Land Tenure Insecurity Research Articles

Sustainable Agricultural Practices in Sub-Saharan Africa: A Review of Adoption Trends, Impacts, and Challenges Among Smallholder Farmers

Sustainable agricultural practices (SAPs) remain the panacea to addressing challenges relating to climate change, low rainfall, and low agricultural productivity in many rural parts of sub-Saharan Africa (SSA). These practices include but are not limited to crop rotation, intercropping, cover cropping, and conservation tillage. The aforementioned practices have been scientifically proven to enhance crop productivity while safeguarding environmental resources. This review assesses the trends, effectiveness, and challenges associated with the adoption and utilization of SAPs among smallholder farmers in the SSA region, analyzing the literature and reports from 2000 to 2024 sourced from databases such as Google Scholar and Scopus. The inclusion criteria focused on key concepts such as SAPs, adoption, and challenges. Findings indicate that crop rotation, intercropping, improved seed varieties, manure, and mulching are among the most adopted practices. In reality, practices such as conservation tillage, agroforestry, and water harvesting systems remain the least adopted practices in many rural parts of SSA. The review further reveals that challenges relating to land tenure insecurity, lack of knowledge, training, and limited access to financial institutions all have a direct or indirect influence on farmers’ choice of adoption. Overcoming the aforementioned challenges through policy interventions and capacity building is vital for improved crop productivity and rural livelihoods.

Sustainable agriculture impacts in urban settings make the case for federal investments [Policy brief

Urban agriculture has flourished in American cities under the care of communities, but its growing popularity faces a number of challenges related to scant funding, insecure land tenure, and environ­mental pollution. Both local and national policy in the U.S. have struggled to adequately address those challenges and meet the demand for fresh food, local production spaces, and resilient communities. In this policy brief, we explore an emerging apparatus to support urban agriculture in the U.S. Department of Agriculture: The Office of Urban Agriculture and Innovative Production. We describe the relation­ship between urban agriculture’s many bene­fits and future funding, technical assistance, and data collec­tion initiatives through this office. Specifically, we call for consistent, permanent funding that is not subject to the annual federal budget process, which could power more tailored technical assistance programs, reformed granting initiatives, and expanded data collec­tion to inform future policy and practice. Urban agriculture has the potential to transform communities and the future of farming, and federal policy has the potential to provide important support for this transforma­tion. The policies outlined here offer a roadmap for this support.

Analysis of land use land cover change dynamics in Habru District, Amhara Region, Ethiopia

This study examines spatiotemporal changes in Land Use Land Cover (LULC) patterns within Habru District, Amhara Region, Ethiopia, between 1985 and 2021. Employing Landsat imagery and a supervised classification approach, we mapped six LULC classes: water body, settlement area, cultivated land, bare land, shrub land, and forest land. Ground control points (GCP) were obtained through field observations to ensured image accuracy. Complementing the remote sensing analysis, focus group discussions (FGDs) and key informant interviews were conducted to understand local perspectives on LULC changes. The analysis revealed significant LULC transformations over the study period. Between 1985 and 2021, there was a significant increase in cultivated land and settlement areas, which expanded from 12.27 % to 0.23 %–42.12 % and 2.58 % of the total area, respectively. Conversely, shrub and forest lands saw a marked reduction during the same period, declining from 71.52 % to 12.88 %–45.35 % and 7.06 % of the total area, respectively. Water body area showed a minor increase, while bare land exhibited negligible change. Agricultural land and settlement area expansion, population growth, land tenure insecurity, economic challenge, and climatic change were identified as key drivers of observed LULC changes. Our findings underscore the urgency of implementing multifaceted interventions to address these drivers and promote sustainable resource use practices. Such actions are critical for safeguarding Habru District's natural resources and ensuring the long-term viability of ecosystem services.

Evaluating the Sustainability of Incentive-based Conservation: A Case Study of the Taungya System in the Mount Elgon Conservation Area, Uganda

This study evaluates the sustainability of the Taungya system, an incentive-based conservation approach implemented in the Mount Elgon Conservation Area, Uganda. The system integrates reforestation with agricultural practices, aiming to balance biodiversity conservation and local community livelihoods. Utilizing a mixed-methods approach, quantitative data from structured surveys of 240 program participants were analyzed using SPSS, while thematic analysis was applied to qualitative insights from key informant interviews. The findings show a 68% increase in vegetation cover, demonstrating the system’s positive environmental impact. However, socio-economic benefits were uneven, with 86% of participants both consuming and selling crops, yet 93% reported that the benefits were insufficient to sustain them year-round. Key challenges included insecure land tenure, limited land size, and restrictions on agricultural practices like pruning and spraying. Despite these obstacles, the Taungya system fostered reforestation and community livelihoods, though unresolved land disputes and wildlife interactions contributed to negative perceptions of conservation efforts. These findings highlight important considerations for improving incentive-based conservation models, including the need for policy reforms that secure land tenure, expand land allocations, and support sustainable agricultural practices. The broader implications suggest that similar models in tropical regions can benefit from incorporating local needs into conservation goals to ensure long-term success.

Agroforestry: Multifunctional Benefits and Implementation Strategies

Agroforestry, the practice of integrating trees and shrubs into agricultural landscapes, offers many benefits for biodiversity, soil health, climate resilience, and socio-economic development. This review explores the multifunctional benefits of agroforestry systems and discusses implementation strategies to optimize their potential. The article covers ecological, economic, and social aspects, highlighting successful case studies and best practices from various regions. By providing a comprehensive overview of agroforestry's advantages and practical approaches for its adoption, this review aims to inform policymakers, researchers, and practitioners about the transformative potential of agroforestry in sustainable land management and rural development. Agroforestry systems have the potential to transform traditional agricultural practices by promoting biodiversity, enhancing ecosystem services, and increasing farm productivity and resilience. Integrating trees and shrubs into farming landscapes can improve soil health through enhanced nutrient cycling and erosion control, sequester carbon to mitigate climate change, and create microclimates that protect crops and livestock from extreme weather events. Additionally, agroforestry offers significant economic benefits by diversifying income sources for farmers, reducing reliance on chemical inputs, and improving market opportunities for agroforestry products. The review also addresses the social implications of agroforestry, emphasizing its role in enhancing rural livelihoods, promoting food security, and supporting community resilience. Agroforestry practices can empower smallholder farmers by providing them with new skills and knowledge, increasing their adaptive capacity, and fostering social cohesion through community-based initiatives. The article presents a comprehensive analysis of the barriers to agroforestry adoption, such as lack of awareness, financial constraints, and insecure land tenure, and proposes solutions to overcome these challenges. In-depth case studies from various regions illustrate the successful implementation of agroforestry systems and their positive impacts on local communities and ecosystems. The review highlights best practices and lessons learned from these examples, offering valuable insights for scaling up agroforestry initiatives globally. By integrating scientific research with practical experiences, this article provides a holistic perspective on the potential of agroforestry to contribute to sustainable development goals, including climate action, zero hunger, and life on land. Ultimately, this review aims to inspire policymakers, researchers, and practitioners to recognize the value of agroforestry and to implement strategies that support its widespread adoption. By fostering collaboration among stakeholders and promoting innovative approaches, agroforestry can become a key component of sustainable agricultural landscapes, ensuring food security, environmental health, and socio-economic well-being for future generations.

Exploring urban community gardens as ‘third places’: fostering social interaction in distressed neighbourhoods of Cape Town, South Africa

ABSTRACT The process of urbanisation and the associated urban lifestyle have been linked to social isolation and negative mental health impacts. As urbanisation and mobility continue to surge in African cities, urban planners face the challenge of creating inclusive spaces that encourage social interaction among urbanites. This research utilises the conceptual lens of ‘Third places’ to assess the role of urban community gardens in cultivating spaces that mitigate the negative effects of urbanisation within distressed communities in Cape Town, South Africa. A qualitative approach, involving open-ended questions and semi-structured interviews, along with observations, was employed to achieve the research aims. Findings revealed that individuals perceive community gardens as a channel for breaking free from isolation and fostering informal interactions among neighbourhood residents. However, the effectiveness of these gardens is hindered by several factors, such as their location and land tenure insecurity, which impede their ability to bring about meaningful changes within their communities. This research urges scholars to critically reconsider established criteria for third places, advocating for a nuanced understanding that acknowledges the diverse dynamics of community gardening in global South cities, thereby enriching theoretical discourse and informing practical interventions for fostering inclusive and sustainable urban communities.

Land Tenure Insecurity and Agricultural Recovery: Evidence from Displaced Farmers in North-Central Nigeria

Land Tenure Insecurity and Agricultural Recovery: Evidence from Displaced Farmers in North-Central Nigeria

Searching for Ways of Settling Land Conflicts by Peaceful Means in Cameroon: A Critical Analysis of the Peacemaking Role of the ‘Land Consultative Board’

The regulation of Land tenure systems is one of the main sources of conflicts in Africa and one of the continent’s most difficult realities to pin down. In its 1974 land reform, the Cameroonian legislature sought to strike a balance between traditional norms and modern instruments, between administrative, judicial and customary authorities, in order to establish an inclusive, democratic and peaceful system of land tenure. The establishment of the Land Consultative Board as the regulatory instrument the state planned to use in land matters was projected as the answer to this quest. While the original intention remains laudable - to enable the state, guarantor of the general interest to acquire a local instrument with the appropriate legitimacy and capable of ensuring the peaceful regulation of land tenure. It has to be said that, almost 50 years later, this ambition has not been achieved. The recurrence of land conflicts and the density of disputes reflect the inadequacy of the rules governing land tenure in Cameroon, depriving the board of any real regulatory authority. The central argument of this paper is that the legislator's ambition was not sincere because of the precedence of the administrative authority to the detriment of other actors. The choice of evaluating this working assumption through the theory of the instrumentation of public action is therefore essential. It makes it possible not only to determine the legislator's intention through textual and contextual analysis, but also to observe the interplay of actors around this regulatory instrument through an interdisciplinary approach. Between its structural inability to acquire real autonomy and the barely concealed desire to downgrade custom, its role has steadily diminished along with its influence, though without disappearing. It remains, however, the institutional relic where the philosophy of the “palaver tree,” supported by the practice of non-violence and democratic dialogue, can still survive, as well as the keystone of the entire land tenure system of the country. The analysis of the consultative Board’s peacemaking role through its instrumentation (or its instrumentalisation) opens up new perspectives for understanding the regulation of public action in our so-called Southern countries, especially for decision-makers, donors and any actor interested in the thorny issue of land tenure insecurity.

Tenure Security Perception Patterns among Amazonian Communities in Peru: Gender and Ethnicity

This study delves into perceptions of land and forest tenure (in)security among Indigenous and mestizo populations in the Peruvian Amazon. Despite all having collective lands, the selected communities vary in their formalisation processes. This research seeks to enhance comprehension of tenure security perceptions in the Peruvian Amazon by investigating sources of security and insecurity across key tenure components. A combination of descriptive, bivariate, and multivariate analyses is employed, based on fieldwork conducted between July 2015 and December 2017 in 22 Native and Peasant Communities in Loreto and Madre de Dios, utilising 1006 intra-household surveys, 52 in-depth interviews, and 44 focus group discussions. The results reveal similarities and differences in (in)security sources between titled and untitled communities. The study also explores the influence of gender and ethnicity on these perceptions, finding ethnicity-based variation in security perception over the past 20 years (1995–2015). Recognising these differences in perception is critical for assessing the robustness of exercising acquired collective rights.

Legal Issues in Land Acquisition for Agricultural Production in Nigeria

Land is the nations’ most valuable asset, as it provides sustenance. Legally speaking, land tenure in Nigeria is a complicated web of connections between many organizations that establishes land ownership patterns in connection to various land uses. This study examined the legal issues in land acquisition for agricultural production in Nigeria. Secondary data sourced from books, journals, and the internet were used. Normative legal research techniques were adopted to discuss legal issues in land acquisition, while qualitative content analysis was used to ascertain the level of agricultural production in Nigeria, as well as the relationship between land acquisition and agricultural production in Nigeria. The study’s findings showed that Nigeria's land tenure system supports land partitioning (land fragmentation), which leads to scattered small-scale farming. Tenure rules stipulated in the Nigerian Land Use Act of 1978 hinder agricultural productivity in Nigeria. Additional relevant factors and challenges influencing Nigeria's agricultural production include land tenure insecurity, and political and bureaucratic bottlenecks in the acquisition of land rights for agricultural uses. To ensure improved agricultural productivity, the government should initiate and implement a new land tenure reform that will address the inherent challenges in the current land tenure system.

Informal land markets and ethnic kinship in West African cities

We present an urban land use model with land tenure insecurity and information asymmetry regarding risks of contested land ownership, a very common issue in West African cities. A market failure emerges as sellers do not internalize the impact of their market participation decision on the average quality of traded plots, which in turn affects other sellers and buyers’ decisions. The equilibrium is suboptimal and has too many transactions of insecure plots and too few transactions of secure plots. This market failure can be addressed when agents trade along trusted kinship lines that discourage undisclosed sales of insecure plots. Such kinship matching is an important feature of West African societies, including on the market for informal land, as illustrated by a unique survey administered in Bamako, Mali. In the model, the extent to which the market failure is addressed increases with the intensity of kinship ties. When sellers also have the possibility of registering their property right in a cadastre, this not only further attenuates information asymmetry but also helps reduce risk. We find complementarity between kinship matching and registration: As transactions along trusted kinship lines tend to involve plots that are more secure on average, kinship matching makes registration better targeted at insecure plots traded outside kinship ties. In this context, a partial registration fee subsidy can bring the economy to the social optimum.11We are grateful to the editor and two anonymous referees for comments that helped us substantively improve the paper as well as to Amadou Cissé for the many discussions about social structures in West Africa that initially motivated this paper, to Demba Karagnara who coordinated field surveys in Bamako in 2012 and 2022, and to Pierre M. Picard, Jan Brueckner and Tony Yezer for suggestions and technical comments on the model. We are also grateful to Eliana la Ferrara and Karen Macours for useful insights on kinship and land markets in developing countries, as well as to Thierry Verdier, Miren Lafourcade and the participants to the Labor and Public Economics Seminar at the Paris School of Economics, to the International Conference of Development Economics and to the Annual Conference of the Centre for the Study of African Economies for various suggestions. We gratefully acknowledge the funding of the World Bank and of the Paris School of Economics Mobility Grant, a public grant overseen by the French National Research Agency (ANR-18-CE22-0013-01), the Labex OSE and the Labor and Public Economics Group at the Paris School of Economics .

Informal settlements and the continuity of Gujarati building traditions in Ahmedabad

Informal settlement is a widespread form of development in rapidly urbanising countries, yet the architectural form of dwellings and the design intention of the residents has received scant attention across the extensive literature on informality. Architectural scholars have drawn parallels between informal and vernacular environments, but the empirical evidence to support this assertion is limited. Comparing accurate and detailed architectural drawings, this article demonstrates how Gujarati building traditions influence the arrangement of dwellings and their plans in two informal settlements in Ahmedabad. Despite insecurity of land tenure and limited services, dwellings are built incrementally but planned with architectural intent informed by traditional rural housing types. The function and arrangement of traditional room types are consistent across dwellings in different contexts, from world heritage-listed havelis, rural Gujarati villages, to the incremental housing in two informal settlements in Ahmedabad. This evidence is at odds with popular and political views that informal settlements are unplanned accretions of ad hoc shelters. Such views, embedded in policy, can be part of the rationale for ‘slum’ clearance and relocation, which frequently disrupts social and economic networks. The findings and methods used in this study can inform architects or planners seeking to upgrade, redevelop, or relocate informal settlement communities.

Breaking barriers to agroforestry: FAO’s global capacity needs assessment

The FAO's Global Agroforestry Capacity Needs Assessment (CNA) revealed persistent challenges which are hindering widespread adoption of agroforestry despite its recognised benefits. Three primary action areas were identified: transforming agroforestry into an economically viable production system; strengthening enabling environments through agroforestry policies and strategies; and improving agroforestry extension for more biodiverse and agroecological systems. Stakeholders - governmental entities, NGOs, land users and community groups, researchers, private-sector entities and investors and donors - demonstrated expertise in agroforestry planning but identified gaps in socioeconomic aspects, and policy analysis and implementation. Challenges included insecure land tenure, limited market access and insufficient financial incentives for farmers. The assessment emphasised the need for collaborative efforts to address these challenges, recommending tailored approaches for the different stakeholder groups. Recommendations included improving data collection on socioeconomic aspects, developing innovative financing mechanisms and promoting peer-to-peer knowledge exchange. Efforts to strengthen policy frameworks, enhance extension services, and integrate local and Indigenous knowledge were also proposed. Concerted action is, therefore, necessary to unlock agroforestry's full potential in addressing global sustainability challenges to promote sustainable land management and food security worldwide.

Leveraging Remote Sensing and Nanotechnology to Overcome Barriers to Agroforestry Adoption by Small Holder Farmers

Agroforestry systems that strategically combine trees and/or shrubs with crops provide ecological and economic benefits. However, barriers including lack of quality tree germplasm, limited access to input and output markets, land tenure insecurity, and inadequate technical knowledge restrict widespread adoption of agroforestry among smallholder farmers. Advances in remote sensing and nanotechnology can help overcome these barriers. Remote sensing through high resolution satellite imagery, light detection and ranging (LiDAR), and aerial photography can map landscapes and provide geospatial information to facilitate agroforestry planning and optimization at farm scales. Nanotechnology involves manipulating matter at nanometer scales and has emerging applications in agriculture. Nanobased tools are emerging for targeted seed and agrichemical delivery, enhanced plant protection, soil remediation, and real-time field-level monitoring. The convergence of nanotechnology with information technology and biotechnology presents new opportunities to enhance agroforestry value chains to benefit smallholders. For example, nanobiosensors integrated with mobile platforms can monitor tree health and translate alerts to remedial actions and services customized to small farm contexts. In spite of significant potential, the use of remote sensing and nanotechnology in agroforestry remains limited and targeted capacity building is needed to promote wider adoption of these innovations in smallholder systems to make agroforestry a viable climate-smart approach to sustaining rural livelihoods.

Analysis of the enabling environment for delivering land degradation neutrality in Nigeria: perspectives from the sub-national to local level

The discourse around the planning, monitoring, and assessment of land degradation neutrality (LDN) has been communicated strongly on global and national scales; however, there is relatively little information on the enabling environment that will support the achievement of LDN targets locally. Recognising the dearth of studies that apply the LDN concept at the local scale, this study investigated local stakeholders’ perspectives on the progress towards, and challenges around, establishing the enabling environment for achieving LDN. It developed and used an extended LDN enabler framework that incorporates the gender component of LDN. The data for this study were collected from stakeholders from sub-national and local institutions concerned with LDN in Nigeria. The study findings indicate the presence of several relevant institutions and policy instruments to support progress towards LDN. However, this did not create an enabling environment for land users due to the lack of sufficient funding, weak systemic capacities of the relevant institutions, and the operational challenges for delivering policy incentives. Moreover, shortcomings in the regulatory framework give rise to land tenure insecurity and gender-biased land administration systems. Also, the findings indicate that entrenched traditional norms are a major challenge in achieving gender-balanced LDN outcomes. The extended LDN-enabler framework developed in this study will extend the scope of future studies examining progress toward LDN at regional and local scales.

Agriculture against the wall: barriers and opportunities for agroecological transitions in California’s industrial agricultural landscapes

ABSTRACT Agroecology emphasizes a shift from low diversity, high chemical input farming to more biodiverse agroecosystems cultivated in conjunction with natural ecosystem processes and embedded in socially just relationships. Yet achieving such agroecological transitions presents enormous challenges in industrial agricultural landscapes dominated by consolidation and overproduction. We examine both the challenges and the opportunities for agroecological transition in one particular industrial agricultural context: the fumigant-dependent strawberry production of California’s Central Coast. We do so by exploring adoption of Anaerobic Soil Disinfestation (ASD), an agroecological alternative to fumigation which has shown considerable promise but has been historically underutilized. Building on previously identified “domains of agroecological transformation,” we characterize the enabling and disabling conditions for agroecological transitions in California’s agricultural landscape. Through semi-structured interviews with farmers, extensionists, and industry stakeholders we uncover significant regime lock-ins: most prominently insecure land tenure and unequal access to land, unequal systems of exchange, and a culture that favors silver bullet narratives and top-down knowledge transfer; as well as drivers of change. The case of ASD, we conclude, reveals that technology-led agroecological transitions will have difficulty succeeding unless they are embedded in broader efforts to transform the social and political relationships of industrial agriculture.

Adaptation to land scarcity among small-scale farming households in South Kivu in the Democratic Republic of the Congo

Rural farming households in Sub-Saharan Africa, facing limited land access, engage in land purchase, rental, and other land access practices. However, the highly unregulated land markets expose these farmers to wide-ranging vulnerabilities. In this study, we investigated the land access mechanisms and the related constraints among the small-scale farmers in the densely populated Eastern part of The Democratic Republic of the Congo (DRC). We randomly selected 240 consenting farmers for inclusion in the study and collected data using semi-structured interviews to obtain data on land access characteristics. Then, the data was subjected to descriptive statistics to obtain measures of central tendency and dispersion on the responses and correlation statistics to understand the patterns and relations of factors affecting the land access and strategies used to cope with the limited land situation in the South Kivu province of DRC. Our results showed an insecure land tenure system among smallholder farmers. Most of the farmers in the study purchased and leased land to cope with poor land access and, in so doing, faced high price-related limitations that were unsustainable to these farmers; they also faced highly restrictive leasehold contracts. Given the limited access to financial resources and support, improving regulations of land markets and resource support interventions could promote land access among these smallholder farmers. We conclude that the challenges of land access and the current methods farmers use to obtain additional land among the smallholder farming households in the south Kivu province of DRC are precarious and unsustainable and continue to pose a food insecurity and poverty risk among these farmers. We recommend developing and implementing measures to support resource access by these farmers, such as finance, farmer-focused cooperative societies, and better land policy reforms and tenure systems to improve access to land among these farmers and farmers facing similar scenarios in other parts of sub-Saharan Africa.

Land Tenure System and Security of Kumal Community in Gorkha

This paper analyzes the land tenure system, its history, demographic and socio-economic characteristics and tenure ownership and security of Kumal community in Gorkha district of Nepal. Land is a fundamental natural resource for living, an economic asset for production, legal entity with multiple rights over it and above all, a societal factor for self-actualization. So, ownership of land has multi-faceted understanding. The objective of this paper is to analyze the existing land tenure system of Kumal community of Gorkha by reviewing the history of the tenure system and current tenure system, and carrying out HH survey to improve the tenure ownership and security. However, the tenure rights of socially and economically disadvantaged community like Kumals have not been properly addressed and those people are at high risk of eviction from the place they are living. The study recommends that land tenure insecurity arising from political, legislative and organizational behavior should be managed by appropriate interventions and policy reforms. As most of the analyses of land tenure security in Nepal have been performed in a descriptive way, this study explicitly investigates the issue through household survey. As Nepal is in the process of implementing federalization, assessment of land tenure security shall be one of the instruments for developing new land related policies and assessing the effect of new policies afterward.

Adaptive investment with land tenure and weather risk: Behavioral evidence from Tanzania

Two important risks faced by many smallholder farmers in Sub-Saharan Africa are erratic weather patterns and insecure land tenure. It is likely these risks will increasingly interact as projections of more erratic weather make small-scale farming more difficult and demand for rural land grows. This paper asks how farmers in Western Tanzania view these compound risks and the influence this has on levels of investment in adaptive agricultural technologies and the demand for land certification in a lab-in-the-field setting. Presenting novel data from a series of framed decision tasks linked to a household survey, this paper explores the relationship between individual risk preferences, adaptive investment and the demand for land certification from a group of 645 rural households in Kigoma, Tanzania. While adaptive investment increases with weather related risk, we find it responds negatively to land tenure risk. Individual risk preferences and past experiences of land disputes play significant roles in adaptive investment. Demand for land certification is high, investment increases significantly after certification, especially for risk-averse individuals.

Impact of Insecure Land Tenure on Sustainable Housing Development: A Case Study of Urban Housing Lands in the Republic of Benin, West Africa

This study focuses on land tenure in an urban environment. Specifically, it intends to elucidate the influence of land tenure security on access to housing in urban communities. The conurbation of Grand Nokoué, which is an agglomeration of five cities in the Republic of Benin, West Africa, captures attention due to its particular features as a developing city. Based on the literature, this study outlined three major factors of insecure land tenure, namely, lack of recognition by authorities, lack of protection from eviction or expulsion, and informal community-based rights. In addition, we examined four characteristics of relevant housing issues, namely, the development of shantytowns, the multiplicity of precarious housing, the loss of housing for the development of public projects, and exposure to house demolition under judicial decision, to formulate our hypotheses. The results of field observation and semi-structured interviews supported the hypotheses and demonstrated that legal access to land, the protection of the population from anarchic eviction, and informal community-based rights may positively influence the development of sustainable urban housing.