Resilient Urban Communities: A Case Study of the Cvjetno Housing Estate, a Modern Period Predecessor in Urban Planning in Croatia

Abstract

The paper analyzes the concept of resilience in the context of the Cvjetno housing estate in Zagreb, Croatia, a recognized cultural and historical complex. While extensive literature exists on the estate’s architectural and historical significance, limited research explores its resilience. This study aims to fill this gap by examining the Cvjetno estate’s planned resilience to natural hazards and socioeconomic challenges. It investigates the estate’s design, historical context, and physical characteristics through archival documents, historical records, and field research. The analysis focuses on the estate’s planned resilience to natural disasters, particularly flooding from the nearby river Sava and seismic risks due to its location in a seismically active area. Based on the literature on resilient communities, the study draws on dimensions, characteristics, and qualities of resilience, and explores how the Cvjetno estate exemplifies these traits. Future research could explore and compare similar mid-20th century European settlements to enhance the understanding of urban resilience during the modern era.

1. Introduction

Resilience is often defined as the ability to anticipate, adapt, and recover from adversity [1], incorporating climate adaptation, responsible use of resources, healthy and inclusive environments, and participation [1], enabling people to plan their environment as best suited for their needs. Other definitions claim that resilient systems have the capacity to adapt and evolve following disturbances, resulting in a state that differs from the condition prior to the disruption, which ensures the preservation of essential functions and the restoration of distinctive structures [2].

The notion of community is also considered as a valuable social structure in the context of achieving resilience, as it functions best in the context of “collectivist, small scale societies … living in harmony with their environments” [3], which may well be attributed to the mid-war European example of the Cvjetno housing estate. These theoretical perspectives can be evaluated through concrete case studies, such as the Cvjetno housing estate, to understand resilience in practice.

The research examines natural hazards, particularly floods and earthquakes, to understand how the Cvjetno estate features the concept of resilience. It aims to explore the relationships between proactive planning, absorptive capacity, vulnerability, stability, fragility, robustness, and resilience, and how these concepts are applied in Cvjetno.

The Cvjetno housing estate is often referred to as a unique and highly valuable mid-war example of a well-planned settlement based on the principles of CIAM (Congrès internationaux d’architecture modern). It is protected as a cultural and historical complex listed in the Register of Cultural Property of the Republic of Croatia [4,5]. Consequently, it has been extensively studied in numerous academic and scientific publications [6,7,8,9,10,11,12,13,14,15,16]. However, there is limited research focusing on the concept of resilience at this protected site, which could provide insights into the various dimensions of resilience, including resilience to natural disasters, financial and economic resilience, and social resilience.

The Cvjetno estate was chosen for this study for several reasons. First, it is in the vicinity of the Sava River, which has historically flooded the southern parts of Zagreb, including the Trnje district and the Cvjetno estate. Second, Zagreb is located in a seismically active region with multiple epicentral areas and is prone to experiencing significant earthquakes. Additionally, the Cvjetno estate was chosen since it was planned according to the principles of CIAM and constructed within an organized housing program for known users. As such, it included creating affordable housing for future tenants, which is regarded as an indicator of resilience. The following chapters of the Section 1 provide a brief overview of resilient communities and related concepts (Section 1.1), natural hazards as context for establishing resilient communities (Section 1.2), and descriptions of the urbanization of Trnje and the Cvjetno housing estate (Section 1.3).

1.1. The Concept of Resilient Communities

Resilient communities endorse a “safe-to-fail” strategy [17] and possess the capacity to resist, absorb, adapt to, and recover from the effects of both specified and unspecified [17] hazards swiftly and efficiently [18]. This entails being flexible, robust, interconnected, independent, and inclusive [19,20]. Accordingly, a resilient community should foster persistence and sustainability in social, economic, and ecological dimensions through thoughtful planning and design, while considering future community needs and quality of life amidst multiple crises arising from natural disasters, climate change, and socio-economic shifts.

The concept of resilience is sourced from the Latin word “resiliere”, meaning “to bounce back” [21], and is ambiguously referred to in various scientific and gray literature as a “paradigm shift, a governance model […], and a destination to reach” [22]. In terms of when resilience is accomplished, it can be described as passive resilience and transformational resilience. Passive resilience is concerned with the aftermath of a crises and concentrates on activities such as recovery and reconstruction, while transformational resilience takes place before the crises and addresses the minimizing of potential risks and vulnerabilities [22]. Zeng et al. [18] consider three major components of urban resilience, being adaptive capacity, absorptive capacity, and transformative capacity. Adaptive capacity is defined as the ability to make minor, intentional adjustments proactively or retroactively to enhance flexibility. The focus is on improving adaptability through continuous learning, innovation, and adjustments. Absorptive capacity is the ability to implement deliberate preventive measures and effectively manage established shocks and stresses. It includes strengthening the system’s resilience to absorb and withstand disruptions. Transformative capacity refers to the ability to implement changes to eliminate or reduce the root causes of risk and vulnerability [18]. In sum, adaptive capacity focuses on making small, incremental changes to enhance flexibility and maintain stability, absorptive capacity emphasizes preventing and coping with shocks to sustain functionality, and transformative capacity, on the other hand, involves making profound changes to address the underlying causes of risk and vulnerability, leading to significant, systemic transformations. Thus, resilience does not only imply optimization of infrastructure and public services, but is considered to be a cyclical process that includes four stages, namely preparing, resisting, recovering, and consolidating [23].

Resilience is closely related to other underlying concepts such as vulnerability, stability, fragility, robustness, and reliability. Vulnerability can broadly be defined as the likelihood of experiencing damage in the event of a shock or disturbance [24]. As defined in the Hyogo Framework for Action and the Sendai Framework (both borrowing the definition from the UNISDR publication [25]), it refers to “the conditions determined by physical, social, economic, and environmental factors or processes, which increase the susceptibility of a community to the impact of hazards” [26,27]. While this is a more comprehensive definition of the term, some authors highlight the aspect of vulnerability in the context of the built environment and infrastructural resilience [21,28], whereas others consider all four vulnerability factors [29]. Vulnerability can also be defined as the measure to which people and structures are exposed to risks due to natural hazards and climate change [30], or the “propensity to be adversely affected” [31], and can be described through social, ecological, and technical vulnerability indices [32].

The notions of resilience and stability, as well as their correlation, have undergone an evolution in their understanding, moving from single-state equilibrium to dynamic non-equilibrium, i.e., from “bouncing back” to “bouncing forward”. Holling made the first step in more clearly defining the relationship of the concepts in Resilience and stability of ecological systems. He gives a clear distinction between the terms and states that resilience, in the context of ecosystems, is characterized by three stability properties: recovery, resistance, and persistence [33]. In contrast to “engineering resilience”, which advocates the return to the single-state of stability, Holling makes an emphasis on the persistence of functions, and the notion of multiple-state equilibrium, which implies that a system has several stable states. The notion of dynamic non-equilibrium moves away from the idea that systems have a stable state and proposes that systems are in a perpetual state of change [31,34].

As a concept that acknowledges the inevitability of certain crises, urban resilience is featured by predictability of failure, robustness, diversity, equity, decentralization, flexibility, redundancy, and adaptive capacity [33]. As an important feature of resilience, flexibility can be improved through the dimension of adaptive capacity, i.e., the “ability to make small, deliberate changes” prior to or as a response to a disturbance [18]. Flexibility means that systems have the capacity to change, evolve, and adapt in response to varying circumstances. It can be accomplished by implementing new knowledge and technologies, but it can also benefit from using old knowledge in new and innovative ways [20,35]. Robustness, on the other hand, is applied in order to enhance the ability to endure during and after potential risks to the urban environment [18]. Robust systems are characterized by well-planned, constructed, and managed physical assets, enabling them to endure the impacts of shocks and disturbances without major damage or loss of function. They anticipate potential system failures, ensuring that any failure is predictable, safe, and proportionate to its cause [20,35].

Community resilience pertains to the ability of communities and societies to adapt to various forms of change, including environmental, social, economic, or political changes. It is related to the umbrella concept of social resilience, which can be applied to any social level from the community to society in general [36]. Other definitions of community resilience interpret it as the presence, growth, and utilization of community resources by its members to thrive in an environment marked by change, uncertainty, unpredictability, and unexpected events [37]. Koliou et al. bring a development to the concept of community resilience and state that it included “planning for, resisting, absorbing, and rapidly recovering from disruptive events”. It later evolved to address the enduring impacts of hazards and disturbances on entire communities, rather than concentrating on individual facilities or organizations. The authors emphasize the importance of addressing the intricate relationships between physical, social, and economic infrastructure that support community resilience [38]. Norris et al. contend that community resilience encompasses various adaptive capacities such as economic development, social capital, information and communication, and community competence. These capacities encompass access to resources, social support networks, community cohesion, local attachment, citizen engagement, and collaborative decision-making [39].

The social fabric conducive to resilient communities could be grounded in the concept of community envisioned as “local loops” and “empathetic communities” [40], wherein most of the population’s needs are fulfilled within the community itself. This entails the shared and responsible utilization of local resources, energy autonomy, and reduced dependence on global production and distribution networks. It involves robust local supply chains and proximity to social, health, economic, cultural, and public facilities, ultimately fostering community resilience in the face of crises stemming from socio-economic and climate-ecological changes.

1.2. Natural Hazards as Context for Establishing Resilient Communities

Considering the challenges linked to climate change, natural hazards, economic uncertainty, and social crises, planning should aim to create resilient communities for quality living. Attempting to plan and respond adequately to the challenges that the environment might inflict, the City of Zagreb identified five risks that may potentially threaten its area: earthquakes, floods, industrial accidents, extreme temperature, and epidemics and pandemics [41]. This research primarily focuses on floods and earthquakes, but it also acknowledges the impact of extreme weather events like high temperatures and flash floods, albeit with less detailed exploration. Future research should further evaluate these extreme weather events, especially in the Trnje area.

In the context of resilient communities, the Cvjetno housing estate exemplifies the need to address natural hazards due to its proximity to the Sava River. The river has a history of flooding Zagreb, notably in the 1890s and several times between 1923 and 1936 [42]. Major efforts to protect against flooding began in the late 19th century, with significant work continuing through the mid-war period. With the partial construction of the Sava embankment [43,44], the area was still under threat from the river. The most extensive flooding happened in late October 1964 when the river surged beyond its banks, inflicting substantial damage to the embankment. This led to the inundation of over 6000 hectares of the city [43]. The flooded area encompassed approximately one-third of all residential apartments in Zagreb that were home to as many as 180,000 people. It was after the flood of 1964 that the extension of the embankment was built, along with an efficient flood defense system for the wider Zagreb area [42,45]. The area possibly affected by flooding of the river is shown in Figure 1.

However, floods are not the sole natural hazards posing a threat to the city of Zagreb. Situated in a region prone to earthquakes due to its location in a seismically active area, the City of Zagreb is encompassed by multiple epicentral areas renowned for seismic activity, with the most notable being the Medvednica epicentral area, just north of the city.

The second-to-last significant earthquake struck on 9 November 1880, registering a magnitude of 6.3 on the Richter scale. The earthquake caused two deaths, 29 serious injuries, and damage to 3830 residential and commercial buildings, large state buildings, and churches [41].

The most recent major earthquake occurred on 22 March 2020, with a magnitude of 5.5. This event was followed by 1650 aftershocks over two months, the strongest being 4.9. The quake, felt within a 1000 km radius, resulted in one fatality and damaged over 25,000 buildings. The earthquake’s toll in human casualties could have been higher if not for strict pandemic measures enforced just days earlier, compelling nearly all citizens to remain indoors.

The most damage was caused in the oldest parts of the city—the Upper and Lower City, as well as the areas north and east from the city center [46]. The Trnje district suffered relatively minor damage, and there were no significant reports of damage in the Cvjetno estate (Figure 2). The 2020 earthquake highlighted the longstanding neglect of earthquake preparedness, especially in the historic city center, due to poor maintenance and a focus on decorative rather than structural investments [47].

Figure 1. Zagreb flood map—extent and depths of water in a low-probability flood scenario. Adapted from [48].

Figure 1. Zagreb flood map—extent and depths of water in a low-probability flood scenario. Adapted from [48].

Figure 2. Zagreb 2020 earthquake damage map. The Trnje district and Cvjetno estate are marked with a red line. Adapted from [49].

Figure 2. Zagreb 2020 earthquake damage map. The Trnje district and Cvjetno estate are marked with a red line. Adapted from [49].

1.3. The Urbanization of Trnje and the Origins of the Cvjetno Housing Estate

The Cvjetno housing estate is situated in Trnje, a district south of Zagreb’s city center (Figure 3, Figure 4 and Figure 5). This area, approximately 300 m from the left bank of the river Sava, is, in terms of topography, predominately flat and features wide flood plains. Although it is now highly urbanized, this area was frequently flooded in the past until the construction of the embankment along the river. Consequently, the settlements were built relatively late, in the mid to latter half of the 20th century. The climate conditions correspond to moderate continental climate type, but the last ten years show a rise in average annual temperatures, as recorded by the Croatian Meteorological and Hydrological Service [50].

During the construction of the Cvjetno estate, this area was characterized by small- to medium-sized industries, along with unplanned houses resulting from “wild” construction [52]. The urbanization and industrialization of the Trnje area began in the second half of the 19th century with the construction of industrial complexes like “Paromiln” and the first planned workers’ settlement in Zagreb, Strojarničko estate. During the mid-war period, Zagreb, like many cities, faced a housing crisis, leading to intensified construction in Trnje with the development of additional industrial facilities and housing complexes to accommodate the growing workforce.

In the early 1930s, an international competition for Zagreb’s extension identified Trnje as an area of great urban potential [9,12,53,54,55,56,57], leading the way for new planned construction. In 1939, Croatian urban planner and architect Vladimir Antolić planned the construction of the Cvjetno housing estate in the southwest corner of the Trnje area. The estate was intended for city officials lacking building capital; therefore, it was the architect’s objective to find a way to address all related financial matters, including “loan supply, building costs and payment of loan” [58]. The city officials were then able to acquire homes through loans that they paid off monthly over the course of 10 years. The loan rate was approximately equivalent to one-third of an official’s salary [58].

The estate covers a surface area of 0.10 km² and is situated north of the river Sava and its embankment, with its southern edge on Prisavlje Street, northern along Zagreb Avenue, eastern boundary along Cvjetno naselje IV Street, and western boundary along Cvjetna and Odranska Street. The orthogonal plan of the site adheres to the CIAM principles, ensuring adequate sunlight, living space, and greenery in individual parcels. The ties between CIAM and Antolić were very close, as Antolić was a member of the national CIAM group for Yugoslavia—Work Group Zagreb—and contributed to prepare the materials for the 4th CIAM congress in Athens, “The Functional City” [59,60].

Figure 4. Three-dimensional model of the Cvjetno estate and the surrounding area. Boundaries of the Cvjetno estate are marked with a red line. Adopted from [61].

Figure 4. Three-dimensional model of the Cvjetno estate and the surrounding area. Boundaries of the Cvjetno estate are marked with a red line. Adopted from [61].

CIAM was an international group of architects who advocated an approach in urban planning which aimed to create high-quality environments for all. This involved designing individual dwellings efficiently within neighborhood units to ensure good sunlight and ventilation and easy pedestrian access to collective recreational facilities. Ideally, these neighborhood units were connected by transit ways and highways to reduce commuting times to business and industrial areas [62]. According to the CIAM planning principles, Cvjetno features an orthogonal layout, the physical separation of functions, public and private green spaces, and adequate sunlight and living space. These were meant to insure an efficient, affordable, and healthy living environment. While some of these principles have been criticized since the 1960s [63], they still might have a role in positively effecting health and wellbeing as dimensions of resilience.

Figure 5. Cvjetno housing estate during construction, circa 1940. Source: [58].

Figure 5. Cvjetno housing estate during construction, circa 1940. Source: [58].

2. Materials and Methods

This research uses a case study approach to better understand the concept of resilience in urban planning history. By focusing on a single settlement project within a program of organized housing, the research might lack cross-scalar analyses. Still, it might also bring relevant insight to the broader understanding of how historical urban environments demonstrate the concept of resilience in practice and how they can be evaluated. The research is focused on flooding and seismic risks, given the area’s historical susceptibility to these hazards.

This study analyzes the historical context and physical characteristics of the Cvjetno estate in Zagreb (Croatia), drawing insights from archival documents, historical records, and previous studies. The methodology combines historical contextualization, archival and field research, a literature review, and the City Resilience Index framework [35].

Data collection included archival and field research. Primary data sources comprised archival documents sourced from the National Archives in Zagreb, encompassing planning and construction records of the Cvjetno housing estate, including architectural plans, construction documentation, and correspondence. The material was essential in identifying the period, location, and type of house being constructed. Additionally, valuable visual insights were derived from historic photographs obtained from the Zagreb City Museum, which mostly showcase the Cvjetno estate with planned front yards and birch trees along the main alley. The photographs also evidenced the flood of 1964 in the extended Trnje area.

To augment the archival data, field research was conducted to evaluate the contemporary state of the estate and its buildings. This entailed on-site observations focused on the street facades of houses, facilitating a comparison between the current condition and the original plans and projects. It also gave valuable additional insight into the effects of the 2020 earthquake.

Analytical frameworks include historical and contextual analyses of the Cvjetno estate through the review of archival documents and historical records. This study uses a literature review method, and examines the concept of resilience in the scientific literature and draws new insights using the Cvjetno estate as an example of mid-war architecture and planning. This research particularly examines its planned resilience to natural hazards such as flooding from the nearby river Sava and seismic risks due to its location in a seismically active area.

This research examines the Cvjetno estate using eight characteristics of resilient urban communities, as defined by Wang et al.: 1. Multifunctionality of space; 2. Adaptability of spatial processes; 3. Interactive facilities; 4. Diverse components; 5. Intelligence of public services; 6. Human-centricity of public services; 7. Predictive management concepts; and 8. Collaborative governance. These characteristics can be grouped into two categories based on their systemic qualities. The first group encompasses multifunctionality, adaptability, interactivity, and diversity, which are inherent features facilitating the system’s operation during non-crisis periods. The second group involves adaptive qualities of urban communities such as intelligence, human-centricity, predictiveness, and collaboration, which contribute to resilience during crises [64]. This framework is considered to be valuable, as it focuses on urban resilient communities.

Additionally, for this research, the City Resilience Index (CRI) was deemed particularly valuable. There are several publications that address indicators and index systems for urban resilience, such as the “10 Essentials of City Resilience” and the “Resilience Capacity Index” [65]. The CRI is structured around 4 dimensions, 12 goals, and 52 indicators, all considered essential for achieving resilience in complex urban environments. The dimensions are: 1. Health and Wellbeing; 2. Economy and Society; 3. Infrastructure and Ecosystems; and 4. Leadership and Strategy. Each dimension is further broken down into three specific goals that are essential for achieving overall resilience, and each goal is supported by multiple indicators. These indicators provide detailed metrics for evaluating progress toward each goal, covering a broad spectrum of factors that contribute to urban resilience [35]. Some indicators from the CRI were deemed irrelevant for the Cvjetno estate, particularly those that are standard in Zagreb and do not contribute unique insights for this specific assessment. This selective approach ensures that the resilience evaluation is both relevant and focused on the unique aspects of the estate.

3. Results and Discussion

3.1. Planning for Community Resilience

The Cvjetno housing estate stands as a testament to the principles of CIAM, and anticipates some features of a resilient community long before the concept emerged in contemporary discourse. Situated in Trnje, a district historically disrupted by flooding and socio-economic challenges, the Cvjetno estate was planned to mitigate these risks and foster resilience in its residents. The estate acknowledges the risk of and vulnerability to flooding and earthquakes in its planning and construction. Antolić’s design incorporates elements such as raised housing units on reinforced concrete columns, spacious front and back yards, and a pedestrian street with greenery, ensuring habitability during floods and promoting community cohesion.

The Cvjetno housing estate was designed as an “independent unit” [58] with four north-to-south residential streets—now known as Cvjetno naselje I, II, III, IV—connected by a west-to-east pedestrian street with greenery running approximately through the middle of the estate (now Vladimir Antolić Alee). In addition to the residential area, Antolić planned social and public areas around the estate. On the western side, from north to south, he planned a playground, school, and a school playground, while on the eastern side, he designated a market and public buildings (Figure 6). The estate aimed to provide affordable homes for city officials, incorporating innovative financial plans to facilitate ownership. The estate’s design adheres to CIAM principles, ensuring ample sunlight, living space, and greenery [58,66].

The estate was intended to accommodate 70 family houses, described as “modern pile dwellings”, on reinforced concrete columns that were designed to mitigate flood risks [58,66]. The houses are situated on elongated east-to-west rectangular parcels 20 × 40 m on both sides of the streets. The housing units were set back 8 m from the street border, providing a relatively large front garden area with lawns, bushes, uniform hedges, and fences. They were positioned to maximize the sunny space of the parcel. Each house featured a spacious backyard with an orchard, vegetable garden, and lawns, as shown on Figure 7 [58].

The ground floor of the units was designated for auxiliary rooms, and the upper floor(s) served as residential living areas with bedrooms, kitchens, living rooms, and bathrooms. The treatment of certain exterior elements, such as the roof with a mild slope and concrete columns, were determined by a regulation [12,16,58], and these became characteristic elements of the settlement that contribute significantly to its identity. Antolić collaborated with another member of the Work Group Zagreb, architect and structural engineer Zvonimir Kavurić, to design four types of houses in Cvjetno. The main distinction among the types was the number of floors and inhabitable surface area. There were three two-story types of 95, 110, and 140 m² (A 95, A 110, A 140), and one three-story type of 170 m² (B 140) [12,16,58,67]. All houses had a reinforced concrete frame with brick filling and a sloped roof. Type A 95 featured auxiliary rooms on the ground floor, and a kitchen, bathroom, living room, and two bedrooms on the first floor. Type A 110 (Figure 8) included a large porch and an additional workroom on the ground floor, with a kitchen, bathroom, living room, and three bedrooms on the first floor. Type A 140 had an additional living room on the ground floor, along with a kitchen, two bathrooms, living room, and three bedrooms on the first floor. The three-storied B 140 type had a large porch and a living room along with auxiliary rooms on the ground floor, and two upper floors with identical floor plans, each featuring three bedrooms, a bathroom, living room, and kitchen [10,12,16].

Construction on the Cvjetno estate begun in 1939, with approximately 40 houses completed by 1940, according to Antolić [58]. Interestingly, this early phase of development saw the first modifications to the plan and specific building projects, as prompted by the future inhabitants. Antolić himself attributed these changes to “exceptional circumstances and misunderstandings among certain plot owners” [58]. Notably, future residents largely disregarded the regulation specifying the gently sloped design of the roofs, leading to what Antolić described as a “chaotic appearance” in parts of the settlement [58]. Originally, the plan called for a total of 70 houses arranged along four streets in six north–south rows, with an additional four houses situated on the westernmost part of the estate. Each of the six rows comprised eleven houses, with six to the north of Josip Antolić Alee and five to the south, summing to a total of sixty-six houses. However, during the site’s development, an extra row of houses and parcels was added to the north.

The planning of the estate did not include any particular landscape aspects as a respond to flooding risks. It did, however, include spaces for public and social use on both the western and eastern sides of the estate that could have addressed the social needs of the community. The only structure intended for public use that was constructed is the Primary School, designed by Croatian architect Zlatko Neumann and built from 1957 to 1962 [68]. Positioned in accordance with Antolić’s plan on the western section of the estate, the school was, however, situated slightly farther south than originally envisioned. The market and public buildings to the east were never constructed, and instead, residential buildings now occupy that space. In comparing the current state of the settlement with Antolić’s concept and particular house types, most changes refer to the design of the roof and adaptations that include extending the ground floor level to incorporate the porch to the enclosed living area. The rest of the construction carried out in the Cvjetno estate, around 20 houses, were built as new house types which do not adhere to Antolić’s original design as modern pile dwellings, reducing the resilience to flooding.

3.2. Cvjetno Housing Estate as a Resilient Community

According to the indicators of resilient communities (CRI), the Cvjetno housing estate enhances the “Health and Wellbeing” dimension by achieving two primary goals: “Minimal Human Vulnerability”, and “Diverse Livelihood and Employment”. The estate meets the basic needs of its residents by providing adequate housing for city officials, ensuring affordability through a structured loan system [58].

In the “Economy and Society” dimension, Cvjetno housing estate supports the goal of “Collective Identity and Community Support”. It was planned as a cohesive community with public spaces and communal facilities, fostering a strong sense of community [58].

For the “Infrastructure and Ecosystems” dimension, the estate contributes to “Reducing Exposure to Fragility” through robust protective infrastructure (embankment, house design, and construction) designed to withstand hazards and disturbances.

Lastly, the dimension of “Leadership and Strategy” is well-served through “Effective Leadership and Management”, and “Appropriate land use and zoning” is achieved via government decision-making and support [58] (

Table 1. Dimensions, goals and indicators from CRI framework used to assess Cvjetno’s resilience.

Dimension	Goal	Indicator	Quality
Health and wellbeing	Minimal human vulnerability	Safe and affordable housing	Robust construction and protective infrastructure
Health and wellbeing	Diverse livelihood and employment	Supportive financing mechanisms	Cost-efficient building and affordable loan repayment
Economy and society	Collective identity and community support	Cohesive community	Integrated community
Infrastructure and ecosystems	Reduces exposure to fragility	Protective infrastructure	Robust protective infrastructure and physical environment
Leadership and strategy	Effective leadership and management	Appropriate government decision-making	Support in affordable housing
	Integrated development planning	Appropriate land use and zoning	Rational and appropriate use of space

).

As suggested by some authors, green infrastructure also has a valuable role in resilience [69,70,71]. The estate incorporates public and private green infrastructure elements that mitigate the effects of severe heat. Two relatively small parks, featuring diverse trees and shrubs, are situated in the west and southwest parts of the estate. Additionally, the school is surrounded by landscaped areas. The main east-to-west alley, along with the eastern and northern borders of the estate, is lined primarily with deciduous trees [13]. These public green zones provide protection from noise, traffic, and heat, thereby enhancing the well-being and safety of the residents. Each house is also equipped with green infrastructure, which includes spacious front and back gardens, promoting self-sufficiency, health, and community resilience.

Vulnerability is reduced through the elevated design and flood mitigation measures. It also ensures stability by maintaining habitability during floods, as well as robustness, which is achieved by implementing reinforced concrete structures.

Drawing the characteristics of resilient communities from Wang et al [64], the Cvjetno estate benefits from multifunctionality and flexibility of space on the scale of the estate and particular parcels. The estate features a residential area, along with public spaces of greenery and a primary school. Public green spaces are equipped with various components that support diverse activities and function for different age groups that might foster interactions within the residents. Although the multiple planned social functions of the estate were not built, the developed spaces are flexible and adaptable, and can welcome various types of functions. It also has the characteristic of a human-centered approach. The planned settlement was to have all the necessary buildings for social purposes within walking distance. On top of that, as the modern design of Antolić’s houses was not accepted by some future residents, they were able to modify the design to suite their esthetic preferences (changing the roof type) [58,72]. The estate also includes the characteristic of prediction in the structural design of specific house types that accept and are prepared for natural hazards such as floods and earthquakes (

Table 2. Characteristics of the Cvjetno estate as a resilient community using Wang et al.’s classification [64].

Layer	Performance Dimension	Characteristic	Description
Fundamental layer	Spatial pattern	Multi-functionality	Parcels with multi-functional spaces for living and food growing Rational planning
		Flexibility	Flexible and adaptable living spaces
	Environmental components	Interactivity	Public spaces support community interaction of different age groups
		Diversity	Different types of equipment in public spaces offer diverse activities
Core layer	Public service	Intelligence	-
		Humanity	Planned public spaces within walking distance
Top layer	Management system	Prediction	Houses planned and constructed to adapt to flooding and absorb the effect of earthquakes
		Collaboration	-

).

Today, the estate has a Local Board as a type of self-governance that enables citizens to participate in decisions that enhance communal life. It might also serve as an information and meeting hub where citizens can exchange information and knowledge or interact in general.

After the construction of the Cvjetno estate, several developments in its vicinity significantly influenced its socioeconomic, cultural, and demographic conditions. Key additions included the Student Residence Hall (1955), Jedinstvo factory (1946, later transformed into the Pogon–Zagreb center for independent culture and youth), a political administration building (1968), Vjesnik Skyscaper (1972, newspaper and publishing building), and the Croatian Radio Television (1975). The gradual addition of new facilities in the area surrounding the historic estate and the influx of diverse user groups have transformed both the overall physical landscape and its social dynamics. Originally an enclave for city officials, the construction of a student dormitory introduced a vibrant urban life brought by young intellectuals from across Croatia, enriching the settlement’s identity and creating new cultural symbols. The establishment of the Jedinstvo factory transformed the residential area into a hub of work and daily transit. The construction of the political administration building for the political elite elevated the area’s symbolic representation to a state level. Over subsequent decades, the wider area of the Cvjetno estate saw continuous additions of new facilities, attracting varied users and imbuing new symbols into the urban space, thereby diversifying its identity, economic, and demographic structure. The introduction of two major media houses, Vjesnik and Croatian Radio Television, further redefined its identity by incorporating media professionals into the wider neighborhood [57]. This transformation illustrates the concept of resilience in urban development, where communities adapt to external influences by incorporating new functions and populations, thereby fostering resilience through socio-economic diversification and cultural enrichment.

While Cvjetno Estate showcases many elements of resilience, it also faces several limitations, failures, and challenges that underscore the complexity of achieving true resilience. One significant limitation is the partial realization of planned public spaces, such as markets, which were never fully developed within the estate’s historic boundaries. This gap reflects a broader issue in maintaining a balance between communal and private needs, which is essential for a resilient community. Additionally, while the estate’s design is aimed at flood mitigation, the posterior modifications of some houses reveal challenges in strictly adhering to original resilience-enhancing plans. These modifications potentially compromised some aspects of robustness and adaptability. The estate’s reliance on outdated mid-20th-century technologies presents a challenge in meeting contemporary environmental and technological demands. Assessing the Cvjetno Estate through a resilience lens highlights the importance of continuous adaptation and re-evaluation of urban planning strategies to address both the historical context and present-day realities for fostering truly sustainable and resilient communities.

4. Conclusions

The Cvjetno housing estate in Zagreb exemplifies resilience in various aspects, as it embraces proactive planning strategies that enhance transformational resilience and post-trauma livability. Situated in the Trnje district, which historically faced frequent flooding and socio-economic challenges, the Cvjetno estate was meticulously planned to mitigate these risks enhancing its absorptive capacity. Its orthogonal design adheres to CIAM principles, and includes spacious front and back gardens, orchards, and vegetable gardens, providing residents with self-sufficiency in food production and contributing to the community’s resilience by enhancing food security.

However, the estate also faces limitations and challenges. Notably, the incomplete development of planned public spaces and modifications to houses that compromised original resilience plans highlight the complexity of achieving true resilience. The reliance on outdated mid-20th-century technologies poses challenges in meeting contemporary demands. These issues underscore the need for continuous adaptation and re-evaluation of urban planning strategies.

Future research could expand to include other natural hazards such as extreme weather conditions—high temperatures, strong winds, heavy rainfall, and flash floods—that have recently impacted the Zagreb area.

Further research could also explore and compare similar mid-20th century European settlements to deepen the comprehension of urban resilience and architectural innovation during the modern era. Such studies can provide fresh insights and methodologies for understanding modernist heritage within interdisciplinary research approaches, extending beyond the traditional focus on symbolic values of design principles in architecture and urban planning [73]. But to achieve this, it would be essential to acknowledge that these structures, constructed approximately a century ago and still in use today, utilized the cutting-edge technology available at that time. Given the significant changes in technology, socioeconomic conditions, and environmental factors since then, it would prove crucial to assess these settlements through the perspective of resilience, considering multiple dimensions and contemporary challenges. The findings of such an approach to modernist heritage could be vital in exploring the paths towards a design method which would help in the better assessment of past experiences. This might facilitate establishing sustainable grounds to face future environmental challenges in design and urban planning of resilient environments.