Urban Regeneration Assessment in Castilla and León (Spain): A Comparative Study of Proposals in Homogeneous Residential Neighborhoods Built Up during Developmentalism

Abstract

Urban regeneration is perceived as an efficient solution addressing multiple problems in today’s cities, offering answers to the social, economic, physical, and environmental challenges faced by consolidated fabrics. This paper utilizes the assessment tool developed in the Urban Regeneration Strategy of Castilla and León to conduct a comparative analysis of proposals formulated since 2014 in neighborhoods built after the Spanish Civil War in this region. The aim is to validate the effectiveness of this methodology to establish the quality and sustainability of these initiatives and to identify the strengths and weaknesses of the cases analyzed. The results obtained endorse the operability of this evaluation process since it makes it possible to assess the scope of the planned measures at an early stage. This makes it possible to introduce improvements during the implementation phase or in future interventions, which will have a positive impact on their outcome. In any case, it is necessary to complement this study with analyses at later stages in order to establish an overall diagnosis of the real relevance of these operations.

1. Introduction

The 21st-century global structural crisis underscored the inefficacy of the expansionist urban model in addressing the challenges inherent in shaping the future city. Consequently, this has driven the implementation of strategies by which to safeguard, reinforce, and optimize urban progress [1,2]. Despite the lack of urban planning competencies in European Community institutions, they are committed to building consensus on urban planning policies at national, regional, and local levels. A fundamental document in this regard is the 2007 Leipzig Charter on Sustainable European Cities, which delineated two primary lines of recommendations for achieving this objective [3,4,5].

First, it advocates for increased utilization of urban development policies targeting social cohesion, enhancing quality of life, establishing and fortifying quality public spaces, and fostering energy efficiency. On the other hand, it recommends focusing on the most disadvantaged neighborhoods of cities, advocating for integrated actions by which to improve the physical environment, stimulate economic growth and employment, and promote social cohesion, inclusion, and efficient and affordable urban transport. In 2020, the principles and validity of the document’s message were reaffirmed without prejudice with respect to the imperative need to update its content to address the challenges emerging in recent years [6].

Since the end of the 20th century, Europe has been deliberating on appropriate interventions in degraded areas. Analyses of such policies have consistently shown a strong preference for interventions focused on the built heritage. Other actions have been supplementary, exerting minimal influence on domains such as transportation, commerce, industry, services, and cultural amenities, let alone on socioeconomic aspects like employment or training. Furthermore, interventions in existing urban fabrics are often associated with gentrification. In general, this term is associated with any phenomenon related to the displacement of people and businesses [7]. However, it is usually linked to real estate rent-seeking, especially in working-class districts that have been converted into tourist or residential areas for wealthier social groups, with the consequent expulsion of the original population [8]. Although interventions in these environments sometimes suggest that the neighborhoods were devitalized or culturally moribund, the truth is that gentrification sometimes destroys the social life and local economic activity that sustains these communities [9].

During the Spanish Presidency of the European Union in 2010, significant steps were taken in defining the concept of Integrated Urban Regeneration (IUR). The Toledo Declaration, adopted that same year, characterized it as a process of intervention in the existing city focusing on environmental, social, and economic integration. It also underlined the imperative of applying this approach to policies aimed at revitalizing the built environment and the existing fabric [10]. IUR has therefore positioned itself as a key procedure among the range of options to address the current urban crisis and reaffirms its central role in efforts to achieve a sustainable and cohesive urban landscape [11,12]. In this regard, it aligns with the Sustainable Development Goals of the UN 2030 Agenda and addresses the imperative of establishing inclusive, safe, and resilient settlements [13]. This becomes increasingly urgent considering the post-COVID reality, where measures to curb pandemic activity in urban settings have exacerbated existing social disparities and inequalities [14].

To achieve a genuinely integrated approach to urban regeneration, it is necessary to tailor available instruments to its specific demands and formalize such actions within the regulatory framework. In Spain, since 1983, interventions on buildings, called Integral Rehabilitation Areas, have been prioritized under Royal Decree 2329/1983 [15]. Currently, Law 8/2013 on urban rehabilitation, regeneration, and renovation shapes the legal and administrative processes required to enact this practice [16].

However, the autonomous communities hold jurisdiction over urban planning affairs. Therefore, they are tasked with delineating these general principles for application within their respective territories. Castilla and León emerged as a trailblazer in this regard, approving Law 7/2014 on measures on rehabilitation, regeneration, and urban renewal [17] just one year after the enactment of the state law.

The characteristics of the region, among other factors, justify the urgency with which this new provision was developed. Castilla and León faces a significant depopulation challenge despite being the largest region in Spain. It also has the largest number of municipalities, almost 2300, many of which have no more than 1000 inhabitants. Consequently, the bulk of the population is concentrated in medium-sized cities, primarily organized around historically significant city centers. The initial residential suburbs, constructed between the 1950s and 1970s, are characterized by their high population density and substandard construction quality. Nowadays, these early developments, built post-Spanish Civil War, have become vulnerable areas where social and economic issues converge. Castilla and León law acknowledges this situation and the limited attention given by urban planning to the established urban fabric of its cities, despite the clear necessity for rehabilitation and enhancing the quality of life in many disadvantaged neighborhoods. The approval of this law has positioned this autonomous community as one of the most advanced in providing instruments for urban regeneration [18].

Furthermore, since 2016, it has also introduced its own Urban Regeneration Strategy (URSC&L), developed by the University Institute of Urban Planning of the University of Valladolid [19]. This document serves as a comprehensive tool with which to guide such policies through three primary mechanisms: analyzing the urban fabric and diagnosing its needs to delineate priority intervention areas, providing guidelines for best practices to enhance the quality and positive impact of actions on the urban environment, and establishing management criteria to coordinate the efforts of various administrative entities involved [20].

Undoubtedly, the evaluation of regeneration initiatives is a fundamental mechanism for optimizing processes in future actions [21,22]. However, the bureaucratic complexities inherent in all urban development actions have hindered the progress of the initiatives implemented in the community in recent years. This has made it difficult to reach comprehensive conclusions on the true impact of such operations in the region beyond the partial perceptions gleaned from the analysis of specific cases at an advanced stage or fully executed stage [23,24,25].

This circumstance leads us to reconsider the paradigm of that studies and establish as the aim of our research the examination of the initial urban regeneration proposals presented in Castilla & León since 2014. The objective of the paper is, on the one hand, to validate the methodology established in the URSC&L document to assess in advance the satisfaction of the quality and sustainability goals of this type of initiatives and, on the other hand, to analyze the evolution of the urban regeneration proposals developed in the region and to establish the strengths and weaknesses of the examples examined, to improve the quality of the design and management processes and reduce possible negative impacts in future interventions.

Section 2 delimits the case studies, describes the evaluation tool conducted by the University Institute of Urban Planning of the University of Valladolid, selecting the quality and sustainability objectives on which the degrees of compliance are established, and explains the research process. Section 3 and Section 4 present the characterization of the areas and the results of the evaluation, respectively. Finally, Section 5 interprets the results and proposes future lines of research, while Section 6 highlights the main contributions of the work.

2. Materials and Methods

We have confined the field of the study to neighborhoods composed of high-density social housing developments, typically public, constructed between the 1950s and 1970s. This decision is primarily warranted by the vulnerability of these fabrics, which, as previously noted, are currently undergoing severe processes of urban degradation. Moreover, these districts exhibit homogeneity due to their origination from the same program or plan. This facilitates recovery efforts as the corresponding projects for their execution can be more readily applied to larger areas that share similar design and construction conditions and, therefore, deficiencies [26]. This situation makes it likely that their revitalization will probably exceed, in quantitative terms, the actions planned in other sectors, making them a substantial sample of regeneration activity in Castilla and León.

The methodology through which to achieve our objective involves assessing compliance with a set of variables incorporated by URSC&L as indicators of quality and sustainability in the analyzed rehabilitation and redevelopment operations, gathered under the name “Tool for Promoting and Evaluating the Quality of Actions linked to Urban Regeneration”. These guidelines have been extracted from existing literature related to this type of intervention, driven, in most cases, by public administrations [27].

As shown in Figure 1, these items are structured according to a triple logic: the type of action (rehabilitation, regeneration, or renovation); the areas of action (existing building, public space, infrastructure and urban services, and new building); and the variables of action (accessibility and mobility, design, urban metabolism and natural processes, and urban life). Each one of them is linked to a series of recommendations and quality indicators that allow for satisfactory compliance with the objectives indicated through specific guidelines accompanied, where appropriate, by the reference legislation.

To apply this procedure to the proposed case, the following steps have been followed:

• Identification of the areas coinciding with the study parameters was conducted by consulting information available on the website of the government of Castilla and León. Since 2014, 8 Urban Regeneration Areas have been declared that meet these specified characteristics: neighborhoods composed of one or more homogeneous residential developments, primarily publicly promoted, constructed on the outskirts of cities between the 1950s and 1980s. It is worth noting that since 2019, no new scopes have been declared. Only new management phases have been approved. Figure 2 shows the location of the analyzed cases, and Figure 3 below shows the complete delimitation of the Urban Regeneration Areas.
• The documentation phase involves compiling information from various sources, mainly from general and special planning documents that contain the urban needs of the areas and proposed actions. Being public documents, they are accessible to all citizens who require them. This is complemented by reviewing various historical archives and the specific bibliography on this type of urban development and regeneration intervention. The data obtained have been contextualized through on-site visits and news and articles published in local newspapers and magazines. The following aspects were covered:

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  Historical background regarding the origin and formation of neighborhoods.

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  Territorial and urban context of the areas.

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  Characteristics of building construction.

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  Rehabilitation needs of buildings.

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  Redevelopment needs of collective spaces.

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  Planned regeneration strategies.

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  Regulatory and normative framework for actions.

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  Level of development of phases under execution.

• Evaluation of the rehabilitation and redevelopment measures anticipated in the planning instruments involved assessing the actions outlined in the various case studies to enhance the living conditions of residents both within their homes and their surroundings. This assessment was based on a system of indicators grouped into the following categories:

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  Accessibility and mobility: This category includes measures planned to ensure universal accessibility in buildings and integrated mobility in the communal space.

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  Design: This section evaluates the existence of sufficient public living spaces, the adequate proportion of the streets in relation to the height of the blocks, for hygienic reasons, and the spatial and functional continuity between them. It is worth mentioning that the persistence of buildings limits the urban restructuring actions outlined in the proposals examined.

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  Urban metabolism and natural processes: This category includes actions related to improving the thermal envelope of buildings, incorporating renewable energies, increasing the efficiency of energy installations and urban networks, implementing sustainable management of natural resources, and promoting vegetation in the urbanized environment.

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  Urban life: Proposals in this category aim to create hybrid spaces, where the population converges and engages in a diversity of activities, as this is crucial for revitalizing the social life of the neighborhoods.

The favorable assessment of the indicators included in each action variable is confirmed by the achievement of the quality and sustainability goals recommended by the document, listed in

Table 1. Quality and sustainability objectives recommended in the URSC&L for Urban Regeneration Areas.

Variables of Action	Indicator	Goals
Accessibility and mobility	Universal accessibility	Facilitate vertical circulation
		Facilitate horizontal circulation
	Integrated mobility	Universal accessibility in public spaces
		Facilitating multimodal mobility
Design	Urban design	Adequate street ratio
		Sufficient and nearby reserve of open spaces
Urban metabolism and nature processes	Vegetation and urban processes	Incorporation of vegetation in roads and public spaces
		Ensuring sufficient soil permeability
	Thermal enveloped	Improved transmittance
		Solar energy utilization through passive systems
	Renewable energies/Energy-efficient facilities	Solar energy utilization through active systems
		Install high efficiency heating and cooling systems
	Urban network efficiency	Installation of thermal networks
		Efficient network management
	Water and waste management	Reuse of water resources
		Recycling of urban waste
Urban life	Hybridization/Economic activity	Incorporation of community uses
		Balance between residence and other activities
	Urban equipment renewal	Sufficient and nearby equipment supply

. Compliance with the objective is considered “successful” when the implementation of effective actions to attain it throughout the area is foreseen. The “improvable” category is established when the interventions foreseen to achieve the objective are partially effective or only apply to a part of the area. Cases in which only the possibility of incorporating actions to achieve the suggested improvement is mentioned, or their application is exceptional, are qualified as “deficient”. Finally, “unplanned” is associated with the absence of planned enhancements.

3. Characterization of the Areas

3.1. San Cristobal. Burgos

It is situated in the northeast quadrant of the city, bounded to the north by the Vena River, to the south by the Gamonal-Villímar industrial estate, and to the west by the urban core. It comprises social housing units developed by the Town Council between 1969 and 1974 in response to the rapid expansion experienced by the town following its designation as a center of industrial production in 1964.

As depicted in Figure 3a, the neighborhood spans a total area of 12.3 hectares and comprises 26 open five-story blocks, along with 2 H blocks of similar height, and a detached nine-story tower situated across Alcalde Martín Cobos Street. Combined, these structures comprise 644 apartments and several ground-floor premises. Moreover, the area includes three facilities—a cultural center, a velodrome, and a football pitch—for which no interventions are planned. Importantly, expansive green spaces with pedestrian walkways are interspersed throughout, enhancing connectivity between the residential buildings and adjacent streets.

In 2010, the area was designated as an Integral Rehabilitation Area (IRA) with the aim of improving residents’ quality of life and promoting economic activity to support comprehensive neighborhood development. Subsequently, in 2014, it was reclassified as an Urban Regeneration Area (URA). To date, three management phases have been completed, involving renovations to 545 apartments in 23 residential buildings and their surroundings. A fourth phase is pending, which will finalize work on the remaining buildings, grounds, and the majority of public spaces within the sector. While the initial completion target was May 2023, the project has not yet reached its conclusion.

3.2. San José Obrero and El Palo-Mirasierra. Segovia

The sector is located in the southern part of the city and includes two neighborhoods separated by the Valdevilla road. To the west is San José, consisting of three public housing estates dating back to the 1950s. On the steep slope to the east lies El Palo-Mirasierra, characterized by low-quality housing built during the 1960s and 1970s. Additionally, the sector includes a strip of detached houses situated between the two estates. In total, the area spans over 17.6 hectares and includes 46 isolated blocks of flats of various types, ranging from five to six stories in height. Furthermore, there are 33 semi-detached single-family dwellings, totaling 1663 residences, along with several facilities, as depicted in Figure 3b. The scarcity of green spaces is notable, as they comprise less than 5% of the total surface area.

In response to the neighborhood’s deterioration and with the aim of restoring its functionality, the locality was designated as an Integral Rehabilitation Area in 2009. The initial phase of management concluded with the rehabilitation of 315 dwellings and the redevelopment of the surroundings of the former provincial prison, which was repurposed into a multidisciplinary space for artistic creation. Subsequently, in 2015, it was reclassified as an Urban Regeneration Area. Since then, two additional phases have been completed. Currently, work is underway on an additional 201 homes, several commercial premises, and various public spaces, all situated in the San José neighborhood.

3.3. Obra Sindical del Hogar. Zamora

This area encompasses the first two residential groups promoted by the Obra Sindical del Hogar in the neighborhood known as Los Bloques, inaugurated at the beginning of the 1950s. It comprises a total of five linear blocks aligned with the perimeter streets, forming two trapezoidal structures around two interior spaces, one of which has public access, separated by Los Reyes Católicos avenue. This distribution is evident in Figure 3c.

The buildings, predominantly four to five stories in height, also include some structures of two and three levels on the lower sides to mitigate the impact of the new constructions on the surroundings, where low-rise buildings were predominant at the time of construction. Additionally, the complex originally included a nursery school, which has since been repurposed as the headquarters of the residents’ association.

In 1957, an additional floor topped with a gabled roof was added to the blocks consisting of three and four stories, aimed at resolving the moisture issues associated with the original flat roofs, which were causing leaks in the upper-floor units.

In 2008, both groups formed the IRA called “Viviendas de la Obra Sindical”, initiating interventions aimed at rehabilitating the buildings and restoring their original aesthetics. Subsequently, in 2015, a URA was declared in the same area, facilitating the completion of rehabilitation and redevelopment work by 2016. Overall, improvements have been made to the conditions of the 330 dwellings spread across more than 1.7 hectares, in addition to 25 commercial premises and the residents association headquarters. Furthermore, the collective interior space has been urbanized as part of the revitalization efforts.

3.4. Las Eras, 25 Años de Paz, Casas de la Ría, San Isidro, and Las Malvinas. Benavente (Zamora)

The Benavente municipality stands as the sole instance of a discontinuous area within the study group, as seen in Figure 3d. It comprises 743 dwellings dispersed across five sets of publicly promoted social housing erected in the urban vicinity during the latter half of the previous century.

In the Las Eras neighborhood, situated near the central area, there are five linear blocks comprising four to five floors each, alongside two additional edifices within a closed block configuration, all constructed during the 1950s. Towards the southern periphery lies the 25 Años de Paz complex, comprising four open blocks, each with a height of five stories, and the Casas de la Ría building, characterized by a closed block layout and five floors. Both were constructed in the 1960s. In the western region of the municipality is the San Isidro neighborhood, which includes 11 open blocks, consisting of 3 blocks with four levels each and 8 blocks with three, all built during the 1970s. Lastly, in the latter years of that same decade, six open “H” blocks, each with four levels, were erected in the Las Malvinas district.

The area was declared an IRA in 2010 with the purpose of alleviating the deterioration of these economically impoverished neighborhoods. A first phase of intervention was carried out, during which 143 homes and 2 premises located in the Las Eras neighborhood were rehabilitated. Since 2015, now under the denomination of URA, a new management stage has been implemented, intervening in 110 households and several public spaces in the Las Eras, 25 Años de Paz, and Casas de la Ría neighborhoods. Additionally, pending urbanization actions from the previous stage have been completed, along with others planned in the San Isidro neighborhood. A third phase is underway, primarily focused on Las Malvinas, where works are being carried out on the buildings.

3.5. La Cacharra-Seminario. Ávila

This area is located in the northern expansion of the city. It is part of the San Antonio neighborhood, developed between the city wall and the Altos del Seminario site. It encompasses the initial public housing developments built during the early 1950s. The delimited zone has an L-shaped layout and covers nearly six hectares, housing 108 residential buildings with a total of 616 units, all of which have over 50 m² of built area. Additionally, there are two facilities: a primary school and a nursery school with an adjoining sports court. These are the sole non-residential uses present, as there is minimal commercial activity on the ground floors.

Figure 3e shows three zones with differentiated typological characteristics. The first one, which gives its name to the neighborhood, is composed of 11 building groups consisting of the same open linear block of 4 stories. The area called Virgen de la Vega contains a private real estate development, and although the open block also predominates, greater volumetric and typological diversity is perceived, alternating between buildings of two and three stories. Finally, the Virgen de Valsordo section occupies the corner of the area and consists of a single development, forming part of a closed block around an interior courtyard. The public space is seamlessly integrated with the road network.

In 2018, this URA was declared to serve as a model for the implementation of the Castilla and León Strategy in this matter. Currently, the execution of the first phase of the four planned phases is nearing completion. It comprises 154 residences located in the area adjacent to the open space next to the nursery, chosen for its regenerative potential.

3.6. Pinilla. San Andrés de Rabanedo (León)

San Andrés de Rabanedo is a town located adjacent to the city of León, with which it shares the Pinilla neighborhood. The suburb was established in the 1960s and expanded towards the western bank of the Bernesga River to accommodate migrant populations from rural areas in small residences measuring approximately 65 m². It spans eight hectares, distinguishing three different fabric types. In 1963, 450 residences were erected, distributed in small isolated linear blocks, paired, or in rows, each with three floors and a basement. In 1973, a large, detached block of 13 stories, called “La Casita”, was built, comprising 288 residences as well as commercial premises housed in a parallel single-story pavilion. Just one year later, an additional 200 residences were constructed to accommodate those affected by the Riaño reservoir rupture. These residences are organized into isolated blocks consisting of four floors and a coal bunker. The layout of these residences is depicted in Figure 3f.

Like Ávila’s, the Urban Regeneration Area of San Andrés de Rabanedo, also declared in 2018, was selected as a prime example to implement the Castilla and León Urban Regeneration Strategy. Presently, almost half of the population is over 75 years old. Consequently, the objective is to progressively develop a senior-friendly neighborhood, offering a communal living model for the elderly as an alternative to nursing homes. Here, they can relish a high quality of life within the comfort of their own homes. Currently, construction works for the second phase are underway, which will complement those of the already completed first phase. Together, this entails the rehabilitation of 72 residences distributed across four blocks, as well as the improvement of various facilities, streets, and a public park.

3.7. Polígono 29 de Octubre. Valladolid

This residential sector lies east of the historic center in the lower region of Valladolid’s Pajarillos neighborhood. It was developed in the 1960s with the goal of constructing 1200 social housing units with affordable rents. However, only 570 units were completed, along with various communal facilities. In 2013, the area, covering nearly 4.8 hectares, was designated as an Urban Renewal Area due to the extensive degradation of the complex and growing marginalization. It comprised 95 residential linear block buildings of three stories each, a church, two schools, and a building with commercial premises. However, the proposed reconstruction proved economically unviable. Consequently, the corporation initiated a change in strategy in 2018, declaring the sector delineated in Figure 3g as an Urban Regeneration Area.

Between 2015 and 2017, the initial interventions were conducted, targeting 23 blocks comprising 138 households. Furthermore, reurbanization efforts were undertaken on the streets and interstitial spaces between the rehabilitated properties. Additionally, restoration and adaptation works were executed on the Santiago Núñez school, transforming it into a center for Citizen Initiatives. In 2020, a new phase was tendered for another 22 blocks, totaling 132 residences, along with their immediate surroundings. However, the withdrawal of the awarded company has halted execution, leading to a new tender in 2023.

3.8. Chinchibarra. Salamanca

The neighborhood, which lends its name to the regeneration unit, is situated northeast of Salamanca. It was established in the 1960s around a water tank designed by architect Paz Maroto during the post-war period. While initial plans aimed for the construction of approximately 200 housing blocks, only 20 were ultimately realized. These blocks accommodate small and modest residences that have become outdated compared to the newer constructions that have emerged around them.

The area spans just over one hectare and comprises 200 privately promoted social housing units within the 20 original buildings depicted in Figure 3h, constructed between 1962 and 1963. In efforts to counter the entrenched marginalization and gradual population decline, a neighborhood association was established in 2016. This association diligently advocated for the declaration of an Urban Regeneration Area over the zone, a designation which was successfully achieved in 2019. The planned interventions for the neighborhood focus on enhancing social cohesion, revitalizing the area, improving its visual appeal, and addressing existing economic and social challenges. In 2023, the first phase of the intervention was completed, resulting in the rehabilitation of 140 residences and the transformation and enhancement of the surrounding public space.

4. Results

Following the outlined methodology,

Table 2. Planned regeneration actions: accessibility and mobility. Assessment of planned actions: S: successful; I: improvable; D: deficient; U: unplanned.

Variables of Action	Actions Foreseen	San Cris-tóbal BU	San José-El Palo SG	Obra Sindical ZA	Benavente ZA	La Cacharra AV	San Andrés LE	29 de Oc-tubre VA	Chinchibarra SA
Universal accessibility	Vertical circulation	I	I	S	I	I	S	U	S
	Horizontal circulation	S	S	S	S	S	S	S	S
Integrated mobility	Accessibility	S	S	S	S	S	S	S	S
	Multimodal mobility	D	D	U	U	S	S	I	D

,

Table 3. Planned regeneration actions: design. Assessment of planned actions: S: successful; I: improvable; D: deficient; U: unplanned.

Variables of Action	Actions Foreseen	San Cris-tóbal BU	San José-El Palo SG	Obra Sindical ZA	Benavente ZA	La Cacharra AV	San Andrés LE	29 de Oc-tubre VA	Chinchibarra SA
Urban design	Street ratio	U	U	U	U	U	U	U	U
	New public spaces	S	D	I	D	S	S	S	I

,

Table 4. Planned regeneration actions: urban metabolism and natural processes. Assessment of planned actions: S: successful; I: improvable; D: deficient; U: unplanned.

Variables of Action	Actions Foreseen	San Cris-tóbal BU	San José-El Palo SG	Obra Sindical ZA	Benavente ZA	La Cacharra AV	San Andrés LE	29 de Oc-tubre VA	Chinchibarra SA
Vegetation and urban processes	Vegetation	U	U	U	U	S	S	I	U
	Land permeability	U	U	U	U	S	S	U	U
Thermal envelope	Transmittance	S	S	S	S	S	S	S	S
	Passive systems	U	U	U	U	U	U	U	U
Renewable energies/Energy-efficient facilities	Active systems	U	D	U	U	U	U	D	U
	High-efficiency air conditioning	U	U	U	U	S	U	U	S
Urban network efficiency	Thermal networks	U	U	U	U	S	U	U	S
	Network management	S	S	S	S	S	S	S	S
Water and waste management	Water recycling	U	U	U	U	U	U	U	U
	Waste recycling	U	U	U	U	U	U	U	U

and

Table 5. Planned regeneration actions: urban life. Assessment of planned actions: S: successful; I: improvable; U: unplanned.

Variables of Action	Actions Foreseen	San Cris-tóbal BU	San José-El Palo SG	Obra Sindical ZA	Benavente ZA	La Cacharra AV	San Andrés LE	29 de Oc-tubre VA	Chinchibarra SA
Hybridization/Economic activity	Community uses	U	U	S	U	S	S	S	U
	Local trade	S	S	S	U	I	S	I	U
Urban equipment renewal	New equipment	U	I	U	U	U	S	U	U

present planned actions in the various regeneration areas, correlated with the following quality indicators: accessibility and mobility, urban design, urban metabolism, and natural processes and urban life.

4.1. Accessibility and Mobility

The primary approach to eliminating architectural barriers within buildings has been the installation of street-level accessible elevators. However, insufficient consideration for space allocation during the original project planning, except for specific cases like certain entrances in the Burgos neighborhood, has led to the need for alternative locations. Priority has been given to placing elevators in interior courtyards, as observed in the case of Zamora and in various blocks within the urban regeneration area of Benavente, as shown in Figure 4a.

Where implementing the aforementioned solution has not been feasible, an alternative approach has been to advocate for modifications to municipal ordinances to permit the installation of elevators in public thoroughfares. Figure 4b shows the solution envisaged for Salamanca. However, the viability of this measure depends on adherence to urban accessibility regulations.

The installation of lifts is foregone only in the case of the 29 de Octubre housing development. This decision is justified by the buildings’ limited height of just three floors, making their installation economically unfeasible. However, in this area and in all other analyzed instances, the height difference between the street and the building is addressed by either employing elevators themselves or installing ramps or lift platforms.

Similarly, unanimous actions have been planned to enhance accessibility in public spaces. These include pavement renewal, removal of architectural barriers, promotion of urban transportation usage, and expansion of pedestrian pathways whenever environmental conditions permit.

Regarding mobility, significant measures to promote multimodality were not prevalent in proposals made before 2016. The only exceptions were the establishment of a new section of the bike lane along the main avenue in the San Cristóbal area of Burgos and the improvement of walkable access between the San José and El Palo-Mirasierra neighborhoods, as well as in other areas of the city of Segovia. In contrast, the solutions presented in more-recent proposals prioritize pedestrian circulation. This is evident in the planned shared space in Ávila and Salamanca neighborhoods, although in the latter case, it affects only a very limited part of the area. Additionally, restrictions on motorized traffic have been imposed in San Andrés de Rabanedo and Valladolid.

4.2. Design

Regarding planned measures concerning the urban environment, some redevelopment proposals are limited to utilizing residual areas to create seasonal, landscaped, or recreational spaces through the placement of furniture or plant elements, without significantly increasing the amount of open space for resident’s use. In some early cases, these sites are used to increase the number of parking spaces, which conflicts with the objective of promoting pedestrian routes. Undoubtedly, the proposal in León stands out as the most ambitious, aiming to create an environment that fosters the autonomous coexistence of elderly people. To achieve this, the plan proposes to allocate the area delimited by the buildings to increase the number of parks and leisure areas, interlinking these open spaces with walkways and coexistence roads for vehicular access to the properties. Figure 5 compares the scope of the proposal. This includes creating “refuge areas” conceived as meeting spaces on a domestic scale, featuring shade and benches to encourage gatherings of small groups of neighbors.

The formation of a single platform in the districts of La Cacharra-Seminario and Chinchibarra facilitates the use of the interstitial space between residential blocks and its continuity, with the limitations mentioned in the Salamanca case. Similarly, in the San Cristóbal neighborhood of Burgos and in the Obra Sindical neighborhood of Zamora, the creation of new public spaces is envisaged by leveraging the open configuration of their buildings. However, in the latter case, the main aim is to solve the lack of parking spaces in the buildings, as shown in Figure 6.

Another proposal to create new recreational and meeting areas is the reuse of disused school playgrounds, such as the Santiago López school in Valladolid and the La Cacharra nursery school in the homonymous area in Ávila.

4.3. Urban Metabolism and Natural Processes

In the analyzed cases, there is consensus on the goal of reducing energy consumption and, consequently, CO₂ emissions into the atmosphere. Undoubtedly, one of the most effective interventions is the formation of a thermal envelope.

The most common solution for insulating facades has been the installation of an ETICS (External Thermal Insulation Composite Systems) system, chosen for its economic reasons, ease of installation, and performance. However, in the San Cristóbal neighborhood in Burgos, an alternative approach has been adopted: forming a ventilated facade composed of a layer of thermal insulation fixed to the support, an air chamber, and an exterior cladding made of phenolic material panels. In part of the buildings in the La Cacharra neighborhood, it has been decided to insulate the properties through interior cladding for aesthetic reasons. In most cases, these measures are complemented by the replacement of windows and glass with others featuring improved thermoacoustic characteristics, the installation of insulation under the roofs, and the resolution of moisture problems due to wear and construction deficiencies.

Another common action planned to promote energy savings and proper resource management in residential buildings has been the renovation of community installations that had poor conditions and did not comply with current regulations, primarily focusing on lighting, supply, and sanitation systems.

On the contrary, one of the weaknesses of the proposals concerns the effectiveness of thermal installations, as they do not include the replacement of individual boilers with centralized systems. Only in the case of Salamanca has the set-up of district collective heating been arranged to supply all the homes included in the project. It is proposed to study the implementation of this same system in Ávila but this time for the supply of public facilities, taking advantage of their concentration in the northern area of the neighborhood.

Furthermore, the layout of streets and the height and orientation of buildings influence the feasibility of implementing solar energy capture or utilization systems in residential blocks. Therefore, it is only considered to study its possible location in some cases. There is also no proposal for the use of other complementary energy systems or additional measures for the reuse of water resources or waste management in homes.

The renovation of urban installations includes, in all neighborhoods, those energy improvement and resource management actions considered commonplace in any urban redevelopment operation today. Mainly, these actions involve the renewal of deficient or deteriorated supply and sewage networks, the incorporation of new irrigation outlets and hydrants, and the replacement of public lighting with more efficient alternatives. In the latter two issues, the incorporation of automatic systems is envisaged in some cases to enable more efficient resource management, although these measures are limited in monitoring urban metabolism.

As for natural processes, there is hardly any significant planting of vegetation or establishment of sufficient permeable surface in the pre-2016 proposals. It is worth mentioning that the San Cristóbal neighborhood in Burgos already has a significant expanse of natural land within its limits from the beginning, so no expansion is foreseen.

In contrast, in the mentioned case in León and to a lesser extent in the rest of the more recent Urban Regeneration Areas, measures of urban nature and green infrastructure are planned, taking advantage of interstitial and underutilized spaces, as illustrated by the diagrams in Figure 5.

4.4. Urban Life

Among the most common measures to create hybrid spaces is the integration of commercial premises located on the ground floors of many buildings. This approach is often executed in conjunction with the rehabilitation of these buildings, aiming to revitalize urban areas and stimulate local economies.

Similarly, the creation of community spaces, as well as the adaptation and transformation of disused or outdated buildings, plays a crucial role in urban renewal. In the cases of Zamora, Ávila, León, and Valladolid, such initiatives are planned to address deficiencies in amenities and promote stronger neighborly relations. These efforts often include converting abandoned structures into community centers or cultural venues, which can serve as hubs for social interaction and community engagement.

However, not all areas are equally focused on enhancing hybridization and urban life. In the cases of Benavente and Salamanca, there is a noticeable lack of actions aimed at these goals. This deficiency is primarily due to the absence of commercial establishments and public facilities within the designated areas. Without these essential elements, the potential for creating dynamic, multifunctional urban spaces is significantly hindered, leading to missed opportunities for fostering community and economic growth.

5. Discussion

The methodology included in the Urban Regeneration Strategy of Castilla y León has been implemented to evaluate, in advance, the quality and sustainability of the outcomes expected in this type of initiatives through its implementation in eight Urban Regeneration Areas defined in neighborhoods built during developmentalism in the region. Its application to the cases studied has provided a clear x-ray of the foreseeable effect of the proposed measures, revealing not only strengths but also important shortcomings in the implementation of actions, the latter being more significant in the areas defined prior to the existence of this evaluation tool.

This suggests that it is an effective instrument in the process of developing these interventions as it allows the available resources to be properly managed and actions to be focused on the most relevant goals, depending on the needs of each case.

The application of this methodology to the examples included in this study allows us to anticipate the foreseeable effects based on the degree of satisfaction of the quality and sustainability goals analyzed.

5.1. Impact on the Urban System

In all examples, the environmental conditions influence the proposed actions. In this regard, systems are envisioned to provide the required comfort within homes, such as the creation of a thermal envelope, which many buildings lack, given that the Castilla and León region is one of the coldest in Spain. This condition is more pronounced in León, Burgos, and Ávila, where the most extreme temperatures occur. By addressing this issue, energy efficiency is improved, heating consumption is reduced, rain infiltration through walls is prevented, thermal bridges causing interstitial condensation are eliminated, and acoustic insulation is significantly increased.

On the contrary, few bioclimatic urban planning measures are incorporated to improve natural conditions, environmental and acoustic comfort, and contribute to reducing pollutant emissions in the initial proposals. The most common measure in most cases is limited to the planting or replacement of street trees, which helps create friendlier environments but is insufficient to achieve these objectives. Moreover, studies affirm that open urban spaces play a key role in making cities resilient, i.e., with the capacity to survive in extreme conditions caused by extreme weather events and to absorb the changes and disturbances that are increasingly common due to global warming [28]. This question is not negligible in the cases analyzed because, as has been pointed out, they are located in areas where extreme temperatures are reached, both in winter and in summer, so it is advisable to take measures to extend urban greenery in future actions. In fact, the considerable expansion of green areas and the creation of refuge spaces in most of the recent examples reviewed suggests the increasing importance of this type of measure.

5.2. Integration into the Urban Structure: Mobility, Hybridization, and Social Cohesion

Since these are consolidated areas, connectivity and communication with the rest of the city are ensured. In almost all cases, measures are adopted to enhance pedestrian routes, which helps improve mobility and socialization among residents. Beyond these initiatives, there are hardly any actions aimed at promoting multimodal mobility that would ensure optimal sustainability conditions in URAs delimited before 2016. In the most recent examples, where the creation of a shared space is proposed, more effective mobility management is achieved by avoiding the segregation of traffic at different levels, thus guaranteeing universal accessibility. However, the case of Slovakian cities highlights the need to provide sustainable mobility solutions while promoting collective awareness to be successful in this area [29].

Overall, the interventions take advantage of opportunity spaces, reusing interstitial and underutilized areas, including those in private use. Given that the proposals for their use vary significantly between the different cases analyzed, we cannot assume that all of them bring benefits to the intervention itself. However, the number of examples where there is a significant increase in leisure or amenity space is substantial. Similarly, the recovery of ground floors in residential buildings for commercial purposes, a common practice, enhances the relationship between built and public space, facilitating social mixing and activities throughout the day.

The mentioned measures, coupled with the pedestrianization of urban spaces, foster the formation of more intricate environments that promote proximity relationships and easier access to both commercial and amenity services. By incorporating shops, cafes, and other businesses at street level, these spaces become more vibrant and inviting, encouraging foot traffic and enhancing the overall urban experience. This also promotes social cohesion by equalizing access opportunities to these services for a wide diversity of citizens, regardless of their economic capabilities, while facilitating coexistence in the same space and enabling job creation, with benefits directly impacting the local economy.

5.3. Sustainability and Accessibility

As these are regeneration interventions involving existing buildings, passive measures have not been incorporated into the design of the constructions to advance environmental sustainability. However, as noted, constructive measures have been implemented to achieve this goal, such as envelope insulation or the modernization and improvement of supply facility efficiency. Nevertheless, there is a scarcity of complementary actions to improve HVAC (Heating, Ventilation, and Air Conditioning) systems, a critical issue in a region like Castilla y León, where extreme temperatures are experienced. In this regard, it is worth mentioning the forecasted implementation of district heating networks with centralized production in some of the latest studied proposals, despite these being areas of very limited dimensions.

Improving accessibility is, along with energy efficiency, one of the pillars of building rehabilitation interventions. All cases demonstrate accessibility challenges, both within buildings and at the urban level. The advanced average age of residents, with many being original tenants, often hinders their mobility and sociability.

In all cases, the improvement and modernization of urban supply networks are proposed, leading to significant energy savings. However, there is still ample room for improvement in managing the recycling of water resources and urban waste, and even in their reuse, which not only affect the environment as the waste market is proving to have an increasing impact on circular economy programs [30].

In addition, none of the presented rehabilitation proposals include greening solutions, such as incorporating vegetation into patios and other private spaces or employing construction solutions like installing green roofs. If implemented, these measures would offer additional benefits, such as improving thermal insulation, harvesting rainwater, and enhancing air quality [31].

5.4. Future Research Lines

The results obtained in the initial analysis point to the lack of validity of some of the measures proposed to achieve the quality and sustainability goals pursued. This circumstance leads us to propose, as a more immediate line of work, an individualized and more detailed analysis of each of the examples presented. Such an approach would allow us to identify the specific shortcomings and limitations inherent in the current measures, providing a clearer understanding of where adjustments or alternative strategies might be necessary.

The potential of this research will be realized by comparing the initial balance with the evaluation of the implementation processes and subsequent phases once the studied actions are completed.

Although the developed proposal allows for reliable forecasts from the start of the program, based on a system of indicators and expected improvement values, it is evident that unforeseen circumstances and events frequently arise, significantly altering the original conditions. Therefore, it is essential to conduct evaluations throughout the programs, including measures not initially planned. Mongil asserts that the comparison between areas, as outlined in this paper, is an effective way to carry out this monitoring [32].

On the other hand, urban regeneration aims to improve degraded urban areas, so the evaluation of its impact must also consider the changes in the residents’ quality of life compared to their previous state. This balance can sometimes be somewhat subjective, as the transformation might be due to factors unrelated to the process. An evaluation method necessary to ensure that the change results from the intervention is the comparison, over time, between similar areas where such interventions have been carried out [33].

6. Conclusions

Urban regeneration is widely regarded as an effective approach to addressing a range of urban problems and creating lasting solutions to the social, economic, physical, and environmental challenges of contemporary cities.

In this research, urban regeneration proposals applied to neighborhoods built during a period of developmentalism in the region of Castilla y León have been analyzed based on the procedure developed in its Urban Regeneration Strategies. This tool has proven its effectiveness in assessing the quality and sustainability of the measures planned for the recovery of the consolidated fabric.

In contrast to previous studies, which focused exclusively on individual interventions, the application of this methodology to a group of interventions allows for relevant conclusions to be drawn about the current state and potential of these operations. The most relevant issues are as follows:

• Environmental conditions influence the proposed actions, especially the need for systems to improve thermal comfort in homes due to the extreme climate of the region.
• Energy efficiency improvements are incorporated in all cases. However, few bioclimatic urban planning measures are implemented to improve environmental comfort and reduce pollutant emissions, mainly limited to tree planting, which is insufficient.
• Interventions improve pedestrian connectivity and mobility, ensuring universal accessibility and reusing underutilized spaces for leisure and services. This, together with the incorporation of street-level shops, fosters vibrant and socially cohesive environments. Nevertheless, actions to promote multimodal mobility and optimize sustainability are lacking.
• Regeneration interventions enhance energy efficiency and accessibility through envelope insulation and retrofitting. However, complementary measures to improve heating, ventilation, and air-conditioning systems, crucial in Castilla y León, are devoid. The implementation of district heating networks is promising, but there is still room for improvement in water and urban waste management.