测试001

Energy & Buildings 252 (2021) 111409

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Energy & Buildings

journal homepage: www.elsevier.com/locate/enb

Energy retrofit of residential building clusters. A literature review of crossover recommended measures, policies instruments and allocated funds in Spain

N. Soledad Ibañez Iralde ⇑, Jordi Pascual, Jaume Salom

Catalonia Institute for Energy Research (IREC), Jardins de les Dones de Negre 1, 08930 Sant Adrià de Besòs, Barcelona, Spain

a r t i c l e i n f o

Article history:

Received 1 June 2021

Revised 24 August 2021

Accepted 25 August 2021

Available online 27 August 2021

Keywords:

Energy retrofit

Residential building renovation

Energy efficiency retrofitting strategies Energy efficiency

Spain residential retrofitting

Spain subsidies for building renovation State-of-the-art

a b s t r a c t

The building sector is responsible for more than 40% of final energy consumption in Europe; conse- quently, retrofitting existing buildings can significantly contribute to mitigate greenhouse emissions. Nevertheless, although the European Union has introduced relevant policy instruments, up to now the annual retrofit rates are considerably low with an average of 0.2% at European level. Understanding the past would support the success of the new strategies, such as the recent ones launched through the New Green Deal, which reinforces the importance of renovating existing buildings stock, as the main aim of the renovation wave.

As a starting point for assessing the main challenges to allocate the Recovery funds, this paper provides a review of Spain’s relevant literature to clearly define the characterization of the existing building stock, which actions have been typically considered under the scope of retrofits, and which strategies have been implemented until now, considering both, private and public initiatives and public financial schemes. The present work has a strong focus on energy-related strategies, although other interrelated actions are mentioned, such as accessibility measures and interior refurbishment of dwellings. Differences and sim- ilarities within these approaches are presented through the analysis of 27 relevant references of retrofit- ting actions and 52 references of financial mechanisms.

As in Spain 93% of multifamily buildings were constructed prior to the national transposition of the first Energy Performance Building Directive (EPBD), and therefore are in need of deep energy renovations, the retrofitting of multifamily buildings topic has been widely addressed, even though often in a disjointed manner. The study suggests that although historically there have been several recommended strategies, few are conceived as integral actions, only 15% of the intervention packages refer passive and active energy-related measures and renewable energy incorporation. Furthermore, considering the antiquity of the building stock and the advantage of addressing the topic through clusters, only 63% of the resources directly refer these actions to specific clusters among the six distinctive periods, although in most cases focusing their recommendations on buildings constructed before 1980 where the worst energy performance buildings are concentrated.

Concerning public financial and funding instruments, the research illustrates that there has been a sub- stantial increment of programs over the last years promoting energy-related measures, renewable energy and other complementary aspects such as accessibility and interior renovations, mainly for older clusters. Nevertheless, the funds constitute only 8% of the necessary declared investments, which along with the dispersion between the different procedures and the complexity of the processes, have significantly reduced the global impact of these actions without generating robust and oriented market dynamics.

Despite the several resources found, both financial instruments and guidelines tend to describe in more detail strategies related to heating demand and consumption and not delve into other relevant actions for warmer climates, fact associated both to the dynamics coming from other countries, and to a vision of the past in which people do not consume refrigeration. This clear focus on heating loads rather than cooling could present limitations for warmer regions in the near climate-change future.

© 2021 Elsevier B.V. All rights reserved.

⇑ Corresponding author.

E-mail address: nsoledad@irec.cat (N.S. Ibañez Iralde).

https://doi.org/10.1016/j.enbuild.2021.111409 0378-7788/© 2021 Elsevier B.V. All rights reserved.

1. Introduction

In 2018, the building sector in Spain was responsible for approx- imately 30% of energy consumption, being the weight of residential buildings exactly 17.1% [1]. Furthermore, multifamily buildings and apartment blocks represent 69% of the existing residential building stock (16.981.159 apartments). 56% of those residential dwellings were constructed prior to 1980, before the establishment of the NBE-CT79, and 38% between that regulation and the establishment of the first Technical Building Code version [2].

As a consequence, not only to improve the energy efficiency of the existing stock but also to improve the energy performance on new buildings, several actions have been taken by the European Union and transposed by national governments [3]. Initially, with the transposition of Energy Performance Building Directives EPBD 2002/91/EC [4] that lead to the development of the Building Tech- nical Code CTE in 2006 [5], the Building Thermal Installations reg- ulation RITE in 2007 [6], and the Royal Decree 47/2007 related to energy performance certification for existing buildings in 2007 [7]. And later with the modification of the Building Technical Code in 2013 [8] and 2019 [9], the revision of RITE in 2013 [10] and 2021 [11], and the introduction of the RD 235/2013 [12] to comply with the Directives 2010/31/EU [13], 2012/27/EU [14] and 2018/844 EU [15]. Additionally, the Directive 2012/27/EU introduced the requirement to develop long-term renovation strategies by each member state; for Spain case this requirement was transposed with the development of Long-Term Strategy for Energy Renova- tion in the Building Sector in Spain ERESEE in 2014 [16], then updated during 2017 [17] and 2020 [1]. However, although many regulations and strategies have been set to tackle energy efficiency in Residential Buildings, the average energy renovation rate con- sidering deep renovations in Spain’s residential buildings was esti- mated close to 0,3%, evidencing the insufficient progress in this sector [18]. In consequence, a significant amount of research has been conducted to investigate the impact of different energy effi- ciency strategies in improving existing buildings’ energy perfor- mance, from individual actions at dwellings [19] to integral strategies in the whole building [20]. However, the strong interac- tion between the subsystems and the different impacts of the solu- tions results in a very complex selection process to achieve the desired objectives.

The decision as to which retrofit measure should be used for a

particular project is a multi-objective optimisation problem sub- ject to many constraints and limitations, such as specific building characteristics, total budget available and other financial limita- tions, characteristics of building services, building envelope, and human behaviour, all of which influence the success of the imple- mented measures [21].

Complementarily to the subject, the EPBD 2010/31/EU recast in 2009 reinforced the minimum energy performance and underlined the necessity of implementing major renovations and considering the building as a whole whenever possible. The recast also stated that all necessary measures were to be taken to ensure that these interventions were technically, functionally, and economically fea- sible, highlighting the importance of providing appropriate financ- ing and other instruments to improve buildings’ energy performance and achieve nearly zero energy building. In this con- text, all Member States were required to establish national or regional financial support programs. However, even though the Spanish transposition of these articles led to the establishment of a long-term strategy ERESEE on 2014 [16], 2017 [17], and 2020 [1], the implementation mechanisms for the following period are still under development.

This paper aims at providing a review of Spain’s relevant litera- ture to clearly define the characterization of the existing building

park, which actions have been typically considered under the scope of retrofits, and which strategies have been implemented until now, considering both, private and public initiatives and pub- lic financial schemes. The present work has a strong focus on energy-related strategies, although other interrelated actions are mentioned, such as accessibility measures and interior refurbish- ment of dwellings. Differences and similarities within these approaches are presented through the analysis of 27 relevant refer- ences of retrofitting actions and 52 references of financial mechanism.

The paper is organized as follows. The analysis of the antique- ness of residential buildings and current clustering is presented in Section 2. Section 3 presents the regulatory framework and legal definitions related to retrofit and renovation actions. Section 4 introduces the literature analysis of strategies and actions recom- mended, and the most frequently combined measures promoted in guidelines. Section 5 presents an in-depth overview of the finan- cial mechanisms put in place up to this date, and finally the discus- sion and conclusions are presented in the final section.

1. Residential building stock characterization.

The residential building park can be classified according to sev- eral variables. The location considers the different climatic condi- tions in the region and the influence of the surrounding environment, hence the difference between a city location and a rural placement. Secondly, the building’s typology reflects the dif- ference between single-family houses, multifamily houses, and apartment buildings. Lastly, the construction year considers the buildings’ constructive characteristics in each of the corresponding periods.

The clustering of residential buildings has been addressed in several projects and documents. In the international scope TABULA

[22] and MARIE [23] projects have analysed residential building stock in more than 21 European countries, including Spain, and classified buildings according to size, typologies, and year of con- struction, at the same time identifying the main technologies used to supply heat. The matrix elaborated and other equivalent methodologies has been used in several projects such as ENTRANZE [24] to assess retrofitting processes and project future energy consumption, and to distinguish building stock on several countries such as France, Italy, Slovenia, Austria, Sweden, Greece, Germany [25–30]. That analysis has shown that the antiqueness of the park is a common factor in most European countries, with more than half of residential buildings constructed before the establishment of thermal regulations (built before 1970) [31].

In the Spanish case according to the Continuous Household Sur- vey of 2018, 68.9% of Spanish homes are located in urban environ- ments, compared with 31.1% houses that are located in rural locations. Notably, 3.1 M houses (17%) are concentrated in 6 cities with more than 500.000 inhabitants (Madrid, Barcelona, Valencia, Seville, Zaragoza, and Malaga). Regarding the differentiation according to use, 8.7 M houses (67.9%) are located in multifamily buildings [1].

Specifically regarding the clustering, the weight of the different construction periods has been assessed by public and private enti- ties to calculate savings and structure long-term recovery plans. As at the international level TABULA and MARIA projects divided buildings into six and four distinctive periods correspondingly, at the national level, the long-term strategy ERESEE distinguished five periods due to technical or regulatory changes. At the same time, other relevant transversal entities such as the Green Building Council España (GBCe) have equivalent classifications, even the classification, developed during 2012, introduced the concept of ‘‘hotspots” to establish the scenarios for improving energy

efficiency and reducing GHG emissions in the horizon 2020 and 2030 [32]. In addition, some regional and local organisms have pre- sented a more detailed classification for their territory, which are useful to better establish regional or even local public support poli- cies and key relevant actors.

So, although there are some differences between the grouping presented in the references, the Spanish residential building stock can be classified into six distinctive periods (cluster 1 < 1940, clus- ter 2 1941–1960, cluster 3 1961–1980, cluster 4 1981–2007, clus-

ter 5 2008–2013, cluster 6 2014–2020) that have significance due to technical regulation changes. Buildings constructed before 1940 (traditional buildings), between 1940 and 1960 (first urban expan- sion and block typologies), between 1960 and 1980 (second urban expansion with changes in the construction systems), between 1980 and 2007 (application of the NBECT/79, which demanded a minimum of thermal insulation), from 2008 until 2013 (implemen- tation of the 2006 Building Technical Code), and from 2014 to 2020 (implementation of 2013 Building Technical code until the 2019 modification).

More than 54% of the stock constructed before the implementa- tion of energy regulations, and as this stock is directly linked to the population, 56.63% of the residential park prior to 1980 accumu- lates in the Autonomous Communities of Andalusia (18.46%), Cat- alonia (12.79%), Valencian Community (10.97%), Castile and Leon (9.88%), and Madrid (4.53%), representing 64.02% of the country population. As relevant data, 16.21% of the total buildings built in Spain previously to 1980, it is in poor conservation conditions, and 78.90% are not accessible, according to the parameters used in the census, therefore with an urgent need of energy and acces- sibility improvements [33] ¹. These figures are especially relevant for a member state that have one of the worst major energy retrofit- ting ratios all over Europe [34]. Apart from the year of construction, some authors distinguish different typologies among the periods, first according to their use, single-family or multifamily buildings, and secondly considering the characteristics of the volume, such as the number of floors and the boundary conditions of the envelope.

1. Background: regulatory and legal definitions

The terms ‘‘retrofit,” ‘‘refurbishment,” and ‘‘renovation” are three commonly used expressions used in the built environment to describe physical changes executed to improve existing build- ings. The action of retrofitting has been defined as ‘‘providing something with a component or feature not fitted during manufac- ture or adding something that it did not have when first con- structed” [35] or as ‘‘the modification or conversion (not a complete replacement) of an existing process, facility or structure” [36]. However, to establish a common framework to analyse the previous studies, it is necessary to contextualize this terminology specifically for Spain, therefore defining which actions are required in an integral building retrofit (and in which ones the actions can be considered individual changes).

The Building Technical Code defines as a retrofit the actions executed to either achieve structural adaptations, conduct func- tional modifications, such as removing accessibility barriers or introduce adaptation to modify the area destined for housing to create new homes. It also establishes that an integral retrofit will be understood as the interventions in which all three previous adaptations are carried out. In addition, the term ‘‘remodel” or ‘‘re- furbishment” is introduced within the HE0 energy savings section, when introducing the renovation of existing installations or envel- opes. Furthermore, a more precise definition of the concept is

¹ It should be noted that Murcia province did not facilitate data during this study and therefore the statistics are based on 15 of 16 autonomous communities.

introduced in 2019 in section 1 of the updated Building Technical Code, establishing as remodelling any activities conducted in the building that are not related to the required maintenance, there- fore enclosing all former actions in the scope of renovations.

At the other side, the Ministry of Development [37] states that any significant work in existing constructions that do not involve constructing a new building can be considered a retrofit project, independently of whether or not the works include demolitions. The retrofit actions are disaggregated into two categories, expan- sion works, whose objective is to increase the existing area, and restoration or remodelling works, where the existing area is not modified, but an alteration to structural elements are made or new features are incorporated.

In both cases it seems to be clear that retrofit actions are usually considered to be more integral interventions and remodelling as individual renovation actions of a part of the building, even though in neither case energy related interventions are specifically included in the scope of retrofitting as shown in Fig. 1. Further- more, the necessity of executing energy-related interventions dur- ing retrofitting is limited to intervention in which more than 25% of the envelope is intervened, and energy systems are renovated as well, therefore leaving out many interesting synergies that could be useful to improve energy performance. At the other side, the primary energy limits of the Spanish building code related to the nZEB definition are clearly far away to the limits introduced in other European countries [38], being the required values for inte- gral retrofit, more or less the double than for new buildings. These facts could certainly affect the energy savings to be achieved.

1. Review on technical guidelines and public support actions for residential building retrofits
   1. Methodology and literature analysis

Retrofitting measures have been widely analysed over the past years as the main component to reduce energy consumption in existing buildings. Several extensive works have been conducted to establish the current state of building retrofitting at the interna- tional level and listing the different measures promoted in the market and the available solutions. For example, Ma et al. [39] con- ducted a systematic approach to identify the best retrofit options, and Abdul Hamid et al. [40] introduced an extensive literature review of retrofitting measures. In particular, the present study focusses on guidelines and programs developed in Spain and, directly or indirectly, related to energy efficiency retrofitting mea- sures for residential multifamily buildings. Most of the documents have been elaborated by national, regional, and local administra- tions and uploaded in official communication channels and jour- nals, and in most cases, the detailed information is only available in Spanish or other local languages. Consequently, the search has been conducted by reviewing official communication channels such as the State official journal (BOE). The analysis also intro- duced key relevant transversal associations and entities who clo- sely have been collaborating in the sector during the last years. Examples of these associations are The Green Building Council España, Naturgy, and La Casa que Ahorra foundations. Thus, the analysis includes: technical reports and retrofit catalogues at a national, regional, and local level, Ph.D. theses, papers, and plat- forms related to retrofitting measures; reports addressing the mat- ter without indicating specific actions and documents dedicated to single strategies were not included in the final list. The analysis does not include the real impact of the proposed actions and mech- anisms implemented since, so far, the implementation of retrofit- ting actions has been mainly validated through the measurement

Fig. 1. Type of interventions according to the different sources at Spanish level.

of their impact on energy certifications but without detailed deseg- regation of real performances.

The first sifting of references result in over 70 documents refer- ring to building retrofitting, however only 27 reports and studies specifically indicated measures to improve energy efficiency in existing buildings [1,19,20,32,41–63]. Nevertheless, although the focus of the analysis was energy efficiency actions, complementary actions that are carried out during the interventions were reviewed and listed, such as accessibility measures and modifications inside apartments.

The investigation shows that professionals have made a signif- icant effort to develop and promote actions to improve existing buildings’ energy performance. Four documents developed by national public institutions were identified [148 4950], as well as five reports developed by transversal organizations and founda- tions such as La Casa que Ahorra [5152], Spain Green Building Council

[43] and Gas Natural Fenosa [1954], and 12 references were detected at regional and local level, nine of them by public entities [41–43,46,47,57–60] two by Valentia Institute of Building founda- tion (IVE) [5556] and one by Gas Natural Fenosa foundation [53]. Furthermore, the list is complemented by a Ph.D. thesis developed in the framework of MARIA project focused on the analysis of the impact of energy actions [20], two papers [6162], a platform derived from a European project [63], and two platforms devel- oped by Catalonia’s Energy agency [4445]. In total, 56% of the ref- erences were listed by public organizations and 44% by other transversal associations in the sector. Regarding the geographical scope of the literature, the majority of the documents cover the national scope, as it can be shown in Fig. 2.

In regards to the strategies and actions recommended, the crite- ria slightly differ from one source to another. Twenty-five of the studies describe actions to be implemented in the whole building, at the same time. At the other side, express rehabilitation for vul- nerable households low-cost solutions [19], HOLA DOMUS plat- form [63], and papers [6162] can be differentiated for addressing individual users and listing strategies to single dwellings. The majority of the references aim to facilitate the decision-making process before a renovation. However, in some cases, such as the

Ph.D. thesis [20], the main aim also includes the analysis of the real impact on building behavior, and in others such as the papers, the influence of energy efficiency measures in user perception. Fur- thermore, there are several quite extensive detailed reports. Some of the documents incorporate detailed simulations and savings estimations and thresholds and detailed criteria to execute the actions, such as minimum thickness for insulation layers or charac- teristics of the systems to be installed.

The strategies listed can be categorized into four different the- matic groups. Passive interventions addressing elements of the envelope, actions to improve or install systems that require to cover building loads, strategies to eliminate horizontal or vertical accessibility barriers, and adaptations to be executed inside dwellings.

• 1. Categorization of retrofitting actions
     1. Passive measures

Improving the building envelope and intervening over the exist- ing constructive elements can lead to the reduction of energy demand, therefore to the achievement of energy savings. Due to its relevance, all references cite strategies dedicated to improving the envelope. The strategies can be classified into 15 categories, as show in Table 1.

All references cite the increment of insulation at façades and the replacement of windows or glasses as a primary strategy to reduce energy demand. The third most considered aspect is the increase of roof insulation, which could be connected to the fact that roofs usually represent a minor proportion of the envelope, and the impact of the actions are reflected in dwellings located at the top. Solar protections are located in fourth place, which is notewor- thy considering that in the Mediterranean climate, the combina- tion of shading devices with moderate values of window can significant reduce cooling loads [64]. Approximately half of the ref- erences point measures related to the improvement of airtightness, floor and walls insulation, and 30% of the references describe speci- fic actions such as green and ventilated façades and albedo’s influ- ence in the final behavior. Further analysis of the building envelope measures shows that four references can be found that specifically describe devices to capture solar gains, such as galleries and Trombe walls, which promote the increment of insulation on exist- ing ceilings. Finally, only two of all references evaluate alterations to enhance natural ventilation, whether it is by replacing a window or by reconfiguring the backyard, and two documents list actions to increase thermal mass and improve waterproofing.

• • 1. Active systems and renewable energy systems measures

The use of energy-efficient systems and low carbon and renew- able energy technologies is often introduced to lower the energy demand and improve the building’s environmental footprint. Many references incorporate measures on the building services. The strategies addressed can be divided into five categories related to

Fig. 2. Geographical scope and type of references.

Table 1

Proposed improvements for residential building retrofits.

Category	Action	Number of appearances	Weight over the total	Weight of the category	Type of reference
Passive strategy	PS01 Façade insulation	27	9,4%	56%	PA, FA, EP, P
	PS02 Roof insulation	25	8,7%		PA, FA, EP
	PS03 Green or ventilated façade or roof	8	2,8%		PA, FA
	PS04 Albedo – colour – of surfaces.	6	2,1%		PA, FA
	PS05 Insulation in walls (interior party or	11	3,8%		PA, FA
	underground walls)
	PS06 Insulation in interior ceilings	4	1,4%		PA, FA
	PS07 Floor insulation	12	4,2%		PA, FA, EP
	PS08 Alterations on backyards	2	0,7%		FA
	PS09 Replacement of Windows and glasses	27	9,4%		PA, FA, EP, P
	PS10 Solar protections	17	5,9%		PA, FA, EP
	PS11 Solar gain devices (galleries, Trombe wall,	4	1,4%		PA, FA
	greenhouses)
	PS12 Natural ventilation devices (windows, solar	2	0,7%		PA,FA
	chimney)
	PS13 Air tightness (building level or on	13	4,5%		PA, F
	windows)
	PS14 Waterproofing	1	0,3%		PA
	PS15 Thermal mass increment	1	0,3%		PA
System interventions, renewable energy	AS01 Heating and DHW systems	23	8,0%	39%	PA, FA, EP, P
and management	AS02 Water and DHW	9	3,1%		PA, FA, EP, P
	AS03 Air conditioning and alternatives	14	4,9%		PA, FA, EP
	AS04 Ventilation systems	9	3,1%		PA.FA
	AS05 Lightening	17	5,9%		PA, FA, EP
	AS06 Appliances	8	2,8%		PA, FA, EP
	AS07 Renewable Energy	20	7,0%		PA, FA, EP, P
	AS08 Optimization of the use and management	11	3,8%		PA, FA, EP
	of the building
Accessibility	AB01 Vertical barriers	11	3,8%	5%	PA, FA, EP
	AB02 Horizontal barriers	2	0,7%		PA
Adaptation of dwellings	AD01 Redistribution of interior spaces	1	0,3%	1%	P
	AD02 Renovation of interior spaces such as	2	0,7%		EP, P
	kitchen and bathrooms
Total number of references found		287,287

PA: public authority FA: foundation and associations EP: European project P: paper

main building systems: combined heating and domestic hot water systems (DHW), independent water and DHW systems, air condi- tioning, ventilation systems, and lightning; and three additional categories to list complementary actions such as the renovation of the appliances, the incorporation of renewable energy and the improvement of the system management and building use.

The most frequently proposed strategy is improving existing Heating and DHW systems, such as replacing old boilers for high-efficiency boilers and aerothermal heat pumps, followed by the incorporation of renewable energy with photovoltaic panels and biomass boilers, and the improvement of lightning equipment with LED technology. Only half of the references address cooling improvements, and between 30% and 33% of the references point out enhancements in ventilation and water systems, for instance, mechanical ventilation systems with heat recovery and the replacement of appliances This noticeable difference between pro- posed heating equipment interventions and air conditioning could be related to the clear tendency to focus the interventions on reducing heating demand. This prevalence can also be seen in the tendency to promote the increment of envelope insulation and the fact that Spanish residential buildings are not required to have air conditioning systems, and usually, these systems are installed afterward by the owners. Furthermore, building manage- ment improvements such as monitoring and control systems are also quite often considered as 41% of the documents incorporate related strategies. Additionally, some of the documents introduce further details specifying actions to improve or replace parts of the global systems such as pumps and pipe’s insulation.

• • 1. Accessibility improvements

In regards to accessibility measures, two categories were iden- tified at the building level. Measures to overcome vertical accessi- bility barriers include incorporating elevators and platforms and actions to resolve horizontal barriers such as grades and stairs, in this case, by adding ramps. The strategies to overcome accessibility barriers inside dwellings are cover in the following section. 41% of the references point out vertical accessibility, which if often con- sidered on integral interventions to improve their functionality and facilitate access to all stakeholders. Horizontal barriers, on the other hand, are mentioned in only 7% of the documents.

• • 1. Interventions at dwelling level

Even though most documents were focused on actions to be executed at the building level, some references were found that explicitly assess measures in single dwellings. Specifically, two of them either propose or analyse improvements in interior spaces. Marmolejo [61] introduced the aim of analysing the willingness of users to pay for attributes related to energy efficiency, focusing on interior redistributions and bathroom and kitchen renovations. Complementary, HOLA DOMUS platform [63], derived from Euro- PACE European’s project, focuses on offering assistance to building consortiums and individual owners. Therefore two main categories could be listed: the redistribution and adaptation of interior spaces and the renovation of interior spaces being the bathroom and kitchen the most commonly addressed spaces.

• 1. Weighted analysis of retrofitting measures

As shown in Table 1, passive strategies are more commonly referred to in the documents, followed by systems interventions. Regarding the relation between actions and the clusters discussed in section two, 8 out of the 27 references recommend specific strategies for the different clusters [14144464852]. In most cases, the documents target buildings constructed before 2000, even though the ERESEE and the PhD thesis also include representative typologies for the period between 1981 and 2007. Particularly the Housing National Plan [48], The challenge of rehabilitation [52] and the subsidies PARER II [50] are directed at buildings con- structed before 1996, for the first two cases, and 2007 in the sec- ond. In these documents, even though strategies are mentioned, the objective is based on reducing energy consumption by a certain percentage without indicating which specific actions should be implemented. In addition, some documents can be found that use specific building typologies to calculate the energy savings and support the recommendations, even though the general frame- work of the document is not intended for specific clusters, such is the case of the three references elaborated by Gas Natural Fenosa Foundation [195453]. Similarly, the document elaborated by Bar- celona city council [43] introduces four cases of success as an example of actions to be considered in similar buildings. Lastly, two documents use an alternative methodology to structure their recommendations, the Refurbishment Catalogue elaborated by IVE [55] and the Guide to the energy renovation of residential buildings by the Catalonian government [47], which organizes the strategies according to the different constructive systems pre- sent in buildings before 1980, and therefore establishing actions to reduce the thermal transmittance of those specific periods.

Concerning the actions, the intervention of main elements of

the envelope, windows, the renovation of the heating and DHW systems, and the renovation or incorporation of renewable sys- tems, mainly solar panels for DHW, are addressed for all the clus- ters to reduce heating and DHW demand and consumption. Actions directly related to reducing cooling demand, such as solar protections and improvement of the refrigeration systems, are often missed in the main recommendation. An example of this is the long-term renovation strategy ERESEE 2020, in which awnings are only included in the intervention package for buildings within the range of energy poverty. In the same document, bioclimatic devices and other shading devices are considered supplementary actions, and no projections are calculated to value the future impact of cooling demands over the years.

Table 1 denotes the total amount of strategies found, the num- ber of references and their representability over the total, and in parallel the type of documents that reference them and if they are indicated for specific clusters.

• • 1. Frequently joint strategies recommended in residential retrofits A second sifting was conducted to list frequently joint strategies proposed together. Only 16 documents of the previously described reports introduced combined actions that either specifically address clusters or, even though they are not recommended for specific ones, they validated their recommendations through refer- ence buildings from a particular construction period. As it can be seen in Table 2 the combined actions can be classified in four dis- tinctive categories: (1) combined passive strategies; (2) combined active system interventions and renewable energy systems; (3) combinations of passive strategies, active systems, and renewable energy; (4) combined active and passive strategies with the addi- tion of renewable energy systems and accessibility improvements. As shown in Fig. 3, 46% of the proposed combinations are integral interventions of passive and active systems, incorporating renew-

able energy in some cases, followed by joint passive actions.

The renovation of façades, roofs and windows along with the intervention in heating and DHW system is the most frequent pro- posal involving passive and active systems. The majority of these combined actions are focused on the improvement of the elements of the envelope together with the renovation of heating and Domestic Hot Water systems, whilst only four include strategies to reduce cooling demand and cooling expenses. In addition, the improvement of windows, roofs, and façades is the most frequent combination of passive strategies proposed in the documents. Regarding accessibility, incorporating specific actions is recom- mended either for projects where improvements are made in com- mon spaces or for deep renovations where all main systems and elements are renovated. It is noteworthy that considering that most of the existing building park needs deep renovations, more integral combined actions that together with building envelope assess system improvements and renewable energy are referred only in 15% of the intervention packages and accessibility mea- sures only in 5%.

Between 54% and 64% of the intervention are either addressed or validated on buildings constructed between 1940 and 1980 (cluster 1 to 3) where the worst energy performance buildings are concentrated, followed by packages recommended by cluster 4, only one case study of a building constructed after 2007 is listed in the documents. The intervention package A07, insulation of façades, roofs, and replacement of windows is the most referred action among the strategies, being recommended for buildings in the four first clusters, followed by A11 and A12 that include the insulation of floors, ceilings, and solar protections as well. In cate- gory two, A22 includes the improvement of the envelope and the renovation of heating and DWH systems, and A33 that includes all main energy consumption systems and solar panels, are listed as exemplary cases of integral retrofitting. Additionally, A20 is a low-cost intervention that can improve the energy performance of the building without significant investments or long payback periods. In all cases, the packages are referred to in documents elaborated by public authorities.

1. Spain public funding schemes and subsidies for energy retrofit and accessibility
   1. Methodology and literature analysis

Financial mechanisms that can support deep energy renova- tions are essential instruments to secure the feasibility of renova- tions. At the European level, the majority of the conventional incentives are organized mainly through grants and subsidies, fol- lowed by soft loans and tax incentives. Some examples of the most significant public resources spent schemes are the Italian Eco- bonus tax rebate scheme and the French Energy Transition Tax Credit scheme [65]. However, even though several instruments can be listed, their overall efficacy is unclear since very few of the financing mechanisms set clear verification protocols to vali- date the results after implementing the actions. The lack of moni- toring is a clear barrier to further analyse which measures to implement to achieve more ambitious goals [66].

To understand the range of financial instruments available in Spain an investigation was conducted to detect the available national, regional, and local financial instruments for residential energy retrofitting between the years 1984 and 2020; documents either assigning budget or establishing specific financial mecha- nisms were included in the review. The sifting includes all avail- able sources at the moment; some references could not been included, as information is no longer available, as they are mainly past mechanisms already closed. Twenty-seven national plans and financial instruments were distinguished, twenty of them targeting

Table 2

Relation between individual strategies, intervention packages and clusters.

Category	Intervention package	Type of reference	Cluster for which is validated or recommended
	A01 - PS09 PS10 (Windows and blinds)	PA	1	2	3	4
	A02 - PS01, PS02 (Roofs and façades)	EP	1	2		4
	A03 - PS01, PS09 (Façades and windows)	EP, FA	1	2	3
	A04 - PS01, PS09, PS10, PS13, (façades , windows, solar protections, and airtightness)	FA			3
	A05 - PS01, PS02, PS04, PS09, PS10, PS13 (Façades, roofs, albedo, windows, solar protections, airtightness) A06 - PS01, PS02, PS06 (Façades, roofs and interior ceilings)	FA PA	1	2	3 3
	A07 - PS01, PS02, PS09 (Façades roofs and windows)	PA, FA, EP	1	2	3	4
	A08 - PS01, PS02, PS10 (Façades, roofs and solar protections)	EP		2	3
	A09 - PS01, PS02, PS09, PS10 (Façades, roofs, windows and solar protections)	EP				4
	A10 - PS01, PS02, PS04, PS09, PS10, PS13 (Façades, roofs, albedo, windows, solar protections and airtightness)	FA			3
	A11 - PS01, PS02, PS07, PS09 (Façades, roofs, floor and windows)	PA, FA	1	2	3	4
	A12 - PS01, PS02, PS06, PS07, PS09, PS10, (Façades, roofs, ceilings, ground floor, windows and solar protections) A13 - PS01, PS09, PS10 (Façades, windows and solar protections)	PA, FA FA, EP	1	2	3 3	4 4
	A14 - AS01, AS03 (Heating and cooling)	EP	1	2	3	4
	A15 AS01, AS02, AS05 (Heating and DHW, cooling and lightening)	PA	1	2	3	4
	A16 - AS01, AS03, AS04, AS07 (Heating and DHW, cooling and mechanical ventilation and solar	FA	1	2	3	4
	panels) A17 - AS01, AS03, AS05, AS07 (Heating and DHW, cooling, lightening and renewable energy)	EP				4
	A18 - AS01, AS05, AS07 (Heating and DHW, lightening and renewable energy)	EP				4
	A19 - AS01, AS03, AS04 (heating and DHW, cooling and ventilation)	FA			3
	A20 - PS13, AS02, AS05 (Airtightness and DHW flow adjustments and lightening)	PA	1	2	3	4
	A21 - PS01, PS02, AS01 (Façades, roofs, heating and DHW)	EP	1	2
	A22 - PS01, PS09, PS02, AS01 (Facades, windows, roofs, heating and DHW)	PA	1	2	3	4
	A23 - PS01, PS02, PS07, PS09, AS01, AS03, AS05 (Facades, roofs, floors, windows, heating and DHW,	PA	1	2	3	4
	cooling and lightening) A24 - PS01, PS02, PS07, PS09, AS01, AS04 (Façades, roofs, ground floor, windows, heating DHW and	FA	1	2	3
	ventilation) A25 - PS01, PS09, PS10, AS01, AS05, (Façades, windows, solar protections, heating and DHW and	PA			3
	lightening) A26 - PS02, PS07, PS09, AS01, AS04 (Roofs, first floor, windows, heating and ventilation)	FA				4
	A27 - PS01 (partially), PS10, AS05, AS08 (Treatment of thermal bridges, blinds, lightening and a management system)	PA					5
	A28 - PS01, PS02, PS09,AS01, AS03, AS05 (Facades, roofs, windows, heating, DHW, cooling and lightening) A29 - PS01, PS02, AS01, AS03 (Facades, roofs, heating and DHW, cooling)	EP EP	1 1	2 2
	A30 - PS01, AS01, AS03, AS05 (Facades, heating, DHW, cooling and lightening)	EP		2	3
	A31 - PS01, AS01, AS05 (Facades, heating and DHW, and lightening)	EP				4
	A32 - PS01, PS02, PS09, AS01, AS05, AS07 (Façades, roofs, windows, heating and DHW, lightening solar panels for DHW)	EP	1	2
	A33 - PS01, PS02, PS09, AS01, AS03, AS05, AS07 (Facades, roofs, windows, heating and DHW, cooling, lightening and solar panels for DHW) A34 - PS01, PS02, PS09, AS01, AS07, AS08 (Façades, roofs, windows, heating and DHW, solar panels	PA, FA, EP PA	1 1	2 2	3 3	4 4
	for DHW and a management system) A35 - PS01, PS02, PS09, PS10, AS01, AS05, AS07 (Façades, roofs, windows, solar protection, heating	EP				4
	and DHW, lightening and solar and photovoltaic panels) A36 - PS01, PS02, PS09, PS10, AS01, AS03, AS05, AS07 (Façades, roofs, windows, solar protections,	EP				4
	heating and DHW, cooling , lightening and solar and photovoltaic panels)
	A37 - PS01, PS02, PS09, AS07 (Façades, roofs, windows, renewable energy)	PA	1	2	3	4
	A38 - PS01, PS02, PS09,AB01 (Façades, windows, roofs, vertical accessibility)	PA			3
	A39 - PS01, PS02, PS09, AB01, AB02, AS02, AS05 (Façades, roofs, windows, horizontal and vertical accessibility and renovation of shared installations)	PA		2

PA: public authority FA: foundation and associations EP: European project P: paper

Cluster 1: <1940 Cluster 2: 1941–1960 Cluster 3: 1961–1980 Cluster 4: 1981–2007 Cluster 5: 2008–2013 Cluster 6: 2014–2020

Fig. 3. Combined strategies, categorization proposed.

integral retrofitting actions, and five of them specifically address- ing the implementation of renewable energy and the improvement of the building systems. Ten National Housing Plans between the years 1984 and 2021 established retrofitting financial mechanisms [67–75,48], five national strategies and actions plans for improving energy efficiency between the years 1997 and 2020 [76–80], five national financial mechanisms managing European Founds [50,81–84] and two additional plans particularly addressing renewable energy implementation [8586]. Furthermore, three derivative programs were initiated with the aim of funding renew- able energy sources [87–89] together with several funds promoted

by the Spanish Institute for Energy Diversification and Savings (IDAE) and the Spanish Official Credit Institute (ICO) between the years 2000 and 2004 [90] and from 2005 until now [91]. Further- more, since in some cases, national funds are directly distributed among the different regions and managed by regional authorities, a second sift was conducted specifically across Catalonian Region, as a representative example to identify regional and local funds, being Barcelona one of the main regions where older clusters are present [2]. Two regional plans were identified in Catalonian region, Catalonian Energy Plan 2006–2015 [92] and Catalonian Energy and Climate Change Plan PECAC 2012–2020 [93]; from the former, four resulting programs were set up between the years 2006–2011 targeting the renovation of appliances, windows and the improvement of the cooling and heating systems. In addition three grants were established by the three Housing Agency of Cat- alonia [94–96]. At local level sixteen policies were identified, one scheme promoted by the Barcelona City Council [96], eight subsi- dies endorsed by the Housing Consortium of Barcelona Metropoli- tan Area [97–104] and seven local aids set up by the Barcelona Housing consortium [96,105–110].

• 1. Analysis of retrofitting actions promoted by funds

Regarding the promoted actions, even the majority of the finan- cial instruments and plans endorsed integral building retrofitting to reduce final energy consumption through the implementation

of several actions; there are specific aids exclusively dedicated to upgrading individual elements such as windows, renewable sys- tems, or accessibility elements. Moreover, 75% of the policies and plans finance passive measures over the envelope, mainly aiming the increment of insulation on the different elements, even though approximately 31% of the reports include measures to improve o install solar protections and 21% reference precisely other actions such as the implementation of green façades. It is also worth notic- ing that only 2% of the mechanism explicitly includes the execution of devices to capture solar gains. Concerning the systems, nearly 62% of the financial plans and instruments target thermal systems, and up to 56% of the grants and funds promote the improvement of lighting systems. Renewable energy is addressed on 42% of de founds, up until now mainly intending to establish aids to execute solar panels for Domestic Hot Water, even though on the recently updated regulations other renewable sources are promoted. Lastly, accessibility measures are included in over 50% of the funds and, approximately 38% of the aids particularly address interior renova- tions. As shown in Fig. 4, national and regional funds and programs are frequently focused on passive and active measures and renew- able energy, whereas on local instruments, the distribution among the categories is more uniform. The thickness of the lines are sized according to the number of references found in each case.

At the other side, and as shown in Fig. 5, a clear increment in the

evolution of the founds can be perceived starting from 2010, coin- cidently with the recast of the EPBD 2010/31/EU in 2009, especially

Fig. 4. Relation between policies scopes and retrofitting actions —1-column fitting image-

Fig. 5. Evolution of found and subsidies between the years 1984 and 2020. —2-column fitting image-

at the regional and local level even though national plans to improve energy efficiency have been established from 1984. Fur- thermore, European Founds such as FEDER grants have been dis- tributed among the regions from 2013 until today. It is also worth observing that accessibility measures and interior renova- tion of dwellings have acquired more relevance over the last years; particularly from 2017 there are specific funds to overcome acces- sibility barriers and regionals and local aids to renovate dwellings with the aim of improving habitability.

A broad range of financial incentives to facilitate investments in energy efficiency, accessibility, and interior renovation in existing buildings can be found among the different mechanisms set in place. National housing plans, executed from 1986, have progres- sively supported passive and active strategies, accessibility mea- sures, and interior renovations in social housing. The maximum amount of subsidies varies from 10% up to 75% depending on the type of interventions implemented and the applicant’s social- economic status. On the other hand, funding can cover all the nec- essary investment but with a maximum for dwelling and square meter and considering a threshold established by the maximum market price for social housing. Financials mechanism to distribute European Founds commonly address the increasing of buildings’ energy efficiency and the installation of renewable energy. The standard subsidies cover 30% of the cost and up to 80% of the total if the applying part has low incomes, performs an integral retrofit- ting, or if the achieved energy is A or B. These additional subsidies are also influenced by other criteria such as the type of promotor, the geographic location and the total eligible amount. Regional programs frequently address energy efficiency and renewable energy, although there are tailored programs for the dwelling’s

interior renovation. Subsidies vary from 35% up to 100% of the real cost considering the actions included, but with a maximum amount by dwelling or square meter. At last, local aids target gen- erally integral retrofitting, including all main five categories; even though specific programs are developed, such as the recently exe- cuted program for the interiors home rehabilitation to help mini- mize the economic and social impact of COVID-19, subsidies vary from 40% up to 100% of the real cost considering the actions included, but with a maximum amount by dwelling. Concerning the total budget assigned, among the available information and using as an illustration, the Building Energy rehabilitation PREE program that distributes European funds [66], which constituted the major allocated investment of all the introduced programs, the total annual budget assigned is €300 M. Bearing in mind that according to the GTR city report [111] 250.000 houses need to be renovated each year, with average investment of €15.000 per each project, the assigned funds constitute an 8% of the necessary annual investment, therefore diverting even more the achievement of the objectives.

In relation to the clusters, national housing plants have tradi- tionally supported the renovation of older clusters. For example, the last program (2018–2021) included buildings constructed before 1996, targeting clusters 1 to 3 and 4 partially. Financials mechanism of European Founds such as PARER CRECE, PARER II, and PREE program address buildings constructed before 2014 in the first case and 2007 in the last two cases, hence covering all clusters. At the local level, all programs for accessibility, habitabil- ity, and rehabilitation actions promoted by the Housing Consor- tium of Barcelona Metropolitan Area are directed to the first two clusters (buildings constructed before 1981).

As a final point, even a distinct growth of funding could be detected on recent years, either due to the inherent conditions of the funds or due to the limited historical background and knowl- edge, none of the lines analysed allows in a simple and clear man- ner the integration of PPP (Public Private Partnership) schemes with contributions from third parties (ESE / ESCO), beyond the public organisation and the property owner or promotor. This fact, together with a budget considerably distant from the necessary investments, is a clear limitation for large-scale interventions and to achieve the retrofitting ratios required by the Green Deal and the renovation wave.

1. Discussion, results and conclusions

The paper presented a review of the clustering of residential buildings, the current retrofitting definition and scopes considered in the national regulations, public and private guidelines and pro- grammes that explicitly address energy renovations, accessibility measures, and interior renovations, and the financial mechanics set in place to promote the renovation of the different clusters. The establishment of the background and the main limitations found so far could help assess the challenges of successfully imple- menting the renovation wave. In addition, even though the analy- sis was strictly conducted for Spain, this research could be extrapolated to other regions to establish the basis for retrofitting actions.

The analysis of the clusters, the different retrofitting actions, and financial mechanisms offer a first approach to review the cur- rent state of retrofitting interventions in existing buildings. Never- theless, to find the optimal solution is necessary to conduct a thorough analysis of the strategies and mechanisms considering building-specific information. The particular characteristics of a buildings, such as the geographical location and price market are closely related to the social-economic status of the users; there- fore, they could determine the investment threshold that the own- ers are able to allocate. Other urban factors for instance specific or heritage regulations for either the site or the building or manda- tory building inspections could determine the main priorities to execute during the works. Consequently, retrofitting actions must be analysed for each specific case, considering not only economic or energy factors but also other influential aspects such as opera- tion and maintenance, energy sources available, and user’s behaviour.

• 1. Conclusions

At first, even there is a substantial amount of research on the subject, the definition of integral retrofitting and which actions should be executed are not sufficiently clarified at official level, neither in the Technical Code nor by the Ministry of Development. At least at the national level, it would be relevant to have a clear definition to simplify and facilitate comprehension and proce- dures, together with being able to perform an adequate bench- marking of retrofitting interventions.

As for the building stock 93% of multifamily buildings were con- structed prior to EPBD national transposition in 2007 (clusters 1 to 4). In addition, 16.21% of the total buildings built in Spain previ- ously to 1980 are in poor conservation conditions, and 78.90% have limited accessibility, therefore with an urgent need of oriented improvements.

From there, and as demonstrated by the different reports, energy, accessibility and interior retrofitting actions are covered in several guides and references in Spain. The reviewed material introduces different approaches, from individual measures that can be implemented inside dwellings to more integral strategies.

However, even the available guidelines provide relevant informa- tion for easing choices in the renovation process, only 63% of the documents either address or validate their recommendation based on particular clusters, introducing insulation thresholds, specific recommendations for the systems, and proposing combined strate- gies supported by preliminary simulations that validate the energy savings. Most of these documents address buildings constructed until 1980 (clusters 1 to 3) where most of the worst energy perfor- mance buildings are located, yet, the proposals and simulations are based on theoretical models, and none of the documents includes specific information of the energy savings finally achieved after the execution of the renovations. Further analysis could be done to facilitate strategies that have been previously tested in real- world buildings, even more considering that specific conditions, such as particular climatic conditions, are not always included in theoretical analysis.

Furthermore, only 60% of the documents include combined actions, being the majority focused on envelope improvement together with the renovation of heating and DHW systems. It is noteworthy that considering that most of the existing buildings need deep renovations, only 15% of the intervention packages incorporate more integral combined actions of the envelope, sys- tem improvements, and renewable systems.

More deep in detail there is a strong tendency to prioritize ther- mal improvements related to heating, as the most frequent passive strategies and combined actions commonly address the improve- ment of insulation and the replacement of heating systems and installations. Considering the wide range of climate conditions in Spain, this fact seems to become a clear limitation, particularly for more Mediterranean climates and islands locations. Some viable measures are rarely included, for instance, changes to facil- itate natural ventilation or devices to capture solar gains in more cold regions. This problem is assumed to be the result of historical background, in which a reduced amount of residential buildings have cooling systems, as well as the transposition of directives that historically have underestimated cooling loads [112]. It should be noted that cooling loads are significantly relevant in a country with Mediterranean and subtropical regions whose maximum tempera- ture could be considerably affected by climate change [113]. It will be recommendable that the following initiatives consider cooling strategies and actions.

Concerning financial instruments, the research illustrates that there has been a substantial increment of subsidies and financing programs over the last years, with a clear increment of instruments at all levels from 2010, promoting passive and active energy-saving measures and renewable energy. In addition to the three main related strategies, aspects related to accessibility, such as elevators and ramps, and interior improvements to increase comfort and habitability on dwellings have been taking a more relevant role over the last years, nowadays even more accentuated by the cur- rent pandemic outbreak.

Most of the financial mechanisms set in place address the improvement of energy efficiency based on results, for example through energy certification, rather than on concrete measures, although they target specific issues such as insulation and system interventions. Almost 75% of the financial instruments explicitly refer to insulation increments in façades, while ventilation strate- gies or elements to control solar gains are not equally point in the documents, only 31% make specific mentions of solar protec- tions. In relation to the clusters, national housing plants have tra- ditionally supported the renovation of older clusters, including buildings constructed before 1996 (clusters 1 to 3 and 4 partially), while local programs are directed to the first two clusters (build- ings built before 1981). On the other hand, most recently intro- duced European Founds include buildings constructed up to 2014, hence covering almost all clusters.

Nevertheless, even though the introduced several instruments, the implemented funds constitute only 8% of the necessary declared investments being clearly far away of the introduced goals. Furthermore, the dispersion between the different proce- dures and the complexity of the processes, significantly reduces the global impact of these actions. At the other side, the lack of clear verification protocols to validate the results after the imple- mentation hinders the identification of best practices and the improvement of the overall impact. Thus, all these aspects have not historically contributed to generating the market dynamics necessary to achieve the objectives of a true renovation wave.

CRediT authorship contribution statement

N. Soledad Ibañez Iralde: Investigation, Formal analysis, Writ- ing - original draft, Visualization. Jordi Pascual: Supervision, Con- ceptualization, Writing - review & editing, Project administration, Funding acquisition. Jaume Salom: Supervision.

Declaration of Competing Interest

The authors declare that they have no known competing finan- cial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgements

This research is part of the REPAREH project supported by Barce- lona Energy Agency and Barcelona Observatory for Architectural Restoration Association through the College of Architects of Catalo- nia, College of Quantity surveyors, Technical Architects and Build- ing Engineers of Barcelona, Association of Building Developers and Builders of Barcelona, Elevators Business Guild of Catalonia and Barcelona Construction workers’ Guild.

The funding entities had no involvement in the writing of this paper.

Funding

This work was partially supported by the promotors of the REPAREH project.

References

1. Ministry of Transport Mobility and Urban Agenda, ERESEE 2020 Long-Term Strategy for Energy Rehabilitation in the Building Sector in Spain, 2020. https://www.mitma.gob.es/recursos_mfom/paginabasica/recursos/es_ltrs_ 2020.pdf.
2. Ministerio de Fomento Dirección General de Arquitectura Vivienda y Suelo Subdirección General de Políticas Urbanas, (01) Segmentación del parque residencial de viviendas en España en clústeres tipológicos, 2019. https://cdn. mitma.gob.es/portal-web-drupal/planes_estartegicos/1_2020_ segmentacion_parque_residencial_clusteres.pdf.
3. M. Economidou, V. Todeschi, P. Bertoldi, D. D’Agostino, P. Zangheri, L. Castellazzi, Review of 50 years of EU energy efficiency policies for buildings, Energy Build. 225 (2020), https://doi.org/10.1016/J.ENBUILD.2020.110322

110322.

1. European Parliament, Directive 2002/91/EC of The European Parliament and of the Council of 16 December 2002 on the energy performance of buildings, Off. J. Eur. Communities. (2003). https://eur-lex.europa.eu/LexUriServ/ LexUriServ.do?uri=OJ:L:2003:001:0065:0071:EN:PDF.
2. Ministerio de Vivienda, Real Decreto 314/2006, de 17 de marzo, por el que se aprueba el Código Técnico de la Edificación, Boletín Of. Del Estado. (2006). https://www.boe.es/buscar/doc.php?id=BOE-A-2006-5515.
3. Ministerio de la Presidencia, Real Decreto 1027/2007, de 20 de julio, por el que se aprueba el Reglamento de Instalaciones Térmicas en los Edificios, Boletín Of. Del Estado. (2007). https://www.boe.es/buscar/doc.php?id=BOE- A-2007-15820.
4. Ministerio de la Presidencia, Real Decreto 47/2007, de 19 de enero, por el que se aprueba el Procedimiento básico para la certificación de eficiencia energética de edificios de nueva construcción, Boletín Of. Del Estado. (2007). https://www.boe.es/buscar/doc.php?id=BOE-A-2007-2007.
5. Ministerio de Desarrollo, Orden FOM/1635/2013, de 10 de septiembre, por la que se actualiza el Documento Básico DB-HE ‘‘Ahorro de Energía”, del Código Técnico de la Edificación, aprobado por Real Decreto 314/2006, de 17 de marzo, Boletín Of. Del Estado. (2019). https://www.boe.es/buscar/doc.php? id=BOE-A-2013-9511.
6. Ministerio de Desarrollo, Real Decreto 732/2019, de 20 de diciembre, por el que se modifica el Código Técnico de la Edificación, aprobado por el Real Decreto 314/2006, de 17 de marzo, Boletín Of. Del Estado. (2019). https:// www.boe.es/diario_boe/txt.php?id=BOE-A-2019-18528.
7. Ministerio de la Presidencia, Real Decreto 238/2013, de 5 de abril, por el que se modifican determinados artículos e instrucciones técnicas del Reglamento de Instalaciones Térmicas en los Edificios, aprobado por Real Decreto 1027/ 2007, de 20 de julio, Boletín Of. Del Estado. (2013). https://www.boe.es/ buscar/doc.php?id=BOE-A-2013-3905.
8. Ministerio de la Presidencia Relaciones con las Cortes y Memoria Democrática, Real Decreto 178/2021, de 23 de marzo, por el que se modifica el Real Decreto 1027/2007, de 20 de julio, por el que se aprueba el Reglamento de Instalaciones Térmicas en los Edificios, Boletín Of. Del Estado. (2021). https://www.boe.es/buscar/doc.php?id=BOE-A-2021-4572.
9. Ministerio de la Presidencia, Real Decreto 235/2013, de 5 de abril, por el que se aprueba el procedimiento básico para la certificación de la eficiencia energética de los edificios, Boletín Of. Del Estado. (2013). https://www.boe. es/buscar/act.php?id=BOE-A-2013-3904.
10. European Parliament, Directive 2010/31/EU of The European Parliament and of the Council of 19 May 2010 on the energy performance of buildings (recast), Off. J. Eur. Union. 53 (2010). doi:10.3000/17252555.L_2010.153.eng.
11. European Parliament, Directive 2012/27/EU of The European Parliament andof the Council of 25 October 2012 on energy efficiency, amending Directives 2009/125/EC and 2010/30/EU and repealing Directives 2004/8/EC and 2006/32/EC, Off. J. Eur. Union. (2012). doi:10.3000/19770677. L_2012.315.eng.
12. European Parliament, Directive (EU) 2018/844 of the European Parliament and of the Council of 30 May 2018 amending Directive 2010/31/EU on the energy performance of buildings and Directive 2012/27/EU on energy efficiency, Off. J. Eur. Union. (2018). https://eur-lex.europa.eu/legal-content/ EN/TXT/HTML/?uri=CELEX:32018L0844&from=EN.
13. Ministry of Development, Long-Term Strategy for Energy Renovation in the Building Sector in Spain persuant to article 4 of the directive 2012/27/UE, 2014. https://ec.europa.eu/energy/sites/default/files/documents/ES Art 4 EN ENER-2014-01009-00-00-EN-TRA-00.pdf.
14. Ministry of Development, 2017 Update of the Long-Term Strategy for Energy Renovation in the Building Sector in Spain, 2017. https://www.mitma.gob.es/ recursos_mfom/paginabasica/recursos/es_building_renov_2017_en.pdf.
15. N. Directorate-General for Energy (European Commission) , IPSOS, Comprehensive study of building energy renovation activities and the uptake of nearly zero-energy buildings in the EU, 2019. doi:10.2833/14675.
16. M. Luxán García de Diego, C. Sánchez-Guevara Sánchez, E. Román López, M. del M. Barbero Barrera, G. Gómez Muñoz, Re-habilitación exprés para hogares vulnerables. Soluciones de bajo coste, 2017. ISBN: 978-84-697-4628-8.
17. J. Ortiz, Detailed energy and comfort simulation of integral refurbishment of existing buildings in Catalonia. Tesi doctoral, Universitat Politècnica de Catalunya, 2016. http://hdl.handle.net/2117/106274.
18. D. Dirutigliano, C. Delmastro, S. Torabi Moghadam, A multi-criteria application to select energy retrofit measures at the building and district scale, Therm. Sci. Eng. Prog. 6 (2018) 457–464, https://doi.org/10.1016/J. TSEP.2018.04.007.
19. Intelligent Energy Europe projects TABULA and EPISCOPE, Building Typologies, TABULA Web Tool. (2017). https://webtool.building-typology. eu/#bm (accessed April 20, 2021).
20. MED Programme – UE, Build a new Energy Renovation Strategy around the Mediterranean, Mediterr. Build. Rethink. Energy Effic. Improv. (2010). https:// www.marie-medstrategic.eu/en/who-is-marie/deliverables.html (accessed July 20, 2021).
21. ENTRANZE Project Intelligent Energy Europe (IEE) programme, ENTRANZE Policies to enforce the transition to Nearly Zero Energy buildings in the EU- 27, ENTRANZE Website. (n.d.). https://www.entranze.eu/pub/pub-data (accessed July 20, 2021).
22. Y. Laaroussi, M. Bahrar, E. Zavrl, M. El Mankibi, U. Stritih, New qualitative approach based on data analysis of European building stock and retrofit market, Sustain. Cities Soc. 63 (2020), https://doi.org/10.1016/J. SCS.2020.102452 102452.
23. K.N. Streicher, P. Padey, D. Parra, M.C. Bürer, S. Schneider, M.K. Patel, Analysis of space heating demand in the Swiss residential building stock: element- based bottom-up model of archetype buildings, Energy Build. 184 (2019) 300–322, https://doi.org/10.1016/J.ENBUILD.2018.12.011.
24. L. Filogamo, G. Peri, G. Rizzo, A. Giaccone, On the classification of large residential buildings stocks by sample typologies for energy planning purposes, Appl. Energy. 135 (2014) 825–835, https://doi.org/10.1016/J. APENERGY.2014.04.002.
25. E.G. Dascalaki, K. Droutsa, A.G. Gaglia, S. Kontoyiannidis, C.A. Balaras, Data collection and analysis of the building stock and its energy performance—an example for Hellenic buildings, Energy Build. 42 (2010) 1231–1237, https:// doi.org/10.1016/J.ENBUILD.2010.02.014.
26. R. McKenna, E. Merkel, D. Fehrenbach, S. Mehne, W. Fichtner, Energy efficiency in the German residential sector: a bottom-up building-stock-

model-based analysis in the context of energy-political targets, Build. Environ. 62 (2013) 77–88, https://doi.org/10.1016/J.BUILDENV.2013.01.002.

1. I. Theodoridou, A.M. Papadopoulos, M. Hegger, A typological classification of the Greek residential building stock, Energy Build. 43 (2011) 2779–2787, https://doi.org/10.1016/J.ENBUILD.2011.06.036.
2. European Commission, EU Buildings Factsheets, Eur. Comm. (2017). https:// ec.europa.eu/energy/eu-buildings-factsheets_en (accessed July 20, 2021).
3. A. Cuchí, P. Sweatman, A. Pagès, Escenarios de reducción de emisiones de gases de efecto invernadero (GEI) para el sector residencial en España, 2012. http://www2.gbce.es/archivos/ckfinderfiles/Investigacion/2012 Inforrme reduccion GEI.pdf.
4. A. Cuchí, I. de la Puerta, Diagnóstico de la rehabilitación en Comunidades Autónomas.Luces y sombras de un sector que no despega, 2016. http://www. observatoriociudad3r.com/biblioteca/diagnostico-de-la-rehabilitacion-en- comunidades-autonomas-luces-y-sombras-de-un-sector-que-no-despega/.
5. ZEBRA2020 project Intelligent Energy Europe (IEE) Programme, Energy efficiency trends in buildings, ZEBRA2020. (2020). https://zebra-monitoring. enerdata.net/overall-building-activities/share-of-new-dwellings-in- residential-stock.html#equivalent-major-renovation-rate.html (accessed July 20, 2021).
6. M. Eames, T. Dixon, S. Lannon, M. Hunt, C. De Laurentis, S. Marvin, M. Hodson,

P. Guthrie, M.C. Georgiadou, Retrofit 2050: Critical Challenges for Urban Transitions, 2014. https://orca.cardiff.ac.uk/65743/.

1. V.E. Sanvido, L.S. Riggs, Managing retrofit projects. A Final Report Submitted to the Construction Industry Institute. Technical Report No.25, State College, Pennsylvania, 1991. https://www.cic.psu.edu/download/tr_025_sanvido_ 1991_managing_retrofit_projects.pdf.
2. Ministerio de Desarrollo, Nota metodológica de construcción de edificios (licencias municipales de obra), Minist. Desarro. Obs. y Estadísticas. (1990). https://www.mitma.gob.es/informacion-para-el-ciudadano/informacion- estadistica/construccion/construccion-de-edificios/nota-metodologica-de- construccion-de-edificios-licencias-municipales-de-obra (accessed April 20, 2021).
3. Buildings Performance Institute Europe (BPIE), Nearly Zero: A review of EU member state implementation of new build requirements, 2021. https:// www.bpie.eu/wp-content/uploads/2021/06/Nearly-zero_EU-Member-State- Review-062021_Final.pdf.pdf.
4. Z. Ma, P. Cooper, D. Daly, L. Ledo, Existing building retrofits: Methodology and state-of-the-art, Energy Build. 55 (2012) 889–902, https://doi.org/10.1016/J. ENBUILD.2012.08.018.
5. A. Abdul Hamid, K. Farsäter, Å. Wahlström, P. Wallentén, Literature review on renovation of multifamily buildings in temperate climate conditions, Energy Build. 172 (2018) 414–431, https://doi.org/10.1016/J.ENBUILD.2018.04.032.
6. Ajuntament de Barcelona. Agencia de l’Energia de Barcelona, Pla de Millora Energètica de Barcelona, Barcelona, 2002. http://hdl.handle.net/11703/ 96304.
7. Ajuntament de Barcelona. Agencia de l’Energia de Barcelona, Pla d’energia, canvi climàtic i qualitat de l’aire de Barcelona 2011-2020, Barcelona, 2011. https://ajuntament.barcelona.cat/ecologiaurbana/sites/default/files/ PlaEnergia_CanviClimatic_QualitatAire-2011-2020.pdf.
8. Ajuntament de Barcelona. Grupo E4 Compromiso de Barcelona por el Clima, Rehabilita’m. Fes-me eficiente¡ i saludable, 2018. https://ajuntament. barcelona.cat/lafabricadelsol/sites/default/files/rehabilitam_fes_me_eficient_ saludable.pdf.
9. Institut Català d’Energia, Simulador de mesures de rehabilitació energètica d’edificis, General. Catalunya. Inst. Català d’Energia. (2019). http:// simuladoredificis.icaen.gencat.cat/ (accessed April 20, 2021).
10. Institut Català d’Energia, Mapa de mesures per a l’estalvi i l’eficiència energètica, General. Cataluya. Inst. Català d’Energia. (n.d.). http:// mapamesures.icaen.gencat.cat/mapamesures/AppPHP/Rehabilitacio- energetica-edificis/ (accessed April 20, 2021).
11. I. Capdevila, E. Linares, R. Folch, Rehabilitació energètica d’edificis, Col-lecció Quad. Pràctic. (2016). http://icaen.gencat.cat/web/.content/10_ICAEN/17_ publicacions_informes/04_coleccio_QuadernPractic/quadern_practic/arxius/ 10_rehabilitacio_edificis.pdf.
12. Generalitat de Catalunya. Departament de Medi Ambient i Habitatge. Secretaria d’Habitatge, Guía de la renovació energètica d’edificis d’habitatges. Envolupant tèrmica i intal-lacions, 2010. https://www. diba.cat/documents/7294824/12608513/ H14GuiaRenovacioEnergeticaEdificisHabitatges_ EnvolupamentTermicaInstalacions_GeneCat.pdf.
13. M. y A.U. Ministerio de Transporte, Real Decreto 106/2018, de 9 de marzo, por el que se regula el Plan Estatal de Vivienda 2018-2021, Boletín Of. Del Estado. (2018). https://www.boe.es/buscar/doc.php?id=BOE-A-2018-3358.
14. Instituto de Diversificación y Ahorro de Energía IDAE, Guía Práctica de la Energia. Consumo eficiente y responsable, 2010. https://www.idae.es/ uploads/documentos/documentos_11406_Guia_Practica_Energia_3ed_ A2010_509f8287.pdf.
15. Instituto de Diversificación y Ahorro de Energía IDAE, PAREER II Programa de Ayudas para actuaciones de rehabilitación energética de edificios existentes, Sede Electrónica IDAE. (2017). https://www.idae.es/ayudas-y- financiacion/para-rehabilitacion-de-edificios-programa-pareer/segunda- convocatoria-del (accessed April 20, 2021).
16. M. Fernández Boneta, Impacto de la rehabilitación energética en el sector residencial y la consecución de los objectivos ambientales para España, 2016. https://www.lacasaqueahorra.org/documentacion.
17. GARRIGUES y Advisory, El reto de la rehabilitación: El Pasaporte Energético y otras propuestas para dinamizar el sector, 2018. https://www. lacasaqueahorra.org/documentacion.
18. A. Cuchi, G. Wadel, Guía de la eficiéncia energética para Administradores de Fincas, 2007. https://www.fundacionnaturgy.org/publicacion/guia-la- eficiencia-energetica-edificios-administradores-fincas/.
19. I. Capdevila, E. Linares, R. Folch, Eficiéncia Energética en la Rehabilitación de Edificios, Fundación Gas Natural Fenosa y Consejo Superior del Colegio de Arquitecctos de España, Barcelona, 2012. https://www.miteco.gob.es/ es/cambio-climatico/planes-y-estrategias/ EficienciaEnergeticaRehabilitacion_FGN_tcm30-70380.pdf.
20. A. García-Prieto Ruiz, B. Serrano Lanzarote, L. Ortega Madrigal, Catálogo de Soluciones Constructivas de Rehabilitación, Instituto Valenciano de la Edificación, Valencia, 2013. https://www.five.es/tienda-ive/catalogo-de- soluciones-constructivas-de-rehabilitacion/.
21. T. Escrig Meliá, L. Soto Francés, T. Soto Vicario, C. Subirón Rodrigo, L. López Sanz, Guía de Proyecto del Perfil de Calidad de Rehabilitación, Instituto Valenciano de la Edificación, Valencia, 2011. https://www.five.es/tienda-ive/ guia-perfil-de-rehabilitacion/.
22. Dirección General de Industria Energia y Minas de la Comunidad de Madrid, Guía de rehabilitación energética de edificios de vivienda, Madrid, 2008. http://www.madrid.org/bvirtual/BVCM005835.pdf.
23. E. Muñoz Alonso, Eficiéncia Energética en Edificios de Vivienda, 2019. https:// www.sustainavility.eu/wp-content/uploads/2020/02/EFICIENCIA_.pdf.
24. E. Muñoz Alonso, Guía Rehabilitación Energética Integral en Edificios, n.d. https://www.sustainavility.eu/wp-content/uploads/2020/02/ REHABILITACION.pdf.
25. Govierno Vasco, Guía de edificación y rehabilitación sostenible para la vivienda en la comunidad autónoma del País Vasco, 2015. https://www. euskadi.eus/web01-a2ingkli/es/contenidos/documentacion/guia_edificacion/ es_pub/index.shtml.
26. C. Marmolejo Duarte, A. Narváez, J.M. Fitch Osuna, Evaluation of willingness to pay (WTP) for attributes for energy efficient dwellings, approaches for your qualification and energy certification, in: Libr. Proceedings, CTV 2018. XII Congr. Int. Ciudad y Territ. Virtual. ‘‘Ciudades y Territ. Intel., 2018: pp. 263–

284. ISBN 978-84-8157-661-0.

1. F. Encinas, C. Duarte, F. Sánchez de la Flor, C. Aguirre-Nuñez, Are consumers willing to pay more for residential energy efficiency in emergent markets?, 2016.
2. H2020 Eurpean’s Project EuroPACE, HOLA DOMUS. Rehabilitacions energètiques per a una catalunya més sostenible, HOLA DOMUS. (2020). https://www.holadomus.com/acompanyament (accessed July 10, 2020).
3. K. Tsikaloudaki, T. Theodosiou, K. Laskos, D. Bikas, Assessing cooling energy performance of windows for residential buildings in the Mediterranean zone, Energy Convers. Manag. 64 (2012) 335–343, https://doi.org/10.1016/j. enconman.2012.04.020.
4. M. Economidou, V. Todeschi, P. Bertoldi, Accelerating energy renovation investments in buildings, Publ. Off. Eur. Union. EUR 29890 (2019), https://doi. org/10.2760/086805.
5. J. Maio, S. Zinetti, R. Janssen, Energy Efficiency Policies In Buildings – The Use Of Financial Instruments At Member State Level, 2012. https://bpie.eu/wp- content/uploads/2015/10/HR-Financing-Paper1.pdf.
6. Presidencia de Gobierno, Real Decreto 3280/1983, de 14 de diciembre, sobre financiación de actuaciones protegibles en materia de vivienda, Boletín Of. Del Estado. (1984). https://www.boe.es/buscar/doc.php?id=BOE-A-1984-252.
7. Gobierno de España, Real Decreto 224/1989, de 3 de marzo, sobre medidas de financiación de actuaciones protegibles en materia de vivienda, Boletín Of. Del Estado. (1989). https://www.boe.es/buscar/doc.php?id=BOE-A-1989- 5275.
8. Ministerio de Obras Públicas y Transporte, Real Decreto 1932/1991, de 20 de diciembre, sobre medidas de financiación de actuaciones protegibles en materia de vivienda del Plan 1992-1995, Boletín Of. Del Estado. (1991). https://www.boe.es/buscar/doc.php?id=BOE-A-1992-604.
9. Ministerio de Obras Públicas Transporte y Medio Ambiente, Real Decreto 2190/1995, de 28 de diciembre, sobre medidas de financiación de actuaciones protegibles en materia de vivienda y suelo para el período 1996-1999, Boletín Of. Del Estado. (1995). https://www.boe.es/buscar/doc.php?id=BOE-A-1995- 27970.
10. Ministerio de Fomento, Real Decreto 1186/1998, de 12 de junio, sobre medidas de financiación de actuaciones protegidas en materia de vivienda y suelo del Plan 1998-2001, Boletín Of. Del Estado. (1998). https://www.boe.es/ buscar/doc.php?id=BOE-A-1998-15136.
11. Ministerio de Fomento, Real Decreto 1/2002, de 11 de enero, sobre medidas de financiación de actuaciones protegidas en materia de vivienda y suelo del Plan 2002-2005, Boletín Of. Del Estado. (2002). https://www.boe.es/ buscar/doc.php?id=BOE-A-2002-689.
12. Ministerio de Vivienda, Real Decreto 801/2005, de 1 de julio, por el que se aprueba el Plan Estatal 2005-2008, para favorecer el acceso de los ciudadanos a la vivienda, Boletín Of. Del Estado. (2005). https://www.boe.es/buscar/doc. php?id=BOE-A-2005-12049.
13. Ministerio de Vivienda, Real Decreto 2066/2008, de 12 de diciembre, por el que se regula el Plan Estatal de Vivienda y Rehabilitación 2009-2012, Boletín Of. Del Estado. (2008).
14. Ministerio de Fomento, Real Decreto 233/2013, de 5 de abril, por el que se regula el Plan Estatal de fomento del alquiler de viviendas, la rehabilitación edificatoria, y la regeneración y renovación urbanas, 2013-2016, Boletín Of.

Del Estado. (2013). https://www.boe.es/buscar/doc.php?id=BOE-A-2013- 3780.

1. Ministerio de Industria y Energía, Orden de 6 de febrero de 1997 por la que se aprueban las bases reguladoras de la concesión de subvenciones en el marco del Plan de Ahorro y Eficiencia Energética para el período 1997-1999 y se convocan las del ejercicio 1997, Boletín Of. Del Estado. (1997). https://www. boe.es/eli/es/o/1997/02/06/(1).
2. Ministerio de Industria Turismo y Comercio. Instituto para la Diversificación y Ahorro de Energía IDAE, Estrategia de ahorro y eficiencia energética en España 2004-2012 E4 Plan de acción 2005 - 2007, 2005. https://www. miteco.gob.es/es/cambio-climatico/legislacion/documentacion/plan_ accion2005_2007_tcm30-178682.pdf.
3. Ministerio de Industria Turismo y Comercio. Instituto para la Diversificación y Ahorro de Energía IDAE, Estrategia de ahorro y eficiencia energética en España 2004-2012 E4 Plan de acción 2008 - 2012, 2008. https://www. miteco.gob.es/es/cambio-climatico/legislacion/documentacion/ resumen_plan_accion_2008_2012_tcm30-178674.pdf.
4. Instituto de Diversificación y Ahorro de la Energía IDAE, Plan de Ahorro y Eficiencia Energética 2011-2020, 2011. https://www.idae.es/ uploads/documentos/documentos_11905_PAEE_2011_2020._A2011_A_ a1e6383b.pdf.
5. Ministerio de Industria Energía y Turismo, Plan Nacional de Acción de Eficiencia Energética 2014-2020, 2014.
6. Instituto para la Diversificación y Ahorro de la Energía IDAE, Programa de ayudas para la rehabilitación energética de edificios existentes (Programa PAREER-CRECE), Portal Transparencia IDAE. (2016). https://www.idae.es/ ayudas-y-financiacion/para-la-rehabilitacion-de-edificios/convocatorias- cerradas/programa-de-ayudas (accessed July 10, 2020).
7. Ministerio de Energía Turismo y Agenda Digital, Resolución de 25 de julio de 2017, del Instituto para la Diversificación y Ahorro. Por la que se establecen las bases reguladoras de, Boletín Of. Del Estado. (2017). https://www.boe.es/ boe/dias/2017/07/29/pdfs/BOE-A-2017-9066.pdf.
8. Instituto para la Diversificación y Ahorro de la Energía IDAE, Programa PREE. Rehabilitació Energética de Edifcios. Fondo Europeo de Desarrollo Regional (FEDER), Portal Transparencia IDAE. (2021). https://www.idae.es/ayudas-y- financiacion/para-la-rehabilitacion-de-edificios/programa-pree- rehabilitacion-energetica-de (accessed April 19, 2021).
9. Instituto para la Diversificación y Ahorro de la Energía IDAE, Guía de Elegibilidad de Proyectos con cargo al fondo JESSICA F.I.D.A.E., (2016). https:// www.idae.es/uploads/documentos/documentos_Criterios_de_elegibilidad_ FIDAE_Mar-2016-v15_653cd980.pdf.
10. Ministerio de Industria Turismo y Comercio. Instituto para la Diversificación y Ahorro de Energía IDAE, Plan de Energías Renovables en España PER 2005- 2010, 2005. https://www.idae.es/uploads/documentos/documentos_PER_ 2005-2010_8_de_gosto-2005_Completo.(modificacionpag_63)_Copia_2_ 301254a0.pdf.
11. Ministerio de Industria Turismo y Comercio. Instituto para la Diversificación y Ahorro de Energía IDAE, Plan de Energías Renovables PER 2011-2020, 2011. https://www.idae.es/tecnologias/energias-renovables/plan-de-energias- renovables-2011-2020.
12. Instituto para la Diversificación y Ahorro de la Energía IDAE, Programa SOLCASA, Portal Transparencia IDAE. (2020). https://www.idae.es/ahorra- energia/renovables-de-uso-domestico/programa-solcasa (accessed April 20, 2021).
13. Instituto para la Diversificación y Ahorro de la Energía IDAE, Programa GEOTCASA, Portal Transparencia IDAE. (2020). https://www.idae.es/ en/support-and-funding/renewable-energy-installations/programa-geotcasa (accessed April 19, 2021).
14. Instituto para la Diversificación y Ahorro de la Energía IDAE, No Programa BIOMCASA II, Portal Transparencia IDAE. (2020). https://www.idae.es/ahorra- energia/renovables-de-uso-domestico/programa-biomcasa-ii (accessed April 19, 2021).
15. Instituto para la Diversificación y Ahorro de Energía IDAE, Instituto para la Diversificación y Ahorro de Energía IDAE Memoria Anual 2004, 2005. https:// www.idae.es/uploads/documentos/documentos_10334_Memoria2004_ 2005_2d81d70f.pdf.
16. Instituto de Crédito Oficial ICO, Líneas ICO. ICO Empresas y Emprendedores, Líneas ICO Nac. (2021). https://www.ico.es//ico-empresas-y-emprendedores (accessed April 5, 2021).
17. Generalitat de Catalunya. Departament de Treball i Indústria, Pla de l’energia de Catalunya 2006-2015, 2005. https://www.aeeolica.org/ uploads/documents/EERR_P_energia_catalunya_06-15.pdf.
18. Generalitat de Catalunya, Pla de l’Energia i Canvi Climàtic PECAC 2012-2020, 2011. http://icaen.gencat.cat/ca/plans_programes/pecac/.
19. Agència de l’Habitatge de Catalunya. Departament de Territori i Sostenibilitat, Subvencions per a la rehabilitació d’edificis d’ús residencial, Tràmits Webpage General. (2021). http://web.gencat.cat/ca/tramits/tramits-temes/

Ajuts-per-a-la-rehabilitacio-dedificis-dus-residencial?category=74c016ba- a82c-11e3-a972-000c29052e2c (accessed April 20, 2021).

1. Agència de l’Habitatge de Catalunya. Departament de Territori i Sostenibilitat, Subvencions per a obres d’arranjament a l’interior dels habitatges per a les persones grans, Tràmits Webpage General. (2021). https://web.gencat.cat/ ca/tramits/tramits-temes/Subvencions_arranjament_interior (accessed July 20, 2021).
2. Estudi Ramon Folch i Assosiats. S.L., Projecte estratègic de rehabilitació energètica. Informe per al Pla Estratègic Metropolità de Barcelona, 2011. https://www.erf.cat/web/php/arxius/PEMB_ERF_Projecte_estrategic_de_ rehabilitacio_energetica.pdf.
3. Consorci Metropolità de l’Habitatge, Programa Rehabilitació 2014, Ajuts Consorci Metropolità de l’Habitatge. (2014). https://www.cmh.cat/web/cmh/ ajuts/programes/programa-rehabilitacio-2014 (accessed July 20, 2020).
4. Consorci Metropolità de l’Habitatge, Programa Rehabilitació 2015, Ajuts Consorci Metropolità de l’Habitatge. (2015). https://www.cmh.cat/web/cmh/ ajuts/programes/programa-rehabilitacio-2015 (accessed July 20, 2020).
5. Consorci Metropolità de l’Habitatge, Programa Rehabilitació 2016, Ajuts Consorci Metropolità de l’Habitatge. (2016). https://www.cmh.cat/web/cmh/ ajuts/programes/programa-rehabilitacio-2016 (accessed July 20, 2020).
6. Consorci Metropolità de l’Habitatge, Programa Accessibilitat 2017, Ajuts Consorci Metropolità de l’Habitatge. (2017). https://www.cmh.cat/web/cmh/ ajuts/programes/programa-accessibilitat-2017 (accessed July 20, 2020).
7. Consorci Metropolità de l’Habitatge, Programa Habitabilitat 2017, Ajuts Consorci Metropolità de l’Habitatge. (2017). https://www.cmh.cat/web/cmh/ ajuts/programes/programa-habitabilitat-2017 (accessed July 20, 2020).
8. Consorci Metropolità de l’Habitatge, Programa Habitabilitat 2018, Ajuts Consorci Metropolità de l’Habitatge. (2018). https://www.cmh.cat/web/cmh/ ajuts/programes/programa-habitabilitat-2018 (accessed July 20, 2020).
9. Consorci Metropolità de l’Habitatge, Programa Conservació 2018, Ajuts Consorci Metropolità de l’Habitatge. (2018). https://www.cmh.cat/web/ cmh/ajuts/programes/programa-conservacio-2018 (accessed July 20, 2020).
10. Consorci de l’Habitatge de Barcelona, Consorci Metropolità de l’Habitatge: ajuts a la rehabilitació d’edificis de tipologia residencial col-lectiva i habitatges, Ajuts Edif. (2019). http://icaen.gencat.cat/ca/energia/ajuts/ edificis/consorci-metropolita-de-lhabitatge-ajuts-a-la-rehabilitacio- dedificis-de-tipologia-residencial-collectiva-i-habitatges/ (accessed July 20, 2020).
11. Consorci de l’Habitatge de Barcelona, Consorci de l’Habitatge de Barcelona: Rehabilitació d’elements comuns a la ciutat de Barcelona, Ajuts Edif. (2019). http://icaen.gencat.cat/ca/energia/ajuts/edificis/consorci-de-lhabitatge-de- barcelona-rehabilitacio-delements-comuns-a-la-ciutat-de-barcelona-00001/ (accessed July 20, 2020).
12. Consorci de l’Habitatge de Barcelona, Consorci de l’Habitatge de Barcelona: Rehabilitació d’interiors d’habitatges per incorporar a la borsa d’habitatges de lloguer de Barcelona i per a l’arranjament d’habitatges de persones en situació de vulnerabilitat, Ajuts Edif. (2019). http://icaen.gencat.cat/ca/ energia/ajuts/edificis/consorci-de-lhabitatge-de-barcelona-rehabilitacio- dinteriors-dhabitatges-per-incorporar-a-la-borsa-dhabitatges-de-lloguer-

de-barcelona-i-per-a-larranjament-dhabitatges-de-persones-en-situacio-de- vulnerabil (accessed July 20, 2020).

1. Consorci de l’Habitatge de Barcelona, Ajuts a la rehabilitació d’interiors per a persones afectades per la Covid-19, Serveis i Ajuts. (2020). https://habitatge. barcelona/ca/serveis-ajuts/rehabilitacio/ajuts/interiors.
2. Consorci de l’Habitatge de Barcelona, Ajuts a la rehabilitació per a finques d’alta complexitat, Serveis i Ajuts. (2019). https://habitatge.barcelona/ca/ serveis-ajuts/rehabilitacio/ajuts/finques-alta-complexitat (accessed July 20, 2020).
3. Consorci de l’Habitatge de Barcelona, Estratègia de rehabilitació 2016-2019. Mesura de govern de rehabilitació urbana, Barcelona, 2016. http://www. bcn.cat/consorcihabitatge/ca/presentacio-rehabilitacio.html.
4. Consorci de l’Habitatge de Barcelona, Consorci de l’Habitatge de Barcelona: Ajuts a la rehabilitació d’habitatges, Ajuts Edif. (2017). http:// icaen.gencat.cat/ca/energia/ajuts/consorci-de-lhabitatge-de-larea- metropolitana-de-barcelona-ajuts-a-la-rehabilitacio-dhabitatges-/ (accessed July 20, 2020).
5. X. Casanovas, A. Cuchí, J.H. Mas, J. del V. Rubio, Por un cambio en las políticas. Los municipios, pieza clave en un marco de cooperación institucional, 2018. http://www.observatoriociudad3r.com/biblioteca/informe-gtr-ciudadespor- un-cambio-en-las-politicas-publicas-de-fomento-de-la-rehabilitacion- residencial-los-municipios-pieza-clave-en-un-marco-de-cooperacion- institucional-2/.
6. S. Álvarez Domínguez, Energy Efficient Buildings in Mediterranean Countries. The Role of the Building Energy Performance Regulations and Certification, Lyon, 2006. https://www.buildup.eu/en/node/966.
7. European Environment Agency, Heating and cooling degree days, Indic. Heat. Cool. Degree Days. (2017). https://www.eea.europa.eu/data-and-maps/ indicators/heating-degree-days-2/assessment (accessed April 20, 2021).