Regional Lessons to Support Local Guidelines: Adaptive Housing Solutions from the Baltic Sea Region for Climate-Sensitive Waterfronts in Gdańsk

Abstract

Across the Baltic Sea region, areas situated in climate-sensitive water zones are increasingly exposed to environmental and socio-economic challenges. Gdańsk, Poland, is a prominent example where the rising threat of climate-related hazards, particularly connected with flooding, coincides with growing demand for resilient and adaptive housing solutions. Located in the Vistula Delta, the city’s vulnerability is heightened by its low-lying terrain, polder-based land systems, and extensive waterfronts. These geographic conditions underscore the urgent need for flexible, climate-responsive design strategies that support long-term adaptation while safeguarding the urban fabric and the well-being of local communities. This study provides evidence-based guidance for adaptive housing solutions tailored to Gdańsk’s waterfronts. It draws on successful architectural and urban interventions across the Baltic Sea region, selected for their environmental, social, and cultural relevance, to inform development approaches that strengthen resilience and social cohesion. To achieve this, an exploratory case study methodology was employed, supported by desk research and qualitative content analysis of strategic planning documents, academic literature, and project reports. A structured five-step framework, comprising project identification, document selection, qualitative assessment, data extraction, and analysis, was applied to examine three adaptive housing projects: Hammarby Sjöstad (Stockholm), Kalasataman Huvilat (Helsinki), and Urban Rigger (Copenhagen). Findings indicate measurable differences across nine sustainability indicators (1–5 scale): Hammarby Sjöstad excels in environmental integration (5/5 in carbon reduction and renewable energy), Kalasataman Huvilat demonstrates strong modular and human-scaled adaptability (3–5/5 across social and housing flexibility), and Urban Rigger leads in climate adaptability and material efficiency (4–5/5). Key adaptive measures include flexible spatial design, integrated environmental management, and community engagement. The study concludes with practical recommendations for local planning guidelines. The guidelines developed through the Gdańsk case study show strong potential for broader application in cities facing similar challenges. Although rooted in Gdańsk’s specific conditions, the model’s principles are transferable and adaptable, making the framework relevant to water sensitivity, flexible housing, and inclusive, resilient urban strategies. It offers transversal value to both urban scholars and practitioners in planning, policy, and community development.

1. Introduction

1.1. Climate Change and Water-Sensitive Urban Regions

Climate change is intensifying pressures on water-sensitive regions worldwide, particularly in coastal and low-lying areas [1]. Altered precipitation and evaporation patterns are driving more frequent droughts and floods, undermining freshwater availability, agricultural productivity, and ecosystem health, and exposing millions of people to heightened risks [2]. The Baltic Sea region, where global climate trends intersect with diverse ecosystems and uneven population pressures, is especially vulnerable to those challenges [3]. Rising temperatures, shifting precipitation regimes, and accelerating sea-level rise are already affecting urban and peri-urban areas. Natural hazards such as floods, droughts, and storms occur with growing frequency and intensity, endangering lives, economies, and ecosystems [4]. Sea levels are projected to rise globally by 0.40–0.63 m by 2100, while the Baltic Sea is warming faster than the global average, with mean sea surface temperatures increasing by +0.59 °C per decade between 1990 and 2018 [5].

1.2. Urban Vulnerabilities and the Case of Gdańsk

In Poland, these climate pressures coincide with a long-standing housing crisis, with an estimated shortage of 1.5 million units [6]. In Gdańsk, high housing demand and income disparities further limit access to adequate housing [7]. Structural inequalities, uneven spatial development, and socio-economic disparities exacerbate these challenges [8]. Situated at the confluence of the Vistula River Delta and Gdańsk Bay, illustrated in Figure 1, the city provides a critical case study of the intersection between hydrological risks, urban growth, and housing adaptation [9].

Urban waterfronts, particularly those in low-lying and densely developed areas, face compounded vulnerabilities due to climate change and urban expansion. Gdańsk exemplifies this complexity [10]. The city is exposed to riverine, pluvial, and coastal flooding, while low elevation, extensive impervious surfaces, and rising urban density exacerbate flood risk and reduce natural water absorption [11]. Between 1985 and 2022, impervious areas expanded from 58.64 km² to 88.89 km², while average runoff depth increased from 41 mm to 47.03 mm, projected to reach 51.10 mm by 2050. The runoff coefficient is expected to rise from 0.44 to 0.50, indicating increasing hydrological stress [12]. Between 1992 and 2016, 23 urban flood events were recorded, showing a rising trend over time [13] with storm surges peaking at 1.36 m in 2004 [14], illustrated in Figure 2. These trends highlight the urgent need for integrated, climate-adaptive urban design and housing strategies.

Today, Gdańsk faces three principal flood risks: (1) rapid surface runoff from moraine hills, (2) river flooding intensified by heavy rainfall, and (3) sea-level rise [12]. Urban flooding in Gdańsk shows a clear upward trend. At the Northern Port, mean annual sea levels rose by about 15 cm between 1955 and 2015, with all storm surge indicators (frequency, duration above Mean High Water, and annual maxima) also increasing. The highest sea level was recorded during the 2004 storm surge (1.36 m above sea level, 50 cm surge). Coastal flood risk in Poland is concentrated at the mouths of the Vistula and Odra rivers [11]. These physical risks translate into social and spatial challenges, including restricted waterfront access, persistent segregation, and unequal housing provision. The city’s historic streams and river systems, particularly the Vistula and Motława, have long shaped its spatial development, and today they remain central to discussions on climate adaptation [15].

1.3. Planning Gaps, and the Need for Adaptation

These risks call for strengthening planning and housing policies to answer the challenges mentioned above. Adaptive housing guidelines rarely integrate flood-resilience measures, stormwater management, or climate projections [16]. Rigid zoning regulations restrict flexibility, while innovations such as amphibious, floating, or modular housing are seldom embraced. Fragmented governance between water authorities managed on the national level and local urban planning further undermines adaptation [17]. Historically, Gdańsk’s expansion reflected hydrological dynamics, a legacy known as the “Hydrourban” model, yet contemporary planning often neglects this relationship [15].

Planning gaps further constrain adaptive capacity: 10% of Gdańsk’s shoreline is obstructed by ownership or technical barriers, while 14% of designated development zones lack clear access strategies [18]. Urban landscape (UL) and greenspace (UG) management, critical for housing resilience, remain weak points within the Polish planning system. Inconsistently applied ecological, structural, and visual standards undermine the potential for holistic, sustainable growth in vulnerable coastal zones [19].

These challenges call for evidence-based, context-sensitive strategies that strengthen housing adaptability while advancing environmental justice, community well-being, and inclusive development. Adaptive housing characterized by flexible layouts, structural resilience, retrofit potential, and strong indoor–outdoor connections, offers a critical pathway. Beyond addressing flood risks, adaptive housing can respond to demographic shifts, evolving work patterns, and diverse household needs.

Urban areas across Europe exemplify these risks, as high population densities and impervious surfaces intensify flooding and pressure on drainage infrastructure [20]. In the Baltic Sea region, extended precipitation and rising temperatures contribute to runoff, eutrophication, and compound flooding events, particularly in low-lying estuarine and deltaic areas [21]. Even modest sea-level rise projected between 0.04 and 0.98 m by 2100 will exacerbate erosion, saltwater intrusion, and inundation of coastal settlements [22]. Countries such as Poland, Estonia, and Germany face significant exposure, as large portions of their GDP are concentrated in flood-prone coastal areas [21]. In Poland alone, nearly 10% of the population resides in areas at risk of flooding, with projections indicating a seven-fold increase in residential flood risk by century’s end without intervention [23].

From the planning perspective, these pressures demand adaptive housing strategies that integrate structural adaptability with water management systems. Elevated, amphibious, and modular housing demonstrate potential in flood-prone areas, while blue-green infrastructure, such as rain gardens, wetlands, and detention basins, provides both protective and ecological benefits [24,25]. Adaptive housing, in this context, refers to solutions that withstand and recover from climate impacts while addressing diverse socio-economic needs. This includes flood-resistant materials, elevated foundations, passive cooling systems, and renewable energy integration [16]. Equally important are affordability, inclusivity, and access to services, ensuring that vulnerable populations are not excluded from resilience strategies [26]. By emphasizing flexibility and community engagement, adaptive housing supports evolving household needs while promoting social equity.

1.4. Research Aim and Questions

This study aims to develop adaptive housing strategy recommendations for Gdańsk’s waterfront, drawing on case studies from other Baltic Sea cities, which can be used as a set of guidelines at both the architectural and urban design scales. It investigates how architecture, urban design, and planning can address climate risks and social vulnerabilities, supported by an assessment framework to evaluate their effectiveness.

The research is guided by the following questions:

• Comparative insights
  • Which adaptive housing projects have been successfully implemented in other Baltic cities, particularly regarding flood resilience, social inclusion, and urban regeneration? How do these projects reflect local responses to environmental risks, demographic shifts, and housing needs? Which architectural and urban design solutions contributed to their success?
• Application to Gdańsk
  • How can these lessons be translated into planning and architectural guidelines tailored to Gdańsk’s waterfront challenges? What barriers may affect the implementation of adaptive housing solutions in Gdańsk, and how can they be addressed through integrated urban policies?

By addressing these questions, the research contributes to broader debates on adaptive housing as a tool for climate-resilient urban development, rooted in regional cooperation yet tailored to local specificity.

2. State of the Art

2.1. Policy Frameworks Supporting Adaptive Climate, Flexible Housing

The relevance of integrated frameworks is reinforced by UN Sustainable Development Goal 11, which advocates for inclusive, resilient, and environmentally sustainable urban development [27]. The EU Strategy on Adaptation to Climate Change (2021), promotes systemic resilience [28], while the New European Bauhaus initiative links sustainability, esthetics, and inclusion to foster high-quality living environments [29].

The Baltic Sea Region has emerged as a significant reference point for integrated climate adaptation and housing innovation, supported by transnational strategies and research initiatives. The European Union Strategy for the Baltic Sea Region (EUSBSR) [28], aligned with the European Green Deal, identifies climate adaptation as a cross-cutting priority. EUSBSR-inspired projects, such as ClimaResponse under the Interreg Baltic Sea Programme, focus on enhancing municipal climate resilience through collaborative governance and policy innovation, with knowledge-sharing initiatives like Urban Climate Change Adaptation workshops further promoting nature-based solutions and flood resilience [30]. The Baltadapt Strategy provides a transnational framework to promote coordinated resilience and embed adaptation objectives within sectoral and spatial planning systems [31]. However, current frameworks tend to focus primarily on sectoral or technical adaptation measures, with limited integration between housing design, governance, and community resilience. This reveals a gap in multi-level approaches that link policy ambitions with spatial and architectural implementation. This study addresses this gap by proposing an analytical framework that links adaptive housing strategies with political, social, and environmental dimensions in the Baltic Sea context.

The BalticClimate Toolkit, developed by the Stockholm Environment Institute, offers practical resources for municipalities and urban planners to assess vulnerabilities and design resilient urban systems [32].

Coastal redevelopment and residential adaptation in the Baltic Sea Region demand integrated analytical frameworks capable of addressing hydrological variability, sea-level rise, and socio-spatial vulnerabilities [33]. Policy instruments emphasize participatory planning and the mainstreaming of adaptation measures across governance levels [34]. Effective climate-resilient housing relies on policy frameworks that coordinate sectoral priorities, mobilize financial mechanisms, and incorporate long-term strategic planning. Zoning, land-use regulation, and environmental assessments can identify high-risk areas and guide the promotion of low-exposure housing designs [35]. Without robust institutional support, housing adaptation remains fragmented and inconsistent, limiting the potential for equitable implementation [36].

National policies in Poland, including the National Housing Program (Narodowy Program Mieszkaniowy) [37]. and the Act on Housing Cooperatives (Ustawa o kooperatywach mieszkaniowych), support housing accessibility and collaborative models [38]. Regional strategies, such as the Pomeranian Voivodeship Development Strategy 2030 and the Strategic Adaptation Plan 2020, integrate climate considerations into spatial planning and construction policies [39]. Locally, Gdańsk’s City Development Strategy 2030+ and Study of Conditions and Directions of Spatial Development, along with initiatives like the Gdańsk Green Policy, and Water Policy, institutionalize climate adaptation in urban development [40]. Collectively, these frameworks underpin adaptive housing strategies that foster inclusive, resilient communities across Gdańsk and the wider Baltic region.

2.2. Urban Housing Vulnerabilities and Resilience

Urban housing systems are increasingly recognized as key components of climate resilience, connecting environmental exposure, social vulnerability, and spatial adaptive capacity. Housing vulnerability arises from a combination of physical challenges, such as flooding, heat stress, and infrastructure degradation, and socioeconomic factors, including affordability, tenure insecurity, and limited adaptive capacity [41]. Many researchers emphasize that housing resilience must go beyond technical solutions to include community networks, governance mechanisms, and equitable access to resources [42,43].

Recent research suggests that the adaptive capacity of housing depends on its spatial flexibility, physical performance, and ability to integrate natural and decentralized infrastructure [44]. Consequently, the concept of “resilient housing” is evolving toward hybrid models that combine physical adaptation with socioecological integration, as demonstrated in studies of amphibious housing, modular retrofitting, and adaptive reuse in coastal contexts [45,46].

In the European and Baltic context, vulnerability assessments highlight that older housing stocks in flood-prone areas often lack energy efficiency and structural resilience, exacerbating risks for low-income residents [47]. Urban resilience frameworks increasingly call for multi-level approaches, bridging building design, neighborhood planning, and governance, to ensure that housing serves as both shelter and social infrastructure under climate events [48]. These perspectives position housing not only as a tool for adaptation, but also as an actor in enhancing community resilience and long-term sustainability.

2.3. Projects Addressing Similar Challenges, Emphasizing Social and Cultural Similarities with Gdańsk

Several urban projects across the Baltic Sea Region provide insights relevant to Gdańsk. Copenhagen’s Sluseholmen integrates water-based design, architectural diversity, and community-scale flood resilience [49]. Multifunctional structures in Copenhagen address flooding, green space shortages, and parking through cohesive interventions [50]. The Lynetteholm project, despite its scale and flood-protection intentions, raises ecological and social equity concerns, while Saint Kjelds demonstrates retrofitting existing urban fabric for resilience using green infrastructure and sustainable drainage systems [51]. Floating architecture innovations, such as Koen Olthuis’s Floating City Apps and MAST’s “Land on Water” system, provide modular, deployable housing for flood-prone areas [52]. In Finland, Ulla Tervo Architects and OOPEAA’s Puukuokka housing block use elevated, water-resilient, and energy-efficient designs that integrate community-focused spatial layouts [53]. Sweden’s Bo01 district in Malmö combines elevated floors, permeable landscaping, renewable energy systems, and sustainable urban density to reduce flood vulnerability while enhancing public space and ecological value [53]. Amsterdam’s IJburg floating homes demonstrate long-term adaptability in flood-prone urban areas [54]. Socially inclusive projects like BIG’s 8 House (8TALLET) in Copenhagen and Sneglehusene in Aarhus integrate mixed uses, modular design, and natural landscapes to foster community identity and sustainability [55]. Lisbjerg Bakke in Aarhus highlights prefabricated timber construction for affordable, environmentally conscious social housing [56]. Collectively, these projects demonstrate principles of architectural adaptability, environmental stewardship, and social integration, providing relevant models for Gdańsk’s waterfront development.

2.4. Identifying Gaps and the Need for Localized, Evidence-Based Guidance

Despite the development of progressive EU-level frameworks, a gap persists in the practical implementation of climate adaptation policies at the municipal level in Poland. Local authorities often lack the regulatory instruments, institutional capacity, and financial support to promote innovative housing solutions. This gap is particularly evident in the limited consideration of alternative residential typologies, such as floating, modular, or amphibious housing, within local planning instruments, even in areas with high flood risk. The absence of enabling policies constrains experimentation with socially inclusive, adaptive housing models, resulting in fragmented adaptation practices. This limitation underscores the urgent need for context-specific, evidence-based spatial development guidance that considers local socio-environmental conditions. Those guidelines can be elaborated based on case study analyses from other Baltic Sea cities assessed using a framework to evaluate their effectiveness. Such guidance should provide actionable recommendations, incentives, and good practice models for stakeholders. Addressing these gaps through practical architectural and urban design recommendations is critical for bridging the divide between EU ambitions and on-the-ground implementation, ultimately supporting equitable and climate-resilient urban development. What distinguishes the framework developed in this study is its integrative perspective: it combines the spatial, technical, and socio-institutional dimensions of housing adequacy, enabling comparison across different Baltic Sea contexts. Unlike other adaptive housing models in Northern Europe, which focus primarily on design patterns or technical performance, this framework emphasizes the interaction between policy frameworks, local governance, and community resilience, offering a more comprehensive and applicable approach.

3. Methodology

3.1. Methods and Materials

Due to the exploratory focus of this paper and the recency of the research topic, a qualitative case study methodology was employed, following Aberdeen [57]. This approach allows for an in-depth understanding of the adaptability of urban structures by analyzing various forms of textual data, including reports, academic studies, and news articles. The study is grounded in the use of conceptual categories, which guided both the inquiry and the interpretation of the data [58]. Subsequent methodological steps are described in Figure 3.

The research primarily employed a desk research method, collecting and analyzing information from secondary data sources. This included examining data on the conditions and approaches to designing adaptive housing solutions for climate-sensitive waterfronts, as well as strategies prepared by regional and local governments.

The study employs qualitative content analysis, which involves identifying patterns, themes, and relationships in textual data. This method consists of extracting excerpts or examples from documents to support a given observation or relationship [59].

The qualitative research method was applied to identify the design solution and assess how these solutions respond to climate change challenges. This approach allows for assessing the impact of built environment solutions responding to climate change challenges. The methodology combines several techniques, including a recognition of the state of the art, collection of planning documents and strategies, and the compilation of a database, following a five-step methodology outlined by Denyer and Neely: (1) key project identification; (2) document identification; (3) qualitative assessment; (4) data extraction; and (5) data analysis [60].

The same methodological procedures were applied across all three case studies to ensure the reliability and comparability of results. Data were collected from multiple complementary sources, allowing for triangulation and cross-verification of information. All data were compiled in a purpose-designed analytical table with standardized categories and headings to facilitate structured comparison among the case studies. The coding process was undertaken by researchers with established expertise in the field and subsequently subjected to independent verification by a second researcher to enhance accuracy and reduce the likelihood of interpretive bias or coding errors. Detailed analyses focused on location, actors, users, the aim/action of the project and applied design solutions.

To assess the social, economic, and environmental impact of each intervention, a 5-point Likert scale [61] was applied, ranging from 1 (very low) to 5 (very high). Each level was defined by clear methodological indicators, including the presence and scope of documented outcomes, references in verifiable sources, and evidence of measurable benefits. Very low impact corresponded to minimal or no observable effects and no reliable reporting, while very high impact indicated transformative, replicable results widely recognized as innovative and producing long-term positive change. Evaluations drew on relevant metrics to ensure consistent and comparable ratings across cases.

Table 1. Five-Point Likert Scale with Methodological Indicators for Evaluating Intervention Impacts.

Impact Level	Extent of Change	Evidence/Indicators
1—Very Low	Minimal or no observable impact	No mention or very limited references in the news or reports. No measurable outcomes were reported.
2—Low	Slight impact, limited effect	Small-scale effects mentioned, limited to isolated instances or minor improvements.
3—Moderate	Noticeable impact, but not widespread	Documented cases of positive effects in some communities or settings; some metrics improved.
4—High	Strong impact with clear benefits	Multiple reliable sources report significant benefits; evident improvements in social/economic/environmental factors.
5—Very High	Replicable, transformative, or model-setting impact	Widely covered in news as innovative/breakthrough; serves as a model replicated elsewhere; measurable long-term positive effects demonstrated.

below summarizes the scale levels, descriptions, and thresholds used for these evaluations.

To enhance methodological transparency, each indicator used in the Likert-scale assessment was traced back to its conceptual and documentary sources, including peer-reviewed literature, policy frameworks, and international guidelines such as the Intergovernmental Panel on Climate Change (2022), the United Nations Human Settlements Programme (UN-Habitat) (2016), and the European Green Deal.

Table 2. Origin and Justification of the Five Methodological Indicators Used in the Likert-Scale Assessment.

Indicator	Primary Source/Reference Type	Supporting Framework or Document	Justification for Inclusion
Minimal or no observable impact	Research on program evaluation and impact measurement	OECD [62] Evaluation Frameworks	Serves as a baseline category for identifying interventions with negligible or unverified effects
Slight impact, limited effect	Urban resilience literature; local adaptation policy assessments	IPCC AR6 [63] Adaptation Metrics; EU Climate Adaptation Strategy (2021)	Captures incremental improvements or pilot actions with minimal scale or duration
Noticeable impact, but not widespread	Comparative case studies on adaptive housing and community resilience	UN-Habitat City Resilience Profiling Tool [36]; European Environment Agency (EEA) reports	Reflects moderate, context-specific outcomes that demonstrate measurable progress but lack systemic reach
Strong impact with clear benefits	Policy evaluation frameworks; sustainability impact assessments	European Green Deal Progress Reports [64]; New European Bauhaus [29]	Identifies cases with demonstrable, multi-dimensional benefits across environmental, social, or economic aspects
Replicable, transformative, or model-setting impact	Innovation diffusion theory; transnational best-practice studies	IPCC Good Practice Case Studies; Interreg Baltic Sea Programme projects [65]	Represents high-impact, scalable interventions recognized as models for replication and long-term transformation

summarizes these sources and justifications. The scoring was conducted collaboratively by three researchers using a consensus-based process. Inter-rater reliability was ensured through independent scoring followed by group calibration and cross-verification to minimize subjectivity and ensure consistency.

Furthermore, we created an impact assessment framework, as described below, while the studies concluded with recommendations that can serve as architectural and planning guidelines to enhance planning practices, identify key boundary conditions for adaptive housing, and support climate-sensitive projects to have a positive impact on the urban environment.

3.2. Impact Assessment Framework

Based on a comprehensive literature review and factors influencing adaptability and flexibility, described in the chapter above, we developed a conceptual framework for impact assessment across three main dimensions: social, economic, and environmental. Within each dimension, specific impact areas were identified to capture relevant aspects of performance, such as affordability, resource efficiency, and environmental sustainability. Each area was evaluated using a 5-point Likert scale [61], reflecting the level of impact, accompanied by a concise justification grounded in project documentation and supporting evidence.

Table 3. Impact Dimensions, Areas, and Justifications for Urban Housing Intervention.

Impact Dimension	Impact Area	Justification
Social	Affordable/adaptable housing	Addresses critical urban housing shortage with accessible pricing.
	Shared public spaces	Enhances social cohesion and interaction.
	Well-being	Quality design improves mental and physical comfort.
Economic	Cost-effective recycled materials	Reuses shipping containers, reducing material and construction costs.
	Efficient waterfront usage	Uses previously underutilized water areas in urban zones.
	Replication potential	Modular and scalable model suitable for other cities.
Environmental	Carbon footprint reduction	Circular materials and reduction in energy flows.
	Use of renewable energy	Incorporates innovative solutions incl. solar power and heat exchange systems.
	Reduction in land-use	Floating structure eliminates the need for land occupation.

below illustrates this framework, including the assigned impact levels and rationales for each assessment. To facilitate interpretation and comparison across categories, results were visualized through Spider Charts.

4. Selected Interventions—Baltic Sea Region

4.1. Selection of the Case Studies

The selection of case studies was informed by both conceptual relevance and practical applicability. The Baltic Sea region was chosen as the geographic focus due to its shared climatic conditions, cultural heritage, and spatial development patterns, which support meaningful comparative analysis and enhance the transferability of findings. Gdańsk’s specific challenges, ranging from hydrological vulnerability to housing pressure, mirror broader regional dynamics, making it an ideal reference point for identifying adaptive interventions.

Three representative projects were selected for detailed analysis (illustrated in Figure 4)

• Urban Rigger (Copenhagen, Denmark): A floating modular housing solution designed to address urban density and flood risk through sustainable, scalable architecture.
• Hammarby Sjöstad (Stockholm, Sweden): An eco-district integrating renewable energy, green-blue infrastructure, and sustainable mobility to enhance climate resilience.
• Kalasataman Huvilat (Helsinki, Finland): A compact, elevated housing development emphasizing environmental performance and community-oriented design.

These projects were chosen based on the following criteria:

• Documented Outcomes: Availability of verifiable data and reporting on social, environmental, and economic impacts.
• Innovative Approaches: Use of modular, amphibious, or nature-integrated design strategies that respond to climate risks.
• Contextual Relevance: Alignment with the socio-spatial conditions of Gdańsk and other Baltic cities.
• Transferability: Potential to inform planning and design guidelines beyond their original implementation sites.

These selected cases represent complementary approaches to adaptive waterfront housing. While all three integrate water-sensitive design, sustainability, and collaborative governance, they differ in scale and implementation strategy: Hammarby Sjöstad illustrates a large-scale, district-level integration of green-blue infrastructure and smart systems; Kalasataman Huvilat demonstrates neighborhood-scale modular and flexible housing with community-oriented design; and Urban Rigger provides a small-scale, floating prototype emphasizing affordability and low-carbon modular construction. Together, they capture a spectrum of adaptive strategies that are conceptually relevant, empirically documented, and transferable to the Gdańsk context.

Other relevant examples within the Baltic Sea region were initially considered; however, many were excluded due to insufficient documentation, or context-specific characteristics that constrained comparative analysis. The final selection therefore prioritizes cases that are both conceptually significant and empirically verifiable.

This purposive sampling strategy enabled an in-depth examination of interventions that are both representative of regional adaptation efforts and instructive for local application. Nevertheless, it is acknowledged that analyzing only three cases imposes limitations on the generalizability of findings. The results should thus be interpreted as indicative of emerging tendencies in adaptive housing rather than exhaustive representations of all practices across the Baltic Sea region. The selected cases offer diverse yet coherent responses to climate-sensitive urban development, providing valuable insights into governance, design innovation, and community engagement across the Baltic Sea region.

4.1.1. Case Study 1: Hammarby Sjöstad

Hammarby Sjöstad in Stockholm is a waterfront eco-district developed by White Arkitekter, known for its integrated approach to climate adaptation. The project combines green-blue infrastructure, energy-efficient buildings, and smart housing technologies, supported by coordinated governance and public–private collaboration. Its emphasis is on sustainable mobility, wastewater reuse, and community engagement (Figure 5).

4.1.2. Case Study 2: Kalasataman Huvilat

Kalasataman Huvilat in Helsinki is a compact waterfront housing development designed by PORTAALI Architects, offering a modular and climate-conscious response to urban densification. The project integrates elevated timber structures, private outdoor spaces, and adaptable unit layouts, supported by collaboration between municipal authorities and private developers. Its emphasis is on sustainable materials, spatial flexibility, and neighborhood-scale resilience (Figure 6).

4.1.3. Case Study 3: Urban Rigger

Urban Rigger in Copenhagen is a floating student housing prototype developed by Bjarke Ingels Group (BIG), designed to address urban housing shortages and climate resilience. The project repurposes shipping containers into modular, energy-efficient housing units that float on the city’s harbor. It combines circular construction principles, renewable energy systems, and compact living strategies, supported by public–private collaboration and innovation in marine urbanism. Its emphasis is on affordability, mobility, and low-carbon design. Specific design strategies and impact assessments are summarized in Figure 7 below.

5. Results—Evaluation of Case Studies and Impact Assessment

The comparative analysis of Hammarby Sjöstad (Stockholm), Kalasataman Huvilat (Helsinki), and Urban Rigger (Copenhagen) illustrates three distinct approaches to adaptive waterfront housing, each shaped by its local context and design philosophy. Through the application of urban and architectural design strategies, these projects address climate adaptation, spatial efficiency, and social inclusion. Their impact is evaluated across nine sustainability indicators using a unified 1–5 scale, where 5 represents transformative or model-setting impact.

Hammarby Sjöstad applies a large-scale, systems-oriented strategy to urban regeneration. Its urban design integrates green-blue infrastructure, open rainwater channels, green roofs, and pedestrian-prioritized shared spaces. Architecturally, it features energy-efficient buildings, smart home systems, and wastewater reuse for heating and cooling. Socially, it achieves moderate impact in shared public spaces (3) and high in well-being (4), but only low in housing adaptability (2), reflecting limited diversity in unit typologies. Economically, it scores low in cost-effective materials (2) and high waterfront usage (4), indicating activating the shoreline, while its replication potential is very high (5), having influenced global planning models. Environmentally, it performs very high in carbon footprint reduction (5), and usage of renewable energy (5), while moderate in land-use efficiency (3) (see Figure 8).

Kalasataman Huvilat offers a human-scaled, modular housing model embedded within Helsinki’s urban fabric. Its urban design emphasizes private outdoor spaces, elevated green zones, and shared courtyards that foster community interaction. Architecturally, it includes diverse townhouse typologies with adaptable interiors, private entrances, and roof terraces. Socially, it scores high in shared public spaces (4), and well-being (4), while moderate in housing adaptability (3) Economically, it achieves very low in recycled materials (1), moderate in replication potential (3), and in waterfront usage (3).

Environmentally, it performs very high in carbon footprint reduction (5), and in renewable energy use (5), and high in land-use efficiency (4), reflecting its compact footprint and solar-powered systems (Figure 9).

Urban Rigger introduces a radical typology for student housing through floating, prefabricated container units. Its urban design reclaims underused waterfronts and enables rapid deployment through modular tessellation. Architecturally, it incorporates solar panels, green roofs, and shared courtyards, with each unit offering private living spaces and access to communal amenities. Socially, it scores high in all three-housing adaptability (4), in shared public spaces (4), and in well-being (4), promoting affordability and community cohesion. Economically, it achieves very high in recycled materials (5), waterfront usage (5), and high replication potential (4), demonstrating spatial and financial efficiency. Environmentally, it leads with very high scores in renewable energy use (5), and land-use efficiency (5), and high in carbon footprint reduction (4), making it the most climate-adaptive model among the three (Figure 10).

Together, these projects represent a spectrum of strategic responses, systemic, intimate, and radical, that inform the development of adaptive housing frameworks for waterfront cities like Gdańsk. Their combined insights underscore the importance of aligning architectural innovation with measurable sustainability outcomes across social, economic, and environmental dimensions. This comparative framework provides a foundation for context-sensitive recommendations, design, and planning principles explored in the next chapter.

The lessons drawn from these case studies can be distilled into a set of design principles with direct relevance to Gdańsk’s waterfront redevelopment. For instance, Hammarby Sjöstad demonstrates the value of systemic planning and green-blue infrastructure, which can be adapted to Gdańsk’s flood-prone districts through integrated stormwater management and multifunctional public spaces. In addition, Kalasataman Huvilat emphasizes modularity and human-scaled design, offering a model for flexible housing that supports community interaction and environmental performance. Moreover, Urban Rigger introduces a radical typology of floating, prefabricated units that activate underused waterfronts while minimizing land consumption and carbon footprint. Together, these strategies form a composite framework for adaptive housing that is spatially efficient, socially inclusive, and environmentally responsive.

6. Results—Urban Planning and Architectural Guidelines

The increasing urgency of climate adaptation in urban environments has elevated the role of housing as both a spatial and social instrument for resilience. International frameworks such as the UN Sustainable Development Goals, the EU Strategy on Adaptation to Climate Change, and the New European Bauhaus initiative advocate for inclusive, flexible, and environmentally responsive urban development. Within the Baltic Sea Region, transnational strategies like EUSBSR offer municipalities guidance for embedding climate resilience into spatial planning. Yet despite this policy momentum, housing projects at the local level, particularly in cities like Gdańsk, often remain disconnected from innovative approaches recommended in spatial design practice.

Gdańsk’s waterfront districts face compounded risks from riverine, pluvial, and coastal flooding, exacerbated by rising impervious surfaces and urban densification. The city’s hydrological stress, documented through increasing runoff coefficients and flood frequency, underscores the need for integrated, climate-adaptive housing strategies. However, local planning instruments rarely accommodate alternative residential typologies such as modular, floating, or amphibious housing despite their relevance to flood-prone urban contexts. This gap between strategic ambition and spatial implementation reveals a critical need for evidence-based design guidance tailored to Gdańsk’s unique socio-environmental conditions.

Translating the lessons from the three evaluated case studies into planning and architectural guidelines for Gdańsk requires a context-sensitive approach. The proposed recommendations are designed to operate across two interlinked scales:

6.1. Urban Design-Level Guidelines

• Green-Blue Infrastructure Integration: Inspired by Hammarby Sjöstad, Gdańsk should embed bioswales, retention ponds, and permeable surfaces into its waterfront public realm to mitigate flood risk and enhance ecological resilience.
• Flexible Zoning and Mixed-Use Planning: Adaptive housing requires zoning reforms that allow hybrid typologies and encourage density through mixed-use developments.
• Floating and Amphibious Districts: Drawing from Urban Rigger, Gdańsk can designate zones for floating housing clusters, particularly in low-lying or underutilized waterfronts, supported by modular docks and water-based mobility.
• Public Space as Climate Buffer: Waterfront parks, elevated boardwalks, and floodable plazas should be designed to absorb excess water while remaining accessible and safe, reinforcing both resilience and community engagement

6.2. Architectural-Level Guidelines

• Modular and Prefabricated Construction: Inspired by Kalasataman Huvilat and Urban Rigger, modular housing allows rapid deployment, cost efficiency, and flexibility. Units can be stacked, clustered, or floated depending on site conditions.
• Elevated and Amphibious Foundations: Buildings should be designed with raised plinths, stilts, or buoyant bases to adapt to fluctuating water levels, especially near the Motława River and Dead Vistula.
• Passive Design and Renewable Integration: Orientation, insulation, and ventilation strategies should be optimized for energy efficiency. Solar panels, heat pumps, and rainwater harvesting systems can be integrated into building envelopes.
• Shared Amenities and Co-Housing Models: Architectural layouts should support communal kitchens, workshops, and greenhouses to foster social resilience and reduce resource consumption.

However, several barriers may hinder the implementation of adaptive housing solutions in Gdańsk. Institutional fragmentation, rigid zoning regulations, and limited financial mechanisms often constrain innovation. Local planning instruments rarely accommodate alternative typologies, and there is a lack of technical capacity to evaluate and monitor climate-adaptive designs. Moreover, public skepticism toward unconventional housing models—such as floating or cooperative units—can slow adoption. These challenges are not unique to Gdańsk but reflect broader structural limitations in municipal governance across the Baltic Sea Region.

Considering the local spatial conditions, a selection of potential building sites or districts was made that meet the criteria established in the research. Potential sites were selected based on a high degree of flood risk and the basis of expert knowledge.

7. Solutions Validations

In order to test planning and architectural guidelines, we identified potential locations in Gdańsk for the development of residential estates and other forms of building structures. The assessment was informed by a multidisciplinary perspective that considered climate risks, ecological conditions, infrastructure accessibility, and the relationship of new interventions to the historical and cultural urban fabric.

As a result of this analysis, four potential locations were selected, each characterized by specific spatial, environmental, and cultural conditions:

• Post-industrial area on Wyspa Portowa: A zone currently undergoing revitalization, shaped by the legacy of industrial functions. Its limited accessibility to waterways, due to the dominance of port infrastructure, poses challenges for integration with public waterfront spaces (but no possibility of amphibious housing due to the importance of port waterway connection), yet it offers opportunities for adaptive reuse of industrial landscapes.
• Old Town—“Na Stępce Canal”: A location embedded within the historic urban fabric, where proximity to water and heritage assets creates conditions for sensitive interventions. The site provides potential for enhancing waterfront accessibility and reinforcing the cultural identity of Gdańsk through carefully scaled residential amphibious developments and limited or impossible mixed-use developments.
• Olszynka and Orunia districts: Situated in a polder landscape, these areas are closely tied to Gdańsk’s hydraulic heritage. Their specific hydrological conditions require flood-resilient planning strategies and climate-adaptive architecture. At the same time, the presence of open green spaces offers a rare potential for sustainable, low-density development integrated with nature-based solutions.
• The area of the historical shipyard “Młode Miasto”: A strategic zone of industrial heritage, symbolically connected to the city’s modern history. Its transformation into a mixed-use urban quarter represents both an opportunity to preserve and reinterpret cultural identity and a challenge to balance large-scale redevelopment with climate adaptation measures, particularly in relation to water management and urban resilience.

Particular attention was given to the capacity of these areas to respond to climate change and to remain adaptable over time. The identified sites were evaluated not only for their immediate suitability but also for their long-term resilience to sea level rise, extreme weather events, and other climate-related pressures.

The comparative assessment of the four proposed locations in Gdańsk demonstrates differentiated potential for the implementation of climate-responsive urban and architectural strategies (see Figure 9). The evaluation, based on the criteria of high applicability (+), limited applicability under specific conditions with legislative or functional barriers (+/−), and non-applicability (−), highlights both the opportunities and constraints of each site.The selected areas—historical shipyard “Młode Miasto” in Gdańsk, Wyspa Portowa, Olszynka, and Orunia districts are flood-prone areas. The maximum water level in the PL-EVRF2007-NH Amsterdam system, representing the water surface level once in 100 years, is crucial for understanding the flood risk in the area. The data suggests that the highest water levels are along the Radunia Canal (9.18–9.63 m) and from the sea side (1.97 m).

Figure 11 provides insights into the potential adaptability for flexible housing in these regions, considering various factors such as infrastructure, housing, services, and urban design guidelines. The geoportal and hydro-portal data highlights the following functions: water level data which provides critical information on the maximum water level in the area, essential for understanding flood risks, infrastructure and housing data which offers insights into the existing infrastructure and housing, which can inform adaptability strategies, and services and amenities data which helps identify the availability of services and amenities in the area, influencing the potential for sustainable and resilient housing.

Integration of green-blue infrastructure is a positive factor for all locations, as it can help manage flood risks and improve the urban environment. Flexible zoning and mixed use-planning have a mixed potential, with some locations showing a positive or neutral outlook. Floating and amphibious districts have a positive potential for most areas, especially along the waterways. Public space as a climate buffer is a positive factor for all locations, as it can help mitigate the effects of climate change and improve urban resilience. Modular and prefabricated construction have a mixed potential, with some locations showing a positive or neutral outlook. Elevated and amphibious foundations are a positive factor for all locations, as they can help protect buildings from floods. Passive design and renewable energy integration have a positive potential for all locations, contributing to sustainable and resilient housing. Shared amenities and co-housing models have a mixed potential, with some locations showing a positive or neutral outlook.

The historical shipyard “Młode Miasto” in Gdańsk, including the Olszynka and Orunia districts, presents a unique opportunity for flexible housing in flood-prone areas. The potential adaptability is generally positive, with several factors supporting the implementation of resilient and sustainable housing solutions. However, some challenges remain, particularly in terms of mixed-use planning and modular construction. To maximize the potential for flexible housing, it is essential to integrate green-blue infrastructure, elevated and amphibious foundations, and passive design with renewable energy integration. Additionally, shared amenities and co-housing models can help foster community resilience in the face of flood risks.

From the perspective of urban design guidelines, all four locations show high potential for the integration of green–blue infrastructure, underscoring the relevance of ecological connectivity across Gdańsk’s diverse urban and post-industrial landscapes. Similarly, public spaces functioning as climate buffers can be effectively introduced in most sites, with the exception of the Old Town canal area, where spatial and heritage constraints significantly limit such interventions (longer administrative procedures). Flexible zoning and mixed-use planning are feasible in most cases, but face notable restrictions in the Old Town, where historical and regulatory frameworks impose limitations. The concept of floating and amphibious districts demonstrates selective feasibility: it is most promising in the polder areas of Olszynka and Orunia as well as in the Old Town waterfront, whereas in Wyspa Portowa, the dominance of port infrastructure precludes such solutions.

Regarding architectural guidelines, the analysis indicates broad potential for the application of passive design principles, renewable energy integration, shared amenities, and co-housing models across all locations, demonstrating their universal relevance. Modular and prefabricated construction is highly applicable in most sites, though in the Old Town, it remains only partially feasible due to heritage protection and morphological constraints. The use of elevated and amphibious foundations is particularly suited to polder landscapes (Olszynka and Orunia) and waterfront areas but requires contextual adjustments in “Młode Miasto” and may be incompatible with parts of Wyspa Portowa’s industrial terrain.

Overall, the findings reveal that the Olszynka and Orunia polder districts and the Młode Miasto shipyard area present the broadest spectrum of applicability for climate-adaptive urban and architectural measures. The Old Town waterfront offers unique opportunities but is constrained by regulatory and heritage-related barriers, while the Wyspa Portowa area remains the most challenging due to its industrial and infrastructural specificity. This differentiated potential illustrates the necessity of tailoring resilience strategies to the spatial, cultural, and functional context of each location in order to achieve sustainable and adaptive urban development in Gdańsk.

8. Discussion and Conclusions

8.1. Theoretical Implication

This research contributes to the broader discourse on climate-resilient urban housing by linking adaptive housing design with climate-responsive urbanism in the Baltic Sea context. It expands the current understanding of resilience by translating conceptual frameworks into spatial and architectural strategies, such as modularity, elevation, and amphibious housing typologies. The study highlights housing as both a physical and social infrastructure that supports adaptation and community well-being. It also bridges global adaptation theories with localized evidence from Gdańsk, illustrating how resilience principles can be grounded in specific ecological and cultural conditions. By doing so, it provides a theoretical framework that connects sustainability, resilience, and urban housing adaptability, reinforcing the importance of integrating physical design with social and environmental systems

8.2. Practical Implication

Addressing the challenges of climate-resilient urban housing in Gdańsk requires integrated policies that align strategic ambition with spatial practice. Zoning and land-use regulations must accommodate elevated, modular, and amphibious housing typologies, particularly in flood-prone areas, while financial incentives such as subsidies, tax breaks, and public–private partnerships can encourage experimentation with adaptive housing models and reduce the economic risks associated with innovation. Building institutional capacity is equally critical and can be achieved through targeted training programs, design competitions, and pilot projects that cultivate local expertise and confidence in implementing climate-resilient solutions. Participatory planning should be prioritized, ensuring that residents are actively engaged in co-designing resilient housing strategies, which fosters public acceptance and strengthens long-term stewardship and community ownership of adaptive urban transformation. The proposed framework thus illustrates how theoretical resilience principles, flexibility, adaptability, and inclusiveness, can be operationalized in real-world planning and design processes, providing actionable guidance for urban planners, architects, and policymakers.

8.3. Conclusions

The recommendations developed through this research are not universal prescriptions but serve as guidelines for context-sensitive design decision-making. They represent the closest alignment between theory and practice based on comparative evidence, yet their successful application depends on careful adaptation to Gdańsk’s ecological, historical, and social conditions. Flexibility, community engagement, and spatial nuance are essential to ensure that adaptive housing strategies not only respond to climate pressures but also reinforce local identity, equity, and social cohesion.

The comparative analysis of Hammarby Sjöstad, Kalasataman Huvilat, and Urban Rigger revealed measurable differences in sustainability performance. Across nine indicators, evaluated on a scale of 1–5, the findings showed that:

• In the environmental dimension, Hammarby Sjöstad and Kalasataman Huvilat both achieved 5/5 for carbon footprint reduction and renewable energy integration, while Urban Rigger scored 4/5 and 5/5, respectively, with an additional 5/5 for land-use efficiency.
• For the social dimension, the projects achieved 3–4/5 in public space quality and 4/5 in user well-being, while adaptability ranged from 2/5 in Hammarby Sjöstad to 4/5 in Urban Rigger.
• Under the economic dimension, the use of recycled materials varied between 1/5 in Kalasataman Huvilat and 5/5 in Urban Rigger. Replication potential was highest in Hammarby Sjöstad (5/5) and Urban Rigger (4/5), confirming their strong scalability potential.

These findings indicate that Urban Rigger performs best in terms of climate adaptability and material circularity, Hammarby Sjöstad demonstrates excellence in integrated environmental systems, and Kalasataman Huvilat provides a refined model for modular and human-scaled living. Together, these examples outline a spectrum of adaptive housing approaches, systemic, localized, and experimental that can inform the sustainable redevelopment of Gdańsk’s waterfront.

Importantly, the principles underlying this framework are transferable to some extent to other geographic contexts, including deltaic urban environments. While local conditions, such as climate, urban form, and socioeconomic structures, require a tailored approach, the framework offers a systematic method to address water sensitivity, flexible housing, and inclusive urban development in diverse settings.

The guidelines tested through the Gdańsk case study also exhibit broader applicability across urban contexts facing similar challenges, demonstrating how local solutions can inform regional and global adaptation strategies.

Polish spatial policies, building permit processes, and legal restrictions on building in flood-prone areas can pose significant challenges to the implementation of flexible housing solutions in areas such as the historical shipyard “Młode Miasto” and Wyspa Portowa in Gdańsk. Current spatial policies in Poland do not specifically address flood-resilient housing, limiting the development of flexible housing in flood-prone areas. Rigid zoning laws may restrict mixed-use planning and flexible zoning, hindering sustainable and resilient housing. The absence of financial incentives for innovative solutions, such as floating and amphibious districts, can deter investment. The lengthy and complex process of obtaining building permits can slow down the implementation of flexible housing solutions, especially in flood-prone areas requiring specialized designs and infrastructure. Strict building codes may impose additional challenges for innovative solutions. This prolonged process can lead to a significant decrease in the profitability of such ventures in Poland.

Legal restrictions on building in flood-prone areas can significantly limit the potential for flexible housing solutions, deterring developers from investing in high-risk zones. The need for costly flood defenses, elevated foundations, or amphibious designs can make housing in flood-prone areas economically unfeasible. To overcome these obstacles, updating spatial policies to prioritize flood-resilient and sustainable housing, simplifying building permit procedures, and introducing financial incentives for innovative solutions are essential. Reevaluating strict legal restrictions on building in flood-prone areas may be necessary to balance resilience with economic feasibility.

Although grounded in Gdańsk’s specific physical, ecological, social, and historical conditions, the underlying principles of the model are inherently adaptable to varied local circumstances. This adaptability enhances the framework’s relevance for cities addressing water sensitivity, flexible housing needs, and inclusive, resilient urban development. Ultimately, the research contributes to the growing discourse on climate-resilient urbanism by offering a practical, context-aware framework that bridges policy ambition and spatial reality, providing planners, architects, and decision-makers with tools to navigate the complexities of housing in a changing climate.

The study also highlights the need for future research through long-term fieldwork and stakeholder participation to further refine adaptive housing strategies and evaluate their social and environmental impacts. Incorporating field studies and conducting in-depth interviews with key stakeholders, such as policymakers and project designers, could represent the next step, adding further value to the study. Another direction for future research that could enrich the discourse on this topic is the multilevel analysis of policies supporting climate-adaptive and flexible housing, spanning from the global to the local level.