In an increasingly urbanizing world where cities play a pivotal role, the sustainable and inclusive development of our planet is intrinsically linked to the capability of governments to fulfill their obligations in offering equal opportunities and in protecting the basic human rights of their citizens. Considering housing and residential use can consume more than 70 percent of the land cover in cities , it is evident that the future of cities will depend on the availability and affordability of housing to accommodate the needs and rights of their growing populations.
Affordability represents one of the seven elements  under the Right to Adequate Housing, an international instrument adopted by the United Nations. This means that in principle, everybody is entitled to the right to live in peace and dignity and have access to adequate privacy, space, security of tenure, materials such as lighting and heating, infrastructure and location with regard to work and basic facilities, and other elements – all at reasonable and affordable prices.
The availability of housing at affordable prices in cities as a human rights matter was underscored on various occasions by the international community. During the adoption of the Habitat Agenda (1996)  and New Urban Agenda (2016)  (global development agendas), 170 nations reaffirmed their commitment to the promotion and the full and progressive realization of the Right to Adequate Housing .
To achieve this ambitious goal, governments must create an enabling environment. In other words, relevant policy, institutional, financial and regulatory frameworks must be in place to allow individuals and households to have access to adequate housing. In practice, to name a few examples, this can take form in:
- policies that stimulate the supply of serviced land at scale
- programs that improve accessibility to affordable housing finance, credit and targeted subsidies (which increase the ability of the different social
- groups to pay for housing while widening their freedom of choice) and
- policies and regulations that discourage sprawl and encourage land development within the urban core instead.
In reality, however, the lack of affordable housing options  in cities in the developing world represents one of the deep-rooted causes of informal urbanization which is characterized by the multiplication of slums and unplanned settlements. This means cities are not growing based on an enacted plan and land-use ordinances but rather based on informal processes of land subdivision. The scarcity of affordable housing is thus intrinsically associated with slums, poor housing, and infrastructure, overcrowding, spatial segregation, as well as negative subletting practices. This, in turn, affects the quality of neighborhoods and public spaces, causes severe distortion in housing markets and worsens living conditions of the population.
This issue is especially exacerbated in Sub-Saharan Africa and parts of Asia where urbanization has become synonymous with slum formation . Worse, it remains a challenge globally. The Global Sample of 200 Cities  gives us an unequivocal evidence of the global housing affordability crisis, which is further confirmed by several other studies . It shows home ownership and rental housing remain largely unaffordable in all of the studied cities.
The lack of affordable housing drives nearly 1 billion people to a poverty trap – a mechanism which forces people to remain poor, socially and spatially segregated and living in appalling conditions located in slums  in cities. This has serious ramifications on the quality of people’s lives, let alone on the sustainability of cities. These numbers will continue to grow if no concerted and comprehensive actions are undertaken by relevant stakeholders including governments at all levels.
The high numbers reveal the failure of governments in facilitating the supply of available, adequate and affordable housing options at scale and diversity in size, location, type, standards and prices. This could provide an alternative to informal urbanization and enable the various social-economic segments of the population to realize their right to an adequate housing.
The adoption of a Human Rights-Based Approach (HRBA) to housing and urbanization will achieve the desired impact. This approach advocates that urban policies recognize, protect and ensure everyone has the right to an adequate standard of living in cities. Such policies will help create cities that meet the human rights standards , such as access to adequate housing, water, and sanitation or any other rights codified in the human rights treaties ratified by the country in question. In Brazil the Statute of the City Law recognizes the social use of land and the right not to be evicted under certain conditions. The law also requires that any profits generated from the sales of air rights (building rights) be used towards infrastructure improvements that benefit the poorest within the defined urban operation zone. Similarly, Colombia has enacted compulsory social housing initiatives. This gives an opportunity to see the development of “cities of rights” where obligations are met for all citizens, instead of “cities of segregation” where everyone has obligations but only some have their basic rights realized, while others are constrained to live in inhuman conditions.
These examples suggest that the adoption of a human rights-based approach in cities will change the face of urbanization in many parts of the world – offer equality of opportunity for the people and allow them an equitable access to an adequate standard of living. It is thus evident that affordable housing is an integral part of creating a sustainable, inclusive, peaceful and a just urban planet.
1. This is drawn from the Global Sample of Cities comprised of 200 cities selected from a universe of 4,231 cities that had more than 100,000 inhabitants in 2010. On average, residential and housing use takes the land cover in cities in a range from 35% to 80%. The research was carried out by the University of New York, in cooperation with UN-Habitat and the Lincoln Institute of Land Policies. See https://unhabitat.org/books/the-fundamentals-of-urbanization-evidence-base-for-policy-making/
2.The Right to Adequate Housing includes: (1) Legal security of tenure; (2) Availability of services, materials, facilities and infrastructure; (3) Affordability; (4) Habitability; (5) Accessibility; (6) Location; (7) Cultural adequacy. In short, the right to Adequate Housing means “the right to live somewhere in security, peace, and dignity with adequate privacy, space, security, lightening and ventilation, with adequate infrastructure and location with regard to work and basic facilities – all at reasonable prices” Urban Jonsson (2015). Programmatic Guidance Note for UN-Habitat staff. Nairobi: UN-Habitat.
6.UN-Habitat (2016a). The Fundamentals of Urbanization. Evidence-base for policy making. Nairobi: UN-Habitat.
https://unhabitat.org/books/the-fundamentals-of-urbanization-evidence-base-for-policy-making/. This publication draws on the Global Sample of 200 cities mentioned above.
9.Demographia (2017). 14th Annual Demographia International Housing Affordability Survey: 2018. Rating Middle-Income Housing Affordability <http://demographia.com/>; McKinsey Global Institute (2014). A Blueprint for Addressing the Global Housing Affordability Challenge. <www.mckinsey.com/mgi>; Property Prices Index for Country 2018 Mid-Year <https://www.numbeo.com/property-investment/rankings_by_country.jsp>; IMF’s Global Housing Watch Second
Quarterly of 2017 < https://blogs.imf.org/2016/12/08/global-house-prices-time-to-worry-again/>
10.Today, around one quarter of the world’s urban population continues to live in slums. Since 1990, 213 million slum dwellers have been added to the global population. The expected global population increase of 1.18 billion combined with the existing housing deficit, implies that approximately two billion people will require housing in 2030. Today, 880 million urban residents are estimated to be living in slum conditions as opposed to 792 million in 2000. UN-Habitat (2013), Streets as Public Spaces and Drivers of Urban Prosperity; UN-HABITAT (2005). Financing Urban Shelter: Global Report on Human Settlements 2005. Nairobi: UN-Habitat ; United Nations (2015). The Millennium Development Goals Report 2015. New York: United Nations.
11.UN-Habitat (2016). A Human Rights-Based Approach to Sustainable Urbanization and the Realization of Human Rights in the City. A Think Piece for the Preparation of the Habitat III Conference by Urban Jonsson. Unpublished.