re-ISSUES—Renewable Energy-Linked Interoperable Smart and Sustainable Urban Environmental Systems

Abstract

Smart cities will be smart if they improve their citizens’ quality of life; to do so, it is essential to listen to citizens and collaborate with service and technological companies. For that, digitalization seems essential. Environmental management systems are complex and expensive. If their lifecycle costs are reduced, these systems would be more sustainable. This can be achieved through citizen collaboration (CS), the use of low-cost Internet of Things (IoT) devices, and collaboration with local renewable energy businesses. All this leads to a real interoperability challenge. Systems engineering offers a valid framework for managing information and knowledge for environmental systems. It offers a range of guides for processes that can improve the quality of the related information and the reusability of knowledge throughout the lifecycles of these systems. After quantifying the opportunity and the cost for a motivational case of atmospheric neighborhood odor impact and introducing trends and opportunities in energy management, the authors propose a model for renewable energy-linked interoperable smart and sustainable urban environmental systems (re-ISSUES). The model’s ontology is used to discover research trends and potential for improvements to the model itself, enabling semantic interoperability and knowledge reuse.

1. Introduction

Listening to citizens and collaborating with service and technological companies as an integral approach is essential for Smart Cities.

First, waste and water treatment facilities may cause undesirable odors because of underestimated uncertainties in using models and data during the design stage. Central heating using biomass boilers may be closer than expected by design to homes and other essential services (health, education, etc.). This is the bad side, but there is a good side because these industrial activities contribute to urban decarbonization by reducing fossil resource consumption. Presumably, they operate within the neighborhood, whose evolution is under continuous adjustments because of the growth of residential areas [1]. It is mandatory to make them compatible, with the help of further public or private activities and developments. At the same time, renewable energies like photovoltaic or solar thermal can be implemented in the city.

As another example, the so-called local or proximity economy after COVID-19 increased so-called “ghost kitchens”, industrial kitchens without an in situ restaurant but for remote consumption, emitting smoke and noise within urban districts [2] and also increasing urban traffic. Usually, they are installed in the basement of a community residence building. In certain extreme cases, not necessarily unlikely ones, homeowners may suffer not only because they must fight to defend their rights to a home not invaded by air pollution, but also because of the loss of property value. A consequence of not attending to their claims can be that the homeowners move, causing re-urbanization, which means urbanizing unnecessarily in other nearby districts. This could be considered a type of public management inefficiency.

The above-mentioned motivating examples are just some problems that can happen, even concurrently. As a general comment, to avoid unfair persecution of industries or human suffering, it is mandatory to identify odor sources with professional measurement and verification services, from the first instant that people complain. For this, digitalization seems essential because it enables data traceability, a requisite for conducting any reliable verification activity.

2. Materials and Methods

The authors hypothesize that promoting interoperability between renewable energy generation and environmental management systems in cities will contribute to the sustainability of both types of systems, at least in the economic and social aspects of their operation. The main purpose of this work is to demonstrate the hypothesis and motivate further research efforts reusing the methods described in this work.

The workflow, summarized in

Table 1. Workflow Summary.

Content	Section	Section Title
Context, engineering framework, and conceptual model of an environmental measurement and verification system (EMVS).	Section 3	Environmental Management and the Smart City.
Motivational example of an EMVS and economics.	Section 4	Motivational Example: An Urban Odor Measurement and Verification.
EMVS economic optimization.	Section 5	Cost Optimization and New Opportunities.
High-level description of the re-ISSUES model.	Section 6	Purpose of the re-ISSUES Model.
Key questions formulation (research questions).	Section 7	Research Questions.
Populated EMVS ontology extended for bibliography search in ScienceDirect, and natural language processing (NLP).	Section 8	Ontology For Using the re-ISSSUES Model.
Textual alerts definition by extending the EMVS ontology.	Section 9	Textual Alerts Definition.
Expert analysis of interest in the literature for each question.	Section 10	Results And Discussion.

, starts by introducing a context, a suitable engineering framework, and a conceptual model of an environmental measurement and verification system (EMVS), presented in Section 3. After that, a motivational example for promoting interoperability between solar energy generation systems and environmental management systems is defined, first stating the environmental problem, followed by proposing the solution’s economics in Section 4, and then adding realistic cost optimization and opportunities for the environmental measurement and verification system (EMVS) economics in Section 5.

In Section 6, a high-level model of an EMVS is defined in terms of an ontology. In Section 7, some key questions to promote interoperability between renewable energy generation and environmental management systems are introduced. The questions are intended to be answered with a set of scientific literature from the ScienceDirect database and its search portal by using the ontology. Then, the ontology is extended in Section 8 to detect research trends through specific questions using the natural language processing (NLP) method as described in Section 9. Acting as experts, in Section 10, the authors verify the degree of interest for each work in each question to find trends, highlighting the main results analyzed to find potential improvements for the model.

3. Environmental Management and the Smart City

This section introduces the context of environmental management in the Smart City, a possible engineering framework for managing complexity, and concludes with an approach for an environmental measurement and verification system (EMVS).

3.1. Environmental Management Context

Environmental management systems are complex and expensive. They involve different devices, simulation models, methods, processes, and regulations. If the lifecycle cost, which is the cost of procuring, operating, and maintaining them, is reduced, these systems can be more sustainable in the economic dimension. However, the social dimension also requires attention. The authors believe that citizen collaboration (CS), the use of low-cost Internet of Things (IoT) devices, and collaboration with local renewable energy businesses can contribute to their sustainability.

One type of environmental management system is an environmental measurement and verification system (EMVS) for air pollution. Although odors can be non-polluting, they can damage private life inside dwellings. EMVS is also considered as a subsystem in larger environmental systems. At the same time, innovative EMVSs can be used for odor measurement.

Although there are several methodologies to assess an odor’s impact, such as dynamic olfactometry (UNE-EN 13725:2022) [3] coupled with the use of dispersion modelling or field inspections (UNE-EN 16841:2017) [4], none of these techniques directly involve the citizens who suffer the nuisance. The recent Spanish standard UNE 77270:2023 on citizen science (CS) [5] is the first standard of its type relating to this topic. This standard describes a method for building collaborative odor maps to assess odor annoyance through real-time communication by participating citizens. This is a term used to define the participatory process through which citizens actively engage in a project, either with their intellectual effort, associated knowledge, or with tools and resources. A CS project should meet the minimum requirements based on the 10 principles of CS established by the European Citizen Science Association (ECSA) [6]. The UNE 77270:2023 standard is already being implemented using mobile apps, and citizen associations have the right to be listened to, implying a political risk for those who do not attend and react to reasonable claims [7]. Nevertheless, the citizens’ co-creation processes have some intricacies because of diverse cultural, societal, and regulatory backgrounds, as the scaling-up co-creation project described previously [8] demonstrates.

The good news is that by using models for forecasting effects, an EMVS can provide alerts for industrial activities to stop operating and start assessing corrective measures to avoid shutdowns when the opportunity cost (or the cost of the risk) is too high. According to experts, low-cost sensors and IoT, in general, can contribute too [9,10].

Urban IoT devices to measure odors should be installed on buildings’ roofs, eventually near solar energy systems and or micro wind energy systems. The reason is presented as follows. These systems need to be maintained regularly and, for this reason, it is expected that renewable energy service providers benefit from the action of measuring odors in the smart city, and vice versa. Communications like 5G and other key enabling technologies should be considered early for this purpose [11]. Combining data from service providers, apps in mobiles (the most used IoT devices), sensors, and calibrated models can be a real interoperability challenge. Herewith, interoperability is the ability of systems or systems’ parts to exchange and use the exchanged information.

3.2. Systems Engineering as a Value-Added Framework for Environmental Management Systems and Environmental Safety

The systems engineering discipline offers a valid framework for managing information and knowledge. It offers a range of guides for processes that can improve the quality of related information and knowledge reuse throughout the lifecycle of these systems.

On the road towards sustainability, we, as technology specialists, can find support in using best practices, such as those stated in the International Council on Systems Engineering’s Guidelines (INCOSE) [12]. These guidelines define a set of processes for engineering successful systems.

Interoperability management processes are key for the different stakeholders, systems, subsystems, and parts, providing an understanding of the information exchange necessary at any stage of the system’s lifecycle.

Currently, the European Administration is progressing in promoting interoperability management, regulating [13] and demonstrating its feasibility with specific projects [14]. A council promoting Smart cities (SCs) or public service providers in general, must comply to ensure seamless delivery of public services.

INCOSE Systems Engineering’s Guidelines also introduce the importance of reliability along the systems lifecycle, from concept to disposal. We can imagine that a failure in a waste treatment plant (a part of the circular economy of the city) may induce a problem for the environment, especially if the failure affects the plant’s environmental safety measures like barriers or other essential parts. This can be extended to the metering systems providing alerts near populations or areas of vulnerable biodiversity. Also, security failures can happen, for example, after a cyberattack affecting electronic systems.

Recent research reveals that, at least for popular urban energy systems in Smart Cities, the nexus between circular economy and environmental safety is not a current trend in research [15]. One solution for avoiding missing known risks and emerging opportunities regarding this nexus and interoperability management could be promoting collaborative public-private projects designed in open innovation environments for reliability, safety, and security [16]. As emerging opportunities, we can consider those related to renewable energy in cities e. g. solar thermal, PV, biomass, and waste heat use.

3.3. Environmental Measurement and Verification System (EMVS) Definition

To promote open innovation about any environmental system, it is crucial to start using shared terminology.

Table 2. Generic EMVS terminology.

Element Name	Element	Definition
CONTEXT	Context of the measurement	Type of impact or damage to detect Regulations, ISO standards, etc. Potentially affected collectives Measurement site
O&M	Operation and maintenance of the measurement and verification system	Measurement quality Models’ quality maintenance Forecasting Operator
PURPOSE	Measurement system purpose	Emissions forecasting Urban mapping
PARTS	Measurement parts	Hardware Software Certifications Communications
ATTRIBUTES	Measurement system attributes	Quality Reliability Availability Cybersecurity Recovery plan
VERIFICATION	Verification activities	Models’ calibration Compliance with limits and regulations
EOL	End-of-life (EOL) condition	Recyclability Environmental footprints of products and services

contains a generic and non-normalized approach for EMVS:

Figure 1 offers a diagram presenting a generic EMVS where the main categories are represented with rounded rectangles, the potential influence relationships with arrows, and the logical and physical system levels with rectangles.

4. Motivational Example: Urban Odor Measurement and Verification

At this point, it is important to quantify the opportunity and the cost for a motivational case of odor management where new devices and subsystems can be added after Citizen Science (CS) and public metering, through identifying the lower integral cost of an EMVS.

A population of circa 100,000 citizens was considered, taken from a real case in a district affected by odors and air pollution. The authors prefer not to mention the name of the district, which is a lovely place to live.

4.1. The Opportunity to Use Existing Urbanization

The selected district is currently fully urbanized (with lighted streets), and includes approximately 5000 new houses, a 20% increase. This should provide no less than EUR 200/house of tax income for the City Council, according to the authors’ assumptions and public tax rules [17,18]. The main assumption is that future use of such urbanized spaces depends on how and to what extent people will be protected against odors (in what follows, the coverage ratio). Figure 2 shows an aerial view taken from Google Earth.

Figure 2 shows an orange arc corresponding to a 4 km radius from the odor sources from waste management activities. In the same figure, individual housing urbanization areas are depicted in yellow: those filled in yellow are existing, and areas where housing is not present are not filled in. Existing buildings are filled in green, and unfilled green outlines indicate future buildings. Notice that new urbanization is growing in the northeast, inside the same space limited by the orange arc.

A simplified economic model was developed to quantify the opportunity and costs. The following sections describe the insights of this cost and profit model.

4.2. The Property Loss Risk or Re-Ubanizing Cost

The consequence of not measuring and verifying the risk is property value loss or depreciation for the homeowners, as detailed in recent research, e.g., [19]. This risk is enough to drive regional and local governments to take odor management actions by contracting environmental advisors to conduct odor mapping using CS, measurement, calibration, and modelling techniques.

In the motivational examples, the yearly property loss risk for homeowners leaving the district due to odor problems is estimated as 5% of an average flat sale price of approx. EUR 200,000. The probability of the value loss was estimated as 3% of the proportion of buildings without representative measurements within the district (1−X). Near the condition of X = 100% buildings covered with representative measurement, the persistence effect was modelled in an integral way with another (1−X) factor. The probability used was, at maximum, that of the yearly wind frequency from the closer odor source based on the available mesoscale wind atlas from an ERA-NET project [20]. The property loss was considered equivalent to the re-urbanizing cost (preparing streets for energy, transport, water, and communications, among other things), estimated at EUR 500 per sq. meters.

4.3. The Upfront Costs of the Measurement System

The CS app (official and based on standards) was assumed to be free for any inhabitant of the district. The major upfront cost is the cost of acquiring and installing a high-quality station, for example, EUR 50,000 € per block. This high-quality station is useful for calibrating low-cost IoT devices and sharing wireless or radio communications.

Combining high-quality stations with low-cost devices defines two measurement types: professional system or PRO (100% of the high-quality cost) and cheap but professional or MIX (50% of the high-quality cost) cost scenarios. It is possible to estimate an amortization cost for the upfront cost by assuming the measurement system lasts 10 years.

4.4. The Maintenance Cost of the Measurement System

The yearly maintenance cost of the measurement system is estimated at 20% of the yearly amortization cost of the measurement system. This estimation included the financing cost of the system (finance interest).

4.5. The Cost of Centralizing Professional Measurement and Verification Services

The cost of the measurement and verification center was estimated by adding the cost of renting 500 sq. meters to the cost of hiring and managing a professional staff, in total, circa EUR 200,000 per year. To this total cost, 15% of the amortization and maintenance cost of the measurement system was also added.

4.6. Results and Discussion of the Motivational Economic Model

For a qualitative comparison of the PRO and MIX cost scenarios, the integrated cost was normalized by the minimum cost of the PRO scenario. The opportunity is explained in 2.1. When the opportunity is greater that the integrated cost (PRO or MIX), the Council has an incentive to promote an EMVS to measure odors. This is theoretical, of course, but it motivates thinking about innovation.

Figure 3 represents the normalized integrated cost and the normalized opportunity cost. The measurement coverage (% of dwellings with representative measurements) starts at 50%, which corresponds to the theoretical case in which 50% of the population are not concerned with odors, but this is something to discover with a survey or continuously via a Social Science app (a CS application).

As a first tentative result for the example, the maximum potential savings through choosing a MIX system instead of a PRO could be, as expected, 0.6 times the maximum cost, and this could make the difference for a generic public purchaser attending to certain feasibility criteria.

The second tentative result is that the environmental system is affordable. It may cost EUR 25/home/year, which is not negligible for a medium-income family, but as an example, it is in the range of the cost of a standard cable-TV subscription, and, as mentioned, it can be reduced via the MIX approach.

The third tentative result is that if the opportunity or the cost is affected by uncertainties, the feasibility is compromised; thus, there is a need for more opportunities (income or scale economics).

5. Cost Optimization and New Opportunities

5.1. Extending Measurement and Verification to Environmental Safety

One can observe that the system can start with a PRO configuration and evolve to a MIX configuration because it is cheaper. This could be a valid (and conservative) strategy for total cost optimization and to obtain profit. This approach requires regular verification actions that are quite automatable using systems engineering enabling software. It would be interesting to include the uncertainty of using only a PRO system to make this optimization more robust. This analysis would require accurate data and could be the object of technological innovation projects (pilots). It would be possible to optimize some costs, as suggested in Figure 4.

Once the convenience of having a measurement and verification center with forecasting capability has been justified, one can think of more opportunities to use such capability for energy management.

5.2. Trends and Opportunities in Energy Management

Choosing the right energy model for a city is not trivial. Urban planners must enable the new energy model’s developments and the broader administration must control the related activities in terms of permitting (access to public assets), market trading freedom, and competitiveness. At the same time, the city purchases energy too. In this situation, urban planners and technologists must pay attention to interoperability and engineering trends and collaborate with professionals for sustainability [15]. The current energy context for cities is also conditioned by the European policy of achieving secure, clean, and affordable energy [21]. In this context, energy efficiency and renewable energy generation are key, but new market agents like the energy communities also enable other key activities like demand aggregation and collective self-consumption, making the urban energy users (private or public) act not as mere consumers, but as prosumers [22].

5.2.1. Energy Communities and Innovation

Energy communities (EC) are the objects of new regulation in Spain by order of a Law Project [23]. The agreed definitions currently include the renewable energies community (in Spanish: CER) and the citizen energy community (in Spanish: CCE) [24]. Energy communities (ECs) may try new activities for the community’s benefit. For example, an EC can provide air quality services and earn money for investing more or better maintaining its renewable energy assets, and it can commercialize its renewable energy surplus or its contribution to demand management services, like distributed storage services (thermal, electric, or even hybrid) or demand response services, all using IoT to promote a smarter grid. There is nothing that forbids an EC from providing innovative services initialized for example under Public Purchase of Innovation (PPI) [25] schemes, for example, by certificating contribution to resilience in analogy to the Spanish Energy Saving Certificate (in Spanish: CAE) [26].

5.2.2. Heat Pumps & Solar Energy Systems Integration

Electric heat pumps in buildings are mostly used to provide heat (as electric heaters) or to evacuate heat (as electric chillers) from/to low thermal energy sources like the atmosphere (autothermic/aerothermic), aquifers, or the ground (autothermic/geothermic), near district heating. Of course, this can be the case for existing or retrofitted solar thermal storage subsystems allocated in buildings. It is rarer, but also possible, to use heat pumps to downgrade and amplify heat; nowadays, this is not available for acclimatization of dwellings.

Heat pump-based systems, in practice, can be allocated in the façade or specific spaces within buildings or in the city, with different environmental impact (noise generation, heating island effect contribution), risks (eventual falling objects, property value degradation, etc.) and opportunities (electric efficiency by recovery of waste heat, local work generation including maintenance, thermal energy lifecycle price optimization, raw materials consumption, circular economy competitiveness).

Cooling is becoming a growing demand in the southern cities of Europe. It is estimated that the risk of dying due to extreme heat in a city like the region of Madrid was 194 deaths/100,000 h in 2023, according to Instituto de Salud Carlos III MoMo statistics [27]. Schools should also be prepared for this important challenge and can be converted into safe spaces for citizens on the hottest days of the year, since not everybody has access to cooling systems or can afford to pay expensive electricity bills.

It is well known that the electric power required for feeding a heat pump is several times less than the heat it can generate for a higher heat sink. This relationship is called the coefficient of performance (COP) and differs from stational and nominal definitions and examples [28]. The lower the temperature difference between the source and the sink, the lower electricity a heat pump demands (higher COP), and this is interesting for future urban consumption for electric mobility at a minimum electric infrastructure cost or the available one. Electricity in summertime (for cooling) may come from local photovoltaic (PV) generation, saving imported power to the city, although PV does not contribute greatly in wintertime (for heating).

Regarding the motivational example, due to the year of construction, around 5000 m² of solar thermal flat plate collectors were installed to cover between 60% to 70% of the heat demand for sanitary hot water after the Spanish Construction Code change in 2006 [29]. The real estate bubble in Spain started in 1997 and burst in 2007 and the quality of installations declined afterwards (see an example in Figure 5). According to the Spanish Association of Solar Thermal Manufacturers (ASIT), 30% of solar energy systems are not well maintained and might not be working properly [30,31]. This problem could be solved with compulsory maintenance supervision, as is starting to happen with fire safety in Spain [32]. The surveillance and maintenance of solar installations could be performed by organizations of engineers and technologists in collaboration with energy agencies and supervised by certification agencies, and it could even be extended to attend to the same potential problem at the European level. Supervising the maintenance of existing and unattended urban thermal networks could be a natural evolution following new standards [33].

Introducing a reversible high-temperature water-X heat pump that takes the solar thermal storage energy for a central (existing or new) heating and cooling system would demand minimal electrical power, which is good for future urban mobility. An additional aerothermal heat pump could complement this solution, being necessary to increase the size of the heat storage tanks. The solution can also use low thermal (condensation) boilers during the energy transition and heating and air conditioning (HVAC) installations like community hydronic networks and fan coils in homes, following national and international guidelines [34,35]. For this to be possible, the building management system (BMS) should be interoperable with the existing controls for the solar thermal system and the environmental measurement system suggested in the motivational case.

According to the authors’ estimations for the case studied, using solar thermal systems in buildings could contribute to GHG savings from 15% (for central hot water systems) to 30% (for a central heating and cooling system for the same building). Of course, there are additional GHG savings to be made in heating and cooling centralization, allowing up to 70% of GHG savings in total. Properly maintaining (and if possible, extending the lifetime of) the existing solar thermal systems is smart, and so too could be the use of hybrid photovoltaic–thermal technologies (PVTs) for those roofs without solar panels yet, according to international assessments [36]. Notice also that the thermal energy storage can be heated directly using the electricity surplus, contributing to new business models for demand management in the city.

5.2.3. Digitalization and Engineering Quality for Small Projects

Engineering works are present in many activities: in the electronic systems configuration used for the demand response subsystem project the energy community (EC) will use, in the heating, ventilation, and air conditioning (HVAC) retrofit project the building owners or an EC will invest in, or in the accounting of the energy saving certificates (CAEs) being acquired by energy companies for hundreds of ECs in the future. To conduct these works, engineering uses computer-aided design (CAD), and building information modeling (BIM) is part of engineering digitalization, along with Excel^® and Word^® files, all containing information; exchanging this information between tools and other digital tools (for HVAC, electronics, etc.) is part of the design stage.

The information used in engineering requires specific management to guarantee certain quality, but also to be affordable for small customers. This is part of the mission that professional engineers societies (PESs), especially the industrial engineering ones, have faced for decades in Spain, according to the law [37] enabling specific insurance access to engineers.

Specific information technologies (ITs) are being used in large engineering projects to enable quality and best technical management processes like knowledge management, interoperability management, validation, verification, and risk and opportunity management, including issues such as, for instance, attending to failure cause and effects [38]. These practices are described in systems engineering guidelines [12]. To be able to transfer and use these or other enablers to small projects is a big innovation challenge for both engineering and technology professionals and the professional engineers’ societies (PESs), and for this, it is necessary to gain experience through pilots in the use of new ITs and the best practices available.

After reviewing 73 recent research publications about energy systems included in the European taxonomy [39], the authors found evidence that the enablers mentioned above are at least understood by technologists, except for interoperability management. Interoperability management is necessary for automating engineering information to make small projects more affordable for customers and freer from avoidable mistakes and for alerting early engineers. PESs can attend to this need by using specific information technologies (ITs), checking engineering documents, and providing training to at least 18% of the engineers who are dedicated to engineering projects as their main activity, according to the latest report about engineering and technology professionals in Spain [40], which stated that 22% of the engineers chose to be trained in ITs.

To acquire many software licenses could be very expensive for small engineering firms. Cloud computing could reduce this cost. It makes sense to share the related infrastructure or service contracts for the environmental measurement and verification system with other benefits like the cybersecurity the Cloud can afford [41] and it becomes mandatory for essential services [42].

There is an opportunity for a measurement and verification center to be expanded to provide homeowners with energy measurement and verification services standings, based on the fact that the same dataloggers, meteorologic sensors, communications, and in-field services required by the odor metering system can be shared.

5.2.4. Circular Economy & Industry

The more savings the City Council achieves, the more interesting the business can be because it can activate public purchase of an innovation tendering process using legal instruments [43]. Of course, conducting pilots beforehand to demonstrate the feasibility of the full investment is necessary. It could be possible to extend the lifespan of the energy system or to plan a local circular economy [44]. This would also be attractive for the emerging industrial solar sector. Altogether, this is an example of the nexus between environmental safety and circular economy but also an opportunity for the application of Industry 4.0 (I4.0) where a flexible reconfiguration of a recycling plant replaces the specific characteristics of diverse types of solar thermal collectors (I4.0, decentralization design principle), aggregating such demand in a decentralized way (I4.0, service-oriented design principle) [45].

5.3. Validation of Interest and Originality of the re-ISSUES Concept

To validate the interest in the idea of linking odor measurement with solar thermal activities in cities, the authors created an online and anonymous rough questionnaire asking about the type of the respondent organization or person, allowing free answers to the questions described in

Table 3. Questions about Energy Management Opportunities for the Spanish Solar Thermal sector.

Energy Management Opportunities	Question	Results	Comments
Energy Communities and Innovation	Would the solar thermal value chain be receptive to attending environmental measurements in cities to increase sales?	Yes 100%	Relevant agents: engineering firm. Not adding other motivations.
Heat Pumps and Solar Energy Systems Integration	Is the sector considering the integration of heat pumps with the existing solar thermal systems?	Yes 100%	Relevant agents: association and engineering firm. As expected.
Digitalization and Engineering Quality For Small Projects	Is the sector concerned about the interoperability challenges in engineering?	Yes 100%	The respondents did not ask about definitions; there are many types of interoperability.
Circular Economy and Industry	Is the sector considering circular economy opportunities around solar thermal installations in cities?	Yes 100%	Relevant agents: association without a specific work group on circular economy.

, which includes the results:

The number of respondents was only a few (three) and we can offer a qualitative analysis; the Association represents almost all the sector players in Spain and its answers are quite representative. A preliminary answer to the general interest in linking odor measurement with solar thermal activities in cities is that the concept is interesting for the solar thermal sector. This work can help to imagine opportunities for the sector and future EMVM sustainability systems.

Regarding the originality of connecting urban renewables to odor management in cities, a search in the European Commission Database CORDIS was conducted and the results are included in

Table 4. Search criteria for European Research and Development projects.

Domain of Application	Keywords	Results
Health OR Society OR Energy OR Digital Economy OR	(‘odour’ OR ‘odor’) AND (‘renewable’ OR ‘renewables’)	Program: H2020. Grant Agreement 788359.

, none specifically covering this link:

The Scalings project defined a policy roadmap in collaboration with companies, universities, policymakers, and citizens enabling or supporting innovation processes for responsible co-creation projects. The project carried out a comparative study in 10 countries about living labs, public procurement of innovation, and co-creation facilities, across a range of technical domains; nevertheless, the project did not use ontologies to promote semantic interoperability.

6. The re-ISSUES Model Purpose

The authors propose a model for renewable energy-linked interoperable smart and sustainable urban environmental systems, from now on referred to as re-ISSUES.

The re-ISSUES model is intended to be the following:

• An URBAN ENVIRONMENTAL SYSTEM enabling environmental management that combines diverse types of data, devices, agents, measurement and verification processes, and methods;
• SMART, because it allows calibrating chemical species dispersion models to provide technical alerts for industrial activities to operate safely or to take further investment actions in the Smart City (SC) context;
• SUSTAINABLE, because the EMVM system cost can be optimized by reusing knowledge and collaborating with local renewable energy businesses;
• INTEROPERABLE, because it introduces interoperability management at a semantic level, through the concerned professionals, and at a technical level, allowing different IoT devices and data sources to exchange and use valuable data.

A first conceptual model, based on Section 3.3, initiates an ontology to discover research trends and potential for improvements to the model itself, enabling semantic interoperability and knowledge reuse using the same methodology already explained in [15].

7. Research Questions

The following questions may uncover trends in the SC knowledge domain:

• (Q1) Is interoperability being considered in environmental management in cities?
• (Q2) Are risk-centered or risk-based approaches being considered in environmental management or environmental engineering?
• (Q3) Is CS being used for odor management in the SC?

The questions were converted into textual alerts in documents obtained from search portals. The research topic was not an urban energy system (UES), like in [15], but the environmental management in a city, although the workflow represented in Figure 6 is the same.

8. Ontology for Using the re-ISSUES Model

Table 5. re-ISSUES Model Ontology.

Concept	Relationship with the Environmental System	Metadata and Operators (for the Search Portal)	Keywords (for the Search Portal)	<Cluster> (for Alerts)
CONTEXT	Context of the measurement	(urban OR city) AND environmental management	Measurement site AND damage AND context AND regulation	Impact, damage, detect, regulation, ISO, affected, affection, collective, measurement, context.
PURPOSE	Measurement system purpose		Purpose AND emission AND measurement system AND (map OR forecasting)	Emission, forecasting, mapping, map, purpose, measurement system.
ATTRIBUTES	Measurement system attributes		Quality AND availability AND recovery	Quality, Reliability, Availability, Cybersecurity, Recovery.
VERIFICATION	Verification activities		Verification AND calibration AND threshold	Calibration, Compliance, comply, limit, threshold.
PARTS	Measurement parts	smart city AND odor	Hardware AND software AND communication	Hardware, Software, Certification, Communication.
O&M	Operation and maintenance of the measurement and verification systems		O&M	Quality, Models’ quality Forecasting, Operator, O&M.
EOL	End-of-life condition		Disposal	Recyclability, Footprint, Disposal.

summarizes the ontology of the first version of the re-ISSUES model, extending the ontology initiated in Section 3.3 and described at a high level in Section 6.

9. Textual Alerts Definition

At this point, the questions were converted to textual alerts and are presented in

Table 6. Textual Alerts.

Question	Filter Cluster	Context Cluster	[Pattern 1]	[Pattern 2]
(Q1) Is interoperability being considered in environmental management in cities?	Interoperability, interoperate, interoperable	<CONTEXT>	<Filter>…<Context 1>	The reverse of pattern 1
(Q2) Are risk-centered OR risk-based approaches being considered in environmental management or environmental engineering?	Risk, risk-centered, risk-based	<ATTRIBUTES> <PARTS> <VERIFICATION> <O&M> <EOL>	<Filter>…<Context 1> OR <Context 2>… <Context 5>	The reverse of pattern 1
(Q3) Is CS being used for odors in the SC?	Citizen, science, community, civic	<PARTS> <VERIFICATION>	<Filter>…<Context 1> OR <Context 2>	The reverse of pattern 1

. The strategy followed was to use semantic clusters corresponding to principles for triggering a textual alert and to close the alert detection with the more suitable semantic clusters. The reverse composition is also possible.

10. Results and Discussion

Using Table 5 search criteria, 247 readings were found in the Science Direct repository. After checking the abstracts, 31 available readings were found within the research scope, but after conducting the textual alerts search, only 9 provided alerts’ results were found interesting or relevant in relation to question Q2, 6 for question Q3, and none for Q1. The most promising readings were the following readings, gathered in

Table 7. Questions and readings for utility validation (R = relevant; I = interesting; IR = irrelevant).

ID	Bibliography Index (DOI) and Title	Verification by Experts
		Q1	Q2	Q3
1	https://doi.org/10.1016/j.seps.2024.101834. Psycho-social conditions of urban communities in the complexity of waste management: Are awareness and waste banks the main solution?		IR
2	https://doi.org/10.1016/j.techfore.2020.120190. Comparative analysis of urban ecological management models incorporating low-carbon transformation			R
3	https://doi.org/10.1016/j.envpol.2024.123385. Assessment of environmental risk areas based on airborne pollen patterns as a response to land use and land cover distribution.		R
4	https://doi.org/10.1016/j.jenvman.2022.115941. Seemingly bounded knowledge, trust, and public acceptance: How does citizen’s environmental knowledge affect facility siting?		R
5	https://doi.org/10.1016/j.jhazmat.2020.123943. An emerged challenge of air pollution and ever-increasing particulate matter in Pakistan; A critical review		I	I
6	https://doi.org/10.1016/j.psep.2023.04.014. Municipal solid waste landfills in lower- and middle-income countries: Environmental impacts, challenges and sustainable management practices		I	R
7	https://doi.org/10.1016/j.jclepro.2022.135460. Supporting sustainability projects at the neighbourhood scale: Green visions for the San Salvario district in Turin guided by a combined assessment framework		IR
8	https://doi.org/10.1016/j.atmosenv.2020.117343. Evaluating the impact of PM2.5 atmospheric pollution on population mortality in an urbanized valley in the American tropics		I	I
9	https://doi.org/10.1016/j.envsci.2021.12.022. Barriers and opportunities to incorporate scientific evidence into air quality management in Mexico: A stakeholders’ perspective		I	I
10	https://doi.org/10.1016/j.wroa.2024.100212. Low-cost monitoring systems for urban water management: Lessons from the field		R

:

With this short list of results, providing statistics is inappropriate. Notice that the nine references are concentrated in the period 2022 to 2024, from a 2020 to 2024 selection.

Q1’s answers are somehow disturbing because interoperability management could be a missing piece of environmental management in cities. Of course, the textual alert for Q1 must be improved to secure this result. Regarding Q2 and Q3,

Table 8. Potential improvements for the model.

ID	Article Title	Evidence for Potential Improvements	Model Element
2	Comparative analysis of urban ecological management models incorporating low-carbon transformation [46]	A new and comprehensive management framework incorporating urban planning, industrial transformation, organizational model, environmental protection, and institutional systems was proposed.	CONTEXT PURPOSE
3	Assessment of environmental risk areas based on airborne pollen patterns as a response to land use and land cover distribution [47]	Spatial regionalisation in environmental risk assessment is a common practice among institutions responsible for managing public health systems. It favors the application of management plans and assessment monitoring measurements and allows the optimization of resources and funds.	CONTEXT PURPOSE
		The risk areas proposed in the Madrid region by scientific criteria can be adjusted to other operational criteria, e.g., demographic, administrative, etc., and an equivalent approach can be applied in other similar monitoring networks.	CONTEXT PURPOSE
4	Seemingly bounded knowledge, trust, and public acceptance: How does citizens’ environmental knowledge affect facility siting? [48]	Results showed robust evidence that citizens’ acceptance of environmental goods provision was negatively related to their perceived environmental knowledge of pollution and risks.	VERIFICATION
		This study extends the literature on citizens’ trust in public service providers. This study adds to the literature by demonstrating the critical role of trust in both the government and facility operators and revealing that environmental knowledge boundedness hurts public trust and further affects public acceptance.	CONTEXT PURPOSE
6	Municipal solid waste landfills in lower- and middle-income countries: Environmental impacts, challenges and sustainable management practices [49]	Environmentally friendly, cost-effective solutions which have community acceptance are needed and are the key to sustainable solutions. Engagement from local governments, generators, NGOs, and community involvement is also required to attain and address the various initiatives taken by the government.	CONTEXT PURPOSE
10	Low-cost monitoring systems for urban water management: Lessons from the field [50]	Low-cost monitoring systems require advanced technology to ensure scientific-grade quality of data for a given research or monitoring objective. To address these limitations, we call for better documentation of the system’s design process and performance for the community of practice to learn effectively from each other.	PARTS O&M
		The economic benefits of low-cost systems are promising. The environmental costs of such systems are poorly understood.	EOL
		Socio–technological challenges associated with low-cost monitoring technology—e.g., data management, communication, and cybersecurity—are highlighted in this article.	ATTRIBUTES

provides some feedback on the re-ISSUES model including conclusions from the most relevant readings:

11. Conclusions and Further Steps

Although CS and IoT are not new, their combined use with the related methodologies and technologies seems to be promising for improving the air quality in cities, which could be especially important in districts near industrial polygons and/or environmental activities attending the city needs.

The authors provide a good motivational example to connect the solar energy integration challenges of maintenance and circular economy with the opportunity to solve air quality problems more sustainably. This example is not the only case that can be found in cities in southern Europe. The knowledge that pilot projects at the example site may generate could contribute to the sustainability of larger or industrial solar energy scales and more digital and local industry opportunities following several 4.0 principles.

The first conclusion of this research work is that there is a certain lack of knowledge about interoperability and interoperability management in recent research in the open literature. This is not a good signal, because air quality assurance is a public issue and the interoperability governance requirements are growing. Pilot projects should promote semantic and technical interoperability early in the project design, supported within an international system engineering framework. The re-ISSUES model proposed should be improved to detect more textual evidence to assure this conclusion, of course, increasing the literature with more repositories and textual alerts at the same time, as stated by the used methodology [15].

The second conclusion of this work is that risk-based approaches and CS are considered in research in environmental engineering and cities, respectively, allowing improvement of the re-ISSUES model with nine relevant inputs pointing to seven model elements. This is favorable because it should motivate the research community to provide expert support to public administration for public procurement of innovation processes and address the potential connection between allergies and odors with experts in this new topic.

Further steps in this work include estimating the effect of cost uncertainties on the economic model and using this sensitivity analysis to motivate specific studies and pilots attending major uncertainties and cost optimization actions. After verifying that the uncertainties do not compromise the contribution of the re-ISSSUES model to EMVS sustainability, it would be possible to extend the re-ISSUES model in terms of Sustainable Development Goals and impact analysis. Another step is to define a case study for an industrial polygon with manufacturing activities to enrich the types of assessments with an example of a recent industrial and urban decarbonization process [51]. For this, it will be necessary to assess first the convenience of professionally supervising the maintenance of thermal networks to set the basis for future maintenance of PVT installations, and for unattended thermal energy networks in Spain and other southern countries in Europe. Of course, the re-ISSUES model will be exported to interoperability formalization standard OWL2, the Web ontology language for the Semantic Web, and RDF, the standard model for data exchange on the Web, to promote semantic interoperability between different urban and industrial businesses and urban planners, and also provide a technical interoperability basis, thereby enabling the contribution of the re-ISSUES model to future EMVS sustainability.