1. THE MEASUREMENT OF URBAN LAND CONSUMPTION AS A SOURCE OF INDICATORS OF ECONOMIC PERFORMANCE AND SUSTAINABILITY Rodrigo Bastías Castillo rbastiasc@minvu.cl Ministry of Housing and Urban Development. Housing and Urban Studies Commission. Urban Observatory. Sergio León Balza sleon@minvu.cl Ministry of Housing and Urban Development. Housing and Urban Studies Commission. Urban Observatory. IAOS-SCORUS Conference, Santiago. Chile. 20-22 October 2010 The International Network for Urban and Regional Statistics Standing Committee of the International Association for Official Statistics

2. The importance of measuring land demand This measurement is used to monitor city growth and the distribution of different types of land use, as well as for observing the economic dynamics associated with different land uses and, at the same time, analyzing the relationship between unoccupied and available land, with the possible impacts on valuable natural or agricultural production sites. This implies not only conducting statistical analyses, but also geographic analyses of the urban and potentially urban areas established in the Land Use Plans. This presentation will refer only to the statistical analysis of construction permits in cities and urban areas across different regions and municipalities.

3. How may land demand be measured by type of use? In 2005, the Urban Observatory began a geographical analysis of urban growth, using satellite images from 1993, 2003 and 2008. This allowed the institution to estimate the amount of occupied and unoccupied land without distinguishing the dynamic contributions of different land uses. Thus, Construction Statistics represent an interesting field of analysis. The calculation of land demand by reviewing construction permits refers to what may has been called “permissed land” in other publications on urban indicators, is only a preliminary approximation to this analysis. This paper includes information from the January 2003 - December 2009 period, at the country’s most basic administrative division: the municipality.

4. Methodological considerations for the estimation of “permissed” land The figures may refer to the net surface of urban land associated to construction permits, that is, they do not necessarily consider urban land that has been occupied through legal cessions authorized by the Municipal Constructions Department (DOM) such as streets and new open space. They do not include parks and geographical accidents (bodies of water and streams, hills, etc.) or their surrounding areas, which may be incorporated as urban land in the process of occupation. New apartment buildings tend to be built on previously occupied land, whereas land consumption associated to houses may imply new consumption. The database has registries with values that appear too high in relation to the square meters of land authorized for construction, originated by digitizing mistakes. For all these reasons, the information listed below was obtained by applying a series of filters, using the criteria that shall be described in the methodology. Finally, these figures were taken from the updated information from the first two months of each quarter, as well as provisional information from the third month.

5. Analysis of the 2003-2009 period: National situation

6. National situation

7. Regional situation

9. Land surface with construction permits in Regional Capital Cities

10. Estimated errors and Restrictions for analysis Underestimation. Repeated construction permits: association of several land uses to a single plot of permissed land: On average, each year around 6% of all permits are thus “repeated”. Since no criteria have been established for selecting one of these multiple land uses over another these repeated permits are not accounted when estimating the demand of permissed land. Overestimation. Repeated entries of permissed land surface for different permits of the same land use: These occur mainly in the “Houses” and “Industry” land uses and, to a lesser degree, in the “Commerce” land use group.

11. Methodology This database includes 46 land uses, traditionally organized into three large groups: Housing (which includes 12 different uses of houses and apartment buildings); Industry, Commerce and Financial Establishments (which includes 15 uses); and Services (which includes 19 uses). In order to generate a more precise analysis of urban construction authorizations –and their diverse impacts on land occupation in each region, city and municipality– the database has been organized into twelve (12) large land use groups.

12. Obtaining the twelve land use groups and applying site surface filters Three key steps were followed: 1.Extracting non-urban land uses: “Agricultural Industry,” “Fishing” and “Mines and Quarries.” After this step, the remaining land uses are organized into the 12 groups mentioned. 2.Selecting the permits for the urban area. This step eliminates approximately 50% of all construction permits to be analyzed. 3.Selecting permits for “New Constructions” and “Regularization of New Constructions”, but not “Extensions” and “Regularization of extensions,” since these take place on plots that already count with permits.

15. Final comments Although it may be necessary to review the methodology for the analysis of plot sizes associated with specific land uses, the methodological process generated data that has been found acceptable by urban development experts. This in itself is a substantial achievement. It could be recommended to define a series of indicators, such as those established by the Urban Audit, for example, –the proportion of different land uses as part of total land; –occupied and unoccupied urban land, and –occupation rates for different land uses, among others. We could also take advantage of the available geographical information systems to calibrate the precision of the information extracted from Construction Statistics.