Redesigning Energy Habits: The Role of Home Renovations in Shaping Tenant Behavior

Abstract

With an emphasis on pilots in Spain and Portugal, this study examines the connection between Efficient, Sustainable, and Inclusive Energy (ESIE) performance improvements, home renovations, and tenant/owner behavior within the framework of the FORTESIE project (CBDC-powered Smart PerFORmance contracTs for Efficiency, Sustainable, Inclusive, Energy Use). This paper investigates the relationship between tenant behavior along with energy consumption and renovation packages that also include digital technologies and energy efficiency measures. It studies the efficiency and effectiveness of the FORTESIE Common Impact Model (CIM) towards engaging homeowners/tenants, comprehending their driving forces, and implementing customized plans to encourage sustainable energy practices. This study presents applied case studies with different digital and energy literacy backgrounds and emphasizes the importance of considering elements such as cultural settings, energy poverty, and digital literacy when creating sustainable energy engagement approaches and putting them into practice. Taking into account these elements, this study investigates whether the CIM can be used effectively in diverse settings to engage with stakeholders and help create customized and appropriate energy behavior pathways.

1. Introduction

According to a 2024 report by the United Nations Environment Program [1], in 2022, 30% of the final energy demand and 37% of energy-related CO₂ emissions globally were attributed to the building sector. Additionally, the same report refers to the fact that 60% of the buildings that will exist by 2050 have not been built yet, and 20% of the existing building stock needs to be renovated to be zero-carbon-ready by 2030. In the European Union (EU), less than 3% of newly constructed buildings satisfy the maximum energy rating requirements, while 97% of older structures need to be renovated to comply with environmental regulations [2,3].

Particularly, in regard to the residential sector, the reduction of greenhouse gases (GHGs) can be achieved by decreasing the final energy use and switching to energy sources with low or no emissions [4], as it accounts for one-fifth of global energy use and corresponding greenhouse gas emissions, largely driven by increasing demand for space heating and cooling [1].

Another critical issue related to the residential sector is household energy poverty, which disproportionately impacts low-income households [5]. According to the European Parliamentary Research Service [6], 9.3% of the EU population was unable to keep their home adequately warm in 2022, 7% of the EU population had arrears on their utility bills, and in 2020, almost 15% of the population lived in dwellings with leaks, damp, or rot.

Due to the challenges presented above, various studies have recognized the potential of the residential sector for energy consumption and carbon emission reduction [4,7,8,9]. Additionally, in 2020, the European Commission (EC) launched its Renovation Wave Strategy to improve the energy performance of buildings, targeting at least double renovation rates in the following ten years and ensuring that renovations lead to higher energy and resource efficiency [10]. Moreover, the acceleration of home renovations across the EU aims to cut emissions, improve quality of life, and reduce energy poverty [11].

To this end, various Efficient, Sustainable, and Inclusive Energy (ESIE) performance improvements and renovation technologies have been identified in the literature, such as increasing building envelope efficiency that may lead to reducing domestic space heating and cooling demand by up to 60% [4,12,13], demand side management impact, as well as lifestyle modifications [14,15,16,17], and rooftop solar photovoltaics (PVs) that could potentially supply 30% of the world’s or 70% of urban households demand for electricity, also highlighting the role of prosumers [4,18].

This paper has been implemented within the framework of the FORTESIE project (CBDC-powered Smart PerFORmance contracTs for Efficiency, Sustainable, Inclusive, Energy Use), funded by the Horizon Europe Programme (Grant Agreement: 101080029), with an aim to design, demonstrate, validate, and replicate innovative renovation packages in the building industry with Smart Performance-Based guarantees and financing, aiming at ESIE use to accelerate the Renovation Wave in Europe [19].

The main objective of this paper is to present the background of the building stock and renovation technologies that are applied in Spain and Portugal and then demonstrate the relation between ESIE performance improvements and home renovations implemented in these areas within FORTESIE and the tenant/owner behavior. This paper leverages the CIM to present the user engagement methodologies developed within the framework of the project and to exhibit the role of digital and non-digital tools towards the potential redesigning of energy habits, as well as the importance of the consideration of parameters such as energy poverty, digital literacy, and energy awareness when designing and implementing engagement strategies. The case studies presented will focus on the area of the Iberian Peninsula (countries of Spain and Portugal), as the climate and architectural similarities, economic and social conditions, and cultural and historical ties allow the development of a shared approach with tailored solutions. However, in spite of this common context, the case studies are explicitly diverse, representing various levels of energy and digital literacy, further analyzed in Section 2.3 and Section 4.2. It also has to be mentioned that the aim of this paper is to present the methodological framework for redesigning energy habits through the creation of tailor-made engagement strategies that have the ultimate goal of reshaping energy behavior. Therefore, this framework will be adjusted according to the common yet diverse context of each case study, while the quantitative results will be published once the FORTESIE project ends and authors are able to provide an extensive discussion based on experimental findings.

According to the above, the underlying goal of this paper is to investigate the effectiveness of leveraging the CIM in conjunction with pilot-specific parameters to engage with potential beneficiaries and create personalized pathways for them to optimize their energy habits and consequent consumption patterns.

This paper is organized as follows. Section 1 is the introduction, and it describes the current challenges in a building’s energy use, as well as the aim of this paper. Section 2 presents a comprehensive literature review regarding home renovations in Spain and Portugal, as well as the specific home renovations that are taking place in the FORTESIE project. Section 3 includes a second bibliographic review on the role of consumer and homeowner behavior in home renovations and energy consumption. Section 4 delves deeper into the methodology that has been developed in the FORTESIE project to ensure homeowner engagement and participation, as well as the application of the methodology in different pilot settings in Spain and Portugal. Section 5 provides a discussion based on the preliminary findings of this research work. Finally, Section 6 concludes the document and offers opinions on future research pathways.

2. Literature Review

2.1. Building Stock in Spain & Portugal

In 2020, according to the Ministry of Transport of Spain [20], there were 25,712,744 dwellings in the country’s building stock, 67.9% of which were block dwellings, and the rest were single-family homes [3]. Before the Building Technical Code (CTE) went into effect in 2007, approximately 91.4% of the housing stock was already constructed [21,22]. Consequently, less than 9% of the housing stock is planned and carried out according to the energy-saving and efficiency presumptions derived from European legislation [3]. Finally, according to estimates from the Spanish Ministry of Transport [20], 58% of residential buildings in Spain were constructed before the first law imposing energy efficiency measures, while 21% of dwellings are older than 50 years [3]. In terms of energy efficiency quality, more than 81% of existing buildings are in the E, F, and G emissions categories, revealing great potential for energy renovation [23].

Following the pattern of Spain and other EU countries, Portugal’s building stock accounts for around 30% of the final energy consumption [24]. Before the EU standards for new buildings were introduced in 1990, over 66% of Portuguese residential buildings were built, while one-third of the stock of buildings constructed prior to 2012 had roofs and external facades in need of repair, resulting in low energy performance levels [25]. Additionally, Portugal ranks 5th among the countries with the largest registered number of people that could not adequately heat their homes (Bulgaria 34%, Lithuania 28%, Greece 23%, Cyprus 22%, Portugal 19%, and Italy 14%). In 2018, approximately 7.3% of the Portuguese population could not sufficiently heat their houses [26,27].

2.2. Categories of Renovation Technologies

Various studies have been conducted assessing renovation technologies and energy efficiency measures concerning domestic houses, while several of them have specifically studied the countries of Spain and Portugal. Two main typologies of energy efficiency interventions have been identified: active measures that can be applied to the active systems of the house (e.g., replacing the Heating, Ventilation, and Air Conditioning (HVAC) equipment with a more efficient one) and passive measures, aiming to improve the housing thermal insulation (e.g., windows and facades) [28]. A short review of the main technologies that seem to appear in the most recent studies (2016–2023), with an emphasis on the Iberia peninsula (Spain and Portugal) following.

To begin with, Ref. [8] reviewed 39 evaluations of 23 residential retrofit programs that incentivized whole house retrofits or improvements to the building envelope, such as attic or wall insulation, installation of storm windows and doors, upgrades to HVAC systems, and caulking or weather stripping. In a study by the authors of [28], 15 measures were evaluated to improve the thermal performance of the envelope in a case study of a social housing neighborhood in Braga, Portugal. The interventions considered included facades, sloped roofs, thermal bridges, and windows, while five new systems were also designed to meet the need for hot water and space heating and cooling. In another Portuguese case study [25], a single dwelling with no insulation, built between 1961 and 1991, was selected as a case study, while various retrofitting strategies were simulated, extrapolating the results to encompass 15,000 dwellings of the same typology in the same area. The retrofitting strategies included the replacement of lighting systems, the application of three types of insulation systems with different thicknesses, and three types of space heating appliances. In 2016–2017, a survey was conducted on a group of 57 Portuguese homeowners of single-family houses regarding the home-related practices and social perspective of energy-related renovation of private homes [29]. The principal renovation works adopted by the homeowners included the replacement of the water heating system, windows replacement, roof/attic insulation, replacement of the air heating system, adoption of renewable energies, wall insulation, and cellar insulation. The authors of [4] used the TIMER energy system model to capture the different energy use characteristics and investment motivations of 260 representative households. The model included four key additions important in determining the energy demand reduction and emission mitigation potential of the residential sector, namely the insulation of the residential stocks, the heating and cooling technologies, and the potential of rooftop photovoltaics. Another study [5] collected data from 15,000 participants of an online survey in eight EU member states, including Spain, in order to analyze adoption rates of high, medium, and low-cost energy-efficient technologies. The study’s dependent variables involved implementing retrofit measures (including insulation of roof or ceiling, insulation of exterior walls, insulation of basement, installation of double-glazed windows, or installation of triple-glazed windows), acquiring new appliances (refrigerator, freezer, dishwasher, and washing machine), and installing new light bulbs. In another study, single-family and block houses constructed during 1980–2007 in Spain (where single-family and block houses correspond to 45% of the total housing stock) were assessed and characterized for energy retrofitting purposes due to their high energy saving potential [3]. In regard to the study’s improvements, those concerned were the thermal generation systems and the building’s thermal envelope. Furthermore, the authors of [30] introduced another Spanish case study by analyzing and comparing the effect of alternative retrofitting strategies on thermal energy services’ affordability in more than 1,000,000 vulnerable consumers. The implemented measures involved included low-cost thermal enclosure retrofitting measures and outdated thermal systems replacement (heating and domestic hot water (DHW) systems and cooling systems). Finally, in 2016, other research in Spain [31] studied the possible intervention scenarios based on the building stock segmentation and the actual energy consumption data. The proposed measures were related to the refurbishment of the building envelope and particularly focused on increasing its insulating performance. Namely, the classification entailed improvements in windows, improvements in roofs, improvements in facades, and combinations of the previous improvements. As the authors mention in their results, the simplest energy-saving measure with the highest potential is the improvement of the façade, having an impact of 27–39% on energy savings.

2.3. The FORTESIE Renovations

As previously mentioned, FORTESIE is a project that aims to accelerate the Renovation Wave in Europe by designing and demonstrating innovative renovation packages in the building industry with Smart Performance-Based guarantees and financing. The renovation packages combine state-of-the-art construction materials and technological components, innovative digital technologies for measurement and verification, and attractive financing to raise the overall Energy Performance Certificate’s (EPC’s) value proposition [32]. FORTESIE renovation packages are demonstrated in 10 pilot cases across 7 countries, including Spain and Portugal. In particular, the presented case studies are both relevant and diverse enough to show the influence of energy and digital literacy on engagement. On the one hand, they share a common climate and architectural background, as well as socioeconomical similarities, but on the other hand, their target groups significantly vary in terms of energy and digital literacy (e.g., two Spanish case studies targeting elderly people with very low energy and digital literacy, a Portuguese case study targeting energy prosumers with high energy and digital literacy, and another Portuguese case study targeting vulnerable energy poor households with no energy and digital literacy).

In Spain, two FORTESIE pilots are involved. One pilot conducts renovations in single-family homes in apartment blocks, and the other one leverages the FORTESIE digital tools in a residential area, where some of the buildings have been renovated in a previous project and now execute EPC contracts, which will be executed in digital form to validate the EPC digital module and mobile application of the project. A total of 36 housing units in El Entrego, Asturias, Spain (Garcia Rama pilot), and 20 buildings in a district called FASA, located in the southeast of Valladolid (Veolia pilot), respectively, are involved.

In regard to the housing units in Asturias, they were constructed in 1958 and suffer from inadequate thermal insulation and thermal bridges, causing heat loss and issues like condensation and lack of indoor comfort, also resulting in high energy demands. Their envelopes have pathologies due to age and inadequate maintenance and they lack sufficient acoustic insulation. The planned renovations include insulating the building facades and under-roof space, replacement of windows in staircases and entrance doors of the buildings, and installation of Photovoltaic (PV) panels with an annual production of 33.000 kWh/year in each building. The renovations will be funded by the property owners, while FORTESIE will finance the sensor purchase that will monitor the house’s improved conditions.

In FASA, the buildings were constructed in the 1950s and 1960s, while all of them, except one, were renovated in 2018. The renovations incorporated elements such as new biomass boilers and new District Heating (DH) network, new substations, new District Energy Management Systems (DEMSs), Building Energy Management Systems (BEMSs), and Home Energy Management Systems (HEMSs), roof and façade buildings retrofitting, and Light-Emitting Diode (LED) lighting in the common areas. The main purpose of the pilot is to measure improvements achieved through the 2018 renovations by comparing measurements between the renovated buildings and the non-renovated building, therefore also assessing how digital tools assist in establishing and promoting long-lasting, sustainable energy habits that lead to reduced energy consumption in the residential sector.

In Portugal, two FORTESIE pilots will renovate the homes of people who suffer from housing deprivation and energy poverty and houses of prosumer members, respectively. The first Portuguese pilot includes ten (10) energy poverty, old residential buildings owned by the beneficiaries as family heirlooms (Just a Change pilot). The houses are typically built of masonry, with wooden floors and tiled roofs, and they have several deficiencies, such as leaky roofs, rotten floors, inadequately insulated walls, etc. The renovations, completely financed by the FORTESIE project, provide basic structures such as roofs, flooring, façades, insulation, doors, and windows, and PV installations while also addressing other basic needs such as piped water and electricity in those houses that are not connected to the grid.

In the second Portuguese pilot, 10 residential, single-family, prosumer houses in different regions of Portugal, including Lisbon and Porto, will be renovated to demonstrate how house renovations can bring improvements to energy efficiency and overall quality (Coopernico pilot). The selected houses are aged 15 years or more and have not benefited from energy efficiency renovations, except for two houses, one built in 2007 and one in 2019. Houses that benefited from some renovation work were also selected in cases where improvement measures implemented in the past proved to be insufficient. The renovations that will be financed by the FORTESIE project will mostly focus on passive measures, such as placing thermal insulation in the external envelope or replacing windows and doors.

According to the above, it becomes obvious that FORTESIE follows the most recent trends regarding renovation technologies, as both passive and active measures have been adopted in Portugal and Spain. The renovation’s impact on the project’s implementation, in terms of actual energy consumption, as well as regarding the engagement of homeowners and their adoption and/or redesign of sustainable behaviors, while considering the increasing role of digital solutions of energy poverty and prosumers, is examined. However, to promote sustainable practices and ultimately contribute to a more energy-efficient and sustainably built environment, one must understand consumer behavior, as it directly impacts consumer decision-making (on the adoption of suitable new technologies), energy-saving behaviors, and the design of effective policies and regulations.

3. The Role of Consumer Behavior in Renovations and Energy Consumption

The reduction of electricity consumption and GHG emissions from the residential building sector is most effectively achieved via a combination of renovation technologies (active and passive) and through the adoption of more sustainable energy habits by the tenants of the renovated houses. While the actual savings that are achieved via behavioral changes are difficult to quantify, it is a fact that they can further the agenda towards carbon neutrality [33]. As pertains to the behavioral parameter in energy sustainability, there are two main areas of research; firstly, what behavioral factors influence homeowner renovation decisions? Secondly, which factors motivate and affect sustainable behaviors?

In general, regarding the drivers of occupant behaviors, personal comfort seems to be one of the key factors as it affects the occupants’ health, well-being, and productivity. However, personal comfort is perceived differently by different individuals depending on various factors such as background, wealth, age, etc. These factors also affect how a person should be engaged and steered towards sustainable energy habits, but there is no horizontally accepted way to group and categorize occupants [34]. Another issue to consider here is how these individual preferences and personality traits interconnect and are affected by economic, political, institutional, legal, technological, social, and cultural factors [35]. For example, in countries with a higher technological penetration level, building occupants would be less resistant to renovating their homes with smart appliances and use them effectively. Similarly, in less developed countries, building occupants do not have the same monetary means to perform meaningful renovations. In addition, previous research [36] has shown that there are certain personality traits, such as altruism and environmental values, that would make it more likely for building occupants to perform renovations or modify their energy behaviors. However, oftentimes, such personality traits do not lead to sustainable actions due to a lack of suitable background and relevant policies that may incentivize them [37]. Similarly, there are certain traits that can negatively affect energy renovations and sustainable behaviors, such as procrastination, negative attitudes, or experiences from past renovation efforts [38]. Based on these sources, it becomes evident that it is very challenging to categorize occupants in order to create appropriate pathways for optimizing their energy behavior, given that the parameters that would need to be taken into account are many and often heterogeneous. As such, a potential solution is to use parameters such as the levels of energy and digital literacy to create categories of occupants and action plans and enrich/personalize these plans by taking into account the specificities of each pilot setting as well as cultural and socioeconomic factors, and personality traits that affect energy behaviors.

On what affects renovation decisions, Ref. [39] researched the factors that might motivate Dutch homeowners to perform certain home renovations. The authors showed that, in many cases, the most important factor in performing certain renovations is the building itself. In fact, homeowners living in buildings with a higher energy class (A or B) are more likely to perform certain renovations, while personal factors did not affect the decisions as much. On the other hand, the authors of [40] showed that several behavioral factors, such as knowledge and awareness, along with social norms, do, in fact, affect decisions about energy renovations as well as energy consumption patterns. The authors performed a study in Spain and the Netherlands and also showed that education level is integral in making more sustainable decisions. Specifically for PVs, the authors of [41] leveraged a survey performed in Italy and Spain and showed that policies and monetary incentives play a major role in shifting the perspectives of householders towards solar power. This agrees with [42], where the authors surmised that suitable policies and governmental support are key in overcoming behavioral barriers (lack of knowledge and awareness) that inhibit the development of more positive energy districts in Spain.

Based on the above, one can conclude that while sustainable home renovations are indeed affected by personal and behavioral factors, financial incentives and policy support are essential to motivate homeowners and tenants. However, occupant behavior is also essential in optimizing energy consumption and the internal conditions of a house. Concerning internal conditions, the most important ones that are also measured by most commercial sensors are CO₂ levels, humidity, and temperature. Research conducted in Spain [43] showed that occupant behavior greatly affects air quality. While most participants were aware of the need to ventilate their houses, the choice to ventilate was also dependent on weather conditions, given that the choice to ventilate a house by opening a window also affects energy and heating efficiency. To overcome this, the authors suggested that mechanical ventilation could improve air quality, at least for months with colder temperatures. In the case of Portugal, the authors of [44] argued that energy literacy is a major factor affecting efficient consumption and environmentally friendly choices. The authors showed that energy literacy can oftentimes improve with age, while level of education, financial knowledge about energy prices, and living in one’s own house can also contribute towards a high level of energy literacy. Concerning the role of education, the authors of [45] performed a survey with higher education students in Portugal. Most students proved to be environmentally conscious and have adopted sustainable practices (energy reduction, recycling, etc.), but they also believe that secondary education should better educate students about the environment.

As shown in the previous paragraph, environmental education is critical in shaping environmentally conscious people who adopt more sustainable behaviors. However, reshaping education in various countries to be more inclusive towards sustainability is policy-driven, requires time to materialize, and has an effect on energy consumption patterns. A solution that is on the rise in the respective literature combines smart applications, Internet of Things (IoTs) devices, data analytics, and algorithms to produce suggestions and recommendations that can optimize energy consumption as well as a house’s internal conditions. This approach can overcome many of the issues and barriers related to promoting energy sustainability among consumers and instead promote the financial benefits and improved house conditions as selling points. Several publications have proposed and tested such solutions by combining personal and house data about user preferences and patterns of consumption, weather data, and energy-efficient recommendations that are tailored to the users’ preferences with encouraging results [46,47,48]. Such advanced solutions can also put the suggestions automatically into effect, thus alleviating the overhead of informing and convincing users about each suggested change.

This is also the approach that the FORTESIE project is following. In FORTESIE, the buildings in the various pilot settings are being renovated and equipped with smart IoTs devices that will gather and analyze consumption patterns. A mobile application is in development, and data analytics will be combined with decision support to offer personalized recommendations to occupants/tenants about how to reduce their energy consumption and optimize internal conditions.

4. The FORTESIE Approach to Redesigning Habits

4.1. Theoretical Background

To achieve its engagement goals and drive behavioral change while enhancing energy habits, the FORTESIE project leverages the Common Impact Model (CIM). The CIM was initially designed to foster community acceptance of local energy solutions in the European Horizon2020 project, E-LAND (Grant Agreement No. 824388) [49]. In FORTESIE, this model was adapted, shifting the acceptance focus from the community to the individual level. Through this individualistic lens, the main aim is to reshape personal energy consumption habits through household-level renovations and the integration of smart technologies. The model aims to change the behavior of tenants and homeowners by empowering residents with tailored knowledge and resources that directly address known barriers to adoption and participation.

The CIM offers a structured approach designed for those with ambitions to implement home renovations or energy efficiency programs in buildings and households. Among the goals of the model, related to the pilot cases of FORTESIE, are the following:

• Understand which motivational factors influence homeowner/tenant renovation and energy-saving behaviors and decisions;
• Assist in the development of digital personalized content that will drive behavioral changes such as gamified challenges, quizzes, tips, and advice, namely the FORTESIE application’s recommendation engine;
• Help in the development of a strategy to engage residents in renovation and energy-saving initiatives in a way that aligns with the tenant’s/homeowner’s values and priorities, taking into account the perceived benefits and concerns of these residents.

The model (Figure 1) is structured around three key phases, data collection, analysis, and engagement strategy development, each of which plays a critical role in facilitating acceptance and behavior modification at the individual level. In each phase, the process is coupled with a complementary toolbox designed to support the facilitation and dissemination of the CIM approach.

The first phase of the CIM focuses on collecting data about individual household’s current energy practices, attitudes toward renovations, and perceived barriers to energy-efficient behavior. Data collection is primarily conducted via questionnaires and interactive workshops with local partners structured around three modules: technological, cultural, and theoretical scope. The technological scope examines baseline aspects of each home, such as its energy consumption patterns, renovation needs, and availability of sensor data (e.g., room temperature, humidity, CO2, energy consumption, etc.). The cultural scope refers to mapping the profiles of residential users, including the characteristics that influence an individual’s acceptance of energy solutions, such as energy and digital literacy, energy poverty, values, lifestyle, and emotional and rational responses to proposed changes. Finally, the theoretical scope refers to specific use cases and implementation goals for the renovation and digital energy services to be introduced to homeowners/tenants.

During the 2nd phase of Analysis, the gathered information undergoes strategic analysis to extract insights into how individuals perceive and react to renovation technologies. This analysis phase aims to build detailed profiles of tenants and homeowners, providing a nuanced understanding of their motivations and obstacles. The analysis phase is based on the user requirements methodology developed in the H2020 MATRYCS project [51]. This methodology defines target groups, use cases, personas, and user stories to segment participants according to their readiness to adopt sustainable energy behaviors.

Target groups, defined in FORTESIE as the potential users (beneficiaries) of the renovation technologies and services are identified by mapping different user roles (e.g., ESCOs, residents, public authorities, etc.) onto a matrix connecting individuals to the roles. This allows for a jointly agreed nomenclature to be defined, as well as a high-level view of the capabilities of the local partners and participants. After defining roles and target groups, basic characteristics and objectives related to the desired renovation or energy efficiency program are described. This includes general objectives and metrics to determine if the service(s) deliver on the user’s goals. Next, personas, defined as fictional characters created to represent the needs, wants, and behaviors of the target groups, ensure various perspectives are considered, capturing the different viewpoints within each target group. User stories are then created for each persona to link the tailored information with potential services in each pilot. This analysis can then be summarized into user templates for each persona, which can be easily disseminated to local partners to ensure alignment and serve as quick reference points for engagement action design (refer to Section 4.2.1 for a practical example).

The final third phase involves the co-creation and development of a targeted engagement strategy. The engagement strategy is developed based on the insights from the first two phases and is tailored to address the specific motivations, concerns, and behaviors of the residential target groups. The engagement strategy is two-fold, combining the digital content delivered via the FORTESIE application’s behavior and recommendation service and traditional non-digital interactions and activities.

The digital behavior and recommendation service is being developed to provide tailored, user-centric content designed to support intentional behavioral changes. This digital service, targeting homeowners and tenants, aims to improve energy literacy, maximize the benefits of home renovation, and support energy-saving behaviors through interactive quizzes designed to increase user knowledge and understanding of concepts (e.g., energy baselines and comfort factor indicators) and gamified challenges. Each of these content categories is coupled with complimentary tips, advice, and recommendations designed to provide tailored support to users as they navigate new home energy and renovation information.

Complementing the digital services, non-digital engagement actions are also developed under phase 3. The goal of these plans is to build community support and end-user satisfaction by involving the end-users in the decision-making process, addressing users’ concerns, and helping them understand the benefits and long-term value of the renovations. These plans include activities such as feedback surveys, interviews or focus groups, events, communication campaigns, educational sessions, and community/building meetings. This holistic approach of including digital and non-digital channels allows for a more robust engagement strategy that may have wider success when targeting a broad range of target end-users. The goals and implemented activities of FORTESIE’s overall engagement strategy can be seen in

Table 1. Methods of End-User Engagement in the FORTESIE project.

Service	Format	Goals	Functionalities/Activities
Βehavior & Recommendation Service	Digital	Improve energy literacy Maximize home renovation benefits Support energy-saving behaviors	Interactive quizzes, Gamified challenges Tailored tips & advice
On-site engagement	Non-digital	Build community support and end-user satisfaction Involve end-users in decision-making Address user concerns Help users understand renovation benefits	Feedback surveys, interviews, focus groups Communication campaigns Educational sessions Community/building meetings & events

below.

Phase 3 is inspired by the plan-do-check-act cycle, which is in line with the ISO 14001 [50] environment management systems standards. As such, the CIM as a dynamic model specifies that phases 1 and 2 should be periodically repeated, given that the homeowner’s and tenant’s behaviors, attitudes, and knowledge evolve over time, to ensure that the changing dynamics of the end-users are captured and factored into future engagement recommendations. An important aspect of this cycle is the evaluation of engagement success via tailored KPIs. In FORTESIE, these metrics have been developed to include a range of data points, including user feedback surveys, digital application analytics, and sensor data. Together, they provide a holistic evaluation of multiple layers of engagement and participation (e.g., satisfaction, behavior, energy savings). The evaluation KPIs, including the target value and the relevant data sources, can be seen in

Table 2. CIM evaluation KPIs (phase 3).

KPI	Target	Data Source
Improvement of perceived comfort	Improvement from baseline	User feedback survey
Satisfaction with FORTESIE renovations	>75% of end-users find the renovation recommendable or highly recommendable.	User feedback survey
Satisfaction with FORTESIE digital services (mobile app/OSS marketplace)	>75% of end-users find the solution recommendable or highly recommendable and the solution feasible for future deployment	User feedback survey
Level of engagement in the FORTESIE app	>75% of target groupof each pilot case download the FORTESIE app	App analytics
Amount of Green Euros awarded for the pilot	The amount will be dependent on the exact implementation of the Green Euro in the FORTESIE app	App analytics
Sensor acceptance	100% of users consent to sensor installation in their home	Signed consent form

below.

At the time of writing, directional findings can already be described for two of these KPIs. Regarding satisfaction with FORTESIE renovations, early anecdotal feedback has indicated a moderate to high level of satisfaction from residents. This directional trend will be confirmed and validated in the project with a user feedback survey. Related to the acceptance of sensors KPI, 80% of targeted residents have signed consent forms to have sensors installed in their homes. Work is now ongoing to gain sensor acceptance for the remaining 20% of residents. KPI results for the remaining evaluation metrics will be collected in the final stages of piloting and reported on in future publications.

4.2. Pilot Applications—Engagement Narratives Case Studies from Spain & Portugal

The case studies from the Spanish and Portuguese pilots represent real-world examples where the CIM methodology has been applied to build and adjust engagement strategies to fit the unique end-user profiles of each pilot context and their evolving needs.

With the following use case examples, the varying levels of digital literacy, as a thread, have been identified, which can be understood as a spectrum. On one side, there is the digitally mature case of Coopernico, where prosumers as a target group are placed with a higher level of technical literacy. In the middle stands the Spanish pilot cases of Veolia and Garcia Rama, where the tailored approach to the engagement must take into consideration the limited technical skills and knowledge of elderly beneficiaries. Lastly, on the other end of the spectrum is the second Portuguese pilot of Just a Change, where the beneficiaries are a specific vulnerable, energy poverty group, where the digital focus does not apply at all. The full spectrum can be seen in Figure 2 below.

The literature highlights the growing deployment of digital services (such as data analytics, smart applications, IoT devices, etc.) to contribute to energy efficiency in residential buildings, especially related to innovative renovations [52]. However, it is evident in the FORTESIE project that the success of these technologies depends heavily on the residents’ ability and willingness to interact with digital tools and understand their value. Therefore, digital literacy, defined as the ability to effectively use digital (computers and/or software) technologies to access, manage, and evaluate information, becomes a crucial factor to look at in this context [53].

Table 3. Summary of pilot engagement strategies.

Pilot	Target Group	Digital Literacy	Energy Literacy	Digital Strategies	Non-Digital Strategies
Portugal (Coopernico)	Digitally mature prosumers	Mid to High	Mid	Behavioral recommendation services Gamified challenges Quizzes	Home visits Newsletters Printed materials Meetings
Spain (Garcia Rama & Veolia)	Elderly residents	Low	Low	Limited digital content Accessibility settings	Persona analysis Community outreach Face-to-face workshops
Portugal (Just a Change)	Vulnerable groups	No device access	Low	None	Community-driven renovations Printed materials

below summarizes the levels of both digital and energy literacy levels of each pilot, as well as the corresponding engagement strategies in digital and non-digital contexts.

At this point, and before proceeding to the case study’s empirical analysis, it is important to mention that target groups in all pilot cases consented to their data processing, according to the General Data Protection Regulation. In particular, all participants were informed that the data that will be processed and further analyzed for research within the FORTESIE project is name, surname, gender, age/date of birth, physical address, telephone number, e-mail address, perceptions of indoor conditions at home, satisfaction with the renovations, opinions on the engagement activities of FORTESIE, fossil energy consumption data, Energy consumption baseline data, live energy consumption and behavioral data collected via sensors and the mobile app, building data about a specific building (size, appliances, energy consumption, etc.), household typology, nr floors and area, geographic region, hours spent at home, the gas user (Y/N), types of electrical appliances and heat/cooling systems and frequency of use, energy performance certificate, household annual income, household plans, PV registration, Building official registration and ID, pictures and metric measures of the house, etc.. No sensitive data (such as data related to health) are collected, while participants were also informed that wherever feasible, data will be anonymized or replaced with mock-up data for the testing of the systems, while in other cases, it will be securely pseudonymized so as to avoid identifying the relevant participant.

4.2.1. Digitally Mature Prosumers (Coopernico Pilot)

The Coopernico pilot in Portugal focuses on renovating the homes of prosumer residents —individuals who both consume and produce energy. The CIM data collection and analysis phases revealed that the end-user group in this pilot was, in fact, quite diverse, meaning the engagement strategy had to cater to a broad group in relation to age, income, and family type. Additionally, it was concluded that the energy literacy levels of the homeowners ranged from highly knowledgeable prosumers (‘informed prosumers’) to those with relatively limited knowledge of optimizing PV production systems (‘uninformed prosumers’). With this understanding, user templates were developed for each persona, as illustrated in

Table 4. Summary of customized user template for the Coopernico ‘Informed Prosumer’ user.

Coopernico Pilot (Portugal)
Use Case		Increase Energy Efficiency and Savings in Prosumer Households
Target group		Prosumers living in a single-family household
Personas		Informed Prosumer Uninformed Persona
Informed Prosumer	User context	Prosumers with a high level of energy-saving knowledge and are interested in increasing the savings of self-generated production. Most in this group have a mid to high level of digital literacy, with access to digital devices. This large group includes prosumers who are mindful of the value generated by self-production and try to optimize self-consumption, whether by reducing the energy necessities of the house or by finding when to heat the home when the energy cost is lower.
	Pain points	Do not have the knowledge or financial capacity to invest in energy renovation techniques. Do not have the knowledge regarding when to heat the house. Do not have access to the best energy-efficiency renovation methods. Distrust to acquire alternative financing schemes
	Goals	Improve self-generated saving by reducing the house consumption. Increase thermal comfort and living conditions in the households. Improve knowledge regarding energy efficiency measures in households. Gain knowledge regarding which renovation techniques and financial ways should be invested.
	User stories	As an informed prosumer, I want to know about financial models regarding energy efficiency interventions so that I can understand how to invest in future renovations. As an informed prosumer, I want to increase my knowledge of energy efficiency measures so that I can know when I should heat my house.
Uninformed Prosumer	User context	Prosumers have limited to no knowledge regarding the energy they produce, only knowing that their photovoltaic systems have the potential to generate savings. Most in this group have a mid to high level of digital literacy, with access to digital devices. Most of these prosumers live in houses that are very energy inefficient.
	Pain points	Have limited to no knowledge when it comes to combining their photovoltaic installation with the comfort of their home. Do not have the financial capacity to invest in energy renovation techniques. Do not have access to the best energy-efficiency renovation methods.
	Goals	Improve self-generated saving by reducing the house consumption. Increase thermal comfort and living conditions in the households. Improve knowledge regarding energy efficiency measures in households.
	User stories	As an uninformed prosumer, I want to improve the energy efficiency of my house to reduce energy consumption and, consequently, the energy bill. As an uninformed prosumer, I want to increase my knowledge of energy efficiency measures so that I can improve my PV system performance.

. These templates enabled the formulation of tailored engagement and content plans for each group, thereby increasing the likelihood of fostering sustainable energy behaviors through customized approaches.

Based on this understanding, the starting point of the engagement strategy work (phase 3 of the CIM) was to establish a common basis of energy literacy understanding across the target group. This was performed by offering personalized, one-to-one home visits to consult with homeowners and tenants about the work to be performed in their homes, both in terms of the renovations and the behavioral changes needed to support the energy efficiency optimization.

Once local renovation organizers were satisfied with the baseline understanding of the homeowners, the engagement focus was updated to a broader communication campaign, including newsletters, social media items, mailing lists, and online meetings to provide homeowners with information and updates at regular intervals to deepen their understanding of the ongoing project work.

The next engagement step included the introduction of digital engagement content via the FORTESIE application’s behavior and recommendation service. Because of the higher levels of energy literacy among this prosumer group, which had been further enhanced by previous engagement actions, the development of the digital content for this pilot focused on gamified challenges and quizzes that leverage the relatively mature digital and energy literacy among the target group. For example, ‘energy baseline challenges’ are shaped to challenge homeowners to use comparatively less energy for a fixed period of time (e.g., a month) relative to their historical consumption baseline average. If successful, end-users will be rewarded with monetary ‘Green Euro’ incentives. Similarly, quiz questions will be sent to homeowners via the FORTESIE application to test their understanding of their home’s energy production and consumption patterns and related optimization behaviors. For example, using personalized data, homeowners will be quizzed on how much energy the home produces or consumes each month and which actions they could adopt to maximize their PV system’s efficiency. By participating in the quizzes, homeowners will again be rewarded with monetized Green Euro incentives. This gamified digital content has been designed to enhance knowledge levels and empower homeowners to make informed decisions related to business renovations and meaningful behavioral changes to optimize their home’s energy consumption.

To enhance clarity on practical applications,

Table 5. Examples of digital content within FORTESIE behavioral and recommendation service (Coopernico Pilot—Portugal).

Category/Type	Examples
Quiz	Time to test your knowledge. Here’s today’s quiz: How much energy does your building produce in a year through the PV panels?
Quiz	Here’s today’s quiz: What can you NOT do with the energy produced by PV panels in residential buildings? (A) Sell the electricity back to the grid (B) Operate high-power appliances solely on solar energy (C) Save it and use it later
Quiz	Time to test your energy consumption knowledge. Here’s today’s quiz: How much energy does your household consume in an average day?
Monthly challenge	Your monthly report card: Excellent habits! || On average, your household comfort price is now <VALUE_comfortprice>. Last month, the comfort price was above this at <VALUE_comfortprice_difference>. This means that you’ve improved your energy efficiency without sacrificing comfort. As a reward for your efforts, you’ve earned <NUMBER> €Gs. Keep up the good work!
Monthly challenge	Your monthly report card gives you information on your comfort price progress. If you’re able to keep your comfort price below your monthly baseline level, you’ll be rewarded with €Gs.

below presents a detailed case study from the Coopernico pilot, showcasing specific engagement items from the digital component (resident app with FORTESIE behavioral and recommendation service). This case study serves to illustrate the practical implementation of the proposed methods, highlighting various types of digital content used to engage residents and demonstrating the interactive and educational features designed to promote energy efficiency.

As previously mentioned, the CIM is an iterative framework. Therefore, the next steps in terms of the engagement work for the pilot include monitoring and validating the effectiveness of the digital content in terms of driving participation and adoption of the renovation programs. This comes with the expectation that the resident’s needs and interests will change and evolve over time, and with it, so too should the supporting engagement actions. The progression of engagement strategies for the digitally mature prosumers of the Coopernico pilot is depicted in Figure 3.

4.2.2. Tech-Avoidant Beneficiaries (Garcia Rama and Veolia)

The Spanish pilots provide an example of an engagement strategy designed for a target group with limited to moderate digital and energy literacy. Despite differences in building infrastructure and renovation needs, both pilots in Spain share a demographic profile with a large proportion of elderly residents. During the pilot scoping and analysis work, it became clear that engaging this target group would pose a significant challenge due to their limited understanding of renovation and energy solutions and varying levels of trust and motivation to adopt digital solutions. Many of these homeowners have limited access, understanding, and/or technical skills to digital services and tools, which calls into question how these can be utilized effectively in this pilot.

To begin the process of tailoring the engagement strategies to address the variability among the group in terms of comfort with digital tools and energy programs, workshops were organized with local pilot partners to take a deep dive into the homeowner profiles and unpack the contextual details of the building environment. A persona analysis framework was applied to the outputs of the workshop to define fictional characters to represent the needs, wants, and behaviors of the different subgroups existing within the larger homeowner population. As a result, three core persona groups were identified (

Table 6. Description of persona profiles.

Persona	Goals/Concerns	Engagement Needs
Motivated owners	Values energy efficiency Contribute to community goals Trusts expected benefits	Recognition to encourage broader participation Community support
Disbelieving owners	Skeptical Concerned about high costs	Clear evidence of benefits Building trust through community leaders
Indifferent owners	Uninterested in energy issues Lacks awareness	In-person outreach Education and simple, direct information

): motivated, disbelieving, and indifferent owners. From this initial analysis, a preliminary strategy for each persona was set to build trust levels and decide on the most appropriate digital content (if any) to be delivered to homeowners.

Motivated owners were defined as residents who recognize the importance of energy efficiency and are willing to participate in initiatives that promote energy consumption analysis and efficiency. Their primary goals include improving the value of their buildings through energy-efficient measures and encouraging others to adopt similar practices. They play a significant role within the community by sharing the benefits of energy efficiency and trusting the expected positive outcomes, such as reduced energy bills.

Disbelieving owners, on the other hand, were characterized by their skepticism toward the benefits of energy efficiency measures. They often view such initiatives as marketing strategies rather than beneficial interventions. Their main concerns are related to the initial investment required and the reliability of projected savings. These owners need substantial evidence to be convinced of the real advantages of energy efficiency improvements.

Indifferent owners are those who show minimal interest in energy consumption, emissions, or comfort and thus require more engagement effort to understand the benefits of energy efficiency measures. These profiles collectively present a challenge for engagement strategies in the Spanish pilots, necessitating tailored communication and educational efforts to address the specific needs and concerns of each group.

The disbelieving owners were viewed as the most challenging group to involve in the project and, therefore, became the primary focus of the initial engagement work. To address this group’s skepticism, external stakeholders and community leaders, such as the chair of the homeowners’ association and the property manager, were recruited by the local project partners to act as key intermediaries, bridging the gap between the project team and the residents. By training these well-known leaders on the FORTESIE project and its benefits, challenges can be overcome through trusted local representatives who can advocate for the digital tools within their community, as well as the satisfaction of the neighborhoods.

Pilot representatives have also leveraged the community leaders to address the indifferent owners group. To ensure a low friction entry point for the project, communication with residents was initiated through non-digital, face-to-face approaches. As an example of this approach, beneficiaries were invited to listen to presentations held on-site at the buildings, where the project benefits for residents were explained. Another example includes the dissemination of printed materials that explained relevant details of the project better to deepen residents’ understanding for informed decision-making. These approaches aimed to invite beneficiaries to participate in the project by opting into the deployment of measurement devices in their homes. Resident’s motivation to onboard this stage is crucial to the success of the project, as a lack of measurement deployments also means that they are unable to participate in other digital solutions, such as the use of the FORTESIE application, as that component depends on data from the sensors.

The engagement work in the Spanish pilots is still ongoing. Above, several of the initial efforts made to address potential concerns of residents to build support buy-in to the FORTESIE project have been described. However, there is still significant work ahead, especially in onboarding more beneficiaries to the deployment of sensors and refining the digital engagement strategy. Initial work in this direction has concluded that digital tools and services must be supported by a simple user interface with robust accessibility settings (e.g., font size, color contrast, etc.) to create a frictionless user experience. In terms of digital content, extra emphasis will be placed on providing tips, advice, and explanations to support decision making. Additionally, before/after features are currently being explored, which would allow residents to compare the difference in energy use and comfort in renovated and non-renovated buildings. This is to highlight that these homeowners can benefit and learn just as much from the insights presented to them about their indoor conditions, energy savings, and consumption if they are performed in a way that fits their digital skills.

Given the challenges of developing an inclusive engagement strategy that caters to a largely tech-avoidant population, it is particularly important that an agile engagement model, like CIM, is used to ensure small steps can be taken, evaluated, and refined to slowly guide the target group towards adoption of the renovation programs, as seen in Figure 4 below.

4.2.3. Community-Centric Transformative Renovations (Just a Change)

The second Portuguese pilot, led by Just a Change, can be seen as an example of how engagement strategies must, sometimes, move beyond digital solutions to achieve meaningful social impact. This pilot focused on renovating homes for people suffering from energy poverty and serious structural deficiencies, evoking safety and health concerns. Given the vulnerable nature of the beneficiaries, the engagement strategy was deeply personal and community-oriented.

Volunteers played a crucial role in this pilot, not only in carrying out the renovations but also in building relationships with the beneficiaries. The renovation process was designed to be an empowering experience, involving the beneficiaries in decision-making and, where possible, in the renovation work itself. This hands-on approach fostered a sense of ownership and pride among the beneficiaries.

Challenges included managing the logistics of volunteer work and ensuring that the renovations met the standards set by the project. However, the personal engagement and community spirit that defined this pilot is intended to lead to transformative outcomes.

In this pilot, the decision to fully move away from digital solutions came more easily, as it was evident from the beginning that it did not constitute a fitting solution for these beneficiaries. Some homeowners do not have mobile devices to begin with, while digital literacy levels are also an occurrent concern. Therefore, the project team concluded after several discussions that any kind of digital services would have been set up for failure in terms of engagement levels. Instead, the deployed sensors in these houses will feed data into the analytics components of the FORTESIE digital application to create useful analyses and visualizations. These results will be communicated by the pilot leaders to the homeowners periodically in an easily digestible way that does not require high or even basic levels of digital literacy. The engagement strategies for the beneficiaries of this pilot can be seen in Figure 5 below.

5. Discussion

Engaging individuals in sustainable energy practices is a multi-dimensional challenge requiring diverse and innovative, as well as adaptable strategies. We propose that the iterative application of frameworks like the CIM, combined with experimentation and evidence-based refinements, can offer a possible path to create scalable energy engagement strategies. In the current section, we discuss the effectiveness of the CIM in creating personalized energy behavior pathways and addressing the diverse needs of users based on its implementation thus far in the context of the FORTESIE project.

The CIM provides an excellent foundation to start generating energy behavior pathways based on initial groupings of users. These groupings are defined based on the energy and digital literacy of the users, two parameters that greatly affect the communication and engagement material that will be used to make initial contact with occupants. The question that arises from this process is, “What material should I generate to engage with users (depends on their energy literacy), and how will this material be communicated to them (depends on digital literacy)?” This first step of the methodology leads to the creation of baseline engagement material that can be horizontally applied to many different users. In FORTESIE, this step was quite successful as most homeowners who were approached and engaged with this material agreed to participate in the next part of the experiment (downloading the FORTESIE application and using it to get recommendations). The only disadvantage was the inability to convince elderly users who were not willing/able to install sensors and participate in the application part of the project.

The challenging part, of course, remains the task of personalizing this material as well as the specific energy behaviors that are proposed based not only on energy and digital literacy but also on parameters such as weather patterns, house equipment, previous renovations, national laws, energy prices, cultural factors, etc. which greatly affect consumption patterns and energy behaviors. Based on our experiences from the FORTESIE project, it is very difficult to automate this step in a way that alleviates the extra effort that is required. The reason for this is that specific suggestions that might be generated from the CIM (e.g., opening your house windows at regular intervals during the day to lower the CO₂ levels of your house) do not have the same application in all cases. As an example, based on discussions with the project’s Portuguese pilots, one of the main issues that they face during cold months is very high levels of humidity to the point that it is now a national law in Portugal that all houses must have built-in ventilation. This means that a suggestion to a Portuguese homeowner to open up their windows would not be as effective, as it would bring in the house a lot of humidity, which would, in turn, require more energy to lower back to normal levels. However, the suggestion would still be fair for a Portuguese homeowner who does not have house ventilation despite the regulation (such regulations are usually slow to be in full effect due to the old building stock, lack of economic incentives, etc.). This homeowner would still require more energy to lower the humidity but would also learn the importance of combating high CO₂ levels in a house’s internal conditions.

What can be surmised from the above example is that each case is different, even in similar settings, and that there are no shortcomings when it comes to truly customizing an occupant’s energy behavior plan. That is why, in FORTESIE, the CIM started by performing an exhaustive round of data gathering so that each individual case can be better defined. Of course, this does not mean that each Portuguese household requires a completely different engagement plan, given that many similar parameters can be consolidated to generate horizontal recommendations. However, this requires a lot of manual work, discussions with homeowners and local representatives, and a great deal of experimentation to fine-tune the behavior pathways and the individual recommendations and challenges that are offered to the users.

The question that still needs to be answered is, “How do we create universally accepted frameworks to correctly categorize occupants and successfully convince them to optimize their energy behavior?”. Based on our research and work so far in the FORTESIE project, one answer could be that the use of frameworks such as the CIM can greatly help researchers and scientists to set up the foundations that will make it easier to split occupants into sub-categories depending on the specificities of each case. If enough experimentation is performed in this area, then the generated material could be leveraged in future projects to avoid reinventing the wheel. Of course, the generated material needs to have sufficient evidence from its application in specific use cases so that the impact of specific actions (e.g., lower the temperature of your house by 1 degree Celsius) can be measured. For the FORTESIE project, this is going to be the next stage of its pilot activities.

Based on the experiences in piloting the CIM in the Spanish and Portuguese demonstrations, we conclude by summarizing several practical recommendations to engage tenants and homeowners using the model:

• Hybrid Engagement Approaches: Digital tools, such as mobile applications, provide effective means of connecting with users and supporting their efforts to implement behavior changes. However, it is important to emphasize that digital solutions alone are not sufficient. They should be complemented with traditional engagement methods, such as face-to-face meetings, presentations, and printed handouts, which can ensure a wider range of beneficiaries are successfully engaged. The execution of phases 1 and 2 of the CIM will play a key role in identifying and achieving the appropriate balance between digital and non-digital engagement approaches, ensuring a tailored and inclusive strategy;
• Long-term knowledge development: Improving digital and energy literacy is a gradual process requiring sustained and iterative engagement to foster a deeper understanding of residential energy efficiency among users over time. To maximize impact, it is critical that the CIM methodology is periodically repeated so that the evolving profile of homeowners and other beneficiaries is captured and reflected in updates to engagement strategy and communication content;
• Local understanding and advocacy: The success of CIM implementation largely depends on the expertise of local stakeholders and partners, who not only understand but champion its use. This local advocacy is critical to gain access and collect reliable data from the target group(s). It is also essential for maintaining a sustainable connection with the end users to allow for the iterative design of the CIM to be executed. Local partners must embrace the engagement goals and vision and hold a meaningful understanding of the CIM methodology. Proper training of these advocates in the CIM methodology, therefore, becomes essential to ensure the reliability and replicability of the approach.

6. Conclusions and Next Steps

The FORTESIE project and the related renovation pilots discussed in this publication highlight the transformative potential of home renovations to advance energy efficiency, combat energy poverty, and drive user engagement. With buildings accounting for significant portions of global energy use and emissions, the urgency to retrofit existing structures and integrate energy-efficient technologies cannot be overstated. By implementing both active and passive measures—such as thermal insulation, HVAC system upgrades, and the incorporation of rooftop PVs—FORTESIE demonstrates how tailored renovation packages can effectively address these challenges while promoting sustainable habits among residents.

The project’s focus on user engagement through innovative methodologies, namely the Common Impact Model (CIM), underlines the importance of aligning technological interventions with human behavior. Pilots in Spain and Portugal exemplify the diversity of engagement strategies needed to accommodate varying levels of digital literacy, socio-economic conditions, and cultural contexts. The integration of digital tools, including data analytics and behavior recommendation services, along with the deployment of smart sensors, has shown promise in enhancing energy literacy and fostering long-term behavior change. Meanwhile, the inclusion of non-digital, community-focused approaches ensures that even the most vulnerable populations can benefit from these advancements. All in all, it can be said that the CIM can help with creating personalized, custom plans for different occupants. However, these plans are not produced automatically as the number of parameters that need to be considered cannot be modeled effectively. As such, information gathering about each case, communication with the users, and appropriate energy recommendations are of utmost importance in creating these personalized plans.

The next steps of this work include the execution and operation of the pilots, which, as of the time of writing this publication, are close to finalizing their renovation work. The successful operation of the pilots will heavily rely on the correct deployment of sensors and their connection to the project’s database, the development of the FORTESIE digital tools, such as the mobile application, and the experimentation of the pilot beneficiaries with these tools. To measure the success of the pilots, the project has defined a number of key performance indicators that mainly address the energy consumption and the internal conditions in each building before and after the renovation work and the deployment of the digital tools. Throughout this process, support will be provided to the beneficiaries when needed, while feedback will be collected for the fine-tuning of the digital tools, as well as the engagement activities. The overall operation of the pilots will generate several lessons learned that will be analyzed and grouped to produce policy recommendations for the next wave of building renovations in the EU.

Beyond the horizon of the FORTESIE project, several actions are recommended to scale and refine these efforts. First, the reach of renovation initiatives should be expanded to additional regions and demographic groups, particularly focusing on areas with high energy poverty rates and outdated building stock. This can be achieved by strengthening collaborations with local governments and community organizations to facilitate access to funding and resources. The pilot leaders who are active in the project will play a central role in the further dissemination of these efforts. Moreover, the development and refinement of digital engagement tools, such as the FORTESIE application, must be prioritized. Enhancing functionalities to include advanced analytics, predictive alerts and notifications, and gamified features can increase user motivation and participation. Ensuring accessibility through multilingual support and usability features will also be critical.

Furthermore, policy advocacy and financial incentives must be pursued to encourage energy-efficient renovations. This includes promoting policies that offer tax credits, subsidies, and low-interest loans while establishing clear frameworks to support prosumers, enabling them to sell excess energy back to the grid and contribute to a circular energy economy. Educational and community programs should also be strengthened to raise awareness about the benefits of home renovations and energy-efficient behaviors. Targeted education campaigns can address regions with low energy literacy, while community-led initiatives can build trust and encourage participation, leveraging successful volunteer-driven models like those seen in the Portuguese Just a Change pilot. Finally, robust monitoring systems should be implemented to track the long-term impacts of renovations on energy consumption, emissions reduction, and user satisfaction. Using collected data to iterate and improve both technological solutions and engagement strategies will ensure adaptability to evolving user needs. By pursuing these steps, the FORTESIE project and similar initiatives can accelerate the transition toward a more sustainable and equitable future, where energy-efficient homes are the norm and user participation is central to achieving carbon neutrality.