TOPSIS and AHP-Based Multi-Criteria Decision-Making Approach for Evaluating Redevelopment in Old Residential Projects

Abstract

This research aims to identify and prioritize key planning elements for the redevelopment of such housing complexes by incorporating perspectives from both experts (supply-side) and residents (demand-side). To achieve this, a hybrid multi-criteria decision-making framework was developed by integrating the Analytic Hierarchy Process (AHP) and the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS). A total of 25 planning elements were identified through Focus Group Interviews and organized into five domains: legal and institutional reforms, project feasibility, residential conditions, social integration, and complex design. The AHP was used to assess the relative importance of each element based on responses from 30 experts and 130 residents. The analysis revealed a clear divergence in priorities: experts emphasized feasibility and regulatory considerations, while residents prioritized livability and spatial quality. Subsequently, the TOPSIS method was applied to evaluate four real-world redevelopment cases. From the supply-side perspective, Seoul A District received the highest score (0.58), whereas from the demand-side perspective, Gyeonggi D District ranked highest (0.69), illustrating the differing priorities of stakeholders. Overall, Gyeonggi D District emerged as the most favorable option in the combined evaluation. This research contributes a structured and inclusive decision-making framework for the regeneration of public housing. By explicitly comparing and quantifying the contrasting preferences of key stakeholders, it underscores the critical need to balance technical feasibility with resident-centered values in future redevelopment initiatives.

1. Introduction

The redevelopment of aging residential buildings has emerged as a critical global issue due to its implications for public health, safety, and urban livability. In South Korea, research has demonstrated that building deterioration is associated with rising medical expenses and structural or functional decline, particularly among low-income populations [1,2,3]. In China, redevelopment is emphasized as a strategy to alleviate urban overcrowding and improve spatial efficiency [4,5]. According to the Ministry of Land, Infrastructure, and Transport (MOLIT), as of 2003, there were approximately 1.775 million units of public rental housing in South Korea, accounting for 54% of the total rental housing stock. Among these, 75,000 units were over 30 years old. The aging of these structures has contributed to the slumification of residential areas and has led to increased maintenance costs [6]. The 2024 Housing Survey by MOLIT reported that 24.3% of residents living in aging buildings expressed dissatisfaction with their housing conditions. High dissatisfaction rates were noted in areas directly related to safety, including indoor noise (73.8%), structural integrity (58.7%), crime prevention (57.7%), waterproofing (57.0%), and fire safety (52.7%). These concerns, coupled with issues raised in previous research, underscore the urgent need for effective redevelopment strategies targeting old public rental housing.

Various approaches can be adopted depending on location and population density. In large urban centers with high housing demand, redevelopment through demolition and new construction is often a viable solution [2,6]. This approach allows for the optimization of the remaining floor area ratio to meet local housing needs, particularly in land-constrained environments. Additionally, construction costs can be partially offset through the development and sale of market-rate housing units [7,8,9,10]. Given the involvement of public funding, redevelopment initiatives must strike a balance between business feasibility and public interest. This necessitates planning strategies that differ from those in the private sector. Public redevelopment efforts must incorporate residents’ rights to adequate housing and reflect not only expert evaluations but also residents’ lived experiences and perspectives [11]. Identifying and prioritizing redevelopment elements is essential due to the multifaceted nature of the issue, which encompasses legal, institutional, economic, and social dimensions. Internationally, research employing the Analytic Network Process (ANP) in urban redevelopment in South India has highlighted the importance of quality of life and economic considerations from a socio-technical perspective [12]. However, prior studies have generally failed to sufficiently account for publicness or to systematically compare the differing priorities of experts and residents.

To address these gaps, the present research proposes a comprehensive decision-making framework that integrates the AHP and TOPSIS. The objective is to identify and prioritize planning elements for the redevelopment of old public rental housing, incorporating both supply-side (expert) and demand-side (resident) perspectives. By applying this hybrid multi-criteria decision-making (MCDM) approach to real-world cases, the research aims to offer a more balanced, inclusive, and sustainable strategy for public housing redevelopment. The structure of this research is organized as follows: First, a review of the necessity of redevelopment and existing research on old public rental housing is presented. Second, the methodology for deriving planning elements and conducting surveys with experts and residents is described. Third, AHP is used to analyze the relative importance of the planning elements, followed by TOPSIS-based evaluation of selected real-world redevelopment cases. Finally, strategic planning directions are proposed based on the results of the integrated analysis.

2. Literature Review

2.1. Challenges in Redeveloping Old Residential Buildings

The redevelopment of aging public housing has garnered increasing attention in recent years due to escalating concerns related to safety, deteriorating living conditions, and insufficient public services. For instance, Liang et al. [2] investigated old housing complexes in China, emphasizing the need for refurbishment to enhance physical safety and improve resident satisfaction. However, the research primarily relied on resident surveys and lacked a structured framework for prioritizing planning elements, thereby limiting its capacity to evaluate the relative importance of contributing factors. Linn Liu [13] proposed a more systematic approach by analyzing renovation cases using structured indicators to assess outcomes. While offering broader analytical scope, the research did not differentiate between stakeholder groups—such as experts and residents—thereby reducing its applicability to participatory planning processes. Similarly, Tajima [14], in research conducted in Japan, categorized the causes of housing deterioration into five dimensions: social, structural, technical, legal, and economic. Although this classification yields valuable insights, the analysis was largely based on expert interviews and literature review, lacking quantitative validation and consistency checks. Collectively, these studies provide important perspectives on the multifaceted challenges associated with deteriorating residential environments. However, most of the existing literature tends to emphasize either qualitative interpretations or technical assessments, without implementing an integrated, data-driven approach to prioritize refurbishment strategies. Consequently, there is a need for a more comprehensive and objective decision-making framework—one that incorporates inputs from both experts and residents through the use of structured, multi-criteria decision-making tools.

2.2. Review and Case Analyses on Redevelopment of Old Residential Building

Numerous studies have explored the redevelopment of aging residential buildings through various evaluation methodologies; however, each exhibits limitations in terms of stakeholder inclusion, methodological consistency, or analytical scope. Yang et al. [15] adopted AHP in conjunction with Grey Clustering to evaluate redevelopment strategies in Harbin, China, with a focus on safety, comfort, environmental conditions, and social benefits. While the approach employed a structured evaluation framework, the selection of indicators lacked sufficient justification, and the research relied solely on resident surveys. Ferreira et al. [16] conducted an analysis of refurbishment projects in Lisbon using Life Cycle Assessment (LCA) and Life Cycle Cost (LCC) methodologies. Although their research identified critical cost drivers—such as steel reinforcement—the research failed to incorporate social considerations or stakeholder-specific evaluations, limiting its comprehensiveness. Bogdanović and Mitković [17] proposed a set of planning strategies aimed at improving residential environments in Serbia, with an emphasis on regulatory reform, community participation, and land reallocation. Also, Chung and Jeon [18] analyzed about Changwon city redevelopment. However, the qualitative nature of their analysis hindered objective prioritization of strategies. Ogunnusi et al. [19] employed a TOPSIS-based framework to evaluate redevelopment alternatives in Nigeria. Although their research identified refurbishment as the most sustainable option, it lacked practical implementation pathways and did not incorporate the perspectives of residents. Battisti et al. [20] examined urban regeneration in a suburban district of Rome, focusing on enhancements to the physical environment and the introduction of social programs, as assessed through resident surveys. Nonetheless, the absence of expert input undermined the technical rigor and generalizability of the findings. Letelay et al. [21] utilized the TOPSIS to assess redevelopment options in Indonesia based on six criteria, including economic feasibility and social benefits. However, these criteria were derived solely from case characteristics, without input from a broader range of stakeholders.

Table 1. Literature review table.

Authors	Objective	Research Method	Evaluation/Research Item					Research/Survey Participants
			I1	I2	I3	I4	I5
Liang Yamei et al. [2]	Propose refurbishment strategies Analyze refurbishment in Hangzhou	Case study in Hangzhou/survey to resident/Interview by expert	O	O	O			Survey—Resident Interview—Expert
Noriyuki Tajima [14]	Propose refurbishment strategies Analyze refurbishment in Japan	Case study in Japan/interview by expert	O	O	O		O	Expert
Yuanhui Yang et al. [15]	Evaluation of refurbishment in Harbin	Case study in Harbin/AHP-grey clustering method	O		O	O	O	Expert
Azarii Lapidus et al. [8]	Evaluation of refurbishment	Case study/comparing real cases’ factors			O	O	O	-
J.Ferrerira et al. [16]	Evaluation of refurbishment in Lisbon	Case study/comparing real cases’ factors				O	O	-
Chung Sam-Seok and Jeon Wan-Min [18]	Analyze refurbishment in Changwon	Case stud in Changwon/AHP method by experts		O	O			Expert
Ivana Bogdanovis and Petar Mitkovic [17]	Propose refurbishment strategies Analyze refurbishment in Nis	Case study in Nis/survey by residents		O	O		O	Resident
Mercy Ogunnusi et al. [19]	Propose refurbishment strategies Evaluation of refurbishment	Case study in Nigeria/survey/TOPSIS method	O		O		O	Resident
Linn Liu [13]	Propose refurbishment strategies	Case study in Sweden/survey/Comparing each cities’ refurbishment	O		O	O	O	Resident
Alessandra Battisti et al. [20]	Propose refurbishment strategies	Case study in Rome/survey by residents			O	O		Resident
Milica Zivkovic et al. [7]	Propose refurbishment strategies	Case study in Serbia/interview by experts	O	O	O		O	Expert
Kornelis Letelay et al. [21]	Propose refurbishment strategies Evaluation of refurbishment	Case study in Indonesia/TOPSIS by 6 factors/interview by experts			O	O	O	Expert

Note: I1—Structure, I2—Law, I3—Sociality, I4—Environment, I5—Economic.

summarizes these case studies, highlighting the varied methodologies employed, the stakeholder groups involved, and the principal findings. While fuzzy MCDM techniques are effective for managing ambiguity and linguistic uncertainty, the current research context involved clearly defined criteria and well-informed expert participation. As such, the AHP was deemed sufficient to ensure clarity, transparency, and consistency in the evaluation process. Despite the diverse approaches observed in the literature, most existing studies lack integrated decision-making frameworks that holistically balance technical, economic, and social considerations across multiple stakeholder groups. In particular, many investigations consider only a single stakeholder perspective—either expert or resident—without systematically integrating both of them. To address these shortcomings, the present research proposes a hybrid decision-making framework that incorporates and balances the perspectives of both experts and residents in a structured and quantifiable approach.

3. Research Methodology

3.1. FGI Process

To develop the evaluation framework, this research employed FGIs to identify key planning elements for the redevelopment of aging public rental housing. FGI is a qualitative research method that elicits expert insights through structured group discussions centered on a specific topic. In this research, the FGIs were conducted with selected professionals from the public, private, and academic sectors, all of whom possessed substantial experiences in the field of urban regeneration and planning. Through systematic interviews, a total of 25 planning elements were identified and subsequently categorized into five overarching domains. These elements formed the basis for the AHP used to determine relative weights and for the TOPSIS applied in the evaluation of redevelopment alternatives. Detailed findings and insights from the FGI process are presented in Section 4 and total research framework is shown at Appendix A Figure A1.

3.2. AHP Process

The AHP is a structured multi-criteria decision-making method that quantifies subjective judgments through pairwise comparisons within a hierarchical framework [22,23,24,25]. Typically, the AHP involves decomposing the decision problem into a hierarchical structure consisting of a goal, criteria, and sub-criteria. Judgments are collected using pairwise comparisons based on a 1–9 scale, relative weights are calculated using eigenvalue methods, and the internal consistency of responses is assessed through the consistency ratio (CR) [26,27]. In this research, AHP was chosen due to the clearly defined hierarchical structure of the decision problem. The AHP method is particularly effective in disaggregating complex decision-making processes into a goal–criteria–alternatives framework, facilitating systematic pairwise comparisons and the quantification of expert judgments. The use of the CR further enhances the reliability and transparency of the evaluation by verifying the internal consistency of responses. While ANP is suitable for modeling interdependencies among criteria, its use was deemed unnecessary given the clearly structured and independent hierarchical design of this research. Similarly, alternative methods such as ELECTRE and VIKOR emphasize elimination or compromise solutions rather than generating a definitive ranking of alternatives, rendering them less appropriate for the research objectives. Accordingly, the AHP was selected as the most suitable methodology to ensure clarity, validity, and interpretability of the assessment outcomes. In this research, AHP was employed to determine the relative importance of the 25 planning elements identified through the FGIs. These elements were organized into a three-level hierarchical structure. Two respondent groups—30 experts and 130 residents—were surveyed using Saaty’s 1–9 scale to perform pairwise comparisons of the planning elements. Individual responses were aggregated using the geometric mean method to generate group-level comparison matrices. Weights were computed by normalizing each matrix and deriving the principal eigenvector. The consistency of responses was assessed by calculating the CR, and any pairwise judgment sets with CR values exceeding 0.1 were excluded from further analysis to ensure the reliability of the results. This approach guaranteed the internal validity of both expert and resident input. The resulting weights for each planning element, as perceived separately by experts and residents, were subsequently used as input parameters for the TOPSIS analysis to evaluate and rank redevelopment alternatives. The general AHP process is shown in Figure 1 and detailed process that describes this research AHP process is shown in Appendix A Figure A2.

3.3. TOPSIS Process

The TOPSIS is a well-established MCDM method used to rank alternatives based on their relative closeness to an ideal solution [28]. As shown in Figure 2, the general procedure of the TOPSIS consists of the following steps: (1) constructing and normalizing a decision matrix, (2) applying criterion weights to obtain a weighted normalized matrix, (3) identifying the ideal and negative-ideal solutions, and (4) calculating the relative closeness of each alternative to the ideal solution. The ideal solution represents the best attainable performance for each criterion across all alternatives, whereas the negative-ideal solution corresponds to the worst [29]. Alternatives that are closer to the ideal solution and farther from the negative-ideal solution are assigned higher rankings [30]. In this research, the TOPSIS method was employed to evaluate four real-world redevelopment alternatives, using the weighted values of 25 planning elements obtained from the AHP analysis. The evaluation was conducted separately for the expert (supply-side) and resident (demand-side) groups, based on the same set of criteria weights. For each alternative, a normalized decision matrix was constructed using actual performance data across the five planning domains. The weighted normalized matrix was subsequently used to calculate the Euclidean distances to both the ideal and negative-ideal solutions. The relative closeness index was then computed for each alternative to determine its ranking. TOPSIS scores were generated for the expert and resident groups, thereby enabling a comparative analysis of differing stakeholder preferences. To obtain an overall evaluation, a final integrated ranking was derived by averaging the normalized closeness values from both perspectives. The detailed process is shown at Appendix A Figure A3.

4. Framework

4.1. Case of Redevelopment Analysis

To validate the applicability of the proposed evaluation framework, four real-world redevelopment cases were analyzed based on their relevance to the regeneration of aging public rental housing. The selected cases exhibit characteristics similar to public rental housing redevelopment, particularly in terms of public sector-led development schemes and deteriorated physical conditions.

Table 2. Summary of case analysis.

District	Type	Publicness Orientation	Reason for Selection	Key Planning Elements
Seoul A	Urban Public Housing	High	Similar redevelopment procedure to public rental housing; located in deteriorated low-rise area	High FAR (599%), social mix, mixed-use zoning, community facilities
Seoul B	Urban Public Housing	High	Same designation as Seoul A; located in deteriorated residential zone	FAR (299%), donation for public use, mixed housing
Seoul C	Public Redevelopment	Medium	Buildings > 30 years old; designated for urban renewal	Small site area, low-rise district, public regeneration project
Gyeonggi D	Public Sale Housing	High	Designed as a social-mix housing complex with superior planning	70% sale/30% rental mix, advanced community programs

presents a comparative summary of the case projects, highlighting the key selection criteria and major planning attributes. The categorization of planning elements was structured to align with the key phases of the redevelopment process—from project initiation to design and approval—based on insights gathered from FGI participants. The total research main frame work is shown in Appendix A Figure A1.

4.2. Derivation of Factors Using FGI

To identify the key planning elements for the redevelopment of old public rental housing, this research began with a comprehensive review of prior research, urban planning theories, and relevant domestic and international case studies with experts in the construction field as shown in

Table 3. FGI participants information.

Classification	Position	Career	Classification	Position	Career
Expert 1	Professor	20 years	Expert 5	Head director	20 years
Expert 2	Professor	20 years	Expert 6	Managing director	15 years
Expert 3	PhD	15 years	Expert 7	Director	15 years
Expert 4	PhD	10 years	Expert 8	Director	10 years

. From this preliminary investigation, twelve initial elements were derived, with a focus on sustainability, community revitalization, and institutional improvement. To further refine and categorize these elements, FGIs—a structured qualitative method used to elicit in-depth insights from experts—were conducted with professionals from both the public and private sectors, as illustrated in Figure 3. Through this process, five major planning categories were identified:

• Legal and institutional reforms (A);
• Securing project feasibility (B);
• Provision of residential conditions (C);
• Social integration planning (D);
• Design of residential complexes (E).

Each of the five major categories was further subdivided into five specific planning elements, resulting in a total of 25 elements, as presented in

Table 4. Derivation of planning elements for setting the refurbishment planning direction of residential complexes.

Planning Category	Planning Elements
A. Legal and institutional reforms	A1. Simplify procedure as zoning approvals
	A2. Shorten project ownership periods
	A3. Institutionalize project execution processes
	A4. Include residents in decision-making processes
	A5. Secure approval from central government
B. Securing project feasibility	B1. Governmental support for funding and financing
	B2. Maximize land use and utilization
	B3. Securing funds through the additional construction of commercial facilities in for-sale housing developments
	B4. Exceptions for sales restrictions
	B5. Relax conditions for contributions-infrastructure funding
C. Provision of residential conditions	C1. Securing rental housing inventory for temporary accommodation of original residents
	C2. Providing housing cost subsidies for temporary accommodation of original residents
	C3. Convenience of public transportation
	C4. Activation of surrounding facilities
	C5. Job creation
D. Social integration planning	D1. Participation of tenant representative meetings in decision
	D2. Specialization of building façade planning
	D3. Mixed placement of sale and rental housing
	D4. Integration of local residents
	D5. Activation of community facilities for residents
E. Design of residential complexes	E1. Vehicular and pedestrian accessibility with surrounding areas
	E2. Expansion of unit size for rental housing
	E3. Excellence in unit floor plan layout and finishing materials
	E4. Planning for long-lasting and adaptable buildings
	E5. Environmentally friendly housing

.

4.3. Determining Defect Importance Using AHP Analysis

To evaluate the importance of planning directions for the redevelopment of aging public rental housing complexes, surveys were conducted targeting both the supply side and the demand side. The objective was to assess the perceived significance of five major planning categories (macro-level) and 25 specific planning elements (micro-level). For the expert group, pairwise comparisons were conducted for each category and element, and their relative importance was derived using the AHP. In contrast, the general public survey employed a sample mean analysis to evaluate the perceived importance of each planning category and element from the resident perspective. The detailed AHP process is shown in Appendix A Figure A2.

4.3.1. Importance Analysis from the Supply-Side (Expert Perspective)

The expert survey was conducted online with 115 professionals working in relevant fields, and detailed respondent information is provided in

Table 5. Affiliation of survey respondents.

Total	Government Officials	Public Enterprises	Universities	Research Institutes	Private Companies	Others
115	3	82	3	3	22	2
100%	2.6%	71.3%	2.6%	2.6%	19.1%	1.8%

and

Table 6. Experience of survey respondents.

Total	More Than 15 years	10~15 Years	5~10 Years	Under 5 Years
115	101	9	2	3
100%	87.8%	7.8%	1.8%	2.6%

. In Category A (legal and institutional reforms), item A₁ was ranked the most important, while A₅ was ranked the least. This indicates that elements such as the relaxation of floor area ratio (FAR) regulations along with the reduction of redevelopment timelines and the securing of resident consent, are viewed as critical procedural requirements. These priorities reflect a supply-side perspective that emphasizes the importance of project implementation and procedural efficiency. In Category B (securing project feasibility), B₁ was identified as the most important, and B₄ as the least. The high ranking of government financial and funding support underscores the perceived necessity of public investment to cover costs associated with demolition and reconstruction. Maximizing the FAR is also considered vital to increasing the urban housing supply and ensuring overall project viability. Furthermore, in Category C (provision of residential conditions), C₁ was regarded as the most important element, while C₅ ranked lowest. The importance of securing temporary housing for displaced residents emerged as a top priority, with relocation compensation also recognized as a key consideration. When selecting sites, factors such as proximity to public transportation, the presence of active surrounding facilities, and the potential for job-linked development were deemed particularly significant. In Category D (social integration planning), D₁ was ranked highest, and D₂ lowest. The prioritization of incorporating the opinions of current public rental housing residents indicates that fostering tenant cooperation throughout the redevelopment process is considered essential for achieving effective social integration. In Category E (design of residential complexes), E₂ was identified as the most important element, while E₅ was rated the least important. The expansion of unit sizes in rental housing was highlighted as a top design priority. A detailed breakdown of these results is presented in Figure 4 below.

4.3.2. Importance Analysis from the Demand-Side (Resident Perspective)

The general public survey assessed the perceived importance of planning categories and elements using a simple 5-point Likert scale. Given that members of the general public may lack specialized knowledge regarding residential area redevelopment, utilization of the AHP could result in inconsistent responses [31]. Therefore, a more accessible approach was adopted, in which the importance of each planning category and element was determined by calculating the sample mean of the 5-point scale responses. This method enables non-experts to provide meaningful input through intuitive judgments. The survey was administered to 169 members of the general public, with detailed respondent information presented in

Table 7. Characteristics of general survey respondents.

Category		Number of Respondents	Ratio (%)
Gender	Male	98	58.0
	Female	71	42.0
	Total	169	100.0
Age	20 s	3	1.8
	30 s	34	20.1
	40 s	68	40.2
	50 s	50	29.6
	More than 60 s	14	8.3
	Total	169	100.0
Job	Office worker	85	50.3
	Professional	14	8.3
	Labor	12	7.1
	Government employees	11	6.5
	Self-employed	19	11.2
	Student	1	0.6
	Homemaker	19	11.2
	Others	8	4.7
	Total	169	100.0

. The demand-side analysis of planning categories indicated that design of residential complexes was perceived as the most important, followed by provision of residential conditions, legal and institutional reforms, social integration planning, and securing project feasibility, in descending order of priority. Within the legal and institutional reforms category, the element “Include residents in decision-making processes” received the highest importance rating, while “Simplify procedures such as zoning approvals” and “Shorten project ownership periods” were rated lowest. In the securing project feasibility category, “Governmental support for funding and financing” was considered most important, whereas “Relaxation of conditions for contributions and infrastructure funding” ranked lowest. For the provision of residential conditions, “Providing housing cost subsidies for temporary accommodation of original residents” received the highest rating, while “Job creation” was viewed as least important. In the social integration planning category, “Integration of local residents” ranked highest, while “Participation of tenant representative meetings in decision making” was rated lowest. Finally, in the design of residential complexes category, “Vehicular and pedestrian accessibility with surrounding areas” was identified as the most important element, whereas “Planning for long-lasting and adaptable buildings” received the lowest importance score. Certain items with incomplete or invalid importance data were excluded from the final rankings. A detailed presentation of these results is provided in Figure 5 below.

4.3.3. Comprehensive Element Importance in Supply and Demand Side

In evaluating the major planning categories, experts assigned higher importance to securing project feasibility, legal and institutional reforms, and the provision of residential conditions, while placing relatively less emphasis on social integration planning and the design of residential complexes. In contrast, the general public prioritized design quality and housing conditions, assigning lower importance to integration planning and project feasibility as shown in

Table 8. Comparison of comprehensive importance in category element by supply and demand side.

Planning Category	Planning Elements	Rank		Overall Importance
		Supply	Demand	Supply	Demand
A. Legal and institutional reforms	A1	1/25	12/15	0.0848	14.4624
	A2	5/25	12/15	0.0520	14.4624
	A3	11/25	-	0.0460	-
	A4	9/25	5/15	0.0465	16.1130
	A5	14/25	-	0.0322	-
B. Securing project feasibility	B1	2/25	9/15	0.0762	14.8932
	B2	4/25	-	0.0730	-
	B3	6/25	11/15	0.0516	15.5530
	B4	10/25	-	0.0460	-
	B5	8/25	15/15	0.0481	14.3262
C. Provision of residential conditions	C1	3/25	-	0.0745	-
	C2	7/25	6/15	0.0493	15.6408
	C3	12/25	15/15	0.0391	-
	C4	16/25	-	0.0294	-
	C5	17/25	7/15	0.0281	15.5211
D. Social integration planning	D1	13/25	15/15	0.0376	13.9093
	D2	23/25	-	0.0167	-
	D3	22/25	-	0.0195	-
	D4	20/25	8/15	0.0228	14.8947
	D5	19/25	10/15	0.0231	14.8189
E. Design of residential complexes	E1	18/25	1/15	0.0240	18.2313
	E2	15/25	-	0.0316	-
	E3	21/25	2/15	0.0212	18.0589
	E4	24/25	4/15	0.0139	16.5935
	E5	25/25	3/15	0.0137	16.8952

. This divergence reflects the differing perspectives of the two groups: experts emphasize financial viability and regulatory compliance as prerequisites for project implementation, whereas the general public, as potential residents, focuses on housing quality, livability, and user-centered outcomes. The contrast in priorities is particularly evident in the ranking of specific planning elements. For example, “simplifying zoning approval procedures (A₁)” was ranked 1st by experts (0.0848) but only 12th by the general public (14.4624), indicating that while experts view regulatory streamlining as essential for project advancement and profitability, the public perceives it as potentially compromising residential quality. Similarly, “government financial support (B₁)” was ranked second by experts (0.0762) but ninth by the public (14.8932), suggesting that although experts consider it critical to funding success, the public may be more concerned with how such support impacts the quality and affordability of housing outcomes. Nonetheless, there was notable consensus between the two groups regarding the importance of securing rental housing stock and providing housing subsidies for displaced residents. Experts also emphasized operational efficiency, ranking “maximize land use and utilization (B₂)” fourth (0.0730) and “shorten project ownership periods (A₂)” fifth (0.0520). In contrast, the public ranked “Shorten project ownership period (A₂)” 12th (14.4624), possibly due to concerns that expedited timelines could lead to diminished construction quality or insufficient oversight. Conversely, the public placed significantly higher importance on design-related aspects. Elements such as vehicular and pedestrian accessibility (E₁) (first, 18.2313), unit floor plan quality (E₃) (second, 18.0589), eco-friendly housing (E₅) (third, 16.8952), and building adaptability (E₄) (fourth, 16.5935) were top priorities for the public but were ranked much lower by experts (18th–25th). This disparity does not imply a disregard for housing quality among experts, but rather reflects their prioritization of technical and financial feasibility over post-occupancy conditions. These findings underscore the need for a balanced redevelopment strategy—one that integrates financial and procedural feasibility with the lived experiences and quality-of-life expectations of residents. Bridging these stakeholder perspectives is essential to ensure both the successful implementation and sustainability of public housing redevelopment initiatives.

4.4. TOPSIS Analysis for Evaluation of Refurbishment

4.4.1. Selection of Evaluation Indicators

To incorporate residents’ perspectives into the evaluation framework, the importance rankings derived from the demand-side AHP results were considered for inclusion in the TOPSIS analysis. However, as shown in

Table 9. Evaluation indicators for TOPSIS.

Supply Side	Demand Side
Simplify procedures such as zoning approvals	Vehicular and pedestrian accessibility with surrounding areas
Governmental support for funding and financing	Excellence in unit floor plan layout and finishing materials
Maximize land use and utilization	Planning for long-lasting and adaptable buildings
Shorten project ownership periods	Governmental support for funding and financing

, the AHP results revealed a significant disparity between the priority rankings of the supply side (experts) and the demand side (residents), making it unsuitable to apply a unified set of indicators across both perspectives for the TOPSIS evaluation. To address this issue, the TOPSIS analysis was conducted separately for the supply-side and demand-side perspectives, enabling a comparative evaluation to determine the most optimal redevelopment alternative for each stakeholder group. To identify appropriate evaluation indicators, additional group interviews were conducted with domain experts. During these interviews, the top-ranking items from the respective AHP surveys were reviewed to determine suitable and mutually agreed-upon criteria for the TOPSIS evaluation. While most top-ranked elements were selected as evaluation indicators, certain items were excluded due to their non-quantifiable nature. Specifically, “Securing rental housing inventory for temporary accommodation of original residents” from the supply side and “Environmentally friendly housing” from the demand side were deemed difficult to measure objectively. As the TOPSIS requires quantifiable input data, these items were excluded during the expert group discussions. Accordingly, evaluation indicators for both the supply-side and demand-side TOPSIS analyses were selected from the remaining top-ranked, quantifiable elements. The finalized indicators for each perspective are presented below and the detailed TOPSIS process is shown in Appendix A Figure A3.

4.4.2. Selection of Evaluation Target

The evaluation targets include Seoul A District and Seoul B District from the Urban Public Housing Complex Development Project, Seoul C District from the Public Redevelopment Program, and Gyeonggi D District from the Public Sale Housing initiative. These projects were selected based on their alignment with the identified evaluation indicators, their similarity to public rental housing refurbishment cases, and their adherence to comparable project implementation processes.

(1)

Seoul A District

Seoul A District is an Urban Public Housing Complex Development Project located near Banghak Station, encompassing a total project area of 8428 m². The surrounding area primarily consists of low-rise multi-family and detached housing (four stories or fewer). The district was officially designated in December 2021. This site was selected due to its alignment with the public refurbishment process and the presence of deteriorated residential conditions, which are characteristic of old public rental housing.

(2)

Seoul B District

Seoul B District, located in Singil-dong, has been designated as a low-rise residential-type Urban Public Housing Complex Development Project. The surrounding environment predominantly comprises multi-family and detached housing with four stories or fewer. Similar to Seoul A District, it was officially designated in December 2021. This district was selected due to its procedural similarity to public refurbishment projects and the deteriorated condition of its housing stock.

(3)

Seoul C District

Seoul C District is situated in Dongdaemun-gu, where the majority of buildings are three stories or fewer, and approximately 86% of the structures are over 30 years old. The area was designated as a redevelopment zone in February 2023. The advanced age and physical deterioration of the housing stock make it a relevant case for evaluation in the context of public housing regeneration.

(4)

Gyeonggi D District

Gyeonggi D District is located in Changneung, Goyang, and was designated as a public housing district in 2020. It is planned as a social-mix housing complex, comprising 70% for-sale units and 30% rental housing. The district was selected for analysis due to its integrated approach to housing provision, which includes both rental and ownership components relevant to public housing strategies. Detailed information for all districts is presented in

Table 10. District information overview.

Information	District A	District B	District C	District D
Site area	7164 m2	46,656 m2	11,204 m2	45,272 m2
Building area	3518 m2	15,672 m2	2416 m2	9288 m2
Building coverage ratio	49.12%	33.59%	23.80%	20.50%
Total floor area	73,050 m2	219,882 m2	46,253 m2	121,901 m2
Floor area ratio	599.36%	299.89%	299.50%	161.47%
Building scale	39 floors, 122.14 m	45 floors, 127.05 m	25 floors	18 floors

.

4.4.3. TOPSIS Analysis

Based on the established evaluation criteria, a TOPSIS analysis was conducted for each of the selected districts as shown in

Table 11. Supply-side TOPSIS overview.

Normalized	District	Evaluation Indicator				Score	Rank
		A1	B1	B2	A2
0.20 0.03 0.26 0.07	Dis. A	100	10	599.36	1/60	0.58	1
0.16 0.03 0.00 0.08	Dis. B	80	10	299.89	1/50	0.2	4
0.12 0.14 0.00 0.07	Dis. C	60	50	299.5	1/60	0.29	3
0.08 0.22 0.00 0.13	Dis. D	40	80	161.47	1/30	0.42	2

. The analysis was carried out using the TOPSIS tool provided by Decision Radar, evaluating both supply-side and demand-side perspectives to generate respective scores and rankings. The evaluation utilized indicators derived from the prior AHP analysis to assess the alignment of each case with the priorities of different stakeholder groups. The results of the TOPSIS analysis provide a ranking of the redevelopment cases, where a higher score indicates a stronger alignment with the requirements and preferences of either supply-side stakeholders (e.g., experts and developers) or demand-side users (e.g., residents). Therefore, a higher-ranked case is considered a more desirable and effective example of public housing refurbishment.

(1)

Evaluation on the Supply Side

The normalized decision matrix is used to standardize data values across evaluation indicators, allowing for fair comparison by eliminating the influence of differing units of measurement. Once the data are normalized, weights derived from the AHP analysis are applied. This enables the identification of both the ideal and anti-ideal solution required for the TOPSIS evaluation. The ideal solution is a hypothetical alternative that has the best value for each evaluation criterion, while the anti-ideal solution has the worst value for each criterion. The relative closeness (Ci) of each alternative is calculated based on its distance from the ideal and negative-ideal solutions, and the final ranking is determined according to the computed Ci values. Using these reference points, each case’s score and ranking are calculated as shown in

Table 12. Demand-side TOPSIS overview.

Normalized	District	Evaluation Indicator				Score	Rank
		E1	E3	E4	B1
0.17 0.13 0.09 0.02	Dis. A	100	50	20	10	0.31	3
0.15 0.13 0.09 0.02	Dis. B	90	50	20	10	0.27	4
0.12 0.13 0.09 0.12	Dis. C	70	50	20	50	0.44	2
0.08 0.13 0.19 0.18	Dis. D	50	50	40	80	0.69	1

. The TOPSIS score is determined based on the relative Euclidean distance of each case from the ideal and anti-ideal solutions. A higher score indicates greater proximity to the ideal solution, thereby designating the case as a more favorable example of refurbishment. According to the TOPSIS analysis results, the Seoul A District Project achieved the highest score. This district performed particularly well in the indicators “Simplify procedures such as zoning approvals” and “Maximize land use and utilization.” In the latter category, Seoul A District demonstrated a significantly superior floor area ratio (FAR) of 599.36%, compared to 299.89% for Seoul B District, the second-highest-ranked case. This substantial difference contributed to Seoul A receiving an exceptionally high score and ranking as the most desirable redevelopment case from the supply-side perspective.

(2)

Evaluation on the Demand Side

The TOPSIS analysis results indicate that, from the demand-side perspective, Gyeonggi D District achieved the highest overall score, as shown in the score column of Table 12. Although Gyeonggi D District received the lowest score for the indicator “Vehicular and pedestrian accessibility with surrounding areas” (evaluation indicators a and d), it attained the highest score in the category “Governmental support for funding and financing.” This outcome is largely attributed to the limited availability of financial support in the other case types. Specifically, Urban Public Housing Complex Development Projects did not receive direct government funding, and Public Redevelopment Projects benefited from only partial support. As a result, Gyeonggi D District, which received substantial governmental funding, scored relatively higher in this category, thereby contributing to its top-ranking position in the demand-side evaluation.

(3)

Comprehensive TOPSIS Analysis

According to the rank columns in Table 12 and

Table 13. Comprehensive TOPSIS analysis rank.

Site	Score			Total Rank
	Supply	Demand	Total
Dis. A	0.58	0.31	0.89	2
Dis. B	0.2	0.27	0.47	4
Dis. C	0.29	0.44	0.73	3
Dis. D	0.42	0.69	1.11	1

, Seoul A District ranked first in the supply-side TOPSIS analysis but third in the demand-side analysis. This suggests that while the redevelopment project successfully addressed planning elements prioritized by supply-side stakeholders, it was less responsive to the needs and preferences of demand-side users compared to other districts. For Seoul B District, which ranked fourth in both the supply-side and demand-side analyses, the results indicate that essential planning elements necessary for successful redevelopment were insufficiently considered. To enhance the project’s effectiveness, comprehensive improvements are needed across key planning categories, including legal and institutional reforms, project feasibility, residential condition provision, and social integration planning. Seoul C District, as shown in Table 11 and Table 12, ranked third in the supply-side analysis and second in the demand-side analysis. While it generally performed consistently across most evaluation indicators—typically ranking second or third—it received the lowest score for the indicator “shortening redevelopment duration.” This implies that, with better planning to reduce project duration and strategic improvements in floor area ratio (FAR) relaxation, pedestrian and vehicular accessibility, and the design of durable and adaptable buildings, Seoul C District could evolve into a redevelopment model that effectively satisfies both expert and resident priorities. Gyeonggi D District ranked second in the supply-side analysis and first in the demand-side analysis. Its consistently high scores across most evaluation indicators highlight it as a redevelopment project that successfully balances the priorities of both stakeholders. However, its lowest performance was observed in the category of zoning enhancement—specifically, in floor area ratio (FAR) relaxation. This identifies a clear area for potential policy or planning improvement to further optimize the project’s overall performance. The total score and ranking is shown in Table 13.

The final ranking was determined by integrating the TOPSIS scores from both the supply-side and demand-side perspectives. As shown in the total rank column of Table 13, Gyeonggi D District achieved the highest overall ranking. Gyeonggi D District scored highly in both evaluations because it performed well in “Governmental support for funding and financing,” an evaluation indicator that was considered important by both experts and residents. In the overall TOPSIS results, Seoul A District and Gyeonggi D District ranked first and second, respectively. However, the difference of more than 0.2 between their supply-side and demand-side scores reveals a significant divergence in priorities between the two groups. In comparison, Seoul B District showed only a slight difference between its supply-side and demand-side scores. Nevertheless, its consistently low ranking suggests that it failed to adequately reflect the key priorities of either group. This indicates a lack of alignment with the essential elements valued by both experts and the public.

5. Discussion

This research developed a structured evaluation framework for the redevelopment of aging public rental housing by incorporating both expert and resident perspectives. Through the sequential application of FGI, AHP, and TOPSIS, several key insights were derived, contributing not only to methodological refinement but also to practical and policy-relevant implications for stakeholder-based urban regeneration.

First, the FGIs revealed a clear divergence in stakeholder priorities from the initial planning stages. Experts predominantly emphasized legal and institutional clarity, whereas residents highlighted livability and community integration. This collaborative refinement process led to the identification of 25 planning elements across five domains, effectively capturing both regulatory and experiential dimensions of redevelopment. This dual perspective laid the foundation for a stakeholder-sensitive evaluation framework, emphasizing the necessity of integrating both administrative feasibility and human-centered considerations from the outset. Second, the AHP analysis quantitatively substantiated these differences, offering structured evidence of the distinct value systems held by each group. For instance, “Simplify procedures such as zoning approvals (A1)” was ranked first by experts (weight = 0.0848) but only twelfth by residents. In contrast, “Vehicular and pedestrian accessibility (E1)” was considered most important by residents (score = 18.23) but ranked eighteenth by experts. Such discrepancies underscore the limitations of conventional top-down redevelopment models, which often overlook fundamental aspects valued by residents. These findings highlight the critical need for stakeholder-informed weighting to mitigate the risk of misalignment between institutional objectives and community expectations. Third, the TOPSIS analysis demonstrated how these differing priorities influence the evaluation of real-world redevelopment alternatives. Seoul A District received the highest expert-based TOPSIS score (0.58), largely due to its high floor area ratio (FAR) and regulatory streamlining. Conversely, Gyeonggi D District ranked highest among residents (0.69), attributed to its superior spatial planning and user-oriented design. When integrating both perspectives, Gyeonggi D District emerged as the overall optimal alternative. Importantly, districts like Seoul B, which exhibited minimal difference between supply-side and demand-side evaluations but low scores in both, reveal the risk of “middle-ground” planning that fails to meaningfully satisfy either group. These results affirm the value of dual-perspective evaluations in identifying redevelopment alternatives that are both technically feasible and socially desirable. Collectively, these findings underscore the need for redevelopment strategies that move beyond technical optimization. By incorporating diverse stakeholder priorities through a structured MCDM framework, planners can reduce the risk of unbalanced development and enhance long-term social acceptance. This research further demonstrates the practical feasibility of hybrid MCDM approaches—not only for ranking alternatives, but also for uncovering the underlying values that drive stakeholder decision making. By linking quantitative analysis with qualitative stakeholder insight, the proposed model advances a practical and adaptive approach to participatory urban planning. Ultimately, the proposed framework serves as a valuable tool for public agencies and developers seeking to achieve both project feasibility and community legitimacy. It promotes a more inclusive model of urban regeneration in which resident-centered values are elevated alongside expert knowledge, ensuring that redevelopment efforts are not only efficient but also equitable. Moreover, the framework provides a replicable tool for policymakers aiming to align institutional performance with democratic accountability in the context of urban housing redevelopment.

6. Conclusions

This research proposed a structured MCDM framework for evaluating the redevelopment of aging public housing, incorporating both expert (supply-side) and resident (demand-side) perspectives. By sequentially applying FGI, AHP, and TOPSIS, the framework facilitated the identification and prioritization of 25 planning elements across five key domains. This integrative approach directly addressed the study’s objective of developing a balanced, evidence-based decision support system for redevelopment planning. The analysis revealed a significant divergence in stakeholder priorities. Experts emphasized regulatory clarity and financial feasibility, whereas residents prioritized spatial livability and accessibility. These contrasting value systems were quantified through the AHP methodology and subsequently applied to four real-world redevelopment cases using the TOPSIS model. The results identified Seoul A District as the most favorable alternative from the supply-side perspective, while Gyeonggi D District ranked highest from the demand-side. When both perspectives were integrated, Gyeonggi D District emerged as the optimal solution, demonstrating its ability to satisfy the core priorities of both stakeholder groups. Gyeonggi D District was identified as the optimal alternative because it met the commonly valued criterion of government financial support emphasized by both experts and the public. Additionally, it achieved a balanced satisfaction of the distinct priorities of each group—addressing institutional factors prioritized by experts and spatial and environmental aspects valued by the public. This outcome affirms the practical utility of the proposed framework in identifying redevelopment alternatives that address diverse stakeholder needs. Furthermore, it contributes to both academic and applied urban planning discourse by presenting a replicable and inclusive tool for decision making in the context of housing regeneration. The framework advances current practice by quantitatively incorporating stakeholder diversity and enabling transparent comparisons of competing priorities—an aspect often overlooked in traditional top-down redevelopment approaches. Future research should expand the scope of case studies and incorporate dynamic performance indicators through real-time data collection. Additionally, the adoption of probabilistic or fuzzy MCDM techniques may enhance the framework’s ability to manage uncertainty and ambiguity in stakeholder judgments. Integrating the framework with spatial modeling tools and simulation techniques could further improve its predictive capacity and support adaptive planning in complex urban environments.