GCRI · Cities and Built Environment
Housing and affordability
Housing determines where people live, what they can afford after rent, how safe they are from hazards and how secure they are against eviction. When housing costs rise faster than incomes, people crowd, move to cheaper risky land, or lose their homes. This page sets out how housing markets and policies shape affordability and risk, how they are measured, and what evidence serves the governments and housing bodies that act on them.
Housing and affordability on the record.
Housing and affordability: how the risk develops.
Housing systems and climate exposure. The dossier below sets out how the risk develops, what is measured, where the data come from, how it is modelled and who decides.
Costs rise faster than incomes
Land prices, construction costs, interest rates and investment demand raise housing costs. When incomes lag, households spend more of their budget on housing or move.
Crowding and poor quality follow
Households squeeze into less space, older stock or informal housing. Crowding and poor conditions raise exposure to disease, heat, fire and damp.
Affordability pushes people to risk
The cheapest housing is often in flood zones, on unstable slopes or far from jobs. Affordability problems become exposure and travel problems.
Tenure security shapes resilience
Renters and people without recognised tenure are more easily displaced after disasters and less able to invest in protecting their homes.
Urban signals in India.
Population density, night lights and daytime surface heat over India, from NASA GIBS. Each layer carries its own date.
The interactive map needs JavaScript; the layer list and sources are below.
Layers 3
Urban signals, for this page
About this layer
- Evidence
- Estimated
- Source
- Gridded Population of the World v4.11 (NASA SEDAC (CIESIN, Columbia University))
- Provider
- NASA SEDAC (CIESIN, Columbia University)
- Licence
- CC BY 4.0
- Vintage
- null; Census-based estimate, static (2020)
- Resolution
- about 1 km grid
- Uncertainty
- Census-based estimate of people per square kilometre in 2020, shown as exposure context; not a count of people affected by any hazard.
- Reached through
- gibs.earthdata.nasa.gov, only after you allow the live map
About this layer
- Evidence
- Observed
- Source
- VIIRS Black Marble (VNP46A2) (NASA LAADS DAAC)
- Provider
- NASA LAADS DAAC
- Licence
- NASA open data
- Vintage
- daily; Satellite radiance, corrected for moonlight and atmosphere
- Newest at build
- 2026-10-12
- Resolution
- about 500 m grid
- Uncertainty
- Satellite night-time radiance for the date shown; lights are a proxy for electricity use and outages, not a measurement of supply or access.
- Reached through
- gibs.earthdata.nasa.gov, only after you allow the live map
About this layer
- Evidence
- Observed (persistent cloud still leaves gaps)
- Source
- VIIRS NOAA-20 Level 3, 8-day (NASA LANCE)
- Provider
- NASA LANCE
- Licence
- NASA open data
- Vintage
- 8-day; Satellite 8-day composite; persistent cloud still leaves gaps
- Newest at build
- 2026-09-14
- Resolution
- about 1 km grid
- Uncertainty
- Satellite skin temperature of the ground over the 8 days ending on the date shown, a heat exposure indicator; not air temperature, heat index or a heat warning.
- Reached through
- gibs.earthdata.nasa.gov, only after you allow the live map
About this layer
- Evidence
- Observed
- Source
- VIIRS NOAA-20 corrected reflectance (NASA LANCE)
- Provider
- NASA LANCE
- Licence
- NASA open data
- Vintage
- daily; Satellite image
- Newest at build
- 2026-10-14
- Resolution
- about 250 m grid
- Uncertainty
- Satellite image. Satellite or model raster as the provider publishes it. Clouds, swath gaps and retrieval error leave gaps and noise; values are indicators, not measurements at a place.
- Reached through
- gibs.earthdata.nasa.gov, only after you allow the live map
About this layer
- Evidence
- Modelled (latest year GIBS publishes)
- Source
- MODIS Terra and Aqua land cover (MCD12Q1) (NASA LP DAAC)
- Provider
- NASA LP DAAC
- Licence
- NASA open data
- Vintage
- yearly; Satellite classification; latest year GIBS publishes
- Newest at build
- 2024-01-01
- Resolution
- about 500 m grid
- Uncertainty
- Satellite land cover classes for the year shown, including croplands; a classification with known errors, not a farm register.
- Reached through
- gibs.earthdata.nasa.gov, only after you allow the live map
About this layer
- Evidence
- Observed (clouds leave gaps)
- Source
- OMI Aura (NASA GES DISC)
- Provider
- NASA GES DISC
- Licence
- NASA open data
- Vintage
- daily; Satellite retrieval; clouds leave gaps
- Newest at build
- 2026-10-10
- Resolution
- about 2 km grid
- Uncertainty
- Satellite column of nitrogen dioxide in the lower atmosphere on the day shown, mostly from combustion; not a ground-level concentration or a health warning.
- Reached through
- gibs.earthdata.nasa.gov, only after you allow the live map
Keyboard, with the map focused
Hold Ctrl or ⌘ and scroll to zoom
Latest available
NASA GIBS / EOSDIS · ASTER GDEM (METI, NASA) · Blue Marble (NASA) · © OpenStreetMap contributors (ODbL) · Natural Earth
Loading the latest NASA imagery.
Drag to move. Ctrl or ⌘ and scroll, pinch or the buttons to zoom; hover for the values under the pointer; reset returns to the region.
Urban signals, framed on India.Satellite and model products as NASA publishes them, each with its own date. They are indicators, not assessments of any place.
Data: NASA GIBS · ASTER GDEM · Blue Marble · © OpenStreetMap contributors · Natural Earth · NASA EONET · U.S. Geological Survey · NASA JPL OPERA DIST-ALERTSources and licences
- We acknowledge the use of imagery provided by services from NASA’s Global Imagery Browse Services (GIBS), part of NASA’s Earth Science Data and Information System (ESDIS). Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). NASA open data
- We acknowledge the use of imagery provided by services from NASA’s Global Imagery Browse Services (GIBS), part of NASA’s Earth Science Data and Information System (ESDIS). Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). NASA open data
- Center for International Earth Science Information Network (CIESIN), Columbia University. 2018. Gridded Population of the World, Version 4 (GPWv4): Population Density, Revision 11. NASA Socioeconomic Data and Applications Center (SEDAC). Licensed under CC BY 4.0. Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). doi:10.7927/H49C6VHW. CC BY 4.0
- VIIRS Black Marble night-time lights, NASA Goddard Space Flight Center; distributed by the NASA Level-1 and Atmosphere Archive and Distribution System (LAADS DAAC); imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). NASA open data
- VIIRS near-real-time products (flood, land surface temperature, snow cover, corrected reflectance), NASA LANCE; imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). NASA open data
- MODIS land products (vegetation indices, gross primary production, land cover), NASA LP DAAC and LANCE; imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). NASA open data
- OMI nitrogen dioxide (Aura) and OMPS aerosol index (Suomi NPP), NASA; distributed by the NASA GES DISC; imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). NASA open data
- ASTER GDEM is a product of METI and NASA (ASTER Global Digital Elevation Model V003, NASA LP DAAC); imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). Cite as: NASA/METI/AIST/Japan Spacesystems and U.S./Japan ASTER Science Team (2019). ASTER Global Digital Elevation Model V003. doi:10.5067/ASTER/ASTGTM.003. NASA open data
- Made with Natural Earth. Free vector and raster map data @ naturalearthdata.com. Public domain
- © OpenStreetMap contributors (ODbL), via NASA GIBS (coastlines, boundaries, roads and place names). Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). ODbL
- Blue Marble, NASA Earth Observatory; imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). NASA open data
- Context on the globe and flat map: coastlines, boundaries, roads and place names from NASA GIBS reference layers (OpenStreetMap data, ODbL, © OpenStreetMap contributors); Blue Marble imagery as an optional base; 3D terrain and the elevation read-out from the ASTER GDEM elevation colour index (5 m to 200 m classes, exaggerated for legibility). Boundaries are drawn as published and imply no position on any territory.
- Live events: NASA Earth Observatory Natural Event Tracker (EONET); events are indicative and keep their original source links.
- Live: NASA EONET Events are indicative, not authority warnings.
- Live: U.S. Geological Survey Events are indicative, not authority warnings.
- Observed (EO): NASA JPL OPERA DIST-ALERT (contains modified Copernicus Sentinel data 2026). We acknowledge the use of imagery provided by services from NASA’s Global Imagery Browse Services (GIBS), part of NASA’s Earth Science Data and Information System (ESDIS).
- NASA GIBS: We acknowledge the use of imagery provided by services from NASA’s Global Imagery Browse Services (GIBS), part of NASA’s Earth Science Data and Information System (ESDIS).
- Air quality forecast, 5 days, PM2.5 (CAMS via Open-Meteo): Contains modified Copernicus Atmosphere Monitoring Service information 2026.
- Past year, daily temperature and sunshine (NASA POWER): These data were obtained from the NASA Langley Research Center (LaRC) POWER Project funded through the NASA Earth Science/Applied Science Program..
- Weather data by Open-Meteo.com (https://open-meteo.com/), licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/).
- Optional layers (16 sources in the layer list: live, forecast, observed and context) print their provider credit on the map and here when switched on; forecasts are model output and derived indices are estimates.
Layers and dates
- Population density, 2020: Population: CIESIN, Columbia University, Gridded Population of the World v4.11 (2018), NASA SEDAC, CC BY 4.0 · static
- Night-time lights, daily: VIIRS Black Marble (VNP46A2), NASA LAADS DAAC · 12 Oct 2026
- Land surface temperature, day, 8-day composite: VIIRS NOAA-20 Level 3, 8-day, NASA LANCE · 14 Sep 2026
- True colour: VIIRS NOAA-20 corrected reflectance, NASA LANCE · 13 Oct 2026
- Land cover type (IGBP), yearly: MODIS Terra and Aqua land cover (MCD12Q1), NASA LP DAAC · 2024
- Nitrogen dioxide, lower atmosphere column: OMI Aura, NASA GES DISC · 10 Oct 2026
Housing ties household finances to exposure.
- HealthCouplingCrowding, damp and heat in housing drive illness.What to watchHousing deprivation indicators
- EnergyCouplingEnergy costs and efficiency shape affordability.What to watchEnergy cost burden
- WaterCouplingInformal and rental housing often lack safe services.What to watchService access by tenure
Housing analyses are designed for the Evidence Brief series. WHO’s Housing and health guidelines (2018) set health-based recommendations on crowding, temperature and safety.
- Housing condition surveys.
- Studies of displacement after rent or disaster shocks.
Model housing and affordability as a system. Run the cascade.
Assembled from the Nexus Standards area profile Cities and the built environment: the hazards it names, the systems and sectors that carry the loss, the controls that dampen it and the data that observe it. Choose the components, pick an initiating hazard and step through the cascade. The Map view places the run on an example geography with open data. Every coupling weight is a stated assumption you can change. A teaching model, not a forecast, an assessment or a certification. To model a place of your own choosing, open the full System Builder.
Hazards
- Ice-jam flood
- Earthquake
- Dam failure
- Aftershock sequence (set off downstream)
- Fault surface rupture (set off downstream)
- Soil liquefaction (set off downstream)
- Slope slide (set off downstream)
- Rockfall (set off downstream)
- Tsunami (set off downstream)
- Building collapse (set off downstream)
- Widespread power outage (set off downstream)
- Water supply failure (set off downstream)
- Mass displacement (set off downstream)
- Disaster and conflict debris (set off downstream)
- River flood (set off downstream)
- Flash flood (set off downstream)
- Turbidity current (set off downstream)
- Seismically and structurally vulnerable stock (set off downstream)
Systems and couplings
- Cities and the built environment
- Construction and real estate Coupling
- Water utilities and basins Coupling
- Public sector and government Coupling
- Energy utilities and grids Coupling
Controls
NS-0Constitution and principlesNS-3Risk record UNIs (grammar, legacy crosswalk, allocation authority)NS-5Figure, map and visualisation standard (with the UI/UX kit)NS-9Contextual UNIs (deployments, instances, programme instances)NS-10Policies and clauses (machine-readable obligations: definition, binding, evaluation and enforcement)NS-11Verification and monitoring (evidence, attestations, zero-trust conformance observation)NRS-X5Cities and built environment riskNRS-H91Hazard family: Urban and building-stock stress (NHS-1 infra.urban)NRS-H113Hazard family: Financial-system fragility (NHS-1 soc.financial-system)NRS-K7Domain pack profile: Cities urban (DOMAIN-007)NRS-H31Hazard family: Persistent and bioaccumulative substances (NHS-1 poll.persistent)NRS-H34Hazard family: Waste and residue failures (NHS-1 poll.waste)
Observation
- Global Human Settlement Layer (listed for reference)
- WorldPop gridded population (listed for reference)
- Overture Maps buildings theme (listed for reference)
- OpenStreetMap (listed for reference)
- World Development Indicators (listed for reference)
- Direct economic loss in relation to global GDP, damage to critical infrastructure and number of disruptions to basic services, attributed to disasters
- Proportion of local governments that adopt and implement local disaster risk reduction strategies in line with national strategies
- Proportion of urban population living in slums, informal settlements or inadequate housing
- Percentage of local governments that adopt and implement local disaster risk reduction strategies in line with national strategies
Example geography
- India: 65 hexagonal cells
- Surface water through cloud, 30 m (OPERA DSWx-S1 radar), NASA GIBS
- Rain rate, last half hour (IMERG), NASA GIBS
- Night lights tonight, outages (VIIRS Day/Night Band), NASA GIBS
- Surface soil moisture (SMAP), NASA GIBS
What is measured, and how well.
Each indicator carries its unit, its cadence, the kind of source behind it and the evidence label a value would carry. No values are shown: a programme supplies them under its own authority.
| Indicator | Unit | Cadence | Source type | Label |
|---|---|---|---|---|
| Housing cost overburden | percent of households spending above a stated share of income on housing | annual | Household surveys | ESTIMATED |
| House price to income ratio | ratio | annual | Price and income statistics | Published statistics |
| Overcrowding rate | percent of population in overcrowded dwellings | annual | Household surveys | ESTIMATED |
| Households with secure tenure | percent of households | per survey | SDG indicator 1.4.2 surveys | REPORTED |
| Homelessness | people counted by a stated definition | annual or per count | Administrative records and point-in-time counts | REPORTED |
| New dwellings completed | count | annual | Building completion statistics | Published statistics |
How housing and affordability is modelled, measured and tested.
The model, its assumptions, its data and its uncertainty, in the form a scientist or engineer would check. Structures follow published methods. The values drawn are illustrative, not findings.
System model
The couplings between the systems in housing and affordability: signs of influence, a reinforcing and a balancing loop, and cross-links where stress jumps.
Where the evidence comes from.
Named public datasets and institutional records, each with its licence class. Sources by agreement are used only under their terms and never republished.
| Source | What it gives | Licence class |
|---|---|---|
| OECD Affordable Housing Database | Housing costs, conditions and policies across OECD countries | Public, OECD terms |
| UN-Habitat housing and SDG 11.1 data | Population in slums, informal settlements or inadequate housing | Public, UN-Habitat terms (to check) |
| Eurostat housing statistics (EU-SILC) | Overburden, overcrowding and housing deprivation in Europe | Open, Eurostat reuse policy |
| Demographic and Health Surveys housing modules | Dwelling materials, crowding and services | Free with registration, DHS terms |
| Global Land Tool Network and SDG 1.4.2 tenure data | Tenure security measurement | Public, terms per source |
Who decides, and what the evidence serves.
Cities and Built Environment prepares evidence. The decisions below are taken by the authorities named, under their own rules, and never by the platform.
| Who decides | The question | Evidence this page serves |
|---|---|---|
| Housing ministries and agencies | Which housing programmes and subsidies to fund and where | Affordability profiles; supply statistics |
| City governments | Where to zone for affordable housing outside hazard zones | Affordable housing and hazard maps |
| Recovery agencies after disasters | How to protect renters and informal residents in recovery | Tenure evidence; displacement data |
Outputs this topic produces
- Affordability and crowding profiles by city and group
- Maps of affordable housing against hazard exposure
- Tenure security evidence notes
- Briefs on housing in recovery and resettlement
What experts ask.
- 01
Who lives in exposed housing?
How income, tenure, age and disability correlate with hazardous locations and poor building quality.
- 02
How does exposure affect affordability?
How insurance costs, repair costs and energy bills change the true cost of housing in exposed areas.
- 03
What happens after a disaster?
How damage to housing affects rents, displacement and recovery for owners and tenants.
- 04
What retrofits make a difference?
Which improvements to existing stock reduce risk and at what cost to occupants.
What drives the risk.
Housing markets capitalise some risks and ignore others. Visible hazards may lower prices, drawing lower-income households to exposed areas, while slow-onset risks such as heat and subsidence are rarely priced. When insurance becomes unavailable or unaffordable, the risk shifts to occupants and lenders.
Tenants have limited control over the buildings they live in. They cannot retrofit, may lose their homes after disasters and often receive less recovery assistance than owners. Insecure tenure deters investment in safety.
Reconstruction can raise housing costs. Rebuilding to higher standards, land speculation and reduced supply can push former residents out of the areas they left.
How evidence is gathered, and where it stops.
| Method or data | What it shows | Its limit |
|---|---|---|
| Housing condition surveys | Quality and structural defects | Costly and infrequent |
| Census and tenure data | Who lives where and on what terms | Lags behind fast change |
| Exposure overlays | Housing stock in hazard zones | Depend on hazard map quality |
| Post-event studies | Displacement and recovery paths | Hard to follow people who move |
How it is studied, and what the methods cannot say.
- 01Social and behavioural scienceHousing and tenure surveys · Participatory planning research · Displacement studiesApplied here
- 02Spatial statistics and geostatisticsSmall-area estimation · Spatial clustering of disadvantage · Interpolating urban temperatureApplied here
- 03Geospatial information systemsUrban exposure databases · Community mapping · Hazard overlay for planningApplied here
- 04Structural and earthquake engineeringUrban building vulnerability profiles · Retrofit of schools and housingApplied here
Where this page’s references lead.
The bodies and documents this page is read against. Status and editions change; each link goes to the issuing body.
Questions and answers.
What is housing affordability?
What is adequate housing?
Why does tenure security matter in disasters?
Does the platform value properties or advise buyers?
Why include energy costs in affordability?
Are tenants treated separately?
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