Document v1.1 · 9 October 2026 · CasasValue v4
CASAS.ES analyses every building in Spain with its own data-processing and automated valuation system. This page explains how: what data goes in, how it is combined, how CasasValue is calculated and how each layer of information on the property page is built.
CASAS.ES covers 8,111 municipalities, 12,974,035 buildings and more than 31 million cadastral properties, organised into 35,776 census tracts. Every building has its own property page, and every page is built with the same processing chain, with no manual handling: what CASAS.ES offers in a large city it also offers in a village of two hundred people.
One property, one key. The cadastral reference is the backbone of the whole system. Each source is joined to the building through that reference; when a source does not publish it, it is joined by its geographic position.
The immediate surroundings, not the municipal average. Each building is placed geometrically in its census tract, the finest statistical unit published by Spain's National Statistics Institute (INE). So the household income, population structure, voting or reference rent that accompany each home are those of its own surroundings.
Reconciling sources. When several sources describe the same thing —addresses, for example, come from the cadastral map, from the Cadastre's web services and from CartoCiudad— the system cross-checks them and keeps a single value per property.
Checks that block publication. Before being published, each municipality must pass a battery of automatic checks: coverage of buildings assigned to their census tract, presence of income data, an exact match between election results and the official figures, minimum address coverage, plausibility of energy certificates against the regional average, and internal consistency of floor areas, uses and years. A municipality that fails them is not published. We also systematically compare our results with independent external sources.
CasasValue is CASAS.ES's own automated valuation model. It estimates the market value of a single home —not of the building that contains it— and accompanies it with a confidence range and the price distribution of its comparables. It is calculated on our servers, deterministically, for every residential property: the value does not depend on what the user has on screen or on when they look at the page.
CasasValue is a statistical estimate. It is not an official appraisal under Spanish Order ECO/805/2003 and cannot replace one.
The price of a flat, a terraced house and a detached house follow different logics, so the first thing CasasValue does is classify each building. To do so it uses the actual number of floors, taken from the cadastral properties one by one. Where that detail does not exist, a discriminator calibrated on the municipalities that do have it estimates the type from the ratio between built floor area and plot area.
Every valuation starts from a public, verifiable price level. Depending on the municipality, CasasValue uses the best of three routes:
| Route | Source | Where it applies |
|---|---|---|
| Appraised value | Spanish Ministry of Housing and Urban Agenda, appraised value of open-market housing | Municipalities of more than 25,000 inhabitants |
| Value map | Directorate General for the Cadastre, average value modules by homogeneous area, broken down by property type | More than 6,800 municipalities |
| Rent capitalisation | Spanish Ministry of Housing and Urban Agenda, reference rent (SERPAVI) for the census tract | Where neither of the above exists |
In small rural municipalities, an additional safeguard caps the value according to the household income of the census tract, so that a price level designed for another market is not carried over to a rural setting.
On top of that level, our own quality index positions each home against the others in its municipality. It combines three families of variables:
Once the value of each home has been calculated, CasasValue checks it against its comparables: the nearest homes of the same type and similar size (±15%). The search radius is adaptive: it starts at around 400 metres and widens in steps, up to a maximum of around 10 kilometres, until it has gathered twenty comparables.
That sample gives the P10, P50 and P90 percentiles of price per square metre in the area, which the property page draws as a bell curve: they show where each home sits within its local market. A home that is exceptional for its area can legitimately come out above P90. If a home does not have enough comparables, the page says so and does not draw the curve.
Every CasasValue is published with a range whose width depends on how solid the starting data is, and which narrows when the home has a full group of comparables:
| Starting price level | Starting range | With full comparables |
|---|---|---|
| Ministry appraised value | ±15% | down to ±11% |
| Cadastre value map | ±22% | down to ±17% |
| Rent capitalisation | ±30% | down to ±23% |
| Rural setting | ±35% | down to ±26% |
CASAS.ES also estimates the monthly rent of each home, from the reference rent of its census tract, and the gross yield that results from comparing that rent with its CasasValue.
CasasValue aims at the closing price, not the asking price. It is calibrated against hundreds of homes for sale in more than 150 municipalities across Spain, separately for flats and for houses, and every calibration change is measured before it is applied.
Every published value carries the version of the model that calculated it and the date of the data it was calculated with. Any change that alters a single value means a new version.
| Version | Date | Main change |
|---|---|---|
| v4 | 25 Sep 2026 | Corrected reference price per square metre in municipalities with a Ministry appraised value, and a yield check based on the quality of the area |
| v3 | 24 Sep 2026 | Specific valuation of residential buildings not divided into separately registered units |
| v2 | 16 Sep 2026 | Percentiles calculated on each home's real comparables |
| v1 | August 2026 | Server-side calculation for every property, independent of browsing |
Like any automated model, CasasValue is less accurate for exceptional homes —very large or with unusual features—, in areas with few comparable transactions, and when the actual condition of the property differs from what is on the public records, for example after a renovation. In those cases the confidence range widens and the property page reflects it.
| Layer | What it measures and how it is calculated |
|---|---|
| Views | What can be seen from the building. Our own visibility calculation over the Copernicus elevation model and OpenStreetMap peaks: it identifies, by apparent angle, the dominant peak on the horizon and whether the sea is visible. |
| Orientation | Which way the home faces. Our own algorithm over the cadastral geometry: building footprint, plot shape and position of the pools. |
| Sun | The light of each month. Monthly solar radiation from PVGIS-SARAH (European Commission) or sunshine hours measured by AEMET, and daylight hours calculated astronomically for the municipality's latitude. |
| Sea | Water temperature month by month. Climatologies from Puertos del Estado, by stretch of coast. |
| Flood risk | Whether the building is in a flood zone, and with what return period. Each building cross-checked against the SNCZI flood maps (Spanish Ministry for the Ecological Transition). |
| Night lights | The intensity of urban activity around it. NASA VIIRS Black Marble satellite imagery. |
| Connectivity | Real fixed and mobile Internet speeds. Speedtest® by Ookla® measurements around the building. |
| Location | Distance to the beach, golf, port and airport. Geographic calculation over OpenStreetMap. |
| Surroundings | Proximity to main roads, nightlife and industry. Geographic calculation over OpenStreetMap. |
| Mobility | Cycle lanes and pedestrian areas. Geographic calculation over OpenStreetMap. |
| Amenities | Green spaces, sports and cultural facilities. Geographic calculation over OpenStreetMap. |
| Nearby services | Schools, supermarkets, parks, restaurants, pharmacies and health centres. Our own OpenStreetMap extract for each municipality. |
| Energy | Energy rating, demand and indicative heating and cooling cost. Each property cross-checked against the official energy certificate registers of thirteen Spanish regions. |
| Neighbourhood | Income, population, tenure, second homes, unemployment and voting. INE (Household Income Distribution Atlas, 2021 Census, Municipal Register) and the Spanish Ministry of the Interior, for the building's census tract. |
| Safety | Conventional crime. Crime Report of the Spanish Ministry of the Interior, annualised per thousand inhabitants. |
| Municipality | Mayor and party, population and nationalities. Spanish Ministry of Territorial Policy and INE. |
The whole system is reproducible: the same input always produces the same result. Every municipality is processed with the same chain, every stage records what it has done, and every published value identifies the model and the date of the data that produced it. When a source does not publish a figure for a particular place, the property page says so rather than filling it in with an average.
The information on CASAS.ES is indicative. It reflects what the official sources publish at their reference date and does not replace a land registry or cadastral certificate, an official appraisal or a visit to the property. The detail of each source and its licence is in Data sources.
Versión en español: Metodología · See also: Data sources · Legal notice