The Promise and Perils of Using Housing Adverts for Affordability Mapping in Europe

The document discusses the pressing issue of housing affordability in Europe, which has become a significant concern as rising costs push many households toward financial distress. The House4All ESPON project aims to tackle this challenge by creating a comprehensive pan-European housing affordability map at the regional level. This initiative seeks to enhance understanding of affordability issues by utilizing innovative data sources, particularly online housing advertisements.

The project employs repeated web-scraping exercises between April 2024 and April 2025 across 31 countries within the ESPON space. This method allows researchers to gather detailed information from housing adverts on platforms like Nestoria and Properstar, including pricing, geolocation, and property characteristics. By aggregating this data, the project can generate average prices per square meter and compare them to traditional income data, offering a clearer picture of housing affordability.

Traditionally, housing affordability has been measured using the income ratio approach, which often sets the affordability threshold at 30% to 40% of household income. However, applying this method at a regional or urban level is problematic due to insufficient granular data from surveys and governmental records. The lack of detailed information hinders precise assessments of affordability across diverse regions and cities.

Online housing adverts present a promising alternative data source, enabling a more granular analysis of housing affordability than traditional methods. This approach provides flexibility in data aggregation, allowing insights into specific neighborhoods and regions. The ESPON House4All project aims to offer a first-ever comprehensive mapping of housing offers across Europe, distinguishing between various market segments and analyzing differences in affordability between renting and buying.

Despite the potential advantages, using housing adverts also poses challenges. The data may only represent a subset of the market, typically excluding social housing and properties at the extremes of the price range. Moreover, harmonizing data for a pan-European context is complex due to varying components in listed prices across countries. Adjustments are necessary to ensure accurate comparisons.

Listed prices often do not reflect the final amounts paid for properties, as they can be set higher or lower than actual transaction values. The duration a property remains listed may indicate whether it is overpriced or underpriced, but this requires additional data for accurate interpretation. The project aims to address these negotiation gaps, although challenges remain in reflecting them comprehensively.

Calculating price-to-income ratios requires income data that is often available only at an aggregate level rather than for individual households. This reliance on broad averages can obscure significant variations within regions. The project is working on methodologies to adjust income data, but using GDP per capita as a proxy has its own limitations.

The House4All ESPON project exemplifies innovative approaches to researching housing affordability. By refining methodologies and addressing inherent challenges, the project aims to produce actionable insights. Collaboration among governments, private sector platforms, and academic institutions will be essential for improving data access and ensuring the reliability of findings.

While using housing adverts for affordability mapping is still developing, it offers a valuable means of overcoming limitations of traditional data sources. Repeated scraping will allow researchers to monitor the impact of policies on housing prices and track price developments more effectively. With careful methodology, this approach can significantly enhance understanding of housing affordability across Europe.