Designing and developing a platform called ‘rest at restaurant’ to support the basic needs of senior adults

Abstract

This study proposes an alternative technique to support the design and development of products, specifically focusing on creating a new design and platform for restaurants tailored to the needs of senior adults, ensuring easy-to-access experiences. The primary aim is to effectively identify and translate customer requirements into an engineering design through a systematic approach, enabling the extraction and realization of these requirements. The background encompasses insights gathered from interviews with target customers, informing the creation of a new design. Acknowledging that prior designs often stem from the designers’ perspectives, the study highlights the importance of aligning with and meeting specific customer requirements. Research findings demonstrate the popularity of the nature-style restaurant concept in various regions of Thailand, particularly among senior adults aged 61-70 in the Bangkok metropolitan region. Many of these individuals have backgrounds in medical fields or were retired government officers/employees. The study utilized a digital-based questionnaire platform to gather demographic information, financial insights, and perspectives of senior adults. Ultimately, the research contributes significantly to enhancing the conceptual model of the restaurant, identifying key components crucial for meeting the unique needs of senior adults.

Keywords:

• Customer’s perception
• health-related product
• product design and development
• quality function deployment
• house of quality
• usefulness
• character height
• restaurant design

REVIEWING EDITOR:

• Santiago Gutierrez-Broncano, University of Castilla-La Mancha, Professor of Business and Management, Business Administration, Spain

SUBJECTS:

• Environmental Management; Environment & Business; Environment & Society; Environment & Health; Production Engineering; Technology; Design; Economics

1. Introduction

Living and staying with senior adults, especially in Asian countries, can be a rewarding experience that requires understanding, compassion, and appropriate care. To create a supportive and comfortable environment, several key considerations should be taken into account. First, maintaining open and effective communication with senior adults, actively listening to their needs, concerns, and preferences, and showing empathy by considering their perspectives and experiences is crucial. Ensuring the safety and accessibility of the living space is also important. This may include addressing potential trip hazards and making adjustments such as installing handrails or grab bars and ensuring proper lighting. “Trip hazards” refer to objects or conditions in an environment that can cause people to stumble, trip, or fall. These hazards can include things like loose rugs, cords, clutter on the floor, uneven surfaces, or any other obstructions that may impede safe movement and potentially lead to accidents. Encouraging social engagement through activities, outings, or family gatherings that cater to their interests and abilities helps prevent isolation and loneliness. Supporting their physical and mental health by promoting regular exercise, a nutritious diet, and access to healthcare services is essential (Rianmora & Poulpanich, 2022). Additionally, respecting their independence and involving them in decision-making whenever possible, while providing opportunities for maintaining a sense of autonomy and control over their daily lives, contributes to their well-being (Abu-Bader et al., 2003; Archibald et al., 2020; Claassens et al., 2014; Clarke et al., 2008; Moilanen et al., 2021; Moilanen et al., 2022; Nyende et al., 2023).

The classification of senior adults’ age range varies based on cultural norms, legal definitions, and social contexts. While a universally agreed-upon age is absent, it is commonly accepted that senior adulthood typically begins at 60 or 65 years old. Different countries and organizations may, however, establish specific age thresholds for this demographic. For example, in the United States, individuals aged 65 and above are generally considered senior adults and are eligible for certain benefits like Medicare. These age thresholds can differ across countries, and some organizations may consider individuals as senior adults at a younger age, such as 60 or 55 (Administration for Community Living, 2023; United Nations, 2019; WHO, 2021). However, the concept of “senior adulthood” is not only determined by age but also connected to factors like retirement, changes in health and lifestyle, and social roles within a community or society. The age range for senior adults can vary depending on cultural, societal, and organizational factors.

Addressing the challenge of generation gaps in the competitive market, the design team aims to minimize differences by creating a shared product design platform that accommodates various age groups. Key concepts include ergonomic design and health considerations, acknowledging that seniors desire inclusive participation in activities with their families. As seniors adapt to digital technologies, they encounter challenges such as small text and images on screens, necessitating larger fonts and clear visuals. A cherished activity for seniors is dining out with family, creating opportunities for shared ideas and experiences. Through online questionnaires (i.e. google sheet platform) and interviews, limitations in dining experiences emerged, including small text and excessive graphics on menus, improper seating arrangements, inadequate lighting, and a lack of universal wheelchair-friendly designs. Recognizing these issues, the design team conducted interviews with target customers to inform a new design. While drawing inspiration from existing products, it is crucial to note that the design’s physical characteristics may not fully align with customers’ specific requirements, emphasizing the need for ongoing refinement.

Eating out and taking senior adults with other family members offer numerous benefits. It provides an opportunity for social interaction, allowing seniors to connect with family and others, fostering conversation and a sense of belonging. Additionally, dining out introduces seniors to new cuisines and cultural experiences, adding variety and diversity to their meals. It also reduces the burden on family members by relieving them of meal preparation and cleanup responsibilities, providing a much-needed break from cooking. Moreover, eating out offers seniors enjoyment and entertainment, as they get to experience a change of scenery and enjoy delicious food in a pleasant atmosphere. Regarding the primary element known as “scenery,” it encompasses the natural or man-made views, landscapes, or surroundings that are typically visible, particularly in outdoor settings. This includes the visual aspects of an environment, such as the beauty of nature, cityscapes, or specific settings that can be observed. Lastly, dining out enhances special occasions and celebrations, creating lasting memories for the entire family. These benefits contribute to the well-being of seniors by promoting social connections, enjoyment, shared experiences, and easing the daily tasks of meal preparation for family members.

This research aims to present guidelines for restaurants and food businesses to create facilities and menus that specifically support senior adults, ensuring their comfort and happiness while dining out with family. By following these guidelines, restaurants can enhance the dining experiences of senior adults, making them feel valued and appreciated within their society. Recently, the design team conducted interviews with the target customers to gather their opinions and insights regarding the products they use. The data collected from these conversations have been analyzed and utilized to inform the creation of a new design. The designers also conducted research on existing products that are similar to the one they are designing, utilizing their own approaches. However, it is important to note that the physical characteristics of a new product or an innovative design have predominantly been developed and created from the perspectives of the designers themselves. As a result, there is a possibility that the obtained design may not fully align with or meet the specific requirements of the customers.

2. Related works

2.1. Kansei Engineering (KE)

Kansei Engineering (KE) is a discipline originating in Japan within the field of engineering. It has gained global recognition for its significant contribution to user-centered design by focusing on understanding and incorporating human emotions, perceptions, and preferences into the design and development of products, services, and systems (Chen et al., 2015; Enomoto et al., 1993; Lin et al., 2006; Lai et al., 2006; Matsubara & Nagamachi, 1997; Nagamachi, 1995; Schütte et al., 2004; Vieira et al., 2017; Yang & Shieh, 2010; Zhang et al., 2018). KE adopts a multidisciplinary approach, integrating principles from engineering, psychology, and design. By employing a systematic framework, Kansei Engineering enables a comprehensive understanding and incorporation of user emotions. This approach ultimately leads to the creation of products and services that inspire or stimulate positive emotional responses in users, resulting in enhanced user satisfaction and overall product success. The synergy of design and emotions is explored in these studies, contributing to a nuanced understanding of user experiences and cognitive processes. Ahmad et al. (2023) present a pioneering Emotional User Experience Model for Mobile Augmented Reality Application Design, employing a Kansei Engineering approach. This research lays the groundwork for enhancing emotional engagement in mobile AR applications, recognizing the significance of user emotions in design. Ho and Siu (2012) offer a comprehensive review on the intricate relationships among emotion design, emotional design, and emotionalize design, providing insights into the evolving perspectives within the field. Their work highlights the importance of considering emotional aspects in design processes and the evolving nature of emotional design concepts. In a related domain, Zhang et al. (2023) delve into Product Styling Cognition based on Kansei Engineering Theory and Implicit Measurement. Their study explores the cognitive aspects of perceiving product styling, offering valuable insights for designers seeking a deeper understanding of how consumers cognitively process and respond to product aesthetics. Together, these studies contribute to the evolving landscape of design, emphasizing the integral role of emotions and cognitive processes in shaping user experiences and perceptions across various technological and product contexts. Key details regarding KE applied to restaurant design for senior adults:

• Objective: KE aims to capture and analyze emotional responses of senior adults to restaurant experiences, translating them into design features for enhanced emotional well-being during dining.

• Emotion-based design: Recognizing the pivotal role of emotions, KE seeks to identify and incorporate desired emotional qualities (Kansei) into the restaurant design, ensuring a positive and satisfying dining atmosphere for seniors.

• Methods and techniques: Utilizing qualitative and quantitative methods like surveys, interviews, and observations, KE gathers data on senior adults’ emotions. Statistical analysis and data mining extract insights, informing the creation of an age-friendly dining environment.

• Application domains: Applied to senior adults’ restaurant design, KE contributes to creating age-sensitive and emotionally appealing dining spaces, fostering a positive user experience crucial in the hospitality industry.

• Benefits: Implementing KE in restaurant design enhances emotional resonance, leading to increased senior satisfaction, improved dining experiences, positive brand perception, and heightened competitiveness in the senior dining market.

• Integration with other disciplines: Collaborating with fields such as ergonomics, psychology, and hospitality design, KE ensures a comprehensive and holistic approach that addresses both the functional and emotional needs of senior adults in restaurant settings.

The key points, in this research, applying Kansei Engineering (KE) to support restaurants and menu design for catering to senior adults involves considering their emotional responses and preferences. KE techniques such as surveys, interviews, and observation can be used to gather feedback on seniors’ emotional preferences, aiding in the design of emotionally-driven menus. It is important to select visually appealing and easily legible fonts, sizes, and colors that cater to their specific visual needs. Organizing menu items in a way that aligns with seniors cognitive preferences, such as logical categories and clear headings, facilitates easy navigation and decision-making. By incorporating familiar and comforting food choices that generate positive emotions and memories, satisfaction and enjoyment for senior diners can be enhanced. Additionally, creating a comfortable and welcoming dining environment through thoughtful considerations of seating arrangements, lighting, noise levels, and accessibility contributes to an overall enjoyable dining experience.

To optimize the design of restaurants for the comfort and inclusive experience of senior adults, an in-depth review of numerous research studies reveals a consensus. Researchers have identified key elements that significantly influence seniors’ dining experiences, with crucial factors including colors, printings of words and pictures, and considerations for left/right-handed preferences. These elements play a vital role in cultivating a welcoming environment for seniors, bridging generational gaps, and fostering an atmosphere where they can comfortably dine and engage with others. The rationale behind prioritizing colors, printings of words and pictures, and considerations for left/right-handed design within the context of senior adults and restaurant design lies in enhancing visual accessibility, readability, and overall comfort. Colors are particularly instrumental in creating a welcoming and calming environment, while clear printings aid readability, especially for individuals with potential visual impairments. The thoughtful arrangement of these elements, taking into account left/right-handed preferences, ensures a user-friendly and accommodating dining experience for senior customers, guests, or diners.

2.2. The perception of colors by senior adults regarding dishes and restaurant equipment

The perception of colors by senior adults regarding dishes and restaurant equipment plays a significant role in their overall dining experience. As individuals age, changes in vision can occur, including reduced color perception and sensitivity. Understanding how senior adults perceive colors in relation to dishes and restaurant equipment is crucial for designing inclusive and age-friendly dining environments. The certain colors may be more visually appealing and easier for senior adults to distinguish (Bao et al., 2018; Delcampo-Carda et al., 2019; Ishihara et al., 2001; Yu et al., 2023; The Changes in Color Perception for Elderly, 2022; Wang et al., 2022; Wijk et al., 2001).

For dishes, using plates and bowls with high color contrast, such as white or light-colored plates with dark-colored food, can enhance visibility and make it easier for seniors to identify and enjoy their meals. Additionally, choosing dishes with matte or non-reflective surfaces can help minimize glare and improve visual clarity. Similarly, when selecting restaurant equipment such as menus, signage, and utensils, it is important to consider color choices that are visually distinct and easily readable for senior adults. Using high-contrast color combinations, such as black text on a white background, can improve legibility and reduce eyestrain. Additionally, avoiding small or intricate fonts and opting for larger, bold fonts can enhance readability for seniors with age-related vision changes. In terms of color psychology, it is worth noting that different colors can induce varying emotional responses and affect the dining experience. For example, warm colors like red and orange can stimulate appetite and create a welcoming atmosphere, while cool colors like blue and green can promote relaxation. Understanding the emotional impact of colors can help guide the selection of color schemes and create dining environments that are comfortable and enjoyable for senior adults (Tantanatewin & Inkarojrit, 2018; Wang et al., 2022; Wei et al., 2023). However, the perception of colors by senior adults, particularly those aged 70 years and older, can be influenced by age-related limitations, resulting in a different visual experience, particularly with regards to color. As individuals age, changes in vision, such as reduced color discrimination and sensitivity, can occur. For many seniors, there may be a shift in color perception where yellow tones become more dominant and other colors appear altered or less distinguishable (Figure 1).

Figure 1. Comparing the effects of menu color on the visual perception of senior adults, we evaluated the impact of a yellow-like tone (right) versus a normal-shade style (left).

This phenomenon, known as yellowing of the lens or age-related color perception changes, can affect how senior adults perceive colors in various contexts, including when observing dishes and restaurant equipment. Understanding these limitations is crucial for designing inclusive environments that accommodate the unique color perception of senior adults and ensure their comfort and satisfaction. Considering the perception of colors by senior adults when choosing dishes and restaurant equipment can greatly enhance their dining experience, improve visual accessibility, and create age-friendly environments that cater to their specific needs.

The key points, in this research, the importance of considering color perception and limitations in senior adults when designing menus, posters, and printed documents for restaurants are highlighted. By understanding the color preferences and limitations of senior adults, the design team can effectively select colors and shading for food and beverage images that accurately represent the restaurant’s identity and cater to the needs of the target customers. Additionally, creating a harmonious composition of colors and layouts on dining plates or tables can indirectly inspire chefs to generate new ideas for menus and flavors.

2.3. The perception of senior adults regarding the printings of words and pictures on food menus

The perception of senior adults regarding the printings of words and pictures on food menus is influenced by various factors. Age-related changes in vision can affect their ability to read small fonts or discern fine details in images. Therefore, it is important to consider legibility and clarity when designing menus for this demographic. Using larger fonts and clear, high-contrast text can enhance readability for senior adults. This includes selecting appropriate typography styles and sizes that are easy to read, even in low-light environments. Additionally, utilizing a simple and straightforward layout can help prevent visual clutter and make it easier for seniors to navigate the menu. When it comes to pictures of food, clear and appetizing images can significantly impact the perception and decision-making process of senior adults. High-quality, visually appealing images that accurately represent the dishes can generate interest and stimulate appetite. However, it is essential to strike a balance between presenting enticing visuals and ensuring that the images accurately reflect the actual portions and ingredients. Consideration should also be given to color choices in menu design. As mentioned earlier, age-related changes in color perception may affect how senior adults perceive and interpret colors. Selecting colors with sufficient contrast and avoiding color combinations that may cause confusion or blending can aid in clarity and legibility. By understanding the specific needs and limitations of senior adults’ visual perception, menu designs can be tailored to enhance their dining experience. Clear and readable text, coupled with appetizing and representative food images in which materials, size, and font style are carefully considered, contribute to a more enjoyable and accessible menu for senior customers (Akashi et al., 2022; Hou et al., 2022; Magnini & Kim, 2016; Ohyama & Sagawa, 2016; Price et al., 2016; Wasserstrom, 2023).

The key points in this research highlight the importance of considering color perception and limitations in senior adults when designing menus, posters, and printed documents for restaurants. By understanding the color preferences and limitations of senior adults, the design team can effectively select colors and shading for food and beverage images that accurately represent the restaurant’s identity and cater to the needs of the target customers. Additionally, creating a harmonious composition of colors and layouts on dining plates or tables can indirectly inspire chefs to generate new ideas for menus and flavors.

2.4. The preference for using the left or right hand of Asian senior adults

For Asian senior adults, handedness, or the preference for using the left or right hand, can vary similarly to other populations around the world. It is important to consider handedness when designing menus and dining experiences for senior adults in order to provide them with the most comfortable and accessible environment. When arranging tables and seating, it can be beneficial to offer a mix of left-handed and right-handed seating options. This allows individuals to choose a seat that aligns with their preferred hand for dining. Additionally, it is helpful to provide utensils that accommodate both left-handed and right-handed individuals. This means offering cutlery with handles designed for easy grip and use for both hand orientations. Furthermore, when designing menu layouts, it is important to consider the reading direction for languages commonly used in Asian countries. Languages such as Chinese, Japanese, and Korean are typically read vertically from top to bottom, or horizontally from right to left. However, in a comprehensive exploration of the impact of writing direction change in East Asia on consumer perceptions and advertising, Deng et al. (2019) investigated the effects of up-down versus left-right writing. Their study, featured in the Journal of Advertising, sheds light on the significant role that writing direction plays in shaping consumer responses. Meanwhile, Dong and Salvendy (1999) examined the details of menu design for the Chinese population, comparing horizontal and vertical layouts in the context of user preferences. Pae (2020) contributed to the discussion by looking at the differences among Chinese, Japanese, and Korean writing systems, emphasizing their unique characteristics within the framework of East Asian scripts. Permanasari’s (2015) comparative study of Javanese and Japanese eating cultures and utensil designs highlighted cultural differences in dining practices, focusing on the significance of hands and chopsticks. In the realm of linguistics, Song et al.’s (2022) investigation into restaurants’ outdoor signs from a linguistic landscape perspective underscored the nuanced messages conveyed through signage. Finally, Yan et al. (2019) explored sentence reading patterns, specifically the vertical saccade advantage, contributing valuable insights to the understanding of reading processes. These studies collectively enrich our understanding of various aspects of East Asian culture, from writing systems to dining practices and linguistic landscapes. However, in the case of Thai language, sentences or phrases are read from left to right.

The key points, adjusting the menu layout accordingly to match the reading direction can enhance readability and ease of use for Asian senior adults. By taking into account handedness and cultural reading preferences, the design team can create a dining environment that caters to the needs and comfort of Asian senior adults, ensuring an enjoyable and inclusive experience for all.

2.5. Menu design and Restaurant condition

This comprehensive exploration of diverse research studies illuminates various factors influencing human perception and behavior related to text, design, and environmental considerations. Darroch et al. (2005) investigated the impact of age and font size on reading text on handheld computers, providing valuable insights into interface design considerations. Filimonau and Krivcova (2017) explored the relationship between restaurant menu design and consumers’ responsible food choices, with a focus on managerial perceptions. The study delves into the impact of menu design in encouraging environmentally and socially responsible food choices by patrons. It offers insights into how restaurant managers perceive their role in influencing consumer behavior through menu design, contributing to a better understanding of sustainable practices in the food industry. Building on this theme, Hou, Anicetus, and He (2022) conducted a systematic literature review, extending the inquiry to explore the design of font size specifically for older adults using mobile devices. Their work contributes to our understanding of age-related considerations in technology usability. In a parallel investigation, Hou, Yang, and Sun (2017) explored the effects of pictures and food names on menu evaluations, emphasizing the multifaceted nature of visual elements in influencing consumer choices within the context of dining experiences. IP and Chark (2023) conducted a meta-analysis, delving into the effects of menu design on consumer behavior and offering valuable insights for the hospitality industry. This collective body of research enriches our understanding of the intricate interplay between design elements, perception, and human behavior across various contexts. The study by Magnini and Kim (2016) further contributes to this understanding by exploring the influences of restaurant menu font style, background color, and physical weight on consumers’ perceptions. Their work delves into the visual and psychological aspects that shape the dining experience, providing nuanced insights for the hospitality industry. Beyond restaurant settings, diverse studies have explored additional facets of human cognition and perception. Mendes et al. (2021) investigated word frequency effects on judgments of learning, offering insights into cognitive processes beyond mere beliefs. Murphy and Castel (2022) explored selective remembering and directed forgetting, demonstrating how similar stimulus properties influence these memory processes. Piqueras-Fiszman and Spence (2012) contributed to the field of sensory perception by examining how the weight of a container influences expected satiety, perceived density, and subsequent expected fullness. Price et al. (2016) investigated the role of font size and style in both predicted and actual recall performance, specifically considering the differences between younger and older adults. In 2018, Tantanatewin and Inkarojrit investigated the influence of emotional responses to interior color on customers’ decisions to enter a restaurant, and they explored the correlation between color choices in restaurant interiors and customers’ entry decisions, providing valuable insights for the hospitality industry. In 2020, Thiessen, Beier, and Keage conducted a comprehensive review of the cognitive effects linked to disfluent typography in functional reading. Their study meticulously examined how typographical elements influenced cognitive processes during reading, contributing to an enhanced understanding of design implications for functional reading materials. In a practical application of these research insights, Wasserstrom’s guide (2023) on choosing the best fonts for restaurant menus offers valuable advice grounded in design considerations. This resource bridges the gap between theoretical insights and real-world applications, catering to the needs of businesses aiming to optimize their visual communication strategies. Collectively, this body of work contributes to a holistic understanding of how design elements, cognitive processes, and environmental onsiderations intersect to shape human behavior in diverse contexts.

2.6. “User-centered design” and the characteristics of “self-centered” people

“User-centered design” is a paradigm that prioritizes the end user’s needs, preferences, and experiences throughout the design process, ensuring that the final product or service is intuitive and user-friendly (Brambila-Macias et al., 2018; Kajtaz et al., 2015; Ivanov et al., 2024). This approach emphasizes empathy, involving users in the design process through techniques such as usability testing, feedback sessions, and iterative design cycles. On the other hand, understanding the characteristics of “self-centered” individuals is crucial for designing products or services that cater to diverse user personas. Self-centeredness can appear as a focus on personal preferences and desires rather than the needs of others. Such individuals may be less open to considering alternative perspectives or adapting to the preferences of a broader user base (Dambrun & Ricard, 2011; Homburg et al., 2015; Sedikides & Gregg, 2008; Still & Crane, 2017). Incorporating insights from psychology and human behavior studies, the revised content underscores the importance of navigating the balance between user-centered design principles and addressing the potential challenges posed by self-centered tendencies. When designing for senior adults, it is crucial to understand that they may prioritize their personal preferences. This understanding is key to creating a dining environment that meets their needs while also considering the preferences of a broader audience. To achieve this balance, insights from psychology and human behavior studies play a vital role. It helps navigate challenges posed by the self-centered tendencies of senior adults, ensuring that the design is user-friendly and caters to their unique requirements.

3. Research concepts

The nature-style restaurant concept has rapidly gained popularity and widespread adoption in various regions of Thailand. The term “nature-style restaurant” has been introduced through the proposed approach, emphasizing a presentation that centers on a green and fresh environment, offering comfort and coziness during various activities. It communicates and recalls a sensation, memory, or response while establishing a connection to a lifestyle close to nature. This connection provides a platform for relaxation and relief from stress or health conditions. The key concept revolves around rekindling individuals’ connection with nature, enabling them to relish the fresh air and green surroundings reminiscent of earlier generations. In response, business owners have chosen to establish modern, nature-inspired restaurants, designed to cater to customers of all ages. These restaurants prioritize ergonomic design principles, universal signage, and inclusive features for all aspects of the dining experience.

3.1. Customer and Market Surveys

Following the administration of digital questionnaires and direct interviews with a specific group of technologically adept senior adults, the researchers have seamlessly integrated the collected data into the engineering design and development process. Various aspects of restaurant infrastructure and building, including interior and exterior design, have been discussed and analyzed. One significant finding is that senior adults have a reduced level of confidence when it comes to ordering food and beverages independently. This is mainly due to the complex and elaborate nature of modern menus, which differs greatly from their past experiences. Consequently, they prefer to minimize the need for assistance from their family members. These findings have led to the development of guidelines for creating a more comfortable dining experience for senior adults, ensuring they feel at ease and are able to utilize the provided facilities without unnecessary concerns or limitations. The researchers conducted a study on the perceptions and behaviors of senior adults residing in the Bangkok metropolitan region. The survey questions were designed to explore their thoughts and experiences related to dining out and their preferences for food and beverages in the current era. The study aimed to determine the percentage of senior adults who decide to purchase or try these products. Initially, due to a lack of information on the subject, an assumption was made that half of the senior adults purchase and enjoy eating out with their families, which provided maximum variability. Eq. 1(1) $$\left(\frac{{\left(Z\right)}^{2\mathrm{ }}\mathit{x p x q}}{{\left(e\right)}^2}\right)=n$$(1) was then used to analyze the data and derive meaningful insights (Cochran, 2007). (1) $$\left(\frac{{\left(Z\right)}^{2\mathrm{ }}\mathit{x p x q}}{{\left(e\right)}^2}\right)=n$$(1)

Where,

$e$ is the desired level of precision (the margin of error, or confidence interval)

$p$ is the estimated proportion of the population which has the attribute to the question

$q$ is 1 − p

Therefore, in this study, p = .5, and the researcher wanted 95% confidence, and at least 5%—plus or minus—precision. A 95% confidence level gave Z values of 1.96, per the normal tables; thus, we got $$\left(\frac{{\left(1.96\right)}^{2\mathrm{ }}x\mathrm{ }0.5\mathrm{ }x\mathrm{ }0.5}{{\left(0.05\right)}^2}\right)=385.$$

The theoretical calculation indicated a need for 385 respondents from our target population to achieve desired confidence levels. In practice, 400 questionnaires were distributed to target customers, but due to limitations in digital platform access, only 112 respondents participated initially. To expand the dataset, the design teams conducted direct interviews with 80 additional respondents possessing technical skills and business backgrounds, enriching the conceptual restaurant model. Insights from these interviews informed the identification of key components supporting senior adults’ unique needs. Utilizing a digital questionnaire platform (i.e. Google sheet platform), demographic breakdowns based on age were obtained. However, a disparity emerged as the anticipated 385 respondents contrasted with the actual 112 (Table 1). Efforts were made to address this by seeking input from potential users or customers with relevant experiences in restaurant or healthcare settings. These individuals provided insights on specific constraints such as light intensity, graphical artworks on menus, restaurant environments, font sizes and styles, colors of foods or beverages, chair-table set designs, and overall restaurant atmosphere. Fortunately, 80 additional participants were secured through direct interviews, detailed in the current manuscript version post-sample size calculation.

Table 1. Descriptive analysis for the respondent – digital-based questionnaire platform.

Respondent age	Number of respondents (Total 112)	Percentage (%)
51–60	28	25
61–70	78	69.64
71–80	4	3.57
>80	2	1.79
Status	Number of respondents (Total 112)	Percentage (%)
Retired (Government officers/employees)	42	37.50
Previous careers in the medical field, such as being medical doctors, nurses, or working in hospitals.	28	25.00
Business owners	18	16.07
Researchers/Lecturers	10	8.93
Housewife	8	7.14
Did not define occupation	6	5.36
Number of employee(s) in family	Number of respondents (Total 112)	Percentage (%)
1–3	46	41.07
4–6	52	46.43
7–9	12	10.71
>9	2	1.79
Business income per month(THB; 1 USD = 34.42 THB)	Number of respondents (Total 112)	Percentage (%)
<15,000	4	3.57
15,001–30,000	16	14.29
30,001–50,000	20	17.86
50,001–100,000	28	25.00
>100,000	34	30.36
Did not define	10	8.93

In contemporary Thai metropolitan society, individuals aged 60-65, particularly those who have enjoyed five years of retirement post-60, are widely acknowledged as part of the workforce due to their robust education and valuable experiences in their respective fields. Certain sectors, notably in education and healthcare, continue to embrace individuals aged 65–70 or beyond, recognizing their capacity to deliver precise and effective work even in the face of the tech-oriented landscape integrated into traditional practices. Their wealth of 20–30 years of work experience enables them to provide valuable advice, presenting both the merits and drawbacks of various approaches. However, senior adults often have varying levels of expertise in technology. While some may not have grown up with it or had as much exposure as younger generations, others are knowledgeable. Some seniors may also require assistance or guidance to use technology effectively.

The authors categorize senior adults based on their collaborative capabilities: the 55-year-old group, positioned strategically 5 years before retirement, holds significant potential to drive change, particularly in leadership roles like CEO or administrative positions. The 60-year-old group, termed the “retirement” category, retains the autonomy to choose between continued work or the pursuit of personal interests. Finally, the 65-year-old group assumes the role of mentors, leveraging financial stability and available facilities to guide juniors. This group explores diverse interests in shared hobbies, such as sports, singing, gardening, or self-improvement activities at senior centers within the city or near their residences.

The primary questions presented in the questionnaires and interview platforms are:

• “From your perspective, how do you feel about the ambiance, decor, table and chair arrangement, restroom facilities, utensils (size and weight), menu design including colors and font styles, arrangement of pictures, and available amenities in a restaurant?”

• “How do you feel when dining at a restaurant?”

• “What are your thoughts on the decorations and menus at a restaurant from a senior adult’s perspective?”

• “How would you feel about taking your grandparents to a restaurant for a meal, considering your own opinion?”

• “Your dietary restrictions or your food limitations.”

Coincidentally, the majority of participants in the study fell within the age range of 61–70 years old. The data reveal a significant shift in the characteristics of the new generation of senior adults in the 2020s compared to those in the 1900s. Many senior adults in the current era possess the financial capability to take care of themselves, with 55.36% having a monthly income of approximately $1400 or higher. Furthermore, a considerable number of them (around 25%) have worked in hospitals, gaining extensive experience in diseases and mental health issues. As a result, they have provided valuable insights and ideas on how to support and improve the quality of life for senior adults. Additionally, a significant portion of the respondents (the majority) has previous experience working for the Thai government, indicating their familiarity with systematic and organized work patterns. This valuable insight guides the design team in carefully considering the layout and management of facilities within the restaurant, as well as the surrounding environment.

3.2. How can “user-centered design” be linked to “self-centered” individuals?

Upon reviewing the definition and key considerations of “User-Centered Design” and “Self-Centered Individuals”, the essential insights extracted are as follows:

• User-Centered Design

  Definition: Prioritizes end users’ needs, preferences, and experiences throughout the design process.

  Approach: Employs techniques like usability testing, feedback sessions, and iterative design cycles.

  Goal: Ensures the final product or service is intuitive and user-friendly.

• Self-Centered Individuals

  Definition: Focus on personal preferences and desires over the needs of others.

  Challenges: May be less open to alternative perspectives and adapting to broader user preferences.

  Consideration: Understanding these characteristics is crucial for designing products or services that accommodate diverse user personas.

These details are crucial during the design stage to comprehend the fundamental requirements of each concept. Integrating the benefits from both User-Centered Design and insights into Self-Centered Individuals can streamline the design process, minimizing trial-and-error efforts and facilitating the development of a conceptual model for a new product. After conducting direct interviews and online self-administered questionnaires to understand customer behaviors and experiences, the researchers aimed to establish a connection between “user-centered design” and “self-centered” individuals. Their objective was to challenge the perspective of self-centered individuals and cultivate empathy towards others. While self-centered individuals tend to prioritize their own needs and preferences, the principles of user-centered design can significantly contribute to expanding their perspective and encouraging a more inclusive approach. Engaging self-centered individuals in the user-centered design process exposes them to the perspectives and needs of different users. Through user research, observation, and feedback, they gain valuable insights into the experiences and challenges faced by others. This exposure has the potential to create a shift in their mindset, enabling them to understand and appreciate the diverse range of user requirements.

According to the results obtained from the target customers, user-centered design can be regarded as a methodology that employs structured approaches such as personas and user journey mapping. These methods offer self-centered individuals a framework that enables them to empathize with different user types and understand their perspectives. By actively considering the goals, motivations, and pain points of others, self-centered individuals can develop a deeper understanding of user needs and aspirations. Moreover, involving self-centered individuals in usability testing and user feedback sessions exposes them to direct user experiences and perspectives. This direct exposure to user reactions and feedback can challenge their self-centered focus and encourage them to consider the perspectives of others. Involving self-centered individuals in the user-centered design process gives them a chance to learn empathy, see things from different angles, and create designs that work well for more people. This inclusive approach leads to the development of more user-friendly and successful design solutions.

3.3. Enhancing the customer experience: the power of shop decoration and menu design

The decoration of the shop environment and menus plays a crucial role in creating an appealing and immersive experience for customers. By giving careful attention to the design and aesthetics of the shop’s interior, including elements such as lighting, colors, and furnishings, the mood and atmosphere that customers find attractive and inviting are set. Similarly, the presentation of menus, including the layout, typography, and use of visuals, also plays a significant role in capturing customers’ attention and generating interest in the offerings. The thoughtful decoration of the shop environment and menus enhances the overall customer experience and contributes to a positive perception of the establishment. The results of the study emphasize the importance of meticulous attention to shop decoration in creating an inviting atmosphere that appeals to the senses and enriches the overall customer experience. By carefully selecting elements such as lighting, furniture, and decor, the shop can create an ambiance that attracts customers and encourages them to spend time in the establishment. The effects of lighting in a restaurant can vary depending on the tone used. A darker tone of lighting (left) creates a more intimate and cozy ambiance, while a lighter tone of lighting (right) produces a brighter and more spacious atmosphere (Figure 2). The choice of lighting tone can significantly impact the overall dining experience, influencing the mood and perception of the space. However, a darker tone of lighting is not suitable for senior adults as it can create a sense of mystery and make it difficult for them to see objects, such as the food on their plate or dish. The low visibility can impede their dining experience and make it challenging for them to navigate the dining area comfortably.

Figure 2. Comparing the effects of lighting in a restaurant, the darker tone (left) versus the lighter tone (right) can have contrasting impacts on the dining experience (Huibin, 2023; Fohlio, 2023).

Therefore, it is important to consider brighter and well-lit environments that provide sufficient lighting for senior adults to see and enjoy their meals. Furthermore, the design and layout of menus play a significant role in influencing customer perceptions and purchase decisions. Through the use of visually appealing images and clear descriptions, menus can capture customers’ attention and spark curiosity about the offerings. This attention to detail in menu design enhances the aesthetic appeal and entices customers to explore the products further. It is important to note that these activities have a direct impact on the perceived value of the products and can influence customers’ willingness to pay a higher price. The combination of a visually appealing shop environment and enticing menus creates a positive impression and enhances the overall perceived value of the products, increasing the likelihood of customers being willing to pay more for the items.

3.4. Enhancing food menus, font style, and decoration for senior adults

When considering food menus, font style and size, and decoration for senior adults, there are several key points to keep in mind.

1. Food Menus:

   • Clear and readable font: Use a legible font style and size that is easy to read, especially for seniors with visual impairments. Avoid decorative or overly stylized fonts that may be difficult to decipher.

   • Simple language: Use clear and concise language on the menu. Avoid complex terms or jargon that could confuse or overwhelm senior adults.

   • Large print: Consider using larger font sizes to enhance readability. Increasing the font size can make it easier for seniors to browse the menu without straining their eyes.

   • Dietary considerations: Take into account common dietary restrictions and preferences of senior adults, such as low-sodium options, soft food choices, or options for specific dietary needs like diabetic-friendly or gluten-free items.

2. Font Style and Size:

   • Legibility: Choose fonts that are easy to read, with clear distinction between letters and appropriate spacing. Sans-serif fonts like Arial (i.e., Arial style) or Verdana (i.e., Verdana style) are often preferred due to their simplicity.

   • Size and contrast: Choose larger font sizes to accommodate aging eyes. Ensure there is sufficient contrast between the font color and the background to enhance visibility.

   • Consistency: Maintain a consistent font style and size throughout the menu to provide a cohesive and visually appealing experience.

3. Decoration:

   • Simplicity: Keep the overall design clean and uncluttered. Avoid excessive embellishments or complicated visuals that might distract or confuse seniors.

   • High contrast: Use contrasting colors to improve visibility and make important information stand out. For example, use dark text on a light background or vice versa.

   • Clear organization: Arrange menu sections and items in a logical order to facilitate easy navigation. Use headings, dividers, or bullet points to enhance clarity and readability.

However, the preferences and abilities can vary among senior adults who are from different societies and cultures. Conducting surveys or obtaining feedback from the seniors directly can provide valuable insights into their specific needs and preferences. By considering their feedback and implementing user-friendly design principles, the design team can create menus that are accessible, visually appealing, and enjoyable for senior adults. Taking cultural and societal variations into account, the team can ensure that the menus cater to the diverse preferences of senior adults while maintaining legibility, simplicity, and clear organization. This approach promotes inclusivity and enhances the overall dining experience for seniors. Based on the existing design platform of menus (Indian Food menu, 2023; Surang, 2023; Thanasak, 2023), researchers have proposed additional ideas to address customers’ requirements for easily accessible menus.

Figure 3 illustrates the concept of creating menus that empower senior adults by offering information about the food, including key ingredients, spice levels, and clear visibility of the dish’s contents. This approach aims to make them feel involved and connected to the menu, as if they were personally selecting and cooking the food. By providing these details, senior adults can have a sense of agency and experience the joy of cooking for themselves and their loved ones, reminiscent of their past experiences.

Figure 3. The drafted idea aims to create a menu that supports senior adults.

Figure 4 illustrates alternative approaches to displaying ingredient information in food products. These methods are designed to elicit positive emotions and excitement among customers, enabling them to selectively choose or exclude specific ingredients. The key design principle is the utilization of a “universal plus minimal design” platform, which efficiently communicates the essential elements to customers in a clear and concise manner. This concept aligns with a design-by-customer platform, granting individuals the ability to personalize their food choices.

Figure 4. Applying universal and minimal symbol for representing key ingredients.

Figure 5. Different font styles can be used for the same phrase.

3.5. Font styles versus customers’ feelings

Based on the results obtained from questionnaires, the target customers were able to express honest feelings regarding the impact of font styles on their emotions, as depicted in Figure 5. Interestingly, even with the same words, different font styles (left and right) conveyed entirely distinct meanings. The phrase “Please try it” can convey the invitation to engage in a new and experiential testing phase, which implies the involvement of all five senses in the activity. The left font style, resembling a hand-written script, creates a sense of excitement, amazement, and relaxation among customers. They are enthusiastic about trying the food and are willing to provide feedback on their experience. Contrarily, the right font style triggers discomfort to the point where customers feel hesitant to even touch the food with their eating utensils (fork or spoon). This negative feeling is directly attributed to the font style used. When dealing with sentences or phrases that convey a “positive” meaning or emphasize “health concerns,” it is advisable to use a “clean and clear” font style (Figure 6A). Hand-written scripts (Figure 6B) or intricate fonts should be avoided, as they can be challenging to read and may strain customers’ eyesight. Additionally, when using the text “Clean food & Good taste,” the intention is to convey a strong mindset and a commitment to providing customers with high-quality, health-conscious offerings and services. Fonts such as the “C” style, while appearing cute, may inadvertently resemble symbols associated with “germs,” “bacteria,” or “viruses.” This can weaken the perceived cleanliness and compromise the intended message.

Figure 6. Three different font styles for conveying cleanliness and tastiness messages.

3.6. Font color choices to enhance readability for senior adults

As people age, their visual acuity, and contrast sensitivity may decrease, making it more challenging for them to read text, especially if the font colors do not provide sufficient contrast with the background. To address this, it is crucial to choose font colors that offer “a high level of contrast against the background”, ensuring that the text stands out clearly. Optimal contrast can enhance legibility and reduce eye strain, allowing senior adults to read menus, signs, or other printed materials more comfortably. Consideration should be given to factors such as color combinations, brightness, and saturation to find the right balance that promotes readability. The tone of font color that is best suited for making menus clear and legible for senior adults is a high-contrast tone. High contrast refers to using colors that are distinctly different from each other, typically pairing a dark color with a light color. This contrast allows the text to stand out clearly against the background, making it easier for senior adults to see and read. For example, from the master graphic (ArkunDesigns, 2023), using a dark color such as black or a deep shade of gray for the font on a light background, such as white or a light cream color, provides a high level of contrast and ensures clear visibility. This contrast enhances the legibility of the text and helps senior adults distinguish individual letters and words more easily. It is crucial to steer clear of low-contrast color combinations that can hinder readability, such as light gray text on a gray background (Figure 7 – Left one) or dark blue text on a warm-tone background with an unclear text style (Figure 7 – Right one), as they can strain the eyes and make it difficult for senior adults to read the menu content. In addition to font color choices, optimizing font size and the composition of texts and pictures can further improve readability for senior adults. Using larger font sizes and ensuring a well-balanced arrangement of text and visuals in the designated area of interest can enhance legibility and reduce cognitive load. It is important for businesses to prioritize font color choices that enhance readability to create a more inclusive and accessible environment for senior adults. Figure 8 demonstrates the effective use of high contrast texts and pictures with a black and white theme. However, it is crucial to avoid overwhelming readers with excessive information on a single page. While including pictures alongside menu names is recommended, careful consideration should be given to proper arrangement, spacing, and sizing of key elements to ensure a clear and comfortable reading experience. By implementing high-contrast color choices and thoughtful design considerations, businesses can create a more inclusive and accessible environment for senior adults, facilitating their ease in reading and comprehending essential information.

Figure 7. Low-contrast color combinations: Light gray text on a gray background (left), and navy-tone text on a pale orange background.

Figure 8. Demonstrating the effect of high-contrast color combinations on readability.

3.7. Character height concept

The concept of character height refers to the size or height of individual letters in a font (Dhillon, 2006). It plays a crucial role in determining the legibility and readability of text, particularly for senior adults. When designing menus or other printed materials for senior adults, considering the appropriate character height is essential to ensure clarity and ease of reading. Senior adults may experience age-related vision changes, such as reduced visual acuity or difficulties in focusing on small details. Therefore, using larger character heights can help compensate for these visual challenges and make the text more readable. The optimal character height for senior adults can vary depending on factors such as font style, viewing distance, and individual visual abilities. Generally, increasing the character height to a size that is larger than standard fonts can enhance legibility.

However, it is important to find a balance where the text remains visually appealing and does not appear overly large or disproportionate. Incorporating a clear and well-designed font with appropriate character height ensures that senior adults can easily distinguish and comprehend the text. By considering the character height concept and selecting font sizes that accommodate the needs of senior adults, businesses can create menus and printed materials that are accessible and user-friendly for this demographic.

To generate ideas for dining table layouts and lighting arrangements (Figure 9), the design takes inspiration from existing places and research findings. In Figure 9, various lighting styles and dimensions for dining area components are displayed, including the distance between the ceiling and the table, the length of ceiling lamp types, cone-shaped lamp scale, the distance between the lamp and the table, and the size of a table-chair set accommodating six seats in both width and length. These values are represented as averages derived from popular chair, table, lamp, and dining layout designs observed in well-known restaurants across metropolitan areas and cities in Thailand, which are recognized for providing a comfortable ambiance, especially for senior adults. This ensures a pleasant dining experience within spaces adhering to standard table-chair area dimensions. Three design styles are under consideration, emphasizing key elements. By incorporating these different styles, the dining table layout can be creatively designed, taking into account how the lighting sources are interacting with the surrounding environment.

Figure 9. Three lighting styles for the dining area.

• Style A: In this cozy style, a light bulb is placed in a room with a mirrored wall. Natural light is supplemented from one side of the wall. The aim is to create a natural and warm-toned environment, with the lighting focused solely on highlighting the dishes and menus on the table.

• Style B: This style utilizes a turbid-wall type, requiring higher light intensity from light bulbs compared to Style A. It aims to create a more private and modern atmosphere, with lights placed strategically to emphasize and directly project onto the table and its surrounding area.

• Style C: This style combines elements of the turbid-like style (Style B) and the natural-mirror wall style (Style A). The room features a central light source, complemented by potted trees (portable planting pots) and a small open-wall section to allow natural light into the room.

From the customers’ perspective, “Style A” has emerged as the favored lighting style for the dining area. With its cozy ambiance, natural-and-warm tone, and focused lighting on the dishes and menus, “Style A” creates an inviting and comfortable atmosphere that appeals to restaurant-goers. By incorporating this preferred lighting style, establishments can enhance the dining experience and cater to the desires of their customers. Hence, “Style A” is employed in this study to determine the optimal conditions for creating font designs and sizes on menus, specifically aimed at supporting senior adults in comfortably viewing and selecting their desired food items. By implementing this style, the goal is to enhance visibility and provide a comfortable experience for senior customers, enabling them to easily navigate the menu and make their food choices independently.

For suggesting the design of “font size” that will be printed on the menus, and according to the light condition of “Style A,” the condition will be expressed as Equation (2)(2) $${\mathrm{ }H}_C=H_s\times \frac{D_s\mathrm{ }}{28}$$(2) (Dhillon, 2006): (2) $${\mathrm{ }H}_C=H_s\times \frac{D_s\mathrm{ }}{28}$$(2) where H_C is the character height estimate at the specified viewing distance (D_S) expressed in inches, and H_S is the standard or recommended character height at a viewing distance of 28 inches.

In terms of brightness, a 60-watt bulb is generally brighter than a 40-watt bulb. The brightness of a light bulb is measured in lumens, and a 60-watt bulb typically produces around 800 lumens of light, while a 40-watt bulb produces around 450 lumens. The 60-watt bulb provides more illumination and is considered brighter than the 40-watt bulb. To ensure the food is illuminated appropriately, consider using LED lights with either 470 lumens (40 watts) or 806 lumens (60 watts). These options are excellent for creating the ideal lighting in the dining area (LEDVANCE, 2023). The design team recommend selecting dimmable lights, as they allow for adjusting the brightness as needed. During mealtime, the owner may prefer slightly brighter lighting for a more enjoyable dining experience.

Hence, “Style A” serves as the reference environmental framework for the restaurant, emphasizing lighting conditions and visual aspects depicted in Figure 9A. The “Character Height Calculation” will be detailed in Case Studies I and II to determine the appropriate font size for “Heading promotion or Key component” and “Menu,” respectively.

3.7.1. Case Study I: The conditions applied for “Font Design for Heading promotion or Key component”

It is advisable to view the poster from a distance of 88.58 inches (2.25 m), taking into account factors such as the proximity to the light source and the potential for glare at the table (Figure 9), which is the area of focus. Theoretical guidelines recommend that, at a reference distance of 28 inches, the preferred character height is 0.45 inches in a low-luminance environment and 0.35 inches in a high luminance environment. However, in some cases, promotional headings or key components for restaurant campaigns may be placed on cashier counters or tables with a portrait layout, making them difficult to read or easily overlooked. In such cases, where the lighting conditions are considered “slightly difficult to read with lower light provided,” a character height of 0.45 inches in a low luminance environment is suggested. By utilizing Equation (2)(2) $${\mathrm{ }H}_C=H_s\times \frac{D_s\mathrm{ }}{28}$$(2) and considering the available information and space, the estimated font size for this scenario is approximately: $$H_C=0.45\times \frac{88.58\mathrm{ }}{28}$$ ${\mathit{H}}_{\mathit{C}}=1.42$ inch, or 3.61 cm. (102 point-computer)

Results: After careful calculations, it has been determined that the optimal size for graphical art, food descriptions, and prices on the posters or promotion plates attached to walls, tables, or counters should be adjusted to fit within a block space of approximately 3.61 cm. For instance, when considering the dimensions of a standard A3 paper, which measures 297 × 420 mm (or 29.7 × 42 cm), designers can comfortably accommodate around nine menus or sets of food per page. This approach ensures that readers do not feel overwhelmed while browsing through the content.

Font size: to convert the measurement from centimeters [cm] to points (computer) (Unit converter, 2023), the designers can multiply the length value by 28.346 for an approximate result. In this case, the proper font size with a round-clear style should be applied as 102 points for a block-space of 3.61 cm (${\mathit{H}}_{\mathit{C}}\mathit{ }$ value).

3.7.2. Case Study II: The conditions applied for “Font Design for Menu”

The menu placed on the table should be legible from a distance of 12 inches (approximately 30 cm). The light from the light source can project directly onto the area of interest, making the reader feel comfortable with enough illuminance. According to the recommended guidelines, the character height at a standard viewing distance of 28 inches (in a high luminance environment), also known as the reference distance, is considered to be 0.35 inches. Therefore, by using Equation (2)(2) $${\mathrm{ }H}_C=H_s\times \frac{D_s\mathrm{ }}{28}$$(2) and considering the given information and available space, the estimated height (font size) for this scenario is approximately: $$H_C=0.35\times \frac{12\mathrm{ }}{28}$$ ${\mathit{H}}_{\mathit{C}}=0.15$ inch, or 0.38 cm. (11 point-computer)

Results: it has been determined that the ideal size for menu details provided by the restaurant should be adjusted to fit within a block-space of approximately 0.38 cm. For instance, if we consider the dimensions of a standard A4 paper, measuring 210 × 297 mm (or 21 × 29.7 cm), designers can comfortably accommodate around seven menus or sets of food per page.

Font size: Following the conversion concept of centimeters [cm] to points (computer) (Unit converter, 2023), for a block-space height (${\mathit{H}}_{\mathit{C}}$ value) of approximately 0.38 cm, the appropriate font size with a round-clear style should be set to 11 points.

4. Research results

4.1. Customer perceptions and their impact on the overall experience of reading menus and restaurant advertisements

Based on direct interviews with senior adults, the top five concerns when eating out are cost, menus, ingredients, safety and cleanliness, and taste (Figure 10 and Table 2). Exploring the perceptions of dining out in senior adults reveals a multitude of factors that shape their experiences. From the ambiance and atmosphere of the restaurant to the quality of service and the taste of the food, senior adults consider various aspects when evaluating their dining experiences. Understanding these perceptions can help establishments cater to the unique needs and preferences of senior customers, ensuring a pleasant and satisfying dining outing for this demographic. However, not only do senior adults consider factors such as cleanliness, hygiene, and fresh food when forming their perceptions, but they also take into consideration various other factors that contribute to their overall dining experience. These may include the ambiance and atmosphere of the restaurant, the level of customer service provided, the variety and presentation of the menu, the availability of healthy options, the affordability of the meals, and the accessibility and convenience of the establishment.

Figure 10. Key factors of concern for senior adults when eating out.

Table 2. Key factors concerned plus definition.

No	Factors	Details
1	Cost	The cost of each dish should be reasonable and provide good value for the quality (affordability is important).
2	Readability & Clarity	Menus should feature easily readable fonts and provide clear and understandable details.
3	Ingredient Presentation	The main ingredients used in each menu item should be clearly presented through words or pictures.
4	Safety & Hygiene	Senior adults prioritize the safety and cleanliness of the food they consume. It is important that proper sanitation practices are followed, and the ingredients are free from chemical contaminants.
5	Taste and Digestibility	The taste of the food should be enjoyable and not cause any negative effects on digestion or overall health.

To capture the customer perception of dining out in senior adults, Figure 11 showcases seven distinct platforms that highlight their perceptions and experiences, and the details of key points regarding each platform, are listed in Table 3. By understanding and addressing these multifaceted factors, restaurants and food establishments can create an environment that meets the needs and preferences of senior adults, enhancing their dining experiences, and fostering customer satisfaction.

Figure 11. Perceptions of dining out: A case study on senior adults.

Table 3. Key points of customer perception.

No	Key point	Details
	Prohibition of instant food	The prohibition of instant food involves the limitation or outright ban on prepackaged meals that are easy and fast to prepare, usually due to concerns about their nutritional content, additives, or potential adverse effects on health.
	Preference for hot food	The perceived warmth, freshness, comfort, and cleanliness of hot food contribute to a positive dining experience for senior adults.
	High-quality ingredients, cleanliness, and sanitation	High-quality ingredients are carefully selected for their taste, nutritional value, and overall quality, while cleanliness and sanitation practices ensure a hygienic environment and adherence to food safety standards. This combination creates a dining experience that prioritizes top-notch ingredients and a clean, safe environment. It focuses on utilizing fresh, unprocessed ingredients and preserving the delightful flavors experienced in their youth.
	Nourishing bonds through shared meals	The act of eating with family involves sharing meals and enjoying food together in the company of loved ones. It promotes connection, bonding, and a sense of togetherness, creating cherished memories and strengthening familial relationships.
	Becoming familiar and comfortable with the use of cutlery and dining utensils.	The ability of senior adults to handle and use utensils effectively during meals involves developing and maintaining coordination skills for gripping and coordinating hand movements, as well as using proper table manners. This skill promotes independence, dignity, and a sense of normalcy, allowing seniors to confidently and independently consume their meals.
	Feeling like home - reminiscent of a loving mom’s homemade cooking	The reminiscence of a loving mom’s homemade cooking, where every dish is prepared with care, attention to detail, and a touch of motherly love that brings comfort and nostalgia to the dining experience.
	Utensil hygiene and safe cleaning practices	Ensuring the cleanliness of all cutlery and utensils, along with the use of safe cleaning detergents, promotes a hygienic dining experience and helps prevent the risk of contamination or foodborne illnesses.

According to the concept of user-friendly guidelines proposed in this research, targeting diverse restaurant business owners, graphical artworks are employed to effectively communicate with individuals of varying personal backgrounds. This approach aims to clarify senior adults’ preferences and reveal hidden issues, facilitating the creation or modification of restaurants to cater to this specific customer group. Utilizing easy-to-read, universal, and minimalist design images in Figure 11’s seven key considerations proves advantageous for both users and the design team, offering a comprehensive understanding of all key components on a single page. The use of images also encourages a relaxed and quick comprehension. Graphical artworks and colorful design elements play a pivotal role in Product Design and Development (PDD), guiding users through the core concept from “concept development” (including the mentioned “3D virtual model” output) to the final stage of production ramp-up. The incorporation of graphical diagrams, platforms, or charts using universal signs and symbols ensures that users from diverse backgrounds interpret information with the same meaning.

4.2. Uncovering the hidden issues in dining out experiences for senior adults

A food tray with partitioned ends is a type of dining utensil or serving tray that features separate compartments or sections at the ends of the tray (Figure 12(A and B)). These partitions are designed to keep different types of food or food items separate and organized, preventing them from mixing together during a meal. The characteristics of a food tray with partitioned ends include:

Figure 12. A food tray with partitioned ends – (A) rectangular platform, and (B) fantasy platform.

• Division of food: The tray is divided into distinct compartments or sections, allowing for the separation of different foods or food groups.

• Organization: Each partitioned section provides a designated space for specific food items, promoting a neat and organized presentation.

• Prevents mixing: The partitions act as barriers, preventing food items from spilling or mixing together, maintaining the integrity and individual flavors of each item.

• Portion control: The compartments help control portion sizes, ensuring that each food item has its own designated space.

• Easy serving: The tray makes it convenient to serve and enjoy a variety of foods without the need for separate plates or bowls.

• Enhanced dining experience: Using a food tray with partitioned ends can enhance the dining experience by offering a visually appealing and well-organized meal presentation.

• Versatility: The tray can be used for various dining occasions, such as in restaurants, cafeterias, or at home.

For incorporating partitioned ends, these food trays provide a practical solution for serving multiple food items simultaneously while keeping them separated, allowing individuals to enjoy a diverse range of flavors and textures in a convenient and organized manner. Senior adults generally feel uncomfortable and limited when they encounter boundaries or fixed positions that restrict their options and choices. Such limitations can negatively impact their decision-making and design thinking process. For instance, Figure 12(A) depicts a food tray with rectangular traditional style and 90-degree corners, reminiscent of their experiences in school, where they encountered numerous constraints and restrictions while using similar trays. In contrast, Figures 12(B) and Figure 13 presents a tray design created in this study, inspired by the seniors’ positive perception of existing products, such as the Beetle car, which features a cute turtle-like shape. Despite the car’s design representing an older era from the 1960s to 1970s (Volkswagen Beetle 1303S 50 hp Beetle 1973, 25-YD-47), its circular shape creates a sense of boundlessness that brings them joy (Automotive Auctions, 2022). Although both tray designs in (A) and (B) serve the same function, the change in boundary style also affects the emotional response. By considering the impact of boundary design on senior adults, it is crucial to create inclusive and comfortable environments that enable them to feel empowered and unrestricted in their decision-making and use of products.

Figure 13. Customer perception influences the dimensions and structure of the food tray design.

However, despite the several benefits offered by food trays with partitioned ends, there are some potential disadvantages that are commonly expressed by senior adults, with more than 90% of them expressing their dislike for:

• Limited portion flexibility: The predetermined compartments may not allow for varying portion sizes or specific dietary preferences, restricting the ability of senior adults to customize their meals according to their individual needs.

• Difficulty with access and scooping: The presence of partitions can make it challenging for seniors with limited dexterity or motor skills to access and scoop food from each compartment, leading to frustration and difficulty in enjoying their meals.

• Increased risk of spills: The partitions can make it more difficult to balance and carry the tray, increasing the likelihood of accidental spills or tipping over, posing a potential safety hazard for senior adults.

• Cleaning challenges: The presence of partitions adds complexity to the cleaning process, requiring extra effort to ensure thorough cleaning of each compartment, which can be cumbersome for seniors.

• Reduced visual appeal: Some senior adults express their dissatisfaction with the visual presentation of meals served in partitioned trays, as the separate compartments may not provide the same aesthetic appeal as a traditionally plated meal.

It is essential to consider these dislikes and preferences of senior adults when selecting dining utensils or serving trays to ensure their comfort, satisfaction, and overall dining experience.

4.3. Quality function deployment and house of quality

Since the translation of demands into a physical design can be challenging, this research utilizes Quality Function Deployment (QFD) to identify key engineering factors for supporting restaurant design. QFD is a well-established planning process that helps integrate quality considerations throughout the design cycle. Customer requirements (CRs) are translated into engineering characteristics (ECs) to maximize customer satisfaction within budget constraints. The House of Quality (HoQ) method is used to define the relationship between customer requirements and engineering specifications. Table 4 displays the key symbols and their corresponding meanings and scores. These symbols are utilized to identify the relationship between customer requirements and engineering viewpoints for each issue, and they are placed within the HoQ to form the matrix structure. For instance, from Figure 14, the customer requirement regarding “Restaurant decoration” has a strong and direct impact on the engineering viewpoint of “Comfortable - Easy to Access (Atmosphere, Menu, and User confidence).” This relationship is denoted by the symbol “⦿” with a high score of 9. On the other hand, the customer requirement of “Digestibility” has a weaker connection to the engineering viewpoint of “Cost” since the cost of raw materials and per dish does not always directly correlate with the selection of easily digestible food and its quality. Therefore, the symbol “△” with a low score of 1 is assigned to indicate this weak relationship. The relationship between engineering attributes and the correlation between customer requirements and engineering attributes can be quantified using the formula introduced in the publication by Rianmora and Werawatganon (2021).

Figure 14. House of Quality (HoQ).

Table 4. Key points of customer perception.

Relationship between customer requirements and technical requirements
Symbol	Meaning	Score
	Strong	9
	Medium	3
	Weak	1
	No assignment	0

Extensive research has been conducted on three existing restaurant styles, which have been identified as valuable references and competitors for the proposed platform. This platform is specifically designed to support senior adults and is referred to as “Our restaurant” in the House of Quality (HoQ) diagram (Figure 14).

The following are the specific details of each restaurant style, labeled as A, B, and C:

A’s Restaurant – “in-house organic farm”: An in-house organic farm refers to a farm or agricultural area that is located within the premises of a particular establishment, such as a restaurant, hotel, or residential property. These farms are designed to cultivate organic produce, which means the crops are grown using natural methods without the use of synthetic pesticides, fertilizers, or genetically modified organisms (GMOs). By adhering to organic farming practices, in-house farms prioritize environmental sustainability, biodiversity, and the production of fresh, healthy ingredients. One of the primary goals of in-house organic farms is to provide a sustainable and locally sourced food supply for the establishment. By growing their own produce on-site, these farms reduce reliance on external suppliers and transportation, thereby minimizing the carbon footprint associated with food production. This focus on local sourcing also helps support regional farmers and promotes community resilience. Furthermore, in-house organic farms contribute to environmental conservation efforts. By avoiding the use of synthetic chemicals, they help preserve soil quality, protect water sources, and maintain the overall health of the ecosystem. These farms often incorporate practices like crop rotation, companion planting, and natural pest control methods to foster a balanced and resilient agricultural system. In addition to their food production function, in-house organic farms often serve as educational and recreational spaces. Visitors can engage in farm-to-table experiences, where they learn about organic farming practices, participate in harvesting or planting activities, and gain a deeper understanding of where their food comes from. These interactive experiences foster a connection to nature, promote environmental awareness, and encourage healthier and more sustainable food choices. In-house organic farms play a crucial role in promoting sustainable and environmentally conscious practices within establishments. By integrating food production, environmental stewardship, and educational experiences, these farms contribute to a holistic approach that supports local communities, enhances food quality, and nurtures a deeper appreciation for the natural world.

B’s Restaurant – “natural and mini-scale farm”: a natural and mini-scale farming restaurant is an establishment that emphasizes sustainable and environmentally friendly practices by integrating farming and dining experiences. In this type of restaurant, the emphasis is on producing fresh, organic, and locally sourced ingredients on a smaller scale. The concept typically involves cultivating a small-scale farm or garden on the premises of the restaurant. The farm may utilize natural farming techniques, such as permaculture or agroecology, which prioritize ecological balance, biodiversity, and minimal use of synthetic inputs. The focus is on creating a self-sustaining system where the restaurant’s food production is integrated with the surrounding ecosystem. The restaurant then utilizes the freshly harvested ingredients from the farm to create seasonal and farm-to-table menus. The menu offerings often reflect the availability of the produce, allowing for a dynamic and ever-changing dining experience. Customers can enjoy meals that are not only delicious but also sourced sustainably and with a minimal carbon footprint. In addition to serving food, these restaurants may also offer educational opportunities, such as workshops, tours, or classes, where visitors can learn about sustainable farming practices, participate in harvesting or gardening activities, or gain insights into the importance of locally sourced, organic food. A natural and mini-scale farming restaurant aims to provide a unique and sustainable dining experience that connects people with the food they consume, promotes environmental stewardship, and supports local communities.

C’s Restaurant – “Traditional and classic style with contemporary menus”: this platform combines the charm and ambiance of a traditional setting with modern and innovative culinary offerings. This type of restaurant aims to provide a unique dining experience that blends the nostalgia and comfort of classic cuisine with creative and contemporary flavors. In terms of the restaurant’s style, it embraces a traditional and classic ambiance, often characterized by elegant decor, warm lighting, and refined furnishings. The atmosphere may induce a sense of nostalgia and timelessness, creating a cozy and welcoming environment for guests. However, what sets this type of restaurant apart is its contemporary menus. While the restaurant maintains its traditional roots, the culinary offerings are infused with a modern twist. The menu may feature classic dishes prepared with innovative techniques or incorporate global flavors and ingredients to create unique and exciting flavor combinations. The chefs in a traditional and classic style restaurant with contemporary menus are often highly skilled and experienced, combining their knowledge of traditional cooking techniques with a flair for experimentation. They may draw inspiration from various culinary traditions, resulting in dishes that are visually appealing, flavorful, and reflective of current food trends. This fusion of traditional and contemporary elements extends beyond the food itself. The restaurant may also offer a curated selection of wines, craft cocktails, or other beverages that complement the modern twist on classic cuisine. The service staff may be knowledgeable and attentive, providing a high level of hospitality that aligns with the overall dining experience. A traditional and classic-style restaurant with contemporary menus seeks to strike a balance between familiarity and innovation. It caters to customers who appreciate the comfort and elegance of traditional dining while also seeking new and exciting culinary experiences. This combination of old and new creates a unique and memorable dining experience for guests, making it a popular choice for those looking for a blend of tradition and innovation in their gastronomic adventures.

According to the House of Quality (HoQ) analysis, the primary factors of utmost importance to customers are food taste and price. However, when considering engineering attributes, cost emerges as the most crucial factor. This highlights the significant role of cost as a key factor influencing both customers and engineering aspects. It signifies that cost represents the interplay between engineering attributes and customer ratings.

4.4. Discussion

The House of Quality (HoQ) is a comprehensive framework within the Quality Function Deployment (QFD) methodology that facilitates the systematic translation of customer requirements into specific engineering characteristics. In the context of supporting senior adults’ restaurant design, the HoQ serves as a structured tool for aligning and prioritizing key elements, considering the unique needs and preferences of senior individuals. It enables the design team to map out relationships between various design features, ensuring that the final restaurant concept effectively addresses the identified requirements for a comfortable and inclusive dining experience for senior individuals. The designs for three types of restaurants (A, B, and C) were conceptualized based on observations during site surveys in various cities and metropolitan areas. After analyzing key design elements and atmospheric preferences, the research team identified three main styles, as outlined in the proposed research. Designing a restaurant to cater to senior adults necessitates a systematic approach that takes into account their distinct needs and preferences. Moreover, the systematic approaches for this purpose are:

• User-Centered Design:

  Understanding Needs: Conduct extensive research to understand the specific needs and preferences of senior adults.

  Feedback and Iteration: Involve seniors in the design process through feedback sessions, usability testing, and iterative design cycles.

  Accessibility: Prioritize accessibility features, such as comfortable seating, easy navigation, and clear signage.

• Environmental Considerations:

  Lighting and Acoustics: Ensure adequate lighting for visibility and consider acoustics for a comfortable dining atmosphere.

  Comfortable Seating: Choose ergonomic and comfortable seating arrangements, considering factors like height, cushioning, and back support.

• Menu Design:

  Readability: Ensure menus have clear and readable print, with larger fonts and high contrast for easy visibility.

  Visuals: Include appetizing and representative food images to enhance the dining experience.

• Technology Integration:

  Digital Accessibility: Implement technology solutions that cater to the needs of seniors, such as large fonts, simple interfaces, and voice-activated features.

  Online Reservations: Provide an option for online reservations to simplify the process for seniors.

• Inclusive Spaces:

  Wheelchair Accessibility: Design the restaurant layout to be wheelchair-friendly with ramps and accessible pathways.

  Adequate Space: Ensure sufficient space between tables and chairs to accommodate mobility aids.

• Staff Training:

  Sensitivity Training: Train restaurant staff to be sensitive to the needs of senior patrons, including communication and assistance requirements.

  Patience and Understanding: Foster a culture of patience and understanding among staff members when serving senior customers.

• Health and Nutrition Focus:

  Healthy Menu Options: Include healthy and nutritionally balanced menu options suitable for seniors.

  Allergen Information: Clearly communicate allergen information on the menu for seniors with dietary restrictions.

• Cultural Considerations:

  Familiarity: Design the restaurant environment to be familiar and comfortable, incorporating elements that resonate with the cultural preferences of seniors.

• Community Engagement:

  Events and Activities: Host events or activities that appeal to senior patrons, fostering a sense of community and social interaction.

  Collaboration with Senior Centers: Collaborate with local senior centers to understand community needs and preferences.

By adopting systematic approaches, a restaurant can create a welcoming environment for senior adults, addressing their unique requirements. Regular feedback and continuous improvement are crucial in this process. The research identifies gaps in existing literature, highlighting areas not adequately explored in the current stage of the proposed research. Limitations exist in the real implementation due to high costs and infrastructure challenges in modifying the restaurant’s solid structure platform. Initial focus on interior decorations and paperwork materials is recommended for practical implementation. Identifying research gaps is vital for future work, helping researchers pinpoint areas requiring further investigation to enhance understanding and contribute new insights. Though complete numerical satisfaction may not be achieved at this stage, the design team can explore real-world applications in subsequent stages. Future work can focus on establishing validity or reliability, contributing tangible outcomes to fulfill research goals.

5. Recommendations

The design team has considered the “Feasibility of a restaurant project,” “Consistent and Sustainable Supplier,” and “Optimizing vehicle routing” as key factors in understanding the overall frameworks for assessing the feasibility of a restaurant project (Chiadamrong & Sophonsaritsook, 2015; Horng & Yenradee, 2020; Sriklab & Yenradee, 2022; Srizongkhram et al., 2018; Thammatadatrakul & Chiadamrong, 2019). These keywords provide valuable insights for the design team’s decision-making process.

1. Market Analysis: Evaluate the target market, customer demographics, competition, and industry trends to understand demand and potential customer base.

2. Financial Analysis: Examine startup costs, revenue streams, expenses, and conduct a break-even analysis to assess financial viability.

3. Operational Analysis: Evaluate location, layout, equipment, staffing, and supply chain management to determine operational feasibility.

4. Technical Analysis: Assess technological requirements such as POS systems, online ordering platforms, and kitchen equipment to ensure effective technology utilization.

5. Legal and Regulatory Analysis: Examine permits, licenses, health and safety regulations, and compliance with food handling standards to ensure adherence to legal requirements.

6. Environmental Analysis: Evaluate waste management, energy consumption, and sustainability practices to operate in an environmentally responsible manner.

7. Social Analysis: Consider community support, cultural factors, and social responsibility initiatives to align with target market and community values.

For the 7Ps of the marketing mix in a restaurant context:

1. Product: Determine menu selection, quality, variety, and uniqueness to meet customer expectations.

2. Price: Set pricing strategy based on ingredient costs, overhead expenses, profit margins, and market competitiveness.

3. Process: Ensure seamless order taking, food preparation, service speed, payment methods, and additional services provided.

4. People: Hire and train skilled and friendly staff for excellent customer service and a positive dining experience.

5. Place: Create an appealing physical location, interior design, layout, seating arrangement, lighting, and atmosphere.

6. Promotion: Utilize advertising, social media, public relations, loyalty programs, and partnerships to generate awareness and attract customers.

7. Physical Appearance: Focus on visually appealing elements such as signage, exterior design, cleanliness, and overall aesthetic.

For the 7 Cs in the restaurant business:

1. Customer/Consumer: Understand the needs, preferences, and behaviors of target customers.

2. Convenience: Provide a convenient experience with accessible location, parking, online reservations, and efficient service.

3. Communication: Effectively communicate offerings, promotions, and brand message through menus, signage, website, and social media.

4. Coordinated: Ensure coordination and consistency across different touchpoints for a seamless customer experience.

5. Customer Relations: Build strong relationships through excellent service, prompt addressing of feedback, loyalty programs, and personalization.

6. Correlated: Offer products and services that complement each other, creating a cohesive and harmonious experience.

7. Core Values: Align the restaurant with values that resonate with customers, showcasing unique selling points and principles.

6. Limitations of the Case Study

In the case of “approximating character height,” the calculation considered the combination of light intensity from both natural sources and light bulbs (lamps) as key components. Normally, a ceiling with lights provides a height of 2.50–6 meters for a cozy-natural style. However, other factors should also be considered, such as the presence of electric fans or other decorative items, as they can directly impact how the light from the ceiling disperses or causes glare in the area of interest. The fluctuation or waviness of light sources, which occurs when the wind or air turbulence causes long-wire lights to swing, is also taken into consideration. This can affect how light reflects on menus, tables, and food, potentially causing dizziness for senior adults or customers while eating. However, these factors were not explicitly explained in this research. The design team solely focused on the light that is typically vertically attached in a straight and solid form, without any swinging or fluctuating glare.

For “the usefulness calculation,” the study focused only on the key dining equipment: spoons, forks, and knives. This selection was based on the lifestyle and types of food commonly ordered or consumed in Thailand (and other oriental countries). The study considered the relationship and functions of these three utensils to ensure that both senior adults and business owners would understand each other and be on the same page.

Regarding “the QFD-based method,” some limitations are inherent in the parameters of the QFD platform itself. Other limitations are more practical in nature, concerning the perceptions, ideas, knowledge, and experiences of the target customers and design engineers. As indicated by the results, it is challenging to practically prove the optimality of the calculated values. This means that the proposed approach does not guarantee complete customer satisfaction with all components created. Additionally, the success of a product relies on various factors such as pricing strategy, promotions, and manufacturing. The success or failure of a product or service cannot be directly attributed to optimal or unsuccessful product design alone.

Further exploration of the development of an economic cost model for quantifying supply chain costs, as well as an investigation into the relationships among supply chain capabilities, competitive advantage, and business performance, warrants careful consideration (Chiadamrong & Wajcharapornjinda, 2012; Chiadamrong & Tham, 2016).

7. Conclusions, Contributions, and Recommendations

7.1. Conclusions

7.1.1. For senior adults

The research findings indicate that senior adults who took part in the study had diverse perceptions and experiences regarding eating out and purchasing food and beverages. The majority of respondents expressed a preference for dining out with their families, although the extent of engagement and decision-making varied among individuals. Notably, the age range of 61–70 years old was the most common among the participants. Furthermore, a significant number of respondents had previous experience working in medical fields, such as medical doctors, nurses, or hospital employees. The data collected through the digital-based questionnaire platform offered valuable insights into the preferences and behaviors of senior adults, particularly in relation to their career backgrounds, with retired government officers/employees being a prominent group.

7.1.2. For business owners

In terms of restaurant platforms, the suggested ideas encompass menu styles, including fonts, colors, and composition details; lighting in the dining area; understanding competitors; the utility of utensils; and the design of dishes or food plates. These factors can support the development of health-related products that cater to the needs of the next generation society by offering easy-to-use and accessible facilities. Over time, this target group will be able to fulfill their own requirements without relying on financial support from their families. In other words, they will have the freedom to choose options based on their perspective and satisfaction, rather than being limited to low-cost products with lower standards.

7.2. Contributions

7.2.1. For the proposed approach

The findings of this study can serve as valuable insights for companies and manufacturers seeking to allocate resources effectively and establish strategies for product development. By considering these results, companies can enhance product quality, increase consumer satisfaction, reduce product development time, and improve the success rate of their products in the market. It is important for water/liquid filling machine enterprises not only to generate profit from their products but also to meet the needs of their customers. When creating new product designs, it is crucial to identify the appropriate engineering components that support customer requirements. Practically, these contributions can be demonstrated through guidelines for initiating the creation of a new design platform, which involve determining product characteristics and requirements, establishing the relationship between customer requirements and engineering attributes, determining the interrelationships between engineering attributes, and optimizing the design of the new product in a sequential manner.

7.2.2. Guidelines

Figure 15 illustrates the significant key paths and topics applied in this study, aimed at establishing the foundational directions for the design stage. This research benefits manufacturers, business owners, or start-up companies seeking patterns for developing new products, services, or enhancing existing traditional production processes related to food/beverages and restaurant equipment. Utilizing this diagram can reduce the need for trial-and-error design in the initial stages of product design and development (PDD). Furthermore, this proposed framework enhances the service providers’ and owners’ ability to meet customer requirements, particularly those who prioritize comfort and high living standards and are willing to invest in these aspects.

Figure 15. The research framework - guidelines for successful Product Design and Development (PDD).

In contrast to other research, where color theory and restaurant compositions are addressed separately in terms of individual applications for different restaurant components, such as room painting, menu design featuring real-case photos, and the commercial patterns of utensils readily available in the market, this study introduces an integrated approach. It combines the concepts of character height of font patterns, the House of Quality (HoQ), and Product Design and Development (PDD) to create a comprehensive framework that guides font size selection through a detailed calculation process, considering restaurant lighting and environmental conditions. This integrated approach aligns with the broader concept of fostering inclusivity, promoting the idea of ‘living and sharing moments together,’ and striving for greater societal equality. This comprehensive approach also emphasizes the importance of catering to the specific needs and preferences of senior adults in restaurant design, acknowledging their unique requirements, and focusing on creating an environment that prioritizes their comfort and satisfaction. By integrating these diverse elements, the study promotes a holistic perspective that enriches the dining experience for senior patrons and bridges generational gaps while fostering a sense of community within society.

7.3. Recommendations for Future Products

To enhance the reliability of the Quality Function Deployment (QFD) process, it is recommended to incorporate appropriate quantitative methods. This helps to reduce the subjective nature of decisions made during QFD implementation, which often rely on the judgments of design engineers and researchers. In order to obtain meaningful results when applying QFD to a new design, it is crucial to have effective management support (both technical and non-technical) to ensure the availability of necessary data. Additionally, successful implementation of QFD requires collaboration among individuals from diverse fields and departments. It is important to acknowledge that while the proposed approach aims to improve customer satisfaction, it does not guarantee complete satisfaction with all components created. The success of a product is influenced by various factors, including pricing strategy, promotions, and product manufacturing. Therefore, the ultimate success or failure of a product cannot be solely attributed to the design alone, whether it is optimal or unsuccessful.

To enhance the application of Quality Function Deployment (QFD) in the design stage of restaurant platforms aimed at satisfying customer requirements, consider exploring the following insightful future research directions:

• Integration of Technological Innovations: Investigate how emerging technologies, such as augmented reality (AR) or interactive digital interfaces, can be seamlessly integrated into the QFD framework to enhance the overall design experience for both restaurant owners and senior customers.

• Cultural Sensitivity in Design: Explore the impact of cultural factors on customer preferences in restaurant design. Develop a framework within QFD that considers cultural nuances to ensure the design is not only functional but also culturally relevant, addressing diverse senior adult populations.

• Sustainability and Eco-Friendly Design: Examine how QFD can be leveraged to prioritize sustainable and eco-friendly features in restaurant design. Investigate the incorporation of green technologies, waste reduction strategies, and environmentally conscious practices.

• Personalized Dining Experiences: Explore ways to personalize restaurant designs using QFD to cater to individual preferences of senior customers. This might include customizable seating arrangements, personalized lighting, or adaptive design features that consider specific needs and preferences.

• Inclusive Design for Accessibility: Investigate how QFD can be applied to create universally accessible designs, ensuring that the restaurant environment is accommodating to seniors with varying levels of mobility or sensory capabilities. Addressing accessibility can significantly contribute to a positive dining experience.

• Data-Driven Decision Making: Explore the use of data analytics within the QFD process. Investigate how customer feedback, preferences, and usage patterns can be analyzed to inform design decisions, creating a more data-driven and customer-centric approach to restaurant design.

• Cross-Disciplinary Collaboration: Research the benefits of collaborative efforts between design professionals, gerontologists, and experts in fields such as psychology and healthcare. Investigate how QFD can facilitate effective collaboration and knowledge-sharing among diverse disciplines to create holistic and well-informed restaurant designs.

• Long-Term Impact Assessment: Explore methodologies within QFD for assessing the long-term impact of restaurant designs on the well-being and satisfaction of senior customers. Consider factors such as continued usability, evolving preferences, and the adaptability of designs over time.

• Implementation Challenges and Strategies: Investigate the challenges faced during the implementation of restaurant designs based on QFD recommendations. Develop strategies to address potential barriers and ensure a smooth transition from design to operational stages.

• User Training and Familiarization: Examine the role of QFD in designing user training programs to familiarize restaurant staff and customers, particularly senior adults, with the new design features. Investigate effective methods for ensuring a seamless and enjoyable experience for both users and service providers.

These research directions aim to enrich the application of QFD in restaurant design, making it more attuned to the needs and preferences of senior customers while fostering innovation and sustainability.

Author Contributions

Conceptualization, literature review, methodology, formal analysis, investigation, data validation, supervision, and writing—review and editing S.R.; literature review, methodology, writing—original draft preparation, data validation, data collection and primary analysis, L.S. and T.T. All authors have read and agreed to the published version of the manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).