Housing Supply Elasticity in Spain
A spatial proxy based on urban land availability
1 Introduction
This report studies housing supply elasticity (HSE) in Spain using a proxy based on urban land availability.
The main intuition is that municipalities with larger amounts of potentially developable urban land relative to already built urban surface should be able to respond more easily to housing demand shocks. Conversely, municipalities with limited land availability may face stronger housing supply constraints.
The analysis covers Spanish municipalities and autonomous communities over the period 1994–2024.
This work was carried out during a research assistantship at the University of the Balearic Islands.
2 Data and methodology
The dataset combines cadastral information on urban land with municipal geographic boundaries obtained through the mapSpain package in R.
The main proxy is defined as:
\[ HSE_{it} = \frac{\text{Potentially buildable urban land}_{it}}{\text{Built urban surface}_{it}} \]
where \(i\) denotes the municipality and \(t\) denotes the year.
The dataset includes:
- municipality and autonomous community identifiers;
- built urban surface;
- total urban surface;
- potentially buildable urban land;
- yearly values of the HSE proxy.
3 Outlier analysis
The distribution of the proxy contains some extreme values, especially among low-density municipalities. These cases are likely driven by municipalities with very small built surfaces or unusually large amounts of available land.
4 Housing supply elasticity in 2024
The following maps show the spatial distribution of the HSE proxy in 2024.
The top 2% of values are treated as outliers in order to improve readability.
4.1 Outliers
4.2 Municipal-level map without outliers
4.3 Autonomous community level
Municipal ratios are aggregated using total urban surface as weights:
\[ WR_i = \frac{\sum_{j \in M_i} r_j s_j}{\sum_{j \in M_i} s_j} \]
where:
- \(M_i\) is the set of municipalities belonging to autonomous community \(i\);
- \(r_j\) is the municipal HSE proxy;
- \(s_j\) is the municipal total urban surface.
5 Temporal dynamics
The report also analyzes the evolution of the HSE proxy across four-year periods between 1995 and 2023.
Changes in the proxy are measured in percentage points:
\[ \Delta HSE_{it} = (HSE_{it} - HSE_{i,t-4}) \times 100 \]
5.1 Municipal-level variation
5.2 Autonomous community variation
6 Urban surface dynamics
To complement the HSE proxy, the report studies the evolution of:
- built urban surface;
- total urban surface.
For these variables, yearly growth rates over four-year periods are computed as:
\[ g_{it} = \frac{1}{4} \left( \ln X_{it} - \ln X_{i,t-4} \right) \times 100 \]
where \(X_{it}\) represents either built surface or total urban surface.
6.1 Built surface
6.1.1 Municipal level
6.1.2 Autonomous community level
7 Total urban surface
7.1 Municipal level
7.2 Autonomous community level
