or allergic needs: offer gluten-free and lactose-free options	[3,46]
ENV9	Healthy and nutritious: low in fat and reduced in salt.	[3,46]
ENV10	Safety and stock: efficient and well-controlled stock	[3,23]
ENV11	Wild animals: does not use protected animals as food	[23]
ENV12	Regulation: follows safety and sanitation regulations set by the food industry	[23]
ENV13	Recycled materials: uses and separates recycled materials	[42,46]
ENV14	Durable Items: Uses durable items instead of disposables	[12,23,39,42,43,46]
ENV15	Company location: Considered environmental impact when choosing the location of the company	[3]
ENV16	Vegetable garden: cultivates its own food	[3,46]
ENV17	Fertilizers: uses environment-friendly fertilizers for the company’s indoor and outdoor landscaping	[21]
ENV18	Natural decoration: it is decorated with plants and trees	[23]
ENV19	Building materials: building materials made from toxic substances were avoided, using materials with environmental certifications or recycled.	[3,20]
ENV20	Ecological products: the company’s furniture, fixtures and accessories have ecological certification	[3,23,51]
ENV21	Local products: the company buys locally manufactured furniture, fixtures and accessories	[3]
ENV22	Zero Potential Equipment: Electrical equipment is certified as zero potential for ozone depletion.	[3]
ENV23	Efficient equipment: the equipment has low energy and/or water consumption	[44,47,49]
ENV24	Cleaning products: prioritizes cleaning products that do not harm the environment	[7,12,23,28,44,45,49,52]
ENV25	Bulk and concentrates: cleaning and/or food products are purchased in bulk, in larger packages and in concentrated form	[3,23]
ENV26	Equipment cleaning: The company’s furniture, utensils, accessories and equipment are cleaned and sanitized regularly, using appropriate techniques and natural cleaning alternatives	[3,21,23]
ENV27	Self-service: it has a self-service system; it does not replace the offer of a job by machines.	[23,42]
ENV28	Sustainable space: a space on the menu or posters available in the company to encourage sustainable behaviors	[21,23]
ENV29	Efficient and smart building: has efficient/smart methods or equipment that help to save water or energy	[21,28,44]
ENV30	Water Saving: Do you have any practice, strategy or technology to save water?	[3,7,12,16,24,28,42,43,45,46,48,49,51,53]
ENV31	Energy Saving: Do you have any practice, strategy, or technology to save energy?	[7,12,16,23,24,28,43,46,48,53,54,55]
ENV32	Waste: Has any practice, strategy or technology to reduce food and beverage waste	[23,24,42,46,51]
ENV33	Composting or Reusing: Composting or reusing organic waste in some way	[3,12,16,23,28,42,44,46,47,48]
ENV34	Leftover donation: donates leftover food to institutions or people in need	[16,42,43,46,47]
ENV35	Emissions reduction: has any practice, strategy or technology to reduce emissions and prevent pollution	[12,24,51,54]
ENV36	Solid Waste Reduction: Do you have any practice, strategy, or technology to reduce solid waste?	[7,24,49,50,51,54]
ENV37	Renewable energy: the energy used in the company is renewable (solar, wind, etc.),	[3,12,21,39,47,48]
ENV38	Reduce, reuse and recycle: “reduce, reuse and recycle” approach is followed in that order by the company	[3]
ENV39	Classification of dumps: there are classification systems for dumps and waste collection is conducted separately	[3,23,47]
ENV40	Special and/or hazardous waste: special waste (oil, glass, fluorescent lamps, etc.) is collected and delivered to a specialized company or disposed of properly	[3,23,43,47]
ENV41	Excessive packaging: company does not use excessive packaging with unnecessary decorations, avoiding increased waste	[23,46,50]
ENV42	Safe packaging: uses safe packaging materials, made from recyclable or reusable material	[23]
ENV43	Packaging collection: it has a program to collect the packaging used in its products	[51]
ENV44	Water reuse: rainwater is collected for reuse	[23]
ENV45	Environmental performance: environmental performance is monitored and recorded	[47]
ENV46	Environmental reports: publishes regular reports on environmental impacts generated or provides this information via website or social networks	[47]

Table 1. Key results of the environmental dimension.

Code	Key Results	Authors
ENV1	Portion size: avoid waste and the accumulation of organic residues	[42]
ENV2	Menu diversity: options for vegetarian, vegan, and protein substitutes	[23,39,42]
ENV3	Labeled menu: with “carbon footprint”, calories, nutritional content, low fat, gluten free, etc.	[3,42]
ENV4	Organic food: buys and uses organic food and drinks	[3,7,16,28,42,43,44,45,46,47,48]
ENV5	Local food: buys and uses locally produced food	[3,12,16,28,39,42,43,44,46,47,48,49,50]
ENV6	Certifications: opting for foods with certifications.	[3,28,42,44]
ENV7	Seasonal foods: buy and use seasonal foods	[3,16,39,46,50]
ENV8	Dietary or allergic needs: offer gluten-free and lactose-free options	[3,46]
ENV9	Healthy and nutritious: low in fat and reduced in salt.	[3,46]
ENV10	Safety and stock: efficient and well-controlled stock	[3,23]
ENV11	Wild animals: does not use protected animals as food	[23]
ENV12	Regulation: follows safety and sanitation regulations set by the food industry	[23]
ENV13	Recycled materials: uses and separates recycled materials	[42,46]
ENV14	Durable Items: Uses durable items instead of disposables	[12,23,39,42,43,46]
ENV15	Company location: Considered environmental impact when choosing the location of the company	[3]
ENV16	Vegetable garden: cultivates its own food	[3,46]
ENV17	Fertilizers: uses environment-friendly fertilizers for the company’s indoor and outdoor landscaping	[21]
ENV18	Natural decoration: it is decorated with plants and trees	[23]
ENV19	Building materials: building materials made from toxic substances were avoided, using materials with environmental certifications or recycled.	[3,20]
ENV20	Ecological products: the company’s furniture, fixtures and accessories have ecological certification	[3,23,51]
ENV21	Local products: the company buys locally manufactured furniture, fixtures and accessories	[3]
ENV22	Zero Potential Equipment: Electrical equipment is certified as zero potential for ozone depletion.	[3]
ENV23	Efficient equipment: the equipment has low energy and/or water consumption	[44,47,49]
ENV24	Cleaning products: prioritizes cleaning products that do not harm the environment	[7,12,23,28,44,45,49,52]
ENV25	Bulk and concentrates: cleaning and/or food products are purchased in bulk, in larger packages and in concentrated form	[3,23]
ENV26	Equipment cleaning: The company’s furniture, utensils, accessories and equipment are cleaned and sanitized regularly, using appropriate techniques and natural cleaning alternatives	[3,21,23]
ENV27	Self-service: it has a self-service system; it does not replace the offer of a job by machines.	[23,42]
ENV28	Sustainable space: a space on the menu or posters available in the company to encourage sustainable behaviors	[21,23]
ENV29	Efficient and smart building: has efficient/smart methods or equipment that help to save water or energy	[21,28,44]
ENV30	Water Saving: Do you have any practice, strategy or technology to save water?	[3,7,12,16,24,28,42,43,45,46,48,49,51,53]
ENV31	Energy Saving: Do you have any practice, strategy, or technology to save energy?	[7,12,16,23,24,28,43,46,48,53,54,55]
ENV32	Waste: Has any practice, strategy or technology to reduce food and beverage waste	[23,24,42,46,51]
ENV33	Composting or Reusing: Composting or reusing organic waste in some way	[3,12,16,23,28,42,44,46,47,48]
ENV34	Leftover donation: donates leftover food to institutions or people in need	[16,42,43,46,47]
ENV35	Emissions reduction: has any practice, strategy or technology to reduce emissions and prevent pollution	[12,24,51,54]
ENV36	Solid Waste Reduction: Do you have any practice, strategy, or technology to reduce solid waste?	[7,24,49,50,51,54]
ENV37	Renewable energy: the energy used in the company is renewable (solar, wind, etc.),	[3,12,21,39,47,48]
ENV38	Reduce, reuse and recycle: “reduce, reuse and recycle” approach is followed in that order by the company	[3]
ENV39	Classification of dumps: there are classification systems for dumps and waste collection is conducted separately	[3,23,47]
ENV40	Special and/or hazardous waste: special waste (oil, glass, fluorescent lamps, etc.) is collected and delivered to a specialized company or disposed of properly	[3,23,43,47]
ENV41	Excessive packaging: company does not use excessive packaging with unnecessary decorations, avoiding increased waste	[23,46,50]
ENV42	Safe packaging: uses safe packaging materials, made from recyclable or reusable material	[23]
ENV43	Packaging collection: it has a program to collect the packaging used in its products	[51]
ENV44	Water reuse: rainwater is collected for reuse	[23]
ENV45	Environmental performance: environmental performance is monitored and recorded	[47]
ENV46	Environmental reports: publishes regular reports on environmental impacts generated or provides this information via website or social networks	[47]

Regarding the social dimension (

Table 2. Key results of the social dimension.

Code	Description of Key Results	Authors
SOC1	Training: regularly provides training to all employees on sustainable issues	[3,5,6,12,24,28,43,46,47,48,49,51,53,55,58,59]
SOC2	Employee maintenance: avoids high employee turnover and values the maintenance of jobs	[24,58,59]
SOC3	Work climate: it has an excellent work climate and values that, with well-defined standards, creative freedom for employees and a pleasant work environment.	[25,58,59]
SOC4	Professional and family life: has measures to reconcile employees’ professional and family life	[24,55,58,59]
SOC5	Employee health and safety: provides procedures that help ensure the health and safety of your employees	[24]
SOC6	Employee satisfaction: employee satisfaction is a priority for the company	[6,7,24]
SOC7	Environmental initiatives: recognizes and rewards employees’ environmental initiatives	[6,28,47,50,53,58,59]
SOC8	Local employees: chooses to hire local employees	[3,49,55]
SOC9	Higher Salaries: Salaries offered by the company are higher than industry averages
SOC10	Fair conditions and wages: employees work under fair working conditions and receive fair wages	[3]
SOC11	Laws and obligations: prioritizes compliance with all laws and contractual obligations related to employees	[55]
SOC12	Anti-discrimination policies: there are internal policies in the company that prevent discrimination in the remuneration and promotion of employees	[55]
SOC13	Employee development incentive: the company encourages employees who acquire additional knowledge	[55]
SOC14	Customer health and safety: is committed to the health and safety of customers. Has a control system	[24,58]
SOC15	Customer satisfaction: Achieving elevated levels of customer satisfaction is one of the company’s priorities. Has a control system	[6,24]
SOC16	Community development: is committed to cooperating with community development and local programs, with resources such as time, money or other necessary	[3,24]
SOC17	Environmental activities: the company organizes and develops environmental activities, aiming to reduce environmental impacts on the community	[6,28,59]
SOC18	Community participation: customers and the community have the possibility to voluntarily participate in community or environmental development programs offered or supported by the company.	[3]
SOC19	Model company: recognized for its sustainable commitment and serves as a model for other companies	[24,46]
SOC20	Differentiation from the competition: sustainable activities allow the company to differentiate itself from the competition	[7,45]
SOC21	Sustainable education: the company informs, encourages and educates customers about sustainable practices	[3,46,47]
SOC22	Relationship system: it has a relationship system with customers and the community for suggestions, complaints, etc.	[23,55]
SOC23	Rewards policy: has a rewards policy to encourage customers’ ecological behavior	[23]
SOC24	Local support: the company supports and/or sponsors local events, artists and musicians	[46,55]
SOC25	Employment Opportunities: Offer employment opportunities to the young or disadvantaged, assisting in the development of the local community	[46]
SOC26	Accidents and legal actions: sustainable activities help the company to reduce the risk of accidents and legal actions	[7,45]
SOC27	Public support: sustainable activities help the company gain public support for cleaner production	[7,45]
SOC28	Accessible and welcoming environment: it has an accessible and welcoming environment for the most diverse audiences	[46]
SOC29	Human rights: the company selects suppliers not involved in human rights violations or other social issues	[24]
SOC30	Environmental suppliers: selects suppliers that have an environmental management system or environmental commitment	[23,51]
SOC31	Collaboration with suppliers: collaborates with suppliers to improve the product/service, thus collaborating with the development not only of your company but also of the local economy	[6,24]
SOC32	Guidance and involvement: guides suppliers to establish their own sustainable programs	[24,51]
SOC33	Partnership with companies: works in partnership with other companies in the same field	[3]
SOC34	Sustainable associations: partners with organizations or associations that support and promote sustainable practices	[3,46]

), it is important to offer both internal and external support. Internally, it is important to choose local employees, train and encourage them as much as possible, be sensitive to their needs, treat them fairly, and pay them fair wages [3,49]. It is essential to identify ways to generate benefits for the local community; some examples include providing support through development projects, providing the necessary resources [3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24], respect for cultural heritage and local traditions [3], opting for local suppliers [56,57], and being honest and transparent with suppliers and customers [3,6,24].

In the economic dimension (

Table 3. Key results of the economic dimension.

Code	Description of Key Results	Authors
ECON1	Profitability: Company profits have increased in recent years	[6,7,24,45,51,55,58]
ECON2	New Customers: The company has attracted new customers in recent years	[7,24,45]
ECON3	Market Share: Has increased its market share in recent years	[6,24,58]
ECON4	Occupancy rate: The occupancy rate has increased in recent years	[6,7,24,45,58]
ECON5	Sales: Sales have increased in recent years.	[7,45,54]
ECON6	Number of employees: the number of employees has increased in recent years	[7,44]
ECON7	Operating costs: operating costs have reduced in recent years	[7,45,56,59]
ECON8	Business Image: Improved its image in recent years compared to competitors	[7,24,45,59]
ECON9	Market Opportunities: Has the ability to take advantage of new market opportunities	[24,54]
ECON10	Stability in crisis: the ability to remain stable in the market in times of crisis is greater	[7,59]
ECON11	Fair Pricing: Charge fair prices for your products and services	[46]
ECON12	Sustainable marketing: uses sustainable and ecological arguments in the marketing campaigns conducted	[6,23,28,46,53,58,59]
ECON13	Legal Standards: All products offered by the company meet legal standards	[55]
ECON14	Quality: has a quality management and/or culture, always aiming to improve and correct possible errors	[6,24,58]
ECON15	Productivity Monitoring: Constantly monitors employee productivity	[55]
ECON16	Current status: seeks to be always up to date on the topic of sustainability in the restaurant sector	[24]
ECON17	Priority: Implementing sustainability practices is on the restaurant’s priority list	[24]
ECON18	Long-term environmental strategy: have a long-term environmental strategic focus	[6,28,53,58,59]
ECON19	Operating principles: includes sustainable services and attitudes in its operating principles	[50]
ECON20	Corporate policy: incorporates environmental management into corporate policy	[47]

), some aspects should be noted: The opportunity to offer new products and access new market segments [7,52]; improved economic performance and profitability, resulting from better use of resources [6]; increased consumer loyalty, as greater environmental concern naturally results in higher levels of quality and satisfaction [60]; obtaining competitive advantages [45]; and contribution to the construction of knowledge and sustainable values in customers and employees [61].

2.2. Importance Weights Evaluation

To obtain the weights for the key results, the fuzzy direct rating method was used (i) because there are many key results (total of 100); (ii) because of the number of experts who assigned weights to each key result; and (iii) because of the uncertainties in assigning preferences to each attribute. Other methods, such as AHP and Trade Off, are rendered unviable due to the pair-by-pair comparison, SMART and swing weighting due to the difficulty of setting parameters, Delphi due to the difficulty of interacting with the controlled feedback, and so on.

To this end, a questionnaire containing the 100 key results (Table 1, Table 2 and Table 3) was sent by email to 123 researchers from different areas of knowledge who work in the area of sustainability. Thus, the specialists participating in this research correspond to the eighteen individuals who returned the questionnaire.

All specialists participating in the study have a PhD and at least 5 years of experience, with training in different areas such as administration, economic sciences, production engineering, food engineering, civil engineering, environmental technology, agronomy, and nutrition, all with research and/or specializations related to sustainability. The specialists work at several universities, including the State University of Londrina (UEL), the Federal Technological University of Paraná (UTFPR), the University of São Paulo (USP), the Federal University of Rio Grande do Sul (UFRGS), and Atopp Brazil.

There was no inclusion or exclusion of key results by the experts, guaranteeing the validity and reliability of the key results presented in this research.

In the direct rating method, weights are assigned directly to the key results [62]. The theory of fuzzy sets brings linguistic terms and numerical values together, even though linguistic terms are subjective, uncertain, vague, and imprecise, since one of the objectives of this theory is precisely to model problems of uncertainty [63]. A linguistic variable consists of a set of linguistic terms, where each of these terms is represented by a membership function [64].

The theory of fuzzy sets was proposed by Zadeh (1965) [65] to express linguistic terms in a decision-making process. In this study, triangular fuzzy numbers will be used as they are useful to promote the representation and processing of information in a fuzzy environment [66]. The ordered trio here is defined as (a₁, a₂, a₃), yielding the positive triangular number shown in Figure 2. Therefore, the membership function is defined as:

$$\{\begin{array}{c}0, se x<a_1\\ \frac{x-a_1}{a_2-a_1}, se a_1\le x\le a_2\\ \frac{a_3-x}{a_3-a_2}, se a_2\le x\le a_3\\ 0, se x>a_3\end{array}$$

(1)

Figure 3 presents the values of the variables and the linguistic terms defined for this study that were used to obtain the key results. Figure 4 shows the graph of the triangular membership functions of the linguistic terms.

The fuzzification process is used to convert a numerical value into a fuzzy set by mapping the membership functions (contained in the interval [0, 1]) established in the construction of the system. This step provides fuzzy parameters for the processing of a series of rules consisting of propositions involving linguistic variables; and at the end of this processing, the fuzzy value obtained is defuzzied, generating a precise output again [67].

In this study, the defuzzification centroid model was used, in which the arithmetic mean weighted by the pertinence of each element of the fuzzy set is obtained. As a hypothetical example, if an expert assigns a value of 38 to a given key result (which is between “low” and “medium low”), the defuzzied value considering an uncertainty process will be 36.5.

Thus, the arithmetic mean of the weights assigned by the eighteen experts participating in this research for each dimension and the key results are shown in Figure 5.

2.3. Determining the Sustainability Level of Restaurants

A structured interview was conducted with the restaurant manager and contained the 100 key results. For each key result, the restaurant manager chose the option that best corresponds to the restaurant’s current situation regarding its practice, according to the options on the following scale: 0; when such a practice is not applied; 0.25; when a certain practice is applied lightly; 0.50; when the practice is applied in a moderate way; 0.75; when the practice in question is applied satisfactorily; and 1; when the practice is already fully incorporated in the restaurant.

The level of global sustainability (L_Sust) in the restaurant is given by the equation:

$$L\_Sust={\displaystyle \sum }_{i=1}^3{V}_i.Di{m}_i$$

(2)

where V_i (i = 1, 2, 3) represents, respectively, the values obtained by the levels of environmental sustainability (L_Sust_Env), social sustainability (L_Sust_Soc), and economic sustainability (L_Sust_Econ); Dimi represents the weights assigned to the environmental, social, and economic dimensions, respectively.

The values of sustainability levels, OKR objectives, environmental dimensions (L_Sust_Env), social sustainability (L_Sust_Soc), and economic sustainability (L_Sust_Econ) are given by:

$$\_Sust\_Env={\displaystyle \sum }_{j=1}^{46}{P}_j.EN{V}_j$$

(3)

$$L\_Sust\_Soc={\displaystyle \sum }_{k=1}^{34}{P}_k.SO{C}_k$$

(4)

$$L\_Sust\_Econ={\displaystyle \sum }_{l=1}^{20}{P}_l.SO{C}_l$$

(5)

where ENV_j (j = 1…46), SOC_k (k = 1…34) and ECON_l (l = 1…20) represent the values assigned by managers to each key result of the environmental, social, and economic dimensions, respectively. P_j, P_k, and P_l represent the weights assigned by experts to each key result for the environmental, social, and economic dimensions.

In this study, it was considered that the L_Sust results below 0.25, between 0.25 and 0.50, between 0.50 and 0.75, and between 0.75 and 1, represent, respectively, the level of practices adopted by the restaurant in a light, moderate, satisfactory, and fully incorporated way.

3. Results and Discussion

To exemplify and analyze the adherence to the proposed method, five restaurants with different characteristics and themes (size, gastronomy, public profile, etc.) were selected in a medium-sized city in Brazil with the aim of verifying the contributions or barriers to the application of the method. Secrecy and confidentiality will be maintained about each restaurant in accordance with guidelines established by the Ethics Committee.

Appendix A and Appendix B present the values assigned to all key results for each restaurant, and Figure 5 and Figure 6 present, respectively, the weights assigned by the experts to the dimensions and key results and the level of sustainability obtained by all restaurants.

3.1. Weights Assigned by Experts to Dimensions and Key Results

The values assigned by the experts (to obtain the weights, see Figure 5) for the environmental, social, and economic dimensions have low dispersion, with averages of 79.76 (SD = 18.99), 80.84 (SD = 18.97), and 89.86 (SD = 12.83), respectively. SD is the standard deviation. The weights of the key results of the environmental, social, and economic dimensions showed low dispersion, with means of 0.0217 (SD = 0.00240), 0.0294 (SD = 0.0032), and 0.0500 (SD = 0.0033), respectively.

The experts attributed a lower degree of importance to the key results (lower than the first quartile, 1Q) ENV25 and ENV27–28 of the environmental dimension (1Q = 0.0201); SOC17–19, SOC21–25, SOC27, SOC31, and SOC33 of the social dimension (1Q = 0.0268); and ECON3–6, ECON 12, and ECON 19 from the economic dimension (1Q = 0.0482). On the other hand, experts attributed a higher degree of importance to the key results (above the third quartile, 3Q) ENV10–12, ENV14, ENV22–23, ENV30–33, ENV36–38, and ENV40 of the environmental dimension (3Q = 0.0236); SOC3, SOC5–6, SOC10–12; SOC14–15, and SOC28 from the social dimension (3Q = 0.0321); and ECON8–9, ECON11, and ECON13–15 from the economic dimension (3Q = 0.0524).

3.2. The Restaurants

3.2.1. Restaurant 1

Restaurant 1 is a university restaurant that opened in 2012 and operates in the self-service mode. It normally serves students a menu with rice, beans, pasta, two types of salad, one or two types of meat, dessert, and juice, which the student can serve only once. It provides an average of five hundred meals for lunch and three hundred meals for dinner at a subsidized price (16% of the amount charged by restaurants close to the university) and has an environmental awareness program. The company hired to provide the restaurant service is frequently inspected by the university in relation to waste management and conscious consumption of energy and water.

The restaurant has a satisfactory level of sustainability in the environmental (0.59) and social (0.60) dimensions; only the economic dimension (0.46) has a moderate level. The global sustainability level reached a value of 0.54 at the satisfactory level, close to the limit at the moderate level.

The restaurant has a “satisfactory way” or “fully incorporated” application of 56.00% of the total key results and 37.00% that is “lightly” or “not applied.” In the environmental dimension, 56.52% of its key results are applied in a “satisfactory way” or “fully incorporated”. On the other hand, it needs improvement in 43.48% of the key results, with a negative emphasis on energy and waste management items (ENV29–31, ENV33–37, ENV44 and ENV45).

In the social dimension, 61.76% of its key results are applied in a “satisfactory way” or “fully incorporated”, however, 32.35% of the key results are not applied by the restaurant, requiring actions to improve the key results related to customers, the community, and suppliers (SOC18, SOC24–25, SOC27, SOC29–33). In the economic sphere, 45.00% of key results are applied “satisfactorily” or “fully incorporated”, and 55.00% need improvement (ECON2–10 and ECON12).

3.2.2. Restaurant 2

Restaurant 2 opened in 2019, with a capacity of 100 people. It presents a more homemade cuisine with Brazilian rural roots. Due to its location, far from the city center and close to a conglomerate of industries in the manufacturing sector, its target audience is local residents and workers.

The restaurant has a global sustainability level of 0.50, between moderate and satisfactory levels, the environmental (0.44) and social (0.45) dimensions are at a moderate level, and the economic dimension (0.60) is at a satisfactory level. Of the total key results, 41.00% are applied “satisfactorily” or “fully incorporated” and 30.00% are “not applied”.

In the environmental dimension, 36.96% of its key results are applied in a “satisfactory way” or “fully incorporated”; on the other hand, it needs improvement in 63.04% of the key results, mainly those related to construction, fixtures, furniture, energy, and the management of residues (ENV13, ENV15–19, ENV21–22, ENV31–39, ENV43–46). In the social dimension, 64.71% of the key results are applied “moderately” or less, with 32.35% being “not applied”, indicating significant improvement related to employees, customers, the community, and suppliers (SOC4–7, SOC16–18, SOC21–25, SOC27, SOC30, and SOC32–34). In the economic sphere, 60.00% of key results are applied “satisfactorily” or “fully incorporated”, and 40.00% need improvement (ECON1, ECON4, ECON7, ECON12–13, ECON17–18, ECON19).

3.2.3. Restaurant 3

Restaurant 3, which was founded in 2011, has gastronomy aimed at vegetarian and vegan people, although it also serves food that meets and satisfies the general public. It is located in the central area of the city and has an audience capacity of 150 people in a hall marked by decoration and natural lighting.

The restaurant is the best-rated among the analyzed restaurants, with an overall sustainability level of 0.69. The sustainability levels of the social (0.74) and economic (0.74) dimensions are advancing to the point where the key results are fully incorporated, and the environmental dimension has a value of 0.59. Furthermore, 64.00% of key results are applied “satisfactorily” or “fully incorporated” and 22.00% are applied “lightly” or “not applied”.

In the environmental dimension, 56.52% of its key results are applied in a “satisfactory way” or “fully incorporated”. On the other hand, 43.48% of the key results need improvement, mainly in items related to food (ENV1, ENV3–4), construction, furniture, and fixtures (ENV15, ENV21–24), and energy and waste management (ENV31–35, ENV37, ENV43–46). In the social dimension, 70.59% of its key results are applied “satisfactorily” or “fully incorporated”, and only 11.76% are applied “lightly” or “not applied” (SOC23–24, SOC33–34). In the economic sphere, 70.00% of key results are applied “satisfactorily” or “fully incorporated”, and 30.00% are applied “moderately” or less (ECON6–7, ECON9, ECON12, ECON15, ECON18).

3.2.4. Restaurant 4

Restaurant 4 is located in the central area. Founded in 2017, it has the capacity to serve an audience of 120 people and it is organized into two environments, one indoors and the other outdoors, with no specific cuisine or target audience.

The restaurant has the lowest overall sustainability level score (0.28) among the analyzed restaurants, being at the moderate sustainability level, close to the light level. The level of sustainability in the economic dimension showed the worst evaluation (0.26), followed by the environmental dimension (0.27) and social dimension (0.33). Only 14.00% of the key results are applied “satisfactorily” or “fully incorporated”, and 70.00% are applied “lightly” or “not applied”.

The restaurant needs extensive improvement in its sustainability-related practices. In the environmental, social, and economic dimensions, they have, respectively, applied “satisfactorily” or “fully incorporated” only 13.04%, 17.65%, and 10.00% of their key results.

3.2.5. Restaurant 5

Founded in 2011, Restaurant 5 is the most luxurious among those analyzed, aimed at an audience with a higher financial standard, although, during the week, they conduct promotions to attract the general public. Located in the downtown area, it has a capacity of fifty people.

The priority characteristics of the restaurant, as well as the limited public environment, do not guarantee a satisfactory performance in sustainable practices. This is supported by the restaurant’s low scores in the environmental (0.45), social (0.48), and economic (0.42; dimensions, which result in the restaurant’s overall sustainability level of 0.45, being the second lowest evaluated in this study. Moreover, 40.00% of key results are applied by the restaurant “satisfactorily” or “fully incorporated” and 48.00% are applied “lightly” or “not applied”.

In the environmental dimension, 43.48% of its key results are applied in a “satisfactory way” or “fully incorporated”, while on the other hand, it needs improvement in 56.52% of the key results, mainly for those related to food (ENV3, ENV6, ENV7–8, ENV10–11), construction, fixtures, and furniture (ENV13, ENV15–17, ENV19–20, ENV27–29), energy, and waste management (ENV30–31, ENV33, ENV35–39, ENV43–46). In the social dimension, 44.12% of the key results are applied in a “satisfactory way” or “fully incorporated”, and 44.12% are “not applied” or applied in a “light way”, indicating improvements related to employees, customers, the community, and suppliers (SOC16–18, SOC20–24, SOC26–27, SOC29–34). In the economic sphere, only 25.00% of key results are applied “satisfactorily” or “fully incorporated”, and 50.00% are applied “lightly” or “not applied”, requiring significant improvements (ECON1, ECON4–6, ECON9 -10, ECON12, ECON18–20).

3.3. Synthesis

According to the scores shown in Figure 6 and the values assigned by the restaurant managers for each key result (Appendix A and Appendix B), restaurant five is better evaluated in terms of sustainability in the environmental and social dimensions than restaurants two and four. However, in the economic dimension, restaurant five showed a good score; in this dimension, the best score was obtained by restaurant two, making the level of global sustainability of this restaurant the second-worst evaluated, indicating that to achieve an optimal level of sustainability, a restaurant must have a high score on all levels of sustainability in each dimension under study.

Regarding the overall sustainability level of the restaurant, restaurant 4 is at a moderate level (0.28), and closer to the light level; restaurant 5 is also at a moderate level (0.45), but closer to the satisfactory level; restaurant 2 (0.50) is positioned exactly on the threshold between moderate and satisfactory levels; restaurant 1 stands out for being a university restaurant and being at the level considered satisfactory in terms of sustainability (0.54), but with greater proximity to the moderate level; and restaurant 3 is also present at the satisfactory level (0.69); however, it is closer to the level where sustainability practices are fully incorporated.

For restaurant 1, it is recommended to focus on specific improvements in the economic dimension since it is the worst evaluated at present (0.46), being present at the level considered moderate, while the environmental and social dimensions are at a satisfactory level seeking equity between the three. This is a university restaurant, and naturally, some economic aspects are more difficult to work with. However, the ECON7 and ECON9 practices are not currently inserted, and they are practices that should be a priority since they are related to the improvement of operating costs and taking advantage of opportunities that the market offers, factors that are crucial for those who work with a value so far below their competitors.

Restaurant 2 is at a satisfactory level regarding the insertion of sustainable key results (moderate to satisfactory), even if it is not a priority for the manager to meet the basic concepts of sustainability. Therefore, for restaurant 2 to be able to insert more sustainable key results and improve the application of those that are already inserted, a change of perception is essential, in which inserting sustainability in all its processes is an objective. In the economic dimension, restaurant 2 is already at a level considered satisfactory (0.60), requiring greater attention in the environmental (0.44) and social (0.45) dimensions.

Considering the vast space that restaurant two has around it, some environmental practices such as ENV16, which deals with the presence of a vegetable garden for the cultivation of food itself, and ENV44, which addresses the reuse of water, could be easily implemented. With regard to the social dimension, some practices could be adopted to improve the level of this dimension, such as the SOC1 practice, which deals with providing training to employees on sustainable issues, and the SOC22 and SOC23 practices, which both aim for a better relationship with customers.

Restaurant 3 is the most developed in the sustainability theme of all the restaurants studied; however, none of its dimensions reach the maximum level, in which the practices are fully incorporated. The sustainability level scores of the social and economic dimensions are remarkably close to the “fully incorporated” level; however, the environmental dimension is the one that needs to advance the most in order to approach the other dimensions. Restaurant 3 needs investment in materials that collaborate with the company’s environmental efficiency, such as zero-potential equipment (ENV21), efficient equipment (ENV22), ecological cleaning products (ENV24), equipment that generates renewable energy (ENV37), and equipment or strategies that help reduce emissions (ENV35).

Restaurant 4 is rated the worst, with an overall sustainability level of 0.28. The manager points out that it is not a priority to achieve a satisfactory level regarding the topic of sustainability, but that it is a wish for the future. Therefore, restaurant 4 first needs to make sustainability a priority, which refers to the ECON17 practice, and from this change, seek a gradual improvement through the insertion of key results that do not demand much effort from the team, which gradually creates awareness of the importance of this theme for the restaurant. Some practices such as ENV14, ENV32, SOC1, and SOC8 are examples of practices that do not require much effort and are not yet included in Restaurant 4.

Restaurant 5 is the most balanced among all the restaurants analyzed in the study, in which the values of each dimension are similar to each other: Environmental (0.45); social (0.48); and economic (0.42). However, this correspondence is concentrated at the level considered moderate, requiring the restaurant to develop key results in the three dimensions of sustainability. As a result, Restaurant 5 needs advances in all dimensions, and given that quality is one of its main pillars and the price of its products is seen as an obstacle for a large part of the public, certain practices such as ENV16, which refers to the provision of a vegetable garden for own cultivation, in addition to practices such as SOC23 and ECON7, which deal with the use of a rewards policy and the improvement of operating costs, respectively, can be an interesting path for sustainability to begin to be treated more frequently and seriously in the company, considering its strengths and weaknesses.

4. Conclusions

The objective of this study was to propose a method to determine the level of sustainability in restaurants through modeling using the OKR method and fuzzy logic. Therefore, in order to develop a complete method that would guarantee scientific support, (1) a systematic bibliographical review was carried out to select the 100 key results regarding sustainability in the environmental, social, and economic dimensions, (2) obtaining the weights and validation of each key results by means of eighteen experts who are researchers on sustainability in different areas of knowledge (administration, economics, nutrition, food engineering, environmental technology, production engineering, etc.). (3) To verify the adherence to the method, five restaurants with different characteristics and themes (size, gastronomy, public profile, etc.) were selected, in order to verify the contributions or barriers to the application of the method.

Regarding the environmental dimension, experts assigned the greatest degrees of importance to the following key results: Safety and stock, wild animals, regulation, zero potential equipment, efficient equipment, water savings, energy savings, waste, composting or reusing, solid waste reduction, renewable energy, special and/or hazardous waste, and reduce, reuse, and recycle. In the social dimension, the key results are work climate, employee health and safety, employee satisfaction, fair conditions and wages, laws and obligations, anti-discrimination policies, customer health and safety, customer satisfaction, community development, and differentiation from the competition. In the economic dimension, the key results with the highest degrees of importance were the business image, market opportunities, fair pricing, legal standards, quality, and productivity monitoring.

On the other hand, regarding the environmental dimension, specialists attributed lower degrees of importance to key results such as bulk and concentrates, self-service, and sustainable space. In the social dimension, key results include environmental activities, community participation, model company sustainability, sustainable education, relationship systems, rewards policies, local support, employment opportunities, public support, collaboration with suppliers, and partnership with companies. In the economic dimension, the key results with lower degrees of importance were the market share, occupancy rate, sales, number of employees, sustainable marketing, and operating principles.

The key results least used in the analyzed restaurants are portion size, vegetable garden, emissions reduction, environmental performance, and environmental reports (from the environmental dimension); community participation, rewards policy, guidance, and involvement (from the social dimension); and sustainable associations. The most frequently applied key results are special and/or hazardous waste (from the social dimension); employee maintenance; laws and obligations; customer health and safety; and an accessible and welcoming environment (from the social dimension).

It is worth noting that the key result regulation, which includes compliance with the safety and sanitation protocols and other regulations established by the food industry, was the only one of the one hundred practices that was fully implemented in all restaurants. As for the key results, renewable energy, which refers to the use of clean energy in the restaurant, whether generated by itself or purchased from another reliable company, and water reuse, which comprises the collection of rainwater or gray water for reuse, are not applied by any of the restaurants analyzed in the study.

The proposed method proved to be adherent, pointing out which key results and to what intensity they are inserted in each restaurant, indicating their strengths and weaknesses in the context of sustainability, as well as comparisons between them (Appendix A and Appendix B and Figure 6).

Similar to the vast majority of studies found in the literature, this one also has some gaps and limitations, serving as a reference for future studies in the area concerning (i) the absence of intangible measures, that is, practices involving the measurement of intangible factors, such as energy, water, gases, and other possibilities; (ii) the lack of availability or knowledge of more accurate data, that is, some restaurants have sustainable practices in place but do not know how to clearly inform the data regarding such practices; and (iii) improvements in the method of collecting data from restaurants since the current collection method was in accordance with the judgments of the managers of the restaurants.

This study contributes to the scientific community by providing complete key results aimed directly at measuring the level of sustainability in the restaurant sector and presenting the current situation and existing challenges. It provides opportunities for future studies in the search for relationships between the level of sustainability of a restaurant and organizational culture, green intellectual capital, the influence of customers’ perceptions of sustainability on sustainability in restaurants, environmental training, the critical capacities of restaurants, supply chain management, the effects of sustainability on acquiring new customers, public policies to promote more sustainable restaurants, challenges and opportunities to have a more sustainable sector, etc.

Additionally, this study also contributes to the non-scientific community by providing a comprehensive view, in terms of key results, of each of the dimensions of sustainability for restaurants, measuring which key result is inserted into the restaurant and to what intensity, and collaborating in the understanding and incorporation of sustainable practices in restaurants, in addition to directly helping in the search for a lower environmental impact and outlining a reflection of the services provided by companies in this sector.