Drivers of and Barriers to Energy Renovation in Residential Buildings in Spain—The Challenge of Next Generation EU Funds for Existing Buildings

Abstract

The aim of this research was to analyze the drivers and barriers facing the agents involved in the energy renovation process and the effective use of existing subsidies for this purpose. The drive for energy renovation in buildings is undeniable. European policies aiming to completely decarbonize the economy by 2050 will give an important boost to the building sector in Europe by improving comfort conditions in renovated homes. In this study, a questionnaire was developed using the free software LimeSurvey, which was then evaluated by experts. The questionnaire included representative indicators of energy refurbishment and was segmented into the intervening groups to highlight their differences. The results were analyzed using the Mann–Whitney test for group comparisons and Pearson’s correlation coefficient to assess the relationships between the responses. This analysis reveals the complexity of a process, in which excessive bureaucratic requirements to obtain Next Generation EU funds, economic aspects (80%) and owners’ lack of awareness are the barriers that were most highlighted by those surveyed (77%). In terms of motivation, we found that, apart from economic savings (88%), the most valued aspect for users was noise insulation (93%), which is not directly related to energy improvement. This study highlights the lack of knowledge and information that the agents responsible for this change have about energy improvement and their differences in opinions on motivations and barriers.

1. Introduction

Energy production and consumption are directly related to climate change through CO₂ emissions derived from fossil fuels. Many nations have recognized this and have been taking steps to combat climate change since 1992. These actions emerged in the United Nations Framework Convention on Climate Change at the Rio Conference in 1992 [1], the subsequent Kyoto Protocol of 1997 [2] and the most recent agreement in Paris at COP 21 in December 2015 [3]. In Paris, the participants agreed “to prevent the increase in average global temperatures from exceeding 2 °C above pre-industrial levels and seek to promote additional efforts to ensure that global warming does not exceed 1.5 °C” [4]. This agreement is directly linked to reducing energy demand. Later, the Glasgow Climate Pact of 13 November 2021 [5] “recognises that the effects of climate change would be much smaller with a temperature increase of 1.5 °C than with a 2 °C increase, and resolves to continue efforts to limit the temperature increase to 1.5 °C”.

In response to the climate and CO₂ emissions crisis, China and the United States have proposed decarbonization strategies in buildings as part of a government framework to formulate specific climate policies [6]. Although this is a global problem, the actions of different economies are heterogeneous [7]. These proposals are necessary, but users and technicians must be able to carry out these decarbonization processes in the building sector.

In the European Union (EU), according to Tsemekedi-Tzeiranaki et al. [8], “energy production and use is responsible for 80% of all GHG emissions. Buildings, which account for about 40% of the EU’s final energy usage and 36% of CO₂ emissions, are associated with significant untapped energy saving potential”. It is thus evident that obsolete and inefficient building solutions, the use of inefficient systems or appliances and a lack of adequate technical control systems lead to energy loss or gain that increases demand.

In the framework of the Directive on the Energy Performance of Buildings (2010/31/EU) [9], modified in 2018 (2018/844/EU) [10], together with the Energy Efficiency Directive (2018/2002/EU) [11] and the European Green Deal [12], a strategy to decarbonize or reduce net greenhouse gas emissions by 2050 was established to combat climate change and environmental degradation. Coinciding with the COVID-19 pandemic, the European Council approved the creation of the Next Generation EU program [13] and Regulation 2021/241 [14] on 21 June 2020, whereby large sums are to be allocated to recovery investments affecting, among other areas, sustainability in urban and rural environments, depending on their characteristics and potential for improvement.

In Spain, the Recovery, Transformation and Resilience Plan is designed to manage Next Generation EU funds. This Spanish plan is structured around four axes and ten policy levers to create employment and stimulate business activity [15]. Component 2 of Lever 1 focuses on housing renovation [16], which aims to achieve significantly higher energy renovation rates than those that presently exist, with a total investment of 6.82 billion euros. These targets are included in the National Integrated Energy and Climate Plan (PNIEC) 2021–2030 [17] published by the Ministry of Ecological Transition and Demographic Challenge. This plan makes evident the low rate of housing retrofitting in Spain and the aging of existing buildings, resulting in a growing need for renovation to achieve ambitious CO₂ emission reduction targets. The PNIEC aims to renovate 1,200,000 dwellings, starting with 30,000 houses per year in 2021 and ending with 300,000 per year in 2030.

Moreover, the Ministry of Transport, Mobility and Urban Agenda updated its long-term strategy for Energy Renovation of the Building Sector (ERESEE 2020) [18]. This national strategy aims to support the renovation of the Spanish building stock of public and private residential and non-residential buildings and to transform them into energy-efficient and decarbonized buildings by 2050.

ERESEE 2020 provides data on the obsolescence of buildings in Spain, revealing that around 45% of them are pre-1980, a percentage that rises to 50% in the case of residential buildings, or 9.7 million houses. Moreover, around 1 million dwellings are estimated to be in a poor or dilapidated condition.

Furthermore, if the quality of existing buildings is analyzed on the basis of energy ratings, more than 81% of existing buildings are in the E, F or G emissions categories. This rises to 84.5% in terms of energy consumption, highlighting the great potential for energy renovation in the Spanish building stock. According to Arcas-Abella et al. [19], a large part of the energy in our buildings is not used due to obsolete construction solutions, inefficient systems and installations and a lack of control systems.

To limit energy use in buildings, it is necessary to design passive strategies that involve insulating the opaque elements of the envelope, implementing solutions for carpentry in openings and glazing with low transmittance, eliminating thermal bridges and pursuing airtightness throughout the envelope to prevent leaks or undue air ingress. Shading, building orientation, ventilation strategies and prevailing winds are also part of passive strategies [20].

Technical systems, such as heating, air conditioning, ventilation, domestic hot water (DHW) production and lighting systems are part of active strategies [21] which, together with passive strategies, optimize energy consumption and promote thermal comfort in homes. Increasing the capacity for energy savings by adding control systems allows the services provided to be managed, providing information about consumption habits and encouraging new energy and money-saving behavior [22].

In the same direction, the promotion of nearly zero energy buildings (NZEB), as defined in the Energy Performance of Buildings Directive (2010/31/EU) [9], and the use of renewable energy sources in existing buildings contribute to reducing energy consumption and the negative impacts of building use on the environment, according to a study by Jadwiga et al. [23].

CTE-DB-HE 2019 [24], a Spanish regulation governing energy savings in buildings, focused part of its requirements on heating, cooling and DHW services for the residential sector because energy consumption for heating and DHW accounts for about 60% [25], and cooling only accounts for 1% of the total [25].

All these actions contribute to reducing energy demand in buildings, and as a consequence, they also reduce dependence on countries exporting energy, reduce pollution, improve the competitiveness of the economy, reduce energy poverty in households and improve indoor comfort.

Despite these advantages, the rate of energy renovations in buildings in Spain [26] remains at suboptimal levels, even with defined actions and funds for their development. This study aims to analyze the barriers that prevent renovations from reaching their potential numbers and to identify the components that motivate individuals to undertake these actions.

1.1. Barriers to Decisions on Energy Renovation in Buildings

Classifying the barriers to energy retrofitting in buildings can be approached in various ways. Some European studies on the difficulties of energy retrofitting in buildings have identified household financial constraints as the main obstacle to initiating retrofitting, e.g., those by Mortensen et al. [27] and later by Touminen et al. [28]. A study by O’Malley et al. [29] also stated that limited access to finance is a key barrier to energy efficiency. More recent studies, such as those by Lou et al. [30] and Jadwiga et al. [31], again reinforce the financial factor as the most significant barrier for users.

Hirst and Brown [32] classified barriers into structural and behavioral. The first includes the uncertainty of fluctuating energy prices, fiscal and regulatory aspects of standards, and financing, among others. Behavioral barriers include attitudes toward energy renovation, i.e., investment risk, information gaps and other factors that imply a commitment on the part of investors.

Heutel [33] added that investment in energy renovation involves uncertainty. Consumers behave according to the prospect theory in the face of uncertainty, i.e., the choice of investment depends on benchmarks, and they are loss averse. Therefore, probability is a subjective criterion. Along the same lines, Wilson et al.’s [34] and Murphy’s [35] studies show that consumers are averse to long-term investment returns.

Cooremans and Schönenberger [36] indicated that the probability of an investment decision in favor of energy efficiency increases when the energy management system is effective through monitoring and control tools that allow energy efficiency investments to be evaluated and decided upon.

Numerous behavioral studies in various fields have characterized the parameters influencing decision making. Wilson et al. [34] conducted behavioral research on homeowners’ renovation decisions, characterizing the drivers of and barriers to renovations and identifying factors related to people’s attitudes and contextual influences.

Vogel et al. [37] identified a series of barriers to energy efficiency decision making, categorizing them into three analytical levels: project, sectoral and contextual. The first two levels are related to the user’s attitude or behavior toward decision making, and the third is to related structural barriers. The results of the study revealed that most barriers originate at the contextual level, meaning that energy and sustainability are not yet determining factors in the context of building design and construction.

More recent studies, such as that by Stern [38], have focused on the complexity of human behavior and the social aspects of energy renovation, which is overlooked when designing energy policies. Homeowners are considered a homogeneous group rather than being categorized to create specific policies leading to higher rates of housing renovation and, therefore, policy success.

The importance of informing and communicating with owners [39] is also an area that is ignored in these policies; Touminen et al. [28] demonstrated that information should be easily accessible, understandable and relevant to owners’ lives. Moreover, the lack of reliable information is considered a major barrier to energy retrofitting, as stated in a study by Azizi et al. [40]. This lack of user information and knowledge contributes to a lack of awareness in energy-related decision making, according to Gynther et al. [41].

On the benefits of the energy improvement of buildings to the quality of life and the environment, Jadwiga et al. [31] showed in their study that, despite some negative effects of the energy transition, they attach more importance to its beneficial aspects.

1.2. Motivations for Initiating Energy-Efficient Retrofits

The savings potential of upgrading the energy performance of existing buildings is undisputed [42]. Implementing technical measures in building retrofitting actions has a short payback period in many cases, which should convince owners to undertake these actions. However, a study carried out in Germany by Zundel and Stieß [43] showed that many owners do not follow this rationale and do not consider retrofitting as an investment. This opened a discussion about the drivers of retrofitting, which they found to be a combination of economic and non-economic motives and objectives. Owners state that the following economic objectives play a prominent role: reduced energy consumption, reduced energy costs and increased home value. However, they also value non-economic considerations, as follows: increased thermal comfort, contributing to environmental protection or a low carbon economy, and upgrading technological installations in their homes. Similar conclusions were reached by Mortensen et al. [27], who stated that improvements in comfort, the indoor environment and architecture prove to be motivating for homeowners. Nevertheless, a combination of knowledge about non-economic improvements, more information or education about energy improvements, and a reasonable investment are the optimal reasons for homeowners to undertake energy retrofits.

Organ et al. [44] found that improving comfort levels and taking advantage of positive health effects can be prominent motivating factors for energy efficiency improvements. The interrelationship of these benefits leads to positive perceptions among owners. This includes improving the indoor environment of dwellings, which has become more highly valued after COVID-19. Among the indicators designed by the European Commission to assess Building Sustainability Level(s) [45], Section 4 includes healthy and comfortable spaces. Indoor air quality, time outside the thermal comfort range, lighting and visual comfort, and acoustics and noise protection are indicators that can be assessed and that provide these health and indoor comfort benefits.

Environmental awareness is less of a determining factor, according to a study by Achtnicht and Madlener [46], to undertake energy renovation actions, although the quest for environmental protection, renewable energies without the use of fossil fuels, the fight against decarbonization and the quest for energy independence are motivating factors for many owners.

Azizi et al. [41], in their analysis of the benefits of and barriers to energy retrofitting in Swedish single-family houses, found that reducing energy costs is not decisive as a driver for energy retrofitting. It must also be related to other factors, such as improving the indoor environment.

Therefore, in the context of the energy renovation of residential buildings in Spain, this study proposes the following questions:

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What are the main barriers to the adequate development of renovations despite the existence of defined actions and funds for their development?

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From the energy point of view, what are the main benefits of renovations perceived by users and responsible agents that can motivate decision making in this area?

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What behavior and knowledge do the agents responsible for the retrofitting process demonstrate, and are there any significant differences among them?

To answer these questions, we developed a comprehensive questionnaire using the LimeSurvey platform, which was addressed to agents involved in energy refurbishment. The data obtained were analyzed using different statistical methods in the open-source free software R (version 4.1.3). The non-parametric Mann–Whitney test was used to investigate significant differences between the groups, and a correlation analysis was conducted to identify and evaluate relationships among their responses.

With these results, we analyzed the drivers of and barriers to carrying out energy renovation in buildings for the respondents, who were mainly users and technicians-professionals, because, without them, a successful strategy would not be possible.

2. Materials and Methods

2.1. Questionnaire Design and Participants

To gather the opinions of the agents involved in the construction renovation sectors who participate in these actions, including individuals from the financial sector and public administration, technicians, contractors, researchers, and, last but not least, the users of dwellings and their representatives, such as property administrators, a questionnaire was developed with the online free software application LimeSurvey (version 4.4.0), which facilitates broad dissemination to all these agents.

The questionnaire had 93 questions. It included basic questions about the use and typology of the dwelling and technical, budgetary and financial support issues that could influence possible energy renovations in a building.

The first version of the questionnaire was designed by dividing the questions according to the agents to whom they were addressed, the type of building intervention, technical knowledge and knowledge about subsidies. The classification of the agents to whom the survey was sent was the following:

• Category 1: Users, including owners and property administrators (professional managers of homeowners’ associations).
• Category 2: Researchers, technicians from the Public Administration or Technological Centers working in the building field.
• Category 3: Professional technicians (architects, technical architects, engineers, etc.)
• Category 4: Contractors, housing developers and material or construction system manufacturers.
• Category 5: Architecture, technical architecture and building engineering students.
• Category 6: Respondents who did not define their profile in the previous categories.

Categorizing the respondents allowed us to design some questions according to their role and to include questions that were mandatory and others that were voluntary. The questionnaire was divided into sections. The first section asked questions about contextual factors (professional profile or type of building agent, single-family or multi-family house, age of the house, etc.) to be answered by all the agents and others, concerning the barriers preventing more energy renovations from being carried out or the key aspects that could motivate an energy renovation. The questions were evaluated using a 5-point Likert scale. In the following two sections, the questions concerned carrying out works in single-family houses or multi-family buildings, with one section excluding the other. Another included questions about technical solutions for energy renovation, which did not have to be answered by category 1 agents (users). After this, there was a section about the support provided to carry out an energy renovation, in which, among other things, the degree of knowledge about support and the aspects of this support that could be improved were assessed. Finally, questions concerning the respondents’ contact details were asked. Therefore, depending on the type of agent surveyed, between 26 and 32 questions were answered.

Prior to carrying out the survey, a control group of 10 experts from categories 2, 3 and 4 analyzed the survey. They approved the division of the survey into sections and categories and reviewed the questions to improve the readability, language and other aspects of the questionnaire.

The questionnaire was sent by e-mail through business associations; professional associations; central, regional and local government departments dealing with housing; and universities, reaching more than 5000 users, owners, technicians and professionals at the national level to obtain a large sample. The questionnaire was answered by 296 agents from the different categories. All participants in the survey were fully informed about the anonymity of their responses, why the research was being carried out and the protection of their data before beginning the questionnaire.

Table 1. Percentages of respondents according to respondent profile and categories.

Respondent Profile	Category	Answers	%
Users	1	42	14.2%
Public administration	2	29	9.8%
Technology centers	2	24	8.1%
Professional technicians	3	89	30.1%
Manufacturing companies	4	14	4.7%
Construction companies	4	7	2.4%
Students arch./building eng.	5	2	0.7%
Financial sector	5	2	0.7%
Other	6	18	6.1%
Do not know/Do not answer (Dk/Da)	--	69	23.3%
Total		296

shows the percentage of agents who answered the survey according to the categories defined, showing that the two main agents, discarding those who did not identify themselves within a category, were users/property administrators (category 1), with a value of 14.2%, and professional technicians, who belonged to category 2, with 30.1% of the total.

The analysis of the results from the survey focused mainly on the perceptions of users and technicians-professionals about their motivations and the benefits of and barriers to carrying out energy renovations in houses or buildings.

2.2. Statistical Analysis

The first step of the analysis consisted of preparing the dataset to present the data in a structured data frame. This stage facilitates the use of statistical methods, which is crucial when analyzing survey data. Before applying inferential methods, data exploration, including descriptive statistics and bar chart plots, was performed to determine trends in the data and to visualize the behavior of the responses for each question and each group in the study. Our interest was mainly focused on users and technicians-professionals. To compare both groups, the Mann–Whitney test was applied to investigate significant differences between the responses to questions concerning the barriers, motivations and subsidies involved in energy renovation. This statistical test is the non-parametric alternative to the t-test to compare two independent groups when the assumption of a normal distribution for the sample distributions cannot be made. A correlation analysis was also performed to identify and evaluate the relationships among the responses. This analysis involved calculating Pearson’s correlation coefficient, a widely used statistical measure that quantifies the linear relationship between two variables. The results were then visually represented through plots, in which the intensity of color reflected the magnitude of the correlation coefficient. This visual approach provided a clear representation of the associations among the responses.

All statistical analyses and graphs were developed using the open-source free software R (https://www.R-project.org/). Specifically, the likert package [47] was used to examine Likert response items, focusing on visual representations. In this regard, the stacked bar plot was chosen to present the Likert results. The corrplot package [48] was used to visually explore and analyze the correlation matrices because it provides a more intuitive view of the correlations and associations among the variables.

3. Results and Discussion

First, this study aimed to analyze the sample’s degree of knowledge about the implications of improvements from the thermal point of view, which is dealt with in the first section. We found that 57% of those surveyed did not know the meaning of a building’s Energy Performance Certificate. Except for the group of technicians-professionals, those surveyed did not understand its significance, so they would be unlikely to consider energy renovation. Even though these respondents showed a lack of knowledge, the questionnaire asked them whether they were aware of the scope of a renovation, from an energy point of view, to reduce energy demand and consumption in buildings. In this respect, 52.4% of the non-technical users surveyed expressed knowledge about this intervention, which is not as low of a percentage as might be expected. Only 3% of the respondents considered that users and homeowners’ associations are sufficiently informed about how to save energy.

The work or actions that those in the sample recently carried out in their homes involved changing windows, painting and renovating flooring (60% ratings), and actions related to insulation represented 0% of users’ responses, which corroborates a lack of awareness about the implications of incorporating passive strategies in buildings and, consequently, reducing energy demand, without mentioning their advantages in terms of comfort.

Concerning the work that the survey respondents stated had been carried out in the communal areas of their buildings, the most significant were installing or improving the elevator and repairing the façade due to detachments or cracks, with 48% of respondents’ ratings in both cases. These were followed by improving entrance hall accessibility (36% ratings) and improving the appearance of the façade-painting (33%), with actions related to roof and façade insulation at 26% and 7%, respectively, which again shows that users were more aware of conservation and accessibility than energy efficiency and comfort.

A building’s obsolescence from an energy point of view depends to a large extent on its age and on the regulations in effect at the time that the project was drafted. Thus, 62% of those surveyed stated that they lived in buildings that were not designed following the Technical Building Code, which means that their homes lack energy efficiency features in their passive elements. The bulk of the homes of those surveyed were built during the periods of 1961–1980 and 1981–2006. Similarly, 58% of those surveyed were unaware of the subsidies available for energy renovation offered by the administration, which represents a very high percentage of the sample of both users and technicians-professionals. It is interesting to note that practically all of them (100% of users and 93% of technicians-professionals) answered affirmatively when asked whether they would like to know about them.

The administration bases part of its strategies to improve the overall energy performance of existing buildings on promoting renovations in these buildings. In this study, 72% of the sample living in multi-family buildings and 69% living in single-family dwellings stated that no major renovations had been carried out in their buildings in recent years. In the few cases in which work had been performed on the building in general, 78% of those surveyed with a user profile identified the property administrator as the agent promoting this action. The job of a property administrator is to manage the economic and administrative affairs of the homeowners’ association, and therefore, his or her work does not involve becoming a renovation agent, which requires other skills and knowledge.

3.1. Barriers to Retrofitting Existing Buildings

One of the objectives of the questionnaire was to identify the indicators that represent difficulties in energy renovation, quantify them globally and then correlate the variations in these responses between the profiles of the two main groups in the sample: users and technicians-professionals.

Table 2. Question and response options for the survey question about energy barriers.

	In Your Opinion, What Are the Barriers That Prevent More Energy Renovations of Houses/Buildings from Being Carried Out?
V14	Difficulties in reaching agreements in homeowners’ associations
V15	Economic barriers (e.g., high cost of renovation) 1
V16	Legal barriers (e.g., difficulty in obtaining building permits)
V17	Amortization of the investment in the medium term 1
V18	The user does not prioritize the thermal comfort of his/her house
V19	Conservation and accessibility aspects are more important 1
V20	Difficulties in financing
V21	Insufficient subsidies 1
V22	Difficulties in obtaining subsidies (excessive requirements, etc.) 1
V23	High tax impact once aid has been obtained 1
V24	Lack of owner awareness
V25	Lack of information at the time of the renovation
V26	Lack of support from the administration

¹ Significant differences between users and technicians-professionals (p < 0.05) (Mann–Whitney test).

shows the survey question about the barriers that prevent energy renovation and the response options, which range from difficulties in reaching agreements in homeowners’ associations to economic barriers, a lack of knowledge or information on subsidies or a lack of interest in carrying out energy renovations.

Figure 1 shows the answers obtained by all the respondents to the questions asked in Table 2. As we can see, economic aspects (80% of the ratings), together with difficulties in obtaining subsidies (77%) and owners’ lack of awareness (77%), are the most important barriers to initiating energy renovations.

These issues are diverse, and they can be grouped into structural aspects (economic barriers and difficulties in obtaining subsidies) and behavioral aspects (lack of awareness among owners). These are followed by difficulties in reaching agreements in homeowners’ associations (74%), financing difficulties (64%), a lack of information when making decisions (64%) and a lack of support from the administration (60%).

Once the results of the whole sample were analyzed, the next step was to study the results of the evaluations made by the user and technical-professional groups (

Table 3. Comparison of barriers to building energy renovation ratings (users and technicians-professionals).

Barriers	% Score 1 and 2		% Score 3		% Score 4 and 5
	Users	Technicians-Professionals	Users	Technicians-Professionals	Users	Technicians-Professionals
Difficulties in reaching agreements in homeowners’ associations	0%	10%	20%	30%	40%	50%
Economic barriers (e.g., high economic cost of renovation)	60%	70%	80%	90%	100%	75%
Legal barriers (e.g., difficulty in obtaining building permits)	45%	43%	21%	34%	33%	24%
Amortization of the investment in the medium term	10%	16%	31%	53%	60%	31%
The user does not prioritize the thermal comfort of his/her house	17%	19%	24%	28%	60%	53%
Conservation and accessibility aspects are more important	10%	21%	17%	40%	74%	38%
Difficulties in financing	12%	17%	19%	30%	69%	53%
Insufficient subsidies	5%	11%	7%	28%	88%	61%
Difficulties in obtaining subsidies (e.g., excessive requirements)	2%	9%	12%	19%	86%	72%
High tax impact once aid has been obtained	17%	25%	26%	29%	57%	46%
Lack of awareness of owners	5%	2%	17%	18%	79%	80%
Lack of information at the time of renovation	19%	15%	29%	19%	52%	66%
Lack of support from the administration	5%	18%	24%	29%	71%	53%

), because these two groups are the most representative of the sample, and it is interesting to compare their behavior. When analyzing the sample of users and identifying the indicators that were given 4 or 5 points, we found differences in overall opinions. Economic barriers continued to be in first place, although in this case, users rated them higher (95% of the ratings) than the total sample of respondents (80%). In second place, users named insufficient aid (88%). This was not so important at the general level (67%). The third most important aspect for this group was the difficulty in obtaining aid (86%), which was also less important for the whole sample (77%).

In the case of the technician-professional collective, when identifying the indicators that were given 4 or 5 points, the main barrier was owners’ lack of awareness (80%), and economic aspects were in second place, with 75%. The other barriers highlighted by technicians-professionals were difficulties in reaching agreements in homeowners’ associations (73%), which did not appear as an important aspect by users, and the difficulties in obtaining subsidies (72%), which users rated higher than professional technicians.

The results of the Mann–Whitney test applied to the answers to this question showed significant differences (p < 0.05) between the two groups in the following aspects: “Economic barriers (e.g., high cost of renovation),” “Amortization of the investment in the medium term”, “Conservation and accessibility aspects are more important”, “Insufficient subsidies”, “Difficulties in obtaining subsidies (excessive requirements, etc.)”, “High tax impact once aid has been obtained” and “Insufficient government support” (see Table 2). Therefore, we can see that there are barriers that coincide to a greater or lesser degree, which are mainly linked to economic aspects and subsidies, but there are also aspects related to the respondents’ awareness of energy renovation, as was the case with users.

3.2. Benefits Driving the Retrofitting of Existing Buildings

The benefits that drive the implementation of energy renovation actions are also the subject of this study. In

Table 4. Question and response options for the survey question regarding reasons for carrying out energy renovation.

	In Your Opinion, What Are the Key Aspects That Can Motivate Energy Renovation in Houses/Buildings?
V28	Contribution to the environment and decarbonization of the building sector
V29	Improving indoor comfort and well-being
V30	Health-related improvements (e.g., CO2-controlled ventilation)
V31	Economic savings (e.g., electricity expenses)
V32	Noise insulation 1
V33	Increased value of the house/building after renovation 1
V34	The existence of subsidies
V35	The existence of companies that manage the entire process

¹ Significant differences between users and technicians-professionals (p < 0.05) (Mann–Whitney test).

, the question and response options in the questionnaire are shown.

Considering the overall ratings of all the respondents (Figure 2), financial savings (87% of the ratings) and improvement in the comfort and well-being in the dwelling (87%) were the aspects that most motivated the respondents to initiate energy renovations. Noise insulation (78%) and the revaluation of the dwelling after renovation (66%) were the other drivers valued by the sample, although these latter reasons are not linked to energy renovations.

When analyzing the results separately for the samples of respondents in the user and technician-professional groups (see

Table 5. Comparison of motivations for energy renovations in building ratings (users and technicians-professionals).

Motivations	% Score 1 and 2		% Score 3		% Score 4 and 5
	Users	Technicians-Professionals	Users	Technicians-Professionals	Users	Technicians-Professionals
Contribution to the environment and decarbonization of the building sector	19%	31%	24%	19%	57%	49%
Improving indoor comfort and well-being	2%	1%	7%	17%	90%	82%
Health-related improvements (e.g., CO2-controlled ventilation)	14%	11%	29%	34%	57%	55%
Economic savings (e.g., electricity expenses)	0%	1%	12%	11%	88%	88%
Noise insulation	5%	7%	2%	20%	93%	73%
Increased value of the house/building after renovation	10%	10%	10%	28%	81%	62%
The existence of subsidies	19%	10%	17%	21%	64%	69%
The existence of companies that manage the entire process	19%	12%	31%	28%	50%	60%

), we found that users rated noise insulation (93%) as the main advantage or driver for renovations, and technicians-professionals believed that economic savings, with 88% of the ratings, are decisive in this respect. Improving comfort and well-being in the home (90% of users and 82% of technicians-professionals) was the second most important factor for both profiles. Users also highlighted economic savings (88%) in their assessments, which was in third place, but it was surprisingly less important than noise insulation and to a lesser extent than it was for technicians-professionals.

These differences in the choice of parameters motivating renovations show that users cared more about aspects that are not connected to energy renovation (reducing noise) and seemed to associate comfort and well-being with noise insulation. However, technicians-professionals believed that the motivation to renovate is mainly related to saving money.

The motivations related to environmental protection and decarbonization of the sector (49% of technicians-professionals and 57% of users) and improvements related to health (55% of technicians-professionals and 57% of users) are not very relevant in either group (Table 5), which implies that economic aspects and a lack of knowledge in some cases do not motivate decision making.

“Noise insulation” and “Increased value of the house/building after renovation” were the aspects with the largest differences (p < 0.05) between the two groups, according to the Mann–Whitney test (Table 4).

In another section of the survey related to the motivation and impetus to carry out energy renovations, the survey asked about aspects of the administration’s aid processes that could be improved (see Figure 3). It is surprising that, above economic criteria, most of the evaluations focused on simplifying administrative procedures (89% of the responses from all of those surveyed) and indicated that the administration should respond in a few months (88% of all responses). These barriers were almost 20% higher than the indicator stating that the amount of aid is insufficient (69% of all ratings), which could be expected to obtain higher ratings. Modifying procedures to simplify and speed up responses or creating new administrative tools would be appropriate strategies to turn these barriers into motivations.

3.3. Correlation of Barriers and Benefits to Retrofitting Existing Buildings

To provide a clearer view of the results of the questions analyzed separately and to study the coherence of the sample’s responses, the results were compared for two large groups, namely building technicians-professionals, who encourage energy renovations, and end users, who are key to carrying out these renovations. The correlation between the answers to the questions about the barriers preventing energy renovation (Table 2) and the answers concerning the motivations for carrying them out (Table 4) were studied.

From the quantitative analysis carried out above, we cannot correlate the different sections to find coherence in the results among the groups from which we could draw joint conclusions and opinion trends. Observing the answers given by the users’ collective and the correlation between the different answers (Figure 4), we can observe that this collective believed that the amount of aid offered for energy renovation in buildings is scarce and is closely related to the lack of support from the administration (for answers V21 and V26, r = 0.77). They also thought that the legal requirements to apply for subsidies are excessive (between answers V16 and V22, r = 0.64). These results show that this group considered the main barriers to energy renovation to be excessive requirements and a lack of subsidies from the administration.

We can also see that this group’s responses are coherent because they responded similarly about economic barriers involving a sizeable financial outlay (for responses V15 and V21, r = 0.62) and the bureaucratic difficulties in obtaining aid that reflect insufficient support from the administration (between responses V22 and V26, r = 0.61).

To a lesser extent, this group of users was also concerned about the lack of energy renovation awareness, which could lead to difficulties reaching agreements in residential building homeowners’ associations (for responses V14 and V24, r = 0.56). The fact that users did not prioritize thermal comfort contributes to this problem. This response correlates with the lack of awareness, demonstrating its coherence (r = 0.54 between responses V18 and V24).

As with the users, the correlation analysis of the answers given by the group of technicians-professionals (Figure 5) on the barriers to carrying out energy renovation shows that the most outstanding correlation was the difficulty in obtaining aid due to excessive requirements with insufficient aid (r = 0.76, for answers V21 and V22). Similarly, the technicians-professionals correlated the difficulties in obtaining aid due to excessive requirements with the lack of support from the administration (for responses V22 and V26, r = 0.60). Finally, this group believed that the difficulty in financing the necessary actions for energy renovations is linked to the scarcity of subsidies and that these two issues present major obstacles (r = 0.54, for responses V20 and V25).

In correlating the motivations for promoting energy renovations to a greater extent (Table 4), the responses of users and technicians-professionals were more dispersed and less related (Figure 4 and Figure 5). However, both groups gave reasons that are relevant not to the thermal properties of the building but to other benefits. The correlations between responses V32 and V33 are r = 0.84 for users (Figure 6) and r = 0.54 for technicians-professionals (Figure 5), which implies a lack of knowledge about the advantages of energy improvements and that users associated comfort with noise insulation rather than thermal comfort and air quality.

For the group of technicians-professionals, the answers most closely related to motivation were aid from the administration and companies that manage the renovation process (for answers V34 and V35, r = 0.74), but the users’ answers showed a strong correlation among improvement in comfort and health, improvement in the environment and the decarbonization of the sector (r = 0.77 between answers V28 and V29, and for answers V28–30, r = 0.68). Therefore, it is clear that these two concepts are linked and are essential for energy renovation, but this relationship is not reflected as their primary motivation, as shown in Section 3.2. Users’ motivations were generally focused on non-energy and economic criteria. The correlations between the responses provided by the users (Table 5) about their motivations show that this group related improved comfort and well-being in the home with revaluation (between V29 and V32, r = 0.66) and insulation against noise (between V29 and V32, r = 0.65), which again indicates that users did not relate the advantages of improving indoor thermal conditions with comfort and health, in contrast to technicians and professionals, who rated it second as a motivation for renovation (r = 0.66, between responses V29 and V306). Once again, the lack of knowledge among users about thermal improvements and the parameters that determine comfort can be highlighted.

3.4. Strategies for Energy Retrofitting

The group of technicians-professionals, who are responsible for designing and implementing solutions or strategies for energy renovation, answered a part of the questionnaire to help identify the most relevant actions in energy renovation.

In analyzing the responses on façade and roof interventions, the group of technicians-professionals predominantly chose two solutions that mainly affect the carpentry of the dwellings and the insulation of the façade with external interventions (SATE system). As can be seen in Figure 6, 73% of respondents selected the SATE system as the optimal solution to improve façade insulation on the outside of the building, with no relevant responses for the rest of the improvements in the insulation of the envelope (façade insulation with ventilated façade (39%), chamber injection (38%) and insulation on the inside of the façade (30%)). The fact that the energy renovation of the façade employing a ventilated façade received a low score (39%) implies that there is still a lack of knowledge about current possibilities and the advantages and disadvantages of each solution.

The most highly valued strategies were centered on the joinery of the façade openings. Replacing existing joinery for elements with thermal bridge breaks (88% ratings) and installing joinery with good transmittance (Uw) (64% ratings) are strategies that were highly valued by technicians-professionals. This element of the envelope is the best known, of most concern, and is the easiest to replace. For this reason, these solutions are popular. Analyzing these responses, it is interesting that, among the solutions for improving the roof, insulation with floating flooring (45%) and replacing the roof to improve interior insulation (34%) were not considered as relevant as improvement actions, which indicates that they are not frequent in renovations. This type of renovation should be considered more seriously in an intensely sunny climate. In Figure 7, which shows the responses of the technicians-professionals regarding energy renovations in building installations, we can see that the majority of the responses dealt with the use of aerothermal heat pump systems, with a value of 71%. This is due to the ease with which this system can be integrated into the building, and these systems are better known than others. The second most popular option is systems based on replacing boilers with condensing boilers, which perform better than conventional ones (58% ratings). They had a similar opinion about renovating conventional air-conditioning systems (54% ratings), mainly due to a lack of knowledge about other more efficient systems.

It is important to note that the responses for implementing solar photovoltaic building systems (50% ratings) were more numerous than those for solar photothermal systems (49%) in buildings. This would not have been expected a few years ago.

Photovoltaic solar energy systems do not improve air conditioning installations but reduce electricity consumption, in many cases with low yields. However, current advertising campaigns by companies installing these systems are increasing interest in them and lessening the demand for other strategies that involve higher installation costs but greater comfort in the home.

The analysis of these data shows the importance of knowing the motivation of the agents involved in energy rehabilitation. Although this study was carried out in Spain, the methodology can be extended to any country in the process of decarbonizing its building stock. The definition of the questionnaire and the methodology are applicable to any other region or geographical area.

4. Conclusions

The aim of this study was to identify the benefits and barriers for which to act to increase the renovation rate in existing residential buildings in Spain. To do so, we analyzed the results of a survey carried out among different agents involved in the development of these measures. The knowledge and opinions of agents involved in the energy renovation process are key to reducing energy use in the building sector. We focused on the opinions of users and technicians-professionals. The main results are shown below.

• In terms of barriers, economic aspects, with a value of 80%, together with difficulties in obtaining subsidies (77%) and a lack of owner awareness (77%), were the most important barriers for all agents.
• We can conclude from the results analyzed separately for each group that, although economic aspects are considered important barriers, there were differences between the users and the technicians-professionals. For users, economic aspects were the main barrier (95%), followed by the scarcity of aid (88%) and the difficulty in obtaining it (86%). However, for the technicians-professionals, the main barrier was the lack of owner awareness (80%), above economic criteria (75%) and difficulties in reaching agreements in homeowners’ associations (73%). This implies that there are different perceptions within these groups, which must be taken into account to involve these agents in implementing energy renovations.
• Concerning the motivations driving energy renovations, of all those surveyed, economic savings and improving the comfort and well-being of the dwelling stood out, both with values of 87%. However, in the analysis by groups, it is surprising that, for the users, noise insulation was the most valued aspect (93%), followed by improving the comfort and well-being of the dwelling (90%), as opposed to economic savings (88%). The technicians-professionals, however, believed that economic savings (88%) are decisive in this respect, followed by improvements in comfort and well-being (82%) and noise insulation (73%).
• In both groups, the answers were dispersed due to their disparity, but surprisingly, both groups indicated reasons that do not involve the thermal properties of the building but other benefits, such as acoustic characteristics and the economic revaluation of the property. This implies a lack of knowledge about the advantages of undertaking energy improvements and that users associate comfort only with noise insulation, not thermal comfort or air quality.
• The agents were coherent in their answers when identifying important aspects to take into account in energy refurbishment, as was proved with the correlation study, but their priorities when making decisions were based not on these but on economic aspects. Moreover, the respondents acknowledged that they were more concerned about conservation and accessibility issues than energy efficiency and comfort.
• In general terms, this study shows that the bureaucratization currently entrenched in public administration is one of the main barriers to implementing energy renovation, above classic aspects such as economic ones. Without simplifying the bureaucratic process to obtain Next Generation EU funds and providing more support from the administration, the energy rehabilitation of the existing building stock will be very difficult to achieve.
• Our findings highlight agents’ lack of knowledge or lack of information regarding the actions and benefits of energy improvement. These aspects, in a few cases due to behavioral barriers and, in most cases, to different structural barriers, are the ones that hinder the decarbonization of buildings in Spain, which makes it difficult to meet the administration’s renovation goals.
• To mitigate this situation, it is necessary to carry out awareness campaigns about energy rehabilitation and to provide information on its benefits to the environment and the economic savings after its implementation, but these must be directed to the different agents involved.