Alessandra Cappai, Iván Alvarez León, Maurizio Minchilli on "Identification and georeferencing of second homes: a planning support in the Sardinian coastal municipalities"

1. Seventh Interna;onal Conference on Informa;cs and Urban and Regional Planning
Cagliari, 10‐12 May, 2012
Iden%fica%on and georeferencing of second homes:
a planning support in the Sardinian coastal municipali%es
Alessandra Cappai, Iván Alvarez León, Maurizio Minchilli
Facoltà di Archite/ura di Alghero, Università degli Studi di Sassari
Research funded by the Regional Law 7/2009 “PromoFon of scienFfic research and technological innovaFon in Sardinia”

2. Introduc%on
Object of the research: to build an informaFon system that allows to define the amount and
distribuFon of second homes in the Sardinian coastal land.
Methodology: based on the integraFon of data in a geo‐staFsFcs integrated environment such as that
made available by Geographically based InformaFon Systems
Contents :
‐ Methodology for homogenizaFon of the collected database
‐ Monitoring of second homes’ number
‐ LocaFon of second homes in the land through cadastral cartography

3. 1. Choice of case studies
STEP 1: coastal municipaliFes idenFfied by the STEP 4: municipaliFes that collaborate giving
Sardinian Piano PaesaggisFco Regionale or PPR us the requested informaFon
(Regional Landscape Plan)
165 20
STEP 2: number of unoccupied dwellings provided
by ISTAT with a percentage of unoccupied homes
of more than 30% with respect to their total
56
STEP 3: municipaliFes with a total of more than
2000 property units
35

4. 2. Methodology for homogeniza%on of the collected database
In order to calculate the number of dwellings registered as "second homes", it was decided to refer
to those municipal taxes related to the condiFon of residence.
‐ ICI (Municipal Property Tax), which following the fiscal decree 93/2008 is abolished for the first
houses (usual residence involving enrollment in the residents’ Registry in the municipality where
the property is located), and is then charged to the owners of second homes and for other types
of luxury homes, villas, castles and palaces.
‐ TARSU (Urban Solid Waste Tax): municipaliFes choose the criteria by which they calculate this tax,
some of them differ in the rate between the first and second homes, others based on the surface
area or the number of rooms and so on.
Through the analysis carried out we will come to calculate the number of second homes "officially"
registered as such, though knowing that there is a large number of second homes registered as the
first one, but actually used only during the summer months, therefore they are difficult to detect.

5. 3. Monitoring of second homes’ number
The database contains as many rows as
there are ICI or TARSU taxpayers, therefore,
if a house belongs to X different owners, the Sheet Cadastral Subaltern Cadastral % Months Address Owners
Map Category Possession Possession residence
same will appear in the database X Fmes,
2 1576 50 A02 10000 2 Via Guia Saluzzo
according to all the owners who pay tax 2 1055 1 A02 357 5 Via dei Mille s/n Valledoria
according to the percentage of ownership. 2 1055 3 A02 357 6 Via dei Mille s/n Valledoria
2 1055 4 A02 357 6 Via dei Mille s/n Valledoria
2 1055 2 A02 357 12 Via dei Mille s/n Valledoria
2 1055 1 A02 358 12 Via dei Mille s/n Castelsardo
2 1055 2 A02 358 12 Via dei Mille s/n Castelsardo
The operaFon of homogenizaFon has been Typical database based on ICI taxpayers supplied by the
based on skimming the database through Tax Office
which we delete the rows that repeat the
same Sheet, Cadastral Map, Subaltern.

6. 3. Monitoring of second homes’ number
Calcula;on of second homes through the data collected in the Public Administra;on (ICI and TARSU taxes) and
comparison with data from Istat 2001.

7. 4. Loca%on of second homes in the land through cadastral cartography
In order to locate second homes in the land, we proceed by cross referencing cadastral data present in the
revised municipal databases and the available cadastral cartography.
The difficulty encountered in this phase of work is due to the mismatch of the cadastral data: municipal
databases refer to the Buildings Cadastre, while the only available georeferenced or digiFzed cartography is
that of the Land Cadastre.
Following the unificaFon of Land and Buildings Cadastre in a single enFty (Land Agency), it has been made
mandatory to unify the codes for buildings and land, giving priority to the la/er. In recent years it has been
carrying out a process called "Alignment", through which every building is associated with the Sheet and
Cadastral Map code of the land in which it is located.
The following cartography has been used:
‐ numeric CTR in various versions, both vectorial and integrated in GeoDB structure;
‐ Orthophotos from various periods (both based on historical sFlls and on new digital coverage) with GSD
from 1m to 0.1m;
‐ large‐scale vectorial cartography of the coastal municipaliFes;
‐ planning at the local level (P.di F., PRG and current PUC) for an iniFal idenFficaFon of areas of tourism.

8. Plots occupied by Second Homes

9. Density of Second Homes occupied in each plots
Number of Second Homes

10. Discrepancies between tha data base of Second Homes and the reality.

11. Discrepancies plots occupied by Second Homes
“uncertains plots”

12. Summary table of the results obtained by the process of cross referencing data with cartography
Empty
Empty dwellings Not Not
Municipality dwellings Georeferenced Uncertains
Monitoring ICI identifiable georeferenced
ISTAT
Alghero 8720 10447 118 7305 1060 3024
Stintino 3347 4728 9 0 - 4728
Sorso 4833 6049 100 4794 292 1155
Castelsardo 1066 2360 6 1899 354 455
Valledoria 1285 1965 - 0 - 1965
Badesi 1111 1508 3 1033 113 472
Trinità d'Agulta 3466 4805 9 3717 390 1079
Santa Teresa di Gallura 4410 6912 43 5086 916 1783
Palau 4074 4471 12 3819 288 640
Arzachena 8198 9350 64 1687 328 7599
La Maddalena 2773 8864 73 7012 1851 1779
Golfo Aranci 3572 5146 19 897 249 4230
Loiri Porto San Paolo 2236 4171 19 3413 177 758
Muravera 3470 4939 336 2925 1330 1678
Castiadas 513 1680 1148 380 129 152
Villasimius 3752 4933 0 4803 0 130
Maracalagonis 1585 1379 339 - - 1040
Pula 3180 2736 0 1705 584 1031
Domus de Maria 921 1388 239 787 145 362
Teulada 767 699 30 343 72 0
TOTALE 63279 88530 2567 51605 8278 34060

13. System occupancy of second homes in the first three km of the coastline
Diagram of system occupancy Result of system occupancy
First km of the coastline‐municipaliFes
Second km of the coastline‐ municipaliFes
Third km of the coastline‐ municipaliFes

14. Regional Landscape Plan (PPR) + Second homes map

15. Thanks for your a/enFon !!!
alecappai@hotmail.com‐ Alessandra Cappai ial79arq@yahoo.com –Iván Alvarez minchill@uniss.it – Maurizio Minchilli