The Role of Low-Cost Digital Solutions in Supporting Industrial Sustainability

Abstract

Small and medium enterprise (SME) manufacturers are impeded from participating in sustainability initiatives using new technologies due to the high cost and the lack of clarity on where to start. The integration of low-cost digital solutions has enabled SME manufacturers to adopt Industry 4.0 technologies to support operations. However, using low-cost technologies to address sustainability challenges is underexplored. This article addresses three key research questions: What digital solutions do SMEs need to address industrial sustainability challenges? To what extent can existing low-cost digital solutions be used to address industrial sustainability challenges? How should new digital solutions for developing greater sustainability be prioritised? Three main tasks were conducted. Initially, a new sustainability-focused sub-catalogue was created using an existing catalogue of low-cost solution areas for manufacturing. Secondly, a workshop with 17 participants was used to identify the top ten priority solution areas, with process monitoring, energy monitoring, and quality inspection at the top. Lastly, existing low-cost digital solutions within the top ten priority areas were evaluated to identify how they could contribute to lean manufacturing. Predominantly existing solutions could contribute to waste or use reduction in lean manufacturing. This study provides a foundation for the future development of low-cost solutions for sustainability by indicating manufacturers’ key priority areas and outlining how existing solutions could be adapted to support waste reduction.

1. Introduction

Countries are increasingly looking to reduce the emissions and environmental impact of manufacturing; in the UK alone, manufacturing accounted for 10.8% of emissions in 2018 (across scopes 1 and 2) [1]. This must be reduced by 67% by 2035 to align with the UK government’s net zero 2050 targets [2]. Resource use and waste reductions must be implemented across manufacturers of all sizes to achieve this. Beyond these targets, manufacturers also rely on a stream of raw materials that are increasingly environmentally damaging to extract and process.

The past few decades have been marked by advancements in new “smart” factories, which incorporate advanced sensing and monitoring, cyber-physical systems (CPSs), augmented and virtual reality, blockchain technology, additive manufacturing, Internet of Things (IoT), and machine learning [3], to name a few technologies. These technologies are often grouped under the term Industry 4.0. These technologies can significantly improve efficiency, and previous studies have investigated how these new digital technologies can be integrated into manufacturing companies [4].

Although much of the early Industry 4.0 work focused on productivity, previous authors have also reviewed research relating to Industry 4.0 and industrial sustainability. Vrchota et al. [5] reviewed Industry 4.0 research and noted that environmental sustainability outcomes from implementing Industry 4.0 focus mainly on energy saving and resource optimisation. Similarly, Jamwal and colleagues [3] noted that Industry 4.0 research focused on influencing industrial waste reduction, promoting a circular economy, using and producing using renewable sources, and reducing energy and resource consumption. More recently, authors have started to outline definitions of Industry 5.0 [6]. Most definitions indicate a more value-focused approach focusing on human-centric, resilient, and sustainable manufacturing using the technology of Industry 4.0 and new advanced machine learning [7,8]. Many previous studies have noted that small- and medium-sized manufacturers may not see the same benefit from this digital transformation and new technologies as larger companies [4]. The complexity and cost of Industry 4.0 technology are often seen as a barrier to adoption by small- and medium-sized enterprises (SMEs) [9]. These barriers can create a two-tiered system with one set of (often larger) manufacturers with the financial resources and skills available for new solutions and other (often-smaller) manufacturers unable to integrate or afford them.

As the cost barriers diminish, the potential for innovation, growth, and sustainability within SMEs grows. The Digital Shoestring Approach (DSA) [10] was proposed because of the need to increase the digital capabilities of SMEs with very limited budgets. The approach addresses a company’s digital solution requirements with low-cost, off-the-shelf components and open-source software. Capabilities are increased gradually with little pre-requisite infrastructure needed.

Low-cost digital solutions have proven useful in supporting the operation of manufacturing SMEs but have not been explicitly used to address companies’ sustainability challenges. There is a need to investigate if and how low-cost digital solutions could help SMEs address future sustainability challenges and identify the direction this research should focus on. This paper aims to answer three key research questions (RQs):

• RQ1: what digital solutions do SMEs need to address industrial sustainability challenges?
• RQ2: to what extent can existing low-cost digital solutions be used to address industrial sustainability challenges?
• RQ3: how should new digital solutions for developing greater sustainability be prioritised?

This paper initially outlines the background to this study in Section 2, including an overview of low-cost digital technologies, Industry 4.0, and industrial sustainability strategies for SMEs. Section 3 presents the method used, including a company workshop and existing Solution Evaluation. Section 4 presents the results, which are discussed further in Section 5. Finally, Section 6 outlines the conclusions of this paper.

2. Background

2.1. Low-Cost Digital Technology for Industry 4.0

The advent of Industry 4.0, characterised by integrating digital technologies into manufacturing and business processes, presents both challenges and opportunities for SMEs. One of the key challenges is the perceived high cost associated with adopting these cutting-edge technologies. However, a growing array of low-cost digital solutions is designed specifically for SMEs [11]. Embracing these affordable yet powerful tools empowers SMEs to make significant strides towards Industry 4.0 integration, ensuring they remain competitive and thrive in the ever-evolving global marketplace [12].

McFarlane et al. [10] identified five crucial elements required to be in place for creating affordable digital solutions for manufacturing operations:

• The solution must have a low-cost development of operation, maintenance, and component integration.
• A large number of manufacturing companies should require the solutions created.
• The solutions should utilise commercially accessible software and hardware (off-the-shelf) components.
• The solution design should use a modular “building block” strategy to simplify the integration of various technological components and support component reuse.
• It should be simple for digital solutions to exchange data and services employing “incremental architecture”.

As part of this work, Hawkridge et al. [13] presented a modular architecture design approach to build low-cost digital solutions for the DSA. “Building blocks” encapsulating low-cost technologies combine to form service modules (such as data storage, data processing, or visualisation) that comprise a final solution. An example solution is created for tracking jobs during manufacturing [13]. A service layer connects service modules to facilitate communication via protocols such as REST or MQTT within a digital solution [14].

Monitoring processes and operations has been a common theme in Industry 4.0, with accelerometers, temperature sensors, impedance sensors, and cameras identified in previous reviews, which included low-cost options [14]. Several solutions developed using the DSA focused on monitoring operations or processes, including visual quality inspection [15] and energy monitoring [16]. Low-cost digital solutions created for job location tracking, energy monitoring, scrap monitoring, and downtime monitoring are now commercially available to SMEs [17].

Schönfuß et al. [18] introduced an initial low-cost digital solution catalogue specifically in the context of manufacturing operations management. The “working catalogue” was created using these solution areas and was shown to SMEs during research workshops and interviews to obtain their input on the solution areas and recommendations for further solution areas. The DSA and the digital solutions catalogue were used by Yilmaz et al. [19] to map the top low-cost digital solution areas for construction SMEs; 58 digital solution areas were identified through eight interactive digital requirement assessment workshops. Similarly, Macias-Aguayo et al. [20] identified 42 low-cost digital solution areas for logistics SMEs using the original digital solution catalogue. However, prior to this paper, there was no focus purely on low-cost digital solutions for sustainability.

2.2. Low-Cost Digital Technology Used for Industrial Sustainability

Amidst the growing awareness of environmental concerns and a resolute commitment to sustainable industrial practices, the pivotal role of technology in driving these initiatives has come to the forefront. As previously stated, digital technologies have emerged as enablers in enhancing sustainability within manufacturers.

In the agricultural sector, low-cost technology has been studied for natural resource management to reduce excessive water use [21,22]. Challenges such as energy restriction, connectivity issues, limited computing capacity, small available memory, and data security were noted as restrictions that need to be further addressed [21]. Within the textile industry, low-cost solutions have been used for waste management strategies, specifically addressing smart textile waste collection [23]. The authors used a variety of low-cost hardware and open-source software (such as Heltec, CubeCell, and InfluxDB), low-cost laser sensors, and Grafana for visualisation [23]. These solutions were used to monitor textile collection bins and optimise the collection routes accordingly. Several low-cost solutions have also been identified in the mining industry, predominately focused on monitoring air quality for workers but also for monitoring emissions [24].

There has been less research on low-cost digital solutions within manufacturing sustainability. There are two exceptions: one solution focuses on air quality monitoring to monitor production emissions [25]; a second example is a solution for monitoring tool wear during production to reduce unnecessary replacements [26,27]. There is a need for more focus on low-cost digital solutions which can help SMEs address sustainability within manufacturing.

2.3. Industrial Sustainability in SMEs

Manufacturing SMEs often encounter unique barriers to initiating sustainability initiatives, such as a lack of resources, a high upfront cost of implementing sustainability measures, and a lack of expertise [28]. Adding to that, the multifaceted nature of sustainability, many SMEs feel overwhelmed by the sheer volume of information and the diversity of approaches available, leading them to not knowing how to start. Jamwal et al. [29] identified a lack of resources, lack of infrastructure, and lack of digital skills as some of the most common barriers impeding SMEs from adopting Industry 4.0 technologies for sustainability. Studies focusing on developing countries have found similar barriers and a fear of failure preventing SMEs from adopting new technologies for sustainability [30]. These challenges could be addressed using lower-cost digital solutions which are easy to use.

Within the context of this paper, sustainability for SMEs is being approached primarily with a focus on correcting processes and actions that are unsustainable and lead to waste generation. This approach is displayed in Figure 1 in the form of an IDEF0 diagram. IDEF0 is a standardised methodology of function and process modelling commonly used in manufacturing system integration and environmental and economic cost modelling for its quick visual reference representation of information flows [31]. IDEF0 models the activities and their inputs, outputs, control, and mechanisms, as displayed in Figure 2 [32]. Previous studies in sustainability used IDEF0 diagrams to identify waste streams for manufacturing processes [33].

Lean manufacturing is one of the approaches cited as a promising way to eliminate waste and address sustainability on an operational level for SMEs [34,35,36]. Specifically, the concept of “8 Wastes of Lean” is a fundamental framework for identifying and eliminating sources of inefficiency and waste in any process [37]. These eight wastes (defects, overproduction, non-utilised talent, transportation, inventory, motion, waiting, and overprocessing [37]) serve as a critical guide for organisations striving to optimise their operations. Defects highlight the cost of rework and quality issues. Overproduction emphasises the unnecessary production of goods that leads to excess inventory and resource waste. Waiting illustrates the idle time between process steps that can be reduced to enhance flow. Non-utilised talent signifies the underutilisation of employee skills and ideas. Transportation indicates the waste in moving materials or products unnecessarily. Inventory emphasises the capital tied up in excess inventory and storage costs. Motion highlights unnecessary physical movements that can be reduced. Lastly, overprocessing draws attention to activities that do not add value to the final product. Lean principles provide SMEs with a clear framework for identifying and mitigating operational inefficiencies, enhancing profitability, and reducing the environmental footprint.

Figure 1 models the approach we use in this paper. It starts with a monitoring process (A1 in Figure 1) using low-cost digital solutions as the main technological tools. The output data from these solutions allow the identification of the generated waste (A2 in Figure 2). The types and sources of waste can be identified, and accordingly, the changes to the process to reduce or eliminate the waste are planned and implemented (A3 in Figure 3). The standard terminology for such (IDEF0) models is outlined in Figure 2.

2.4. Conclusion

In conclusion, low-cost digital solutions have proven to be an effective way to support SME manufacturers as they try to integrate Industry 4.0 technologies into their processes. Low-cost solutions predominantly focus on monitoring and data collection processes to support production and operation improvements. Only a small amount of research has investigated low-cost digital solutions for sustainability and not within manufacturing. New low-cost digital solutions could support manufacturers in reducing their processing waste and improving their sustainability. Digital solutions could provide data to help reduce defects and errors in production, material use, or energy use. There is no knowledge about which solutions manufacturers need or if existing solutions exist. This study aims to identify which digital solution areas should be prioritised to help SMEs address their sustainability challenges.

3. Low-Cost Sustainability Solutions: Tools and Methods

The approach used in this paper is outlined in Figure 3 and follows three main activities, namely Catalogue Adaptation, Prioritisation Workshop, and Solution Evaluation. Catalogue Adaptation drew on and adapted previous research. Workshop steps were designed to facilitate communication and data gathering from companies, while the Solution Evaluation step involved an in-depth analysis of the specific existing solutions. Each activity follows from the previous one and contains two key stages. This section explains each of these activities in more detail.

3.1. Process of Creating Catalogue for Low-Cost Digital Solution Areas for Sustainability

The low-cost digital manufacturing solution catalogue created by Schönfuß et al. [18] used a literature search and consultancy case studies followed by repeated workshops to create an initial catalogue of low-cost digital solutions, with further studies refining this catalogue for logistics SMEs [20] and construction SMEs [19]. The process carried out in these papers was adapted and extended in this study. The solution areas used were extracted from the initial catalogue of 39 digital solution areas for SME manufacturers [18]. Outside of these, there has been little attempt to catalogue digital solution areas for manufacturing. However, there have been catalogues of existing digital solutions focused on medicine [38] and solutions to support the reuse or recycling of clothing [39]. However, these have not focused on low-cost solutions.

The first stage of this work was to identify categories for the catalogue that related to sustainability. In the workshop outlined later, this was used to help manufacturers identify areas of the catalogue relevant to them. Figure 4 outlines the approach used for selecting the categories in the form of a diagram. The categories were initially derived from the eight wastes of lean. Four areas of lean manufacturing (non-utilised talent, waiting, inventory, and motion) were excluded because they related to labour productivity and did not fit within key sustainability focus areas of material, emission, waste, and energy reduction. The remaining four areas of lean were kept because they related to resource productivity. Further details of the selection of the final categories are outlined in Section 4.1.

Once the categories were created, the expert evaluators reviewed the current catalogue (from [18]) and identified which solution area could contribute to which category. Solution areas fitting none of the categories and with no direct link to sustainability were excluded. The remaining digital solution areas formed an initial sub-catalogue of low-cost digital solution areas for sustainability.

3.2. Solution Prioritisation Workshop

The sub-catalogue of low-cost solution areas to support sustainability was then tested in a workshop with SME manufacturers. The workshop involved SME manufacturers within Southeast England. The manufacturers participated to learn more about potential digital solutions to support sustainability. This impacts the results because only SMEs are considered and only those companies who are proactively interested in sustainability and digital solutions. Nine companies participated in the workshop, with an average of two representatives from each company. Companies were asked to identify three key categories of the sub-catalogue their company should focus on. From this, they were then asked to select the three solution areas within the focus categories of the sub-catalogue that would be a priority for them and seven further solution areas they would be interested in trying. These responses were then used to rank the digital solution areas and identify a top ten list from the workshop. This study was limited by using only one workshop rather than multiple workshops used in previous studies [18,19]. However, we note that the initial catalogue of digital solution areas was taken from a larger study with more SME manufacturers [18]. This exercise was hence designed to simply refine the catalogue, not create a new catalogue, so fewer workshops were necessary. The flow of the workshop is shown in Figure 5.

3.3. Solution Evaluation

The top ten solution areas identified in the workshop were evaluated in further detail. First, implemented solutions from the solution areas were identified, and the IDEF0 diagram of each solution was mapped to examine the data output generated by each of these digital solutions. This analysis aimed to ascertain the specific types of data and insights provided by each solution. The second step involved establishing a clear connection between these digital solutions and the eight wastes of lean according to the insights provided by each solution. The objective here was to determine how each digital solution could be utilised to identify and address specific waste elements within the operational processes and compare it with the workshop results. In this step, all eight wastes of lean were considered. Overprocessing and overproduction were combined because these categories were similar and resulted in identical evaluation results. The evaluation process diagram is shown in Figure 6.

3.4. Summary

The approach developed in this study was designed to generate new insights into the way digital solutions can support sustainability initiatives and to answer the key research questions. An initial catalogue of digital solution areas created using extensive industry workshops was refined for industrial sustainability. New categories were initially designed based on lean manufacturing principles and the reduction in use and waste. An expert evaluation was then used to group relevant digital solution areas into these new categories. This resulted in a new sub-catalogue for low-cost digital solution areas for sustainability. A workshop with industry practitioners was then used to help rank digital solution areas. Expert evaluation and workshops were effectively utilised in previous catalogue creation studies of low-cost-solutions [18,19,20]. The final step involved evaluation using the IDEF0 diagrams of existing solutions from the workshop’s top ten chosen solution areas. Chari et al. [40] used a similar combination of IDEF0 diagrams and workshops with manufacturers to investigate digital platforms to improve supply chain resilience. Combining previous studies, expert evaluation, and industry workshops ensures the research draws on a wide range of perspectives. This study’s results were compared to previous studies to help validate the findings.

4. Results

This section demonstrates how the tools and methods proposed as part of the approach in Section 3 were applied as part of a UK-based study carried out in 2023.

4.1. Low-Cost Digital Solution Catalogue Adaptation

As discussed in Section 3.1, the creation of the categories for the sub-catalogue started with considering the eight wastes of lean. Categories were identified from a resource use reduction perspective because reducing resource use has a larger impact on sustainability. Hence, it addresses material use, energy use, and four out of the eight lean wastes that specifically target resource use. The low-cost (Shoestring) catalogue [18] was initially tested against these five focus areas of sustainability (i.e., internal transport, overprocessing and overproduction, defects, energy usage, and material usage) and it was found that all the benefits of Shoestring’s solutions were covered, except carbon emissions. Hence, carbon emission was included to complete the categorisation with six possible sustainability focus areas below.

• Internal transport;
• Overprocessing and overproduction;
• Defects;
• Energy usage;
• Material usage;
• Carbon emission.

Table 1. Digital solution areas forming the initial low-cost digital solution areas for the sustainability sub-catalogue with the categories they were identified as contributing to. Detailed descriptions of solution areas can be found in the Supplementary Materials.

Digital Solution Area	Categories
	Internal Transport	Over-Processing and Over-Production	Defects	Energy Usage	Material Usage	Carbon Emission
Job tracking	✓	✓
Issue reporting and change management support		✓	✓
Capacity monitoring				✓
Internal lead time monitoring		✓
Process monitoring		✓	✓	✓	✓	✓
Disruption monitoring	✓	✓		✓	✓
Energy usage monitoring				✓		✓
Quality inspection			✓		✓
Inventory management		✓			✓
Digital job cards			✓
Equipment monitoring			✓	✓		✓
Working conditions monitoring				✓		✓
Digital instructions		✓	✓
Demand reporting		✓			✓
Operations simulation	✓			✓	✓	✓
Maintenance support			✓	✓
Setup support	✓		✓	✓
Quality data capture			✓
Product use monitoring		✓
Scheduling support	✓			✓
Layout planning support	✓			✓		✓
Equipment diagnostic support			✓	✓
Goods in management	✓				✓
Waste monitoring					✓	✓
Supply chain monitoring					✓
Tool management support			✓
Employee training delivery			✓
Emission monitoring						✓
Kitting support			✓
Sustainability reporting support				✓		✓
Shop floor replenishment support	✓	✓			✓
Totals	8	10	13	13	10	9

shows the results of the evaluation of the Shoestring solution areas and the selection of which category they relate to. Full descriptions for each solution area provided in the workshop can be found in the Supplementary Materials. A total of 8 of the 39 solution areas in the edited original catalogue were excluded: Project management, quoting support, cash management, costing support, KPI reporting, employee training management, procurement support, and cost variance tracking. Digital solutions in these areas could help with business operations and may utilise information on material use and waste, but would not directly help reduce resource use or waste. Of the solution areas that remained, many of them address multiple waste categories. This is because the solution areas are not specific to a particular process and can be implemented in various scenarios; for example, Job Tracking could be used to monitor internal transport when applied to logistics systems and also for overprocessing and overproduction when applied to the production system.

4.2. Prioritisation Workshop

Once the sub-catalogue of sustainability-oriented low-cost solution areas was constructed, a workshop was organised in early 2023, where 17 employees of SME manufacturers participated. The small number of participants does limit the validity of the results, and further studies could use a larger number of participants to validate these results further. As outlined in the Approach section, participants selected the three most important categories from the six in the sub-catalogue. The results of this selection are shown in

Table 2. Sustainability sub-catalogue categories and the number of times participants selected the category.

Waste Categories	Participants Who Selected
	(%)	(Number)
Internal transport	5.9	1
Energy usage	58.8	10
Material usage	70.6	12
Over-processing/over-production	52.9	9
Defects	100	17
Carbon emission	11.8	2

. All 17 participants selected defects, showing that this is the most important category of solutions for SME manufacturers. The second-most selected was energy and material use. Interestingly, the carbon emission category did not rank highly. There are several potential reasons for such a ranking, but it is outside the scope of this paper to explore this specific issue.

Each participant selected three key digital solution areas they considered a priority and a further seven they were interested in across the previously chosen three categories. The top ten results from aggregating these selections are shown in Figure 7, along with the scores of how many times they were selected. It can be seen that most of the solution areas selected for the sustainability sub-catalogue were monitoring solutions. Most participants chose the process monitoring solution area as a priority (shown in blue in Figure 7); the choice of solution areas of further interest is distributed more widely among the other solution areas (shown in orange in Figure 7). The remaining nine top ten areas only received 3–4 priority votes and can only be distinguished by the number of interested votes they also received. The results indicate demand for low-cost solutions to help with inventory, scheduling, sustainability reporting, and quality management.

4.3. Solution Evaluation

An evaluation of the top ten priority solutions was then performed to explore how existing low-cost digital solutions could be used for sustainability. As previously mentioned in Section 3.3, the solutions were mapped against the eight wastes of lean that they could impact. This mapping builds and expands on this work displayed in Table 1. An example of the IDEF0 diagram created for each solution for the Job Tracking solution can be seen in Figure 8. This diagram was drawn up for all the solutions and allowed the authors to identify the output data of each solution and accordingly evaluate the use of the solution in monitoring or managing the various wastes. The remaining diagrams for all solutions can be seen in Appendix A.

For this evaluation, only the digital solution areas with an implemented solution were considered, which restricted the evaluation to the following: Job Tracking, process monitoring, energy use monitoring, Inventory Monitoring, quality inspection, and quality data capture. This is because it is not possible to consider factors such as data input and output for a solution area; this requires a digital solution. The list of implemented solutions can be seen in

Table 3. List of implemented solution areas with references.

Digital Solution Area	Existing Low-Cost Digital Solution Reference
Process Monitoring	[41]
Energy Use Monitoring	[16]
Quality Inspection	[15]
Inventory Monitoring	[42]
Job Tracking	[13]
Quality Data Capture	[17]

. The evaluation results are summarised in

Table 4. Evaluation of digital solutions with lean manufacturing. The reasoning for each selection is explained in Section Low-Cost Digital Solutions for Lean Wastes.

Solution	Transportation	Inventory	Motion	Waiting	Overproduction and Overprocessing	Defects	Unused Talent
Job Tracking	✓✓	✓✓	✓✓	✓✓	✓	✓	✓
Process Monitoring	✓	✓		✓		✓✓
Energy Use Monitoring
Inventory Monitoring		✓✓	✓✓	✓✓	✓
Quality Inspection	✓				✓✓	✓✓
Quality Data Capture	✓	✓✓			✓✓	✓✓

Legend: ✓✓ = The solution can be used in its current state and has direct impact. ✓ = The solution has a potential impact; however, it requires additional work.

for the eight wastes of lean. Within the tables, the solutions are mapped with (✓✓) indicating that the solution can be used directly in its current state and has a direct impact, and with (✓) indicating that the solution has the potential to have an impact with additional processing capability that needs to be developed, which would require specialist knowledge or skills. Details of the evaluation are described in the subsections below.

Low-Cost Digital Solutions for Lean Wastes

This section elaborates on the evaluation results, displayed in Table 4, describing how each of the eight wastes of lean could be monitored/managed using examples from the digital solutions in Table 3.

Transportation waste: the Job Tracking solution could be used for tracking the movement of pieces within the assembly/shop floor; the unnecessary movement of material and equipment could be reduced, hence reducing wasted time, by monitoring and deducing unwanted or useless movements and eliminating them by restructuring the shop floor or assembly line.

Overproduction and overprocessing: The quality inspection and quality data capture solutions can be used to calculate the percentage of defects expected from the process. This allows the planning of needed production quantities to satisfy the demand without overproducing.

Defects: The process monitoring solution could be used in temperature-sensitive processes and in the monitoring of the temperature of the process (or machine) to detect when the process exceeds the allowed limits, reducing defects and indicating when maintenance to the machine or process might be needed. The process monitoring could also be used for long-term health monitoring of the machines and to plan preventive maintenance. Additionally, the quality inspection and quality data capture solutions allow the automatic identification of defective products as well as the number of defects. This can be used for the calculation of percentages of defects as well as the identification of the trends and patterns of defects from set machines or operations.

Inventory: Excessive inventory that takes up valuable space and resources and ties up capital could be reduced by using the Job Tracking solution to calculate the Work in Progress (WIP). This allows accurate calculation of the capacity needed to store WIPs and for accurate buffer sizing. Additionally, the Inventory Monitoring solution will allow the monitoring of the amount of inventory present within a given time frame and the calculation of how long the pieces remain within storage, on average, over a given time frame. This enables the optimisation of inventory and the planning of when to order new pieces, depending on the inflows and outflows of inventory to match demand.

Motion: The movement or time taken by staff to search for the parts or product locations could be reduced by using the Job Tracking solution to get a clear view of the location of the products and ongoing job statuses. Additionally, the movement effort made by staff searching for the parts or product locations within the inventory space could be reduced using the Inventory Monitoring solution.

Waiting: The Job Tracking could be used for tracking the movement of pieces or products within the shop floor, which allows the identification of the bottleneck processes and the calculation of the blockage and starvation times of the processes or machines. This will allow the analysis of the wasted time within the process and the identification of which part of the process wasted time. The Inventory Monitoring solution could also be used to monitor the waiting time by monitoring the quantity of inventory available. This allows for forecasting when new inventory will be needed, hence reducing inventory shortage and waiting times for customer orders, mitigating the risk of starting production and realising halfway through that there are no supplies available for the completion of the order.

Unused Talent: None of the solutions are designed to be used to monitor and manage unused talent. However, Job Tracking has the potential to be used for the detection of the underutilisation of employees if coupled with an analytics solution or an employee schedule database.

Energy use monitoring was not found to impact any of the lean areas. Excessive power use could be an indication of waste in overprocessing or overproduction. However, it would be difficult to register with the current energy use monitoring solution and would require more process knowledge on what is being made, when, and how. Data from other solutions could help with this. Energy use monitoring would also not help reduce inventory, transport waiting or defects, or other human wastes such as unused talent and motion.

5. Discussion and Future Work

This study initially categorised low-cost solution areas into new categories for sustainability to create a new sub-catalogue for sustainability. The categories chosen focused on resource use and built on the areas of lean manufacturing. Other, previous studies of SMEs and sustainability have also focused on similar categories based on the wastes of lean manufacturing [5]. However, these studies have not considered the role of low-cost technologies. The categories selected here are primarily based on lean manufacturing areas and do not encompass other industrial sustainability strategies. The creation of the sub-catalogue used experts to evaluate and adapt an existing catalogue. Multiple experts were consulted, but the final sub-catalogue is still biased towards their view. Future studies could validate the sub-catalogue with more workshops, allowing participants to contribute solution areas or suggest changes.

A top ten list was created using an industry workshop and the sub-catalogue of low-cost digital solution areas for sustainability. Similar low-cost digital solutions areas, such as process monitoring, Job Tracking, lead time monitoring, and scheduling support, were ranked in the top ten for sustainability and previous manufacturing-focused studies [18]. This highlights that SME manufacturers may seek the same key solutions to address multiple challenges. For example, they may want process monitoring to help reduce costs, waste, and environmental impact. In low-cost construction [19] and logistics [20] catalogues, process monitoring, scheduling support, and tracking solution areas were ranked in the top 10, although in forms specific to those industries. Solution areas with no existing low-cost solutions that have ranked highly in this study and previous studies are likely to be good candidates for future development; these include scheduling support and internal lead time monitoring. It is essential to acknowledge that some solution areas, such as process monitoring solutions, can cover a wide area of solutions. The final solutions for each sector or company may look very different. Further work should focus on further validating the top ten solution areas with more workshops, including manufacturers, and specifying solutions in more detail.

A final evaluation of existing solutions against the areas of lean manufacturing showed that Job Tracking could have the highest potential with a possible impact on all lean manufacturing areas. All lean manufacturing areas could be addressed by at least one of the existing digital solutions, as shown in Table 4. However, some adaptation to the existing system would be needed. The evaluation did not consider how much adaption or further development may be needed for these digital solutions. The existing digital solutions that were evaluated have less use in lean areas focused on labour productivity, such as unused talent, motion, and waiting. The solutions had more use for resource-productivity-related lean areas, with more potential impact on overproduction and overprocessing, defects, inventory, and transportation. These are also identified as the key areas to help with sustainability. Previous studies have highlighted that digital solutions for Industry 4.0 have the greatest impact on resource productivity (reducing use, optimising processes, resource sharing, and reducing waste) [3,43,44].

This study’s key innovation is that it highlights key solution areas that manufacturers want to address sustainability, and how existing low-cost solutions could be used to satisfy this demand. This study provides a foundation which researchers or commercial providers of digital solutions could use to direct their efforts to improve industrial sustainability. There is little consistency in how digital solutions for sustainability have been evaluated in previous studies, which makes it difficult to compare studies [43,45]. Future studies should compare the cost and benefit of existing high- and low-cost digital solutions performing similar functions. The long-term use of digital solutions should also be analysed, considering the whole lifecycle of a solution. Low-cost solutions may be replaced more frequently, leading to higher levels of waste and a higher carbon footprint from the solution itself. This could be avoided by ensuring that they can be repurposed for new uses easily.

This study has focused primarily on sustainability through the lean manufacturing principle of reducing use and waste. However, there are further strategies that SMEs could consider for generating value out of unavoidable waste. For example, circular manufacturing strategies could provide SMEs with tangible methods for minimising waste, reusing resources, and extending product lifecycles, all of which contribute to sustainability and value generation [46]. Sustainable circular manufacturing emphasises environmentally sustainable production by supporting a closed-loop manufacturing pattern and the reuse, remanufacture, and recycle strategies [47]. Future studies could use similar methods to this study to create a specific sub-catalogue for circular manufacturing.

Figure 9 has been created by expanding Figure 1 to show how the existing approach used in this paper could be expanded to also include circular manufacturing and the intersection of the circular economy and lean manufacturing. Both concepts agree that reducing waste is the first and most effective step towards sustainability. A variety of lean tools could be used, as well as some circular strategies such as the Life Cycle Assessment, Design for X, and Cleaner Production [48]. Nevertheless, it is recognised that not all waste can be eliminated. This leads to the next step: creating value from waste that remains in the production process (A4 in Figure 9). This waste valorisation approach hinges on innovation in the production process and the adoption of circular strategies, such as recycling, remanufacturing, and reusing, to extract value from materials and resources that might otherwise go to waste. As can be seen from Figure 9, low-cost digital solutions could be used within this approach to allow the monitoring and provide data needed for further analytics. The current evaluated solutions predominantly focus on individual companies rather than fostering the essential cross-collaboration between SMEs. This lack of collaboration has been noted as a barrier to SME adoption of circular economy strategies [9]. To address this challenge, it is imperative that future digital solutions foster collaboration and communication between partners to support sustainability effectively.

6. Conclusions

Previous studies have investigated Industry 4.0 digital solutions for sustainability in manufacturing, but little consideration has been given to low-cost digital solutions. The purpose of this study was to explore the role of low-cost digital solutions in supporting industrial sustainability in SMEs. Sustainability for SMEs was approached from a lean manufacturing perspective. The approach used in this paper consisted of three main activities: Catalogue Adaptation, Prioritisation Workshop, and Solution Evaluation. The initial Catalogue Adaptation stage started with creating categories and grouping digital solution areas that contribute to sustainability under those categories; this led to the creation of the sub-catalogue of low-cost digital solution areas for sustainability. A workshop with UK-based SMEs prioritised the top ten digital solution areas for sustainability from the sub-catalogue. The last step evaluated the top implemented digital solutions and their use in monitoring the eight wastes of lean.

As identified in other studies, SMEs and low-cost digital solution research have predominantly focused on identifying and helping to reduce the use and sources of waste in production. The most in-demand solution areas are related to monitoring or inspection (process monitoring, energy monitoring, quality inspection). There was also demand for low-cost solutions to help with inventory, scheduling, or sustainability reporting management. Some solutions, such as process monitoring and Job Tracking, have ranked highly in previous studies of low-cost manufacturing. Future research could focus on low-cost solutions to help with sustainability reporting and with demand in other sectors, such as scheduling support or internal lead time monitoring, which have yet to be created.

The final evaluation of solutions created for manufacturers noted that many existing solutions could immediately be used to help reduce waste directly with little adaptation. Existing solutions predominantly focus on resource-focused areas of lean, such as overproduction and overprocessing, defects, inventory, and transportation. This study provides a starting point for researchers or commercial providers of digital solutions looking to address sustainability; it indicates existing technologies and their uses and areas not yet addressed. Future research should focus on creating or adapting existing solutions for circular manufacturing. Solutions could be expanded not only to identify and reduce waste but also to help support recycling, reuse, or remanufacturing processes.