Despite the recognition of housing being a driver for social and economic well-being, existing data on adequate housing and on the respective housing deficit within and especially across emerging economies are scarce. Within countries, there is a wide disparity across income segments when it comes to the quality of housing. Housing quality also varies significantly across other HH characteristics such as location, education, occupation, and gender. These within-country dynamics of housing deficits are often conceptually noted, yet not quantified in a way that is actionable for policy makers and private sector companies along the housing value chain. In addition, existing country-specific figures are often outdated. Nigeria, for instance, the most populous country in Africa, with an urbanization rate of 4.8 percent, since 2000, is estimated to have a housing deficit of at least 17 million. This figure is steadily cited for the last decade, not factoring in the rapid population growth that might have increased the deficit (Bah et al 2018: 7). Globally, the UN estimates that about one billion people live in makeshift structures lacking at least one of the basic services which jointly constitute adequate housing, projecting that the number will rise to 3 billion people by 2030 (UN-Habitat 2012; UNDESA 2013; UNSD 2019). Yet, this is a broad projection mostly estimating the number of people living in slums and is therefore likely underestimating the number of urban dwellers in formal or informal settlements who are lacking access to these basic services.

While providing valuable insights, existing housing deficit estimations, which often rely on macrolevel data, hitherto lack a global standard and a consistent underlying framework that allow for cross-country comparison of deficit numbers. Micro-founded analyses across countries, applying the same rigorous methodological approach to estimate housing deficit for different segments of the population, are, largely, absent. A key constraint to establishing a uniform methodology is often the limitation to consistently identify what qualifies as adequate housing across and within countries. Addressing this void, in this paper, we introduce a micro-founded methodological framework to estimate the housing stock and flow deficit by building up from the adequacy of housing at the HH level. We define housing adequacy based on seven dimensions which are consistently found to be relevant for HHs’ health, educational attainment, and overall economic well-being, and which are embedded in the Agenda 2030: (1) access to improved water; (2) access to improved sanitation; (3) adequate living space; (4) durable material and good structural quality; (5) security of tenure; (6) access to electricity; (7) access to clean cooking (cf. next section).

We introduce a uniform framework for the novel _Adequate Housing Index (AHI)_ that provides a comparable assessment of these seven adequate housing conditions across emerging economies. We implement the _AHI_ by estimating the aggregate stock deficit across and within 64 emerging economies. We estimate that at least 268 million HHs (about 1.26 billion people) currently live in inadequate housing conditions across 64 emerging markets. We estimate that an _additional_ 40