The geography of housing markets

Short-term rentals, especially Airbnb, have become an important expression of tourism pressure in the Greek islands, reshaping local settlement patterns and increasing demand for built space. Although tourism development is usually associated with coastal zones, many island mountainous areas are also affected by second-home development, short-term accommodation and built-up dispersion. These areas are environmentally and culturally sensitive, often linked with traditional settlements, distinctive landscapes and fragile local communities. In this context, built-up area dispersion in mountainous island areas raises important questions for spatial planning and sustainable tourism management. This study focuses on the mountainous areas of Crete and investigates how built-up area dispersion is related to the spatial concentration of Airbnb listings. The mountainous zones are delineated through a terrain-based classification that combines elevation and slope, allowing the distinction between moderate, steep and high mountainous environments. The analysis integrates Copernicus built-up data for 2006 and 2018, digital elevation and slope layers, settlement boundaries and Airbnb listings. Through GIS-based overlay analysis, the study examines whether dispersed built-up development is mainly located within established settlements or expands beyond their boundaries. In parallel, Airbnb density is mapped in order to identify areas where short-term rental activity overlaps with patterns of dispersed development. The results show how urban sprawl and Airbnb activity are spatially related in mountainous island areas. The analysis highlights whether Airbnb concentration is located within existing settlements or extends into outside settlement areas already affected by dispersed development. The study contributes to the discussion on tourism pressure, urban sprawl and spatial planning in mountainous island environments, emphasizing the need for integrated policies that balance tourism development, landscape protection and the resilience of local communities.

Island landscapes are a key factor in the quality of life for local residents, while also representing important economic resource, as they constitute a primary driver of tourism. Rapid tourism development creates a constant demand for the expansion of built-up areas and changes in land use. When these pressures occur outside a coherent spatial planning framework, they can lead to irreversible transformations of the island landscape, ultimately resulting in unsustainable tourism models. Pressures for new constructions are particularly strong across the Cycladic islands, not only in internationally renowned tourist destinations but increasingly in smaller islands that have experienced significant growth in recent decades, such as Sifnos. This study aims to provide a quantitative and spatial analysis of the patterns of built-up area dispersion on Sifnos by examining specific spatial dynamics that influence its expansion. To achieve this, remote sensing methods are employed to detect changes in built-up areas over time. Settlement boundaries are used to delineate dispersed development. Then an overlay analysis is applied to estimate the proportion built-up area dispersion occurring in coastal zones, along road networks, and along ridgelines. The results highlight the increasing pressures on the island’s landscape in recent years, as well as distinct spatial patterns of development. These patterns appear to be closely linked both to existing planning regulations and to the absence of a comprehensive spatial planning framework.

Tourism development constitutes a key pillar of the economy of the Greek island regions, but at the same time it is an activity that exerts significant spatial pressures. The shortcomings at all levels of spatial planning — national, regional, and local — leads to an inability to define clear directions and establish regulatory frameworks for managing tourism pressures and shaping a sustainable tourism model. The present study focuses on Mykonos, an island characterized by particularly intense tourism development. The aim is to examine, in quantitative terms, the spatial distribution of different types of accommodation in relation to areas within settlement boundaries, within traditional settlements, and in the exurban area. Accommodation units in Mykonos were digitized based on listings available on the Booking.com platform, distinguishing between hotels, rental rooms, and short-term rental properties. The boundaries of settlements and traditional settlements were digitized at a scale of 1:5.000. An overlay vector analysis was applied in order to extract quantitative results, followed by the production of the corresponding maps. The results indicate that more than 60% of the total accommodation stock is located in the exurban area of Mykonos. Although, in the case of both hotels and rental rooms, the largest share is also found outside settlement boundaries, this percentage is lower compared to short-term rental properties. The latter are significantly more numerous than the other types of accommodation, with approximately 79% of them located in the exurban area. These findings highlight that the exurban area of Mykonos, which was not originally planned for tourism development, has been subjected to intense pressures and has gradually transformed from rural landscape into dispersed urban formations. Short-term rentals, on the one hand, generate unplanned changes in land uses and, on the other, reinforce urban sprawl, constituting a major new challenge for spatial planning.

The phenomenon of short-term house rentals has developed rapidly in recent years. The most well-known platform offering primarily short-term rentals is "Airbnb". The factors influencing the demand in terms of location and sets the spatial distribution of Airbnb properties have been the subject of many studies. These factors include, among others, social, economic, and demographic aspects, as well as considerations of accessibility, the location and attractiveness of popular areas, and the characteristics of the available accommodations. The present study aims to identify, examine and evaluate the main factors that shape the spatial distribution of Airbnb accommodations in an urban environment, focusing on the Municipality of Athens. The research focuses on examining the relationship between Airbnb density, used as a dependent variable, and a set of euclidean distances and indicators as independent variables. These include euclidean distances from public transport infrastructure, from points of interest, from entertainment venues, etc., as well as walkability indicators. The methodological approach is based on the application of linear regression analysis, allowing for the exploration of direct relationships between Airbnb concentration and the independent variables. Emphasis is placed on identifying general trends and patterns that can improve the understanding of location choices within the short-term rental market. The results of the study are expected to contribute to a better understanding of Airbnb distribution and to support future research and planning approaches related to short-term rentals.

Urban housing markets are characterized by strong spatial differentiation, traditionally explained through factors such as property characteristics, location, amenities and socioeconomic conditions. However, the rapid expansion of short-term rental platforms has introduced new mechanisms of value formation, challenging conventional understandings of how housing prices and rents are determined. This paper empirically tests the concept of Algorithmic Rent Gap (ARG) as a framework for analysing how digital platforms contribute to the production of housing value. The ARG conceptualises the gap between current and potential rental income as increasingly constructed through platform-mediated processes, including dynamic pricing systems, demand forecasting and algorithmic visibility, particularly in short-term rental markets. The analysis focuses on four European cities—Copenhagen, Berlin, Madrid and Athens—representing different housing regimes and regulatory contexts. By examining spatial patterns of rental prices, short-term rental activity and neighbourhood-level market dynamics, the paper assesses whether algorithmic valuation processes contribute to housing price differentiation and market segmentation. The findings suggest that the ARG operates as a significant driver of housing market transformation, particularly in contexts with high levels of tourist demand and limited regulatory control. In Southern European cities, platform-mediated valuation amplifies rental inflation and reinforces spatial clustering of high-value areas, while in Northern European contexts its effects are more unevenly mediated by institutional frameworks. The paper argues that understanding the geography of housing markets requires incorporating digital valuation processes as a key determinant of price formation. The concept of Algorithmic Rent Gap provides a novel framework for analysing how platform-mediated dynamics reshape housing markets and intensify socio-spatial inequalities across urban contexts.

Across European cities, housing systems are under growing pressure from affordability crises, demographic change, and the need to adapt existing building stock to new social, economic, and environmental conditions. While academic and policy debates tend to focus on state-led provision or market-driven development, far less attention has been paid to the role of residents themselves in adapting and transforming the existing housing stock, through incremental changes in their homes. Yet, these alterations are widespread and, as we argue, are becoming increasingly relevant in the context of the current housing crisis. This research adopts the approach of a “multisided individualising comparison” (Hilbrandt et al., 2017), juxtaposing insights from different in-depth case studies to identify shared features and abstract from the specifics of each case. For each case, we examine physical alterations to living spaces, the motivations of residents for altering their homes, the built environment in which these alterations are embedded, and the structure and dynamics of the housing market, as well as the respective regulatory context. Our aim is to document inconspicuous changes to the housing stock, trace the contingencies behind them and reveal the underlying logic of this form of housing production. The analysis draws on three European settings that vary widely in terms of urban design, housing market structures, and regulatory environments: London and Cardiff (UK); Athens (Greece); and Berlin (Germany). Based on a comparative analysis, this paper offers an alternative perspective on current housing developments by recognizing the role of residents in transforming living spaces and housing practices.

The evaluation of major transport projects is a rather critical component of contemporary spatial and transport planning procedures, particularly in metropolitan areas facing growing mobility demand, spatial inequalities and environmental pressure. In this context, appraisal frameworks are expected to go beyond mere cost-based assessments and adopt more integrated approaches that capture the wider spatial and socioeconomic effects of such major investments. Among the available analytical tools, spatial accessibility analysis and Quantitative Spatial Models (QSMs) have emerged as especially valuable for understanding how transport interventions reshape economic geography, urban structure and spatial interactions. This study examines the impacts of a new metro line in the Athens Metropolitan Area (AMA) through the combined use of gravity-based accessibility analysis and a QSM framework. Apparently, the novel approach followed, employs these two models separately. The first model measures the improvement in job accessibility and its distributional implications, while the second one, evaluates how the new rail-based infrastructure influences wages, residents’ and workers’ distributions as well as property values. Both models compare the current situation with a three-line metro system and the future scenario, where a fourth metro line is constructed; the key difference assumed between these two scenarios is travel times. In brief, the results reveal that a new metro line will improve average accessibility by 5.1%, however, the most pronounced changes are found in the Eastern and Northern suburbs (even more than 15%). The QSM predicts that the aggregated welfare level is improved by 2.86% across the city; the most eminent changes regarding wages, residents, workers and floorspace prices could be found again in the same suburbs. The findings are expected to be particularly useful for policymakers and planners seeking to prioritise transport investments that enhance transport inclusion and sustainable urban development.