1 Introduction

Europe is setting ambitious targets for the decarbonization of the building stock by the year 2050. These goals are essential for mitigating the impact of climate change and transitioning towards a more sustainable future. To achieve these objectives successfully, Europe has introduced a comprehensive framework that includes the establishment of indicators to provide an overview of actual energy-saving efforts and the definition of clear, evidence-based targets for expected energy savings.

One of the crucial aspects of this initiative is the use of indicators to assess the current state of energy conservation within Europe. These indicators serve as a snapshot of the region's energy-saving performance. By carefully monitoring and evaluating these indicators, policymakers and stakeholders gain valuable insights into the progress that has been made, as well as areas where more attention and effort are required. This overview ensures that Europe remains on track in its journey towards decarbonization.

Setting realistic and binding targets is a key component of this strategy. While ambitious goals are essential, they must also be attainable. The evidence-based approach ensures that these goals are rooted in a solid foundation of expected energy savings. These targets serve as a roadmap for countries and regions to follow, driving them to reduce carbon emissions and minimize energy consumption effectively. These decarbonization goals are not only important for environmental reasons but also for the development of effective renovation and energy policies. By having clear and measurable targets, policymakers can design policies that align with the overarching goal of decarbonization. They can implement strategies for energy efficiency, renewable energy adoption, and infrastructure improvements with a clear understanding of the intended outcome. These objectives provide a framework for innovation and investment in green technologies, creating opportunities for economic growth and job creation, and improve the health of users.

The Energy Performance of Buildings Directive (EPBD) (European Parliament, Council of the European Union 2003) as well as its updates and recasts establish the obligation for Member States (MS) to set requirements for the calculation of expected energy savings in the context of building retrofitting. In this sense, Directive 2002/27/UE on energy efficiency (European Parliament and the Council of the European Union 2003) and its recast 2018/844 (European Parliament and the Council of the European Union 2018) (which in this book are referred to as 2002 EPBD and 2018 EPBD, respectively) stablish that each MS shall establish a long-term renovation strategy (LTRS) to support the renovation of the national stock of residential and non-residential buildings, both public and private, into a highly energy efficient and decarbonized building stock by 2050, facilitating the cost-effective transformation of existing buildings into nearly zero-energy buildings. In this strategy, MSs must identify expected objectives to be met in the coming years. The EPBD is now being revised. The latest draft version of the ongoing EPBD revision (European Parliament 2023), which in this book it is referred to as 2023 EPBD Proposal recast, states that MSs shall establish a National Building Renovation Plan (NBRP) to ensure the renovation of their national stock of residential and non-residential buildings, transforming them into energy-efficient and decarbonized building stock by 2050, with the aim of transforming existing buildings into zero-emission buildings. Building renovation plans will be based on the principle of ‘energy efficiency first’ and will include, among other things, a roadmap with nationally set targets, measurable progress indicators and specific deadlines for all existing buildings to achieve higher energy efficiency classes by 2030, 2040 and 2050, with a view to the goal of climate neutrality by 2050, in order to ensure a decarbonized and highly energy-efficient national building stock and the transformation of existing buildings into zero-emission buildings by 2050. These roadmaps should include an evidence-based estimate of energy savings and greenhouse gas (GHG) emission reductions. The NRBPs will also serve to determine the joint compliance with the goals and establish actions to correct possible deviations.

Moreover, the energy renovation of buildings entails a series of benefits that go beyond energy savings. Thermal comfort and the healthiness of the interior enclosures are enhanced due to, for example, the improvement of condensations and internal humidity. This leads to an improvement in people’s health and, consequently, economic expenditure in health systems is reduced. These benefits, which transcend the energetic aspect, have also been included as targets in some documents.

The 2020 update of Spain’s LTRS (Ministry of Transport, Mobility and Urban Agenda 2020), often known as 2020 ERESEE for its acronym in Spanish, has set energy saving and decarbonization targets as part of its energy and climate policy for the building sector in Spain. These objectives are designed to address climate change, improve energy efficiency, and promote the use of cleaner and more sustainable energy sources. Within these objectives, specific targets have been set for the renovation of the existing building stock, as they are major contributors to energy consumption and GHG emissions. In addition to including expected energy savings, it includes a section on long-term impact and benefits of energy renovation in housing on air quality, condensation, and human health.

The Spanish National Integrated Energy and Climate Plan (Ministry of Ecological Transition and Demographic Challenge 2020a) (PNIEC for its acronym in Spanish) was planned for the period between 2021 and 2030. The PNIEC is divided into two main blocks: the first one details the process, objectives, existing policies, and measures necessary to achieve the Plan’s objectives. The second block, consisting of the Appendices to the main document, is the analytical part and contains a description of the different models that have made the prospective analysis possible and that provide robustness to the results. In addition to the plan, a report on the Economic, Employment, Social and Public Health Impact of the Integrated National Energy and Climate Plan 2021–2030 (Ministry of Ecological Transition and Demographic Challenge 2020c) is published, which includes the main results of the assessment of the economic, social, and public health impact of the Plan.

The 2023 EPBD Proposal recast also makes it mandatory for buildings to have a building renovation passport (BRP), which is a document that provides a tailored roadmap for the in-depth renovation of a specific building in a maximum number of stages, which will transform the building into a zero-emission building by 2050 at the latest. This passport will include the expected benefits in terms of energy savings, savings on energy bills and GHG emissions reduction over the entire life cycle when a building renovation is carried out. However, this passport should also include more general benefits related to health, comfort, indoor environmental quality, fire, electrical and seismic safety, and improved building resilience to climate change. In the context of benefits beyond energy, the 2023 EPBD proposal includes further developments. The Commission establishes a comparative methodological framework for calculating cost-optimal levels of cost-optimal minimum energy performance requirements for existing buildings undergoing major renovation. This methodological framework will consider, among other things, the environmental, economic and health externalities of energy consumption. These will include, among other issues, the reduction of the costs of health and social security systems.

Scientific literature has addressed the issue of predicting energy savings at the city and country scale. Urban Building Energy Modeling (UBEM) has become an effective way to understand the energy use of urban buildings and explore the potential for energy conservation and emission reductions (Zhang et al. 2022). Some of these studies are carried out for the residential buildings of a city (Zhang et al. 2022), others focus on a typology of buildings obtaining more precise results as in the case of historic buildings (Lin et al., 2023) or non-residential buildings (Ahmed et al. 2023). The automation of processes becomes a useful tool for the constant updating of data (Deng 2023). In Spain, Ortiz and Salom, published a report on how an economic approach to the effect of energy retrofitting on people’s health can be used to improve energy efficiency (Ortiz and Salom 2016).

The objective of this chapter is to propose a set of indicators regarding evidence-based estimate of expected energy savings and wider benefits of buildings renovation, analyze the availability of data in Spain, and develop them when they are available. Furthermore, the intention is to make these indicators adaptable for development at a regional level. To achieve this, the study employs two specific regions, namely Aragon and the Basque Country, as case studies.

2 Methodology

To develop the indicators regarding evidence-based estimate of expected energy savings and wider benefits of buildings renovation in Aragon, the Basque Country and Spain, the process indicated in Fig. 1 was followed.

Fig. 1
A flowchart of the indicators template definition involves the following steps. Analyzing the state of the art estimate the expected energy savings, proposal of indicators, identification of national and regional sources of information, and deployment of each indicator in the summary template.

Source own creation

Methodology implemented to generate indicators regarding evidence-based estimate of expected energy savings and reduction of costs for health systems from buildings renovation in Spain and two of its regions, Aragon and the Basque Country.

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The first step consisted in the development of a common template for these indicators based on:

  • Indicator:

    • Definition of the indicator.

    • Variables to quantify it and their unit of measurement.

    • Purpose and advantages of implementing this indicator.

    • Alignment of the indicator with the directives, agendas, action plans and strategies, covering the European and international, national, and regional scales.

    • Relationship of this indicator with other similar ones.

  • Information sources:

    • Availability of information to generate this indicator at different scales.

    • Entity responsible for providing this information.

  • Measurement:

    • Measurement method.

    • Methodology.

    • Current possibilities of obtaining it.

    • Information necessary to generate it.

    • Availability and quality of data.

With the aim to select the indicators that best represents the evidence-based estimate of expected energy savings and wider benefits of buildings renovation, we considered the indicators which have been suggested in European directives and related documents. First, we studied the indicative milestone included in the Commission Recommendation (EU) 2019/786 (European Commission 2019), which is referred to as 2019 EPBD-related Recommendation in this book and was the first document in which a framework of progress indicators to measure the European building stock decarbonization was proposed. Then, we analyzed the targets, identified as roadmap 2030, 2040 and 2050, included in the 2023 EPBD Proposal recast, which is the document with the last version of the framework of progress indicators. Table 1 shows the indicators recommended by these sources.

Table 1 Indicators regarding evidence-based estimate of expected energy savings and wider benefits of buildings renovation included in selected European directives and related documents.
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In the pursuit of selecting indicators that most accurately reflect the evidence-based estimation of expected energy savings and wider benefits resulting from building renovations, we considered indicators recommended in European directives and associated documents. Our initial examination focused on the indicative milestones outlined in the Commission Recommendation (EU) 2019/786 (referred to as the 2019 EPBD-related Recommendation in this book). This document, recognized as the first to propose a framework of progress indicators for measuring the decarbonization of the European building stock, set the foundation. Subsequently, we scrutinized the targets outlined in the 2023 EPBD Proposal recast, denoted as roadmap 2030, 2040, and 2050. This proposal represents the latest version of the indicator framework to measure the effectiveness of building renovation policies and the building decarbonization progress in Europe. Table 1 illustrates the indicators recommended by these sources.

After consulting the indicators proposed in European legislation, we searched for available sources of information to develop them. The proposed indicators to develop are the following, which coincide with those proposed by Europe:

  • Expected energy saving per building sector and type.

  • Expected reduction in health costs attributable to energy efficiency measures and improved air quality.

Once the key indicators to cover this topic were identified, the available sources of information were studied and the standard template for each indicator was developed and generated.

Subsequently, a summary file was defined for each indicator with the main points covered in the complete file Fig. 1.

3 Indicators

3.1 Expected Energy Saving Per Building Sector and Type

The purpose of this indicator is to know the potential energy savings that could be achieved in the different building sectors and types by implementing energy efficiency actions and measures.

The variables of the indicator are defined by its title, as Commission Recommendation (EU) 2019/786 (European Commission 2019) specifies that ‘building sector’ refers to both residential and non-residential sectors. Additionally, this classification was broken down into a second level for the non-residential sector, which is used in the data sources identified to collect the indicator.

The sources of information to develop this indicator in Spain are national and regional (Table 2). At the national scale, as required by the EU to each MS, Spain drew up a PNIEC (Ministry of Ecological Transition and Demographic Challenge 2020a), which identifies the challenges and opportunities in the 5 dimensions of the Energy Union: decarbonization, energy efficiency, energy security, internal energy market, and research, innovation, and competitiveness. In particular, and among other things, it identifies the cumulative savings potential of the residential sector in the period 2021–2030. In addition, the Long Term Decarbonization Strategy 2050 (ELP2050, in Spanish) (Ministry of Ecological Transition and Demographic Challenge 2020b), prepared according to Regulation (EU) 2018/1999, establishes energy and emissions savings targets for all economic activities in Spain, including the building sector. For the period 2021–2030 these targets are in line with those of the PNIEC. Furthermore, the ERESEE 2020 (Ministry of Transport, Mobility and Urban Agenda 2020) compiles the objectives proposed in the PNIEC and the ELP2050. It also includes a series of complementary reports on specific issues related to the Strategy. Specifically, document 9 ‘Report on typologies, consumption, improvement actions and potential energy savings in the building stock of the tertiary sector’ (A3e. Association of Energy Efficiency Companies 2019), prepared by A3e: Association of Energy Efficiency Companies, sets out the potential energy savings that could be achieved by implementing the proposed measures. This study applies to the buildings in the tertiary sector indicated in the variables section.

Table 2 Sources for indicator Expected energy saving potential per building sector and type.
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At the regional scale, on the one hand, the Department of Industry and Innovation of the Government of Aragon is in charge of preparing the Energy Plans of this region, where energy saving targets are set. On the other hand, the Department of Economic Development and Competitiveness of the Basque Government prepared the Basque Country Energy Strategy 2030, which sets out a vision of the current energy panorama in the region and establishes a series of objectives for 2030, which should be achieved by applying the 8 proposed lines of action. Specifically, line of action L3 ‘Reduce consumption and increase the use of renewables in buildings and households’ establishes energy savings indicators and targets for 2025 and 2030.

To collect the data of this indicator, it was assumed that the expected energy savings of the building sector coincide with the energy savings targets set for them in Spain’s Long Term Decarbonization Strategy (ELP) 2050, in the ERESEE 2020 and in the supporting studies on improvement potential and costs from which said objectives were established, such as the ‘Report on typologies, consumption, improvement actions and potential energy savings in the building stock of the tertiary sector’ (A3e. Association of Energy Efficiency Companies 2019).

A limitation in the collection of the indicator was the different time horizons in which the data are expressed: some of them refer to the savings produced by specific measures at a specific point in time, while others refer to a complete period, which prevents a direct comparison. In addition, the data are expressed in different units in each document, which implies the need to convert the units to establish comparisons.

With these considerations, the indicator was developed at the national scale based on two approaches. Firstly, the energy savings targets established up to 2050 for both residential and non-residential sectors were visually depicted in Fig. 2 using the 2050 ELP data, which are aligned with the 2020 ERESEE data. This chart is produced by transposing the data directly from the cited sources, where the information is readily available.

Fig. 2
A grouped bar chart depicts the G W h versus the period, plotting the values for residential and non-residential buildings as follows. In 2020 to 2030, 26,394 and 17,069. In 2030 to 2040, 21,858 and 23,085. In 2040 to 2050, 15,907 and 7,240. The total for 2020 to 2050 is 64,154 and 47,395.

Source own creation from data in (2019)

Expected energy savings for the residential and non-residential buildings in Spain. A3e. Association of energy efficiency companies.

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The second approach (Fig. 3) shows the potential energy savings that can be achieved by implementing specific energy efficiency improvement measures for the tertiary sector. Each of the proposed measures estimates a range of energy savings that such a measure could produce. Based on this hypothesis, two energy savings scenarios were created: a low energy savings scenario and a high energy savings scenario. In this case, the information is also readily available, and all the necessary data can be found in the ‘Report on typologies, consumption, improvement actions and potential energy savings in the building stock of the tertiary sector’ (A3e. Association of Energy Efficiency Companies 2019). However, no equivalent information applied to the residential sector was found.

Fig. 3
A grouped bar chart of the K W h for the non-residential sector in low and high scenarios with the following values. Small and medium offices, 7960 and 119450. Big offices, 231100 and 1300500. Big hospitals, 4269100 and 7907000. Hospitals, 831000 and 2117800. Schools, 27450 and 532700.

Source own creation from data in (Ministry of Ecological Transition and Demographic Challenge 2020b)

Energy savings targets for 2050 in Spain for non-residential sector.

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At the regional scale, data is only available for the Basque Country. Based on the Basque Country Energy Strategy 2030, and the potential energy savings are presented in Table 3.

Table 3 Potential energy savings in the Basque Country.
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3.2 Expected Reduction in Health Costs Attributable to Energy Efficiency Measures and Improved Air Quality

The purpose of this indicator is to understand the evolution of healthcare costs attributed to implementing energy efficiency measures in residential buildings and to establish a target of reduction.

The indicator is related to the strategies defined by the International Energy Agency (IEA) as stated in its publication ‘Capturing the Multiple Benefits of Energy Efficiency’ (International Energy Agency 2014). The aim of the publication is twofold. On the one hand, it aims to raise awareness of the multiple benefits associated with energy efficiency. On the other, it aims to demonstrate how policy makers and other stakeholders can use existing tools to measure and maximize the benefits they seek. It focuses on five key benefit areas: macroeconomic development, public budgets, health and welfare, industrial productivity, and energy supply.

There are several sources of information internationally, nationally for Spain, and regionally that collect information related to this indicator. However, most of them do not provide the data necessary to collect it. On an international scale, the IEA produced the aforementioned report ‘Capturing the Multiple Benefits of Energy Efficiency’ (International Energy Agency 2014). Although the report proposes some indicators to measure these benefits, these indicators are not developed nor is information provided for this purpose.

At the national level for Spain, through the Spain’s National Institute of Statistics (INE), access to the Hospital Morbidity Survey (EMH) is available, which provides information on hospitalizations at the national, regional, and provincial levels. Despite offering detailed information on the pathologies of hospitalized individuals, allowing the identification of those that may be associated with poor housing conditions that can be addressed through renovation and improvement of energy efficiency, the data is not sufficient to develop this indicator. Similarly, the Aragon Institute of Statistics (IAEST) and the Basque Institute of Statistics (EUSTAT) also provide this information on hospitalizations, but specific to the regions of Aragon and the Basque Country.

The only source (Table 4) that actually compiles the indicator is the Catalonia Institute for Energy Research (IREC) through its report on the estimation of the effect of energy renovation on people’s health from an economic approach (Ortiz and Salom, 2016), in which the energy, economic and health benefits of the energy renovation of the built stock are analyzed on a national scale, as well as the relationship between all of them.

Table 4 Reduction in health costs attributable to energy efficiency measures and improved air quality.
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In the aforementioned source, the public and private economic balances of energy renovation for an average household are presented. These balances include healthcare, labor, and energy costs. Additionally, the balances are divided into four housing scenarios: a base scenario, which is the unrenovated household, a medium scenario, a high scenario, and a low scenario. In turn, each of these scenarios are broken down into different types of energy renovation interventions, although this does not affect the health costs per household.

Subtracting from the healthcare costs of the base scenario those of each of the energy renovation scenarios allows for the calculation of the healthcare cost savings specified in this indicator. In this way, it is determined that for a low renovation scenario, the savings in associated healthcare costs amount to 20 euros per year per household. For a medium scenario, the savings would be 152 euros per year per household, and for a high scenario, they would be 257 euros per year per household.

The data available for calculating this indicator have some limitations that prevent it from being fully developed. One of these limitations is that the calculation has been done for a generic household without specifying its characteristics or location, which, as indicated in the report, has a significant impact on both energy and healthcare costs. Additionally, since the location of the generic household is not detailed, it is also not possible to develop the indicator at a regional level. Finally, to obtain conclusive results at the national level, it would be necessary to have the number of renovated households corresponding to the renovation scenarios outlined in this report, which seems unfeasible. Therefore, despite being able to obtain rough estimates of healthcare cost savings per household, it has not been possible to create a graph with aggregated results at the national or regional scale.

4 Conclusions

European governance encourages the development of indicators to assess the efficacy of building renovation policies and monitor the progress of decarbonization of the building stock. Some of these indicators are meant provide an overview of the current status of the building stock, and others are aimed to measure potential and expected objectives and milestones. In this chapter, indicators were proposed regarding evidence-based estimate of expected energy savings and wider benefits of buildings renovation. The indicators proposed were:

  • Expected energy saving potential per building sector and type.

  • Expected reduction in health costs attributable to energy efficiency measures and improved air quality.

We studied the sources of information available for the development of these indicators and developed them when there were data available.

The first of them, which establishes the potential for energy savings in the building sector, can be fully developed at the national scale, and only partially at the regional scale. The available sources are focused on energy savings targets.

As for the second indicator, it is a topic of interest to European countries, and for them there are different international, national, and regional sources that deal with related topics. However, they do not provide the information necessary to develop the proposed indicator. Generic data on healthcare cost savings was obtained, however there is not enough information to develop indicators on a national or regional scale.

In conclusion, the available data sources provide quite good data on expected energy savings but do not provide sufficient information to determine targets regarding reduction in health costs attributable to energy efficiency measures and air quality improvement.