An assessment-based process for modifying the built fabric of historic centres: the case of Como in Lombardy Pier Luigi Paolillo, Alberto Benedetti, Umberto Baresi, Luca Terlizzi, Giorgio Graj -Polytechnic of Milan

1. Sixth International Workshop on "Geographical Analysis, Urban Modeling, Spatial Statistics" GEOG-AN-MOD 11 in conjunction with The 2011 International Conference on Computational Science and its Applications (ICCSA 2011) June 20 th to June 23 th, 2011, University of Cantabria, Santander, Spain Pier Luigi Paolillo(1), with Alberto Benedetti, Umberto Baresi, Luca Terlizzi, Giorgio Graj (1) Polytechnic of Milan [email_address] - http://webdiap.diap.polimi.it/paolillo/

2. 1. Why the historic centres : a preliminar consideration 2. The methodological process : from the selection of descriptor and variables to the final synthesis in the “ suitability for change” map 3. Method for analysing and assessing the characteristics of centrality and socioeconomic vitality 4. Assessing the values of the built fabric 5. The final step: the map of suitability for change and the relative types of change for the single built fabrics Use an algorithm to create scenarios of suitability for change 0. The framework assumed Estimate: (α) residenzial vitality (β) commercial distribution (γ) services accessibility ASSUMPTION OF THE BEST SCENARIO FOR SUITABILITY FOR CHANGE OF BUILT FABRICS Results: Socio/economic characterization 5 scenarios derived from “f” function Regional Laws Support to administration Identify types of change in built fabrics (art. 27 Lr.12/05) Classify priority of intervent in historic centre Goal: Define degrees of suitability for change of single buildings Goal: Identify and quantify demographic, economic, social tendency Suitability for change Social and economic phenomena Database organised to develop Gis analysis Multi/dimensional analysis Comparison between scenarios and socio/economic aspects, and selection of the best-one

4. 2. The methodological process : from the selection of descriptor and variables to the final synthesis in the “ suitability for change” map Identifying the variables Grouping the variables into summary indices Socio/ economical aspects Identifying the spatial units of investigation Historic/ architectural aspects Multidimensional/ algorythm analysis Areas of iso-problematicity Scenarios for change Identifying the descriptor blocks Selecting the most suitable scenario for change in this specific place Spatialising the phenomena (thematic mapping)

8. 3. Method for analysing and assessing the characteristics of centrality and socioeconomic vitality Indices and variables C) Density of localisation of the most strongly attractive activities Goal: Recognize the competitive areas from the economic point of view Indices: Density of commercial activities Density of service sector activities Density of commercial activities D) Stability of the inter-relating residential fabric Goal: Recognize problematic residential areas Indices: Incidence of the non-Italian resident population Incidence of residential vacancy Distribution of the population within buildings (underoccupation – overcrowding) Density of service sector activities Vacancy Indices Variables Resident nationality Residential buildings size Roots Census of built fabric Residential dataset Census of built fabric

10. 3. Method for analysing and assessing the characteristics of centrality and socioeconomic vitality Viewshed procedure Decomposing the observation points into a number of different viewshed analyses (e.g.: access points to the historic centre, busiest historic streets, open spaces for public socialising, and so on) Selecting observation points Sifting informational strata Summarising , referring as necessary to the qualitative characterisation of the particular building (E) Quantifying and summarising the degree of visibility of any given building Refining the analysis as appropriate (e.g.: distinguishing between buildings seen in perspective and buildings seen in the round ) Analysis: if k = 1 the building is visible

12. 4. Assessing the values of the built fabric Function indicating how various phenomenical aspects flow together into the built fabrics analysis where: F = suitability for retention, intrinsic in the building itself G = suitability for retention, in the relationship between building and urban block H = the urban landscape importance of the context in which the building stands I = suitability for increases in volume Assumption of descriptors block and variables

13. Indices and variables F) Suitability for retention, intrinsic in the building Goal: recognize the inclination towards transformation of built fabrics Indices/variables: F1 - presence of environmental and historic/architectural constraints F2 - persistence of buildings over time F3 - the state of conservation of buildings F4 - presence of facades to be retained F5 - presence of excrescences F1 - Contraints F2 - Datation F3 - Conservation F4 - Facades F5 - Excrescences 4. Assessing the values of the built fabric

14. Indices and variables G) Suitability for retention, in the relationship between building and urban block Goal: recognize the inclination towards transformation of built fabrics, in the relation with the urban blocks Indices/variables: G1 - presence of transformed areas (causing discontinuities in the urban fabric) G2 - degree of uniformity in respect to the first historic threshold adopted G3 - degree of uniformity in respect to the number of storeys G1 – Transformed areas G3 - Uniformity (number of storeys) G2 – Uniformity (first historic threshold) 4. Assessing the values of the built fabric

15. Indices and variables H) Urban landscape importance Goal: recognize the built fabrics impact on perception Indices/variables: H1 – presence of quality elements H2 – presence of elements of contrast H3 – index of perception of the building H4 – incidence of the building on the public space H4 – Perception from public spaces H3 – Index of perception (from historic roads, points of access, public places) H2 – Contrast factors H1 – Quality factors 4. Assessing the values of the built fabric

16. Indices and variables I) Suitability for increases in volume Goal: recognize the building that can be raised as number of storeys Indices/variables: I1 – character of the existing built frontage I2 – possibility of adding extra storeys 1 – Built-front with at least 50% fabrics with same height 3 –Buildings useful for raising storeys 4 –Buildings unuseful (as reference) for raising storeys 2 – Buildings with specific characteristics 4. Assessing the values of the built fabric

17. Algorhythm for assessing suitability for change 4. Assessing the values of the built fabric Assumption of an algorithm to classify the built fabrics Classification of the result values Aggregation of variables and indices in thematic blocks Assumption of different classes of suitability for change, for every built fabrics of the historic centre

18. 4. Assessing the values of the built fabric Building and selecting scenarios of suitability for change Devising the basic algorhythm of suitability for change Creating scenario 1 Types of change permitted by the regulations Correlating the classes of suitability for change to the consented methods of changes to buildings Preparing the map of suitability for change Devising different scenarios Territorial socioeconomic configurations Comparing scenarios and selecting the scenario that is most compatible with these territorial configurations

20. 5. The final step: the map of suitability for change and the relative types of change for the single built fabrics Final scenario of suitability for change Cartography From classes to types of change on built fabrics

21. 5. The final step: Comparison between prescriptions of the old Prg and the new assessment recognized by Pgt From a homogeneous classification of buildings To a new one, coherent with the specific characterization of the single built fabrics Previous planning instrument: Prg -General regulator plan (1975-1993) New planning instrument: Pgt -Plan for territorial government (2010)

22. References 1. Astengo, G.: Assisi: salvaguardia and rinascita. In: Urbanistica, n. 24/25 (1958) 2. Cervellati P.L., Scannavini, R.: Interventi nei centri storici: Bologna, politica e metodologia del restauro. Il Mulino, Bologna (1973) 3. Coppa, M.: Vicenza nella storia della struttura urbana: piano del centro storico. Cluva, Venezia (1969) 4. Cox, J., Thurstain-Goodwin, M., Tomalin, C.: Town Centre Vitality and Viability: A Review of the Health Check Methodology. London: National Retail Planning Forum (2000) 5. Crucitti, P., Latora, V., Porta, S.: The Network Analysis of Urban Streets: A Dual Approach. In: Physica A, Statistical mechanics and its applications, vol. 369, n. 2 (2006) 6. Fabbris, L.: Statistica multivariata. Analisi esplorativa dei dati, McGraw Hill, Milano (1997) 7. Fiale, A., Fiale, E.: Diritto urbanistico. Edizioni giuridiche Simone, Napoli (2008) 8. Fraire, M., Rizzi, A.: Statistica. Metodi esplorativi e inferenziali, Carocci, Roma (2005) 9. Hillier, B., Hanson, J.: The social logic of space. Cambridge University Press: Cambridge (1984) 10. Hillier, B.: Space is the machine: a configurational theory of architecture. Cambridge University Press (1999) 11. Gambino, R., Massarella, G.: Centro storico città regione. Franco Angeli Editore, Milano (1978) 12. Griguolo, S.: Addati. Un pacchetto per l’analisi esplorativa dei dati – Guida all’uso. Istituto Universitario di Architettura di Venezia, Venezia (2008) 13. Mioni, A., Pedrazzini, L.: Valorizzazione dei centri storici. Franco Angeli Editore, Milano (2005) 14. Nijkamp, P.: Soft multicriteria analysis as a tool in urban land-use planning. In: Environment and Planning B, 9 (2), pp. 197 – 208 (1982) 15. Nijkamp, P.: Multicriteria analysis; a decision support system for environmental management. In: Economy and Ecology; Towards Sustainable Development, Archibugi, F., and Nijkamp, P. (eds.), Dordrecht; Kluwer (1989) 16. Paolillo, P.L.: La misura della sostenibilità dei vincoli insediativi: un’applicazione di supporto alla Vas. In: Territorio, n. 25, 65--76 (2003) 17. Paolillo, P.L.: Acque suolo territorio. Esercizi di pianificazione sostenibile. Franco Angeli Editore, Milano, pp. 11--147 (2003) 18. Paolillo, P.L.: New survey instruments: studies for the environmental assessment report of the general plan in a case in Lombardy. In: INPUT08, Conferenza nazionale in Informatica and pianificazione urbana and territoriale, pp. 1 -- 10, Politecnico di Milano, Facoltà di Ingegneria, Polo regionale di Lecco (2009) 19. Paolillo, P.L.: New survey instruments: studies for the environmental assessment report of the general plan in a case in Lombardy. In: Rabino, G., Caglioni, M., (eds.) Planning, complexity and New Ict, pp. 215--224. Alinea, Firenze (2009) 20. Paolillo, P.L.: Sistemi informativi e costruzione del piano. Metodi e tecniche per il trattamento dei dati ambientali. Maggioli, Rimini (2010 ) 21. Rozzi, R.: Il nuovo Prg di Novara. In: Urbanistica Informazioni, n. 76 (1984) 22. Terranova, A.: Il piano particolareggiato per il centro storico di Melzo. In: Urbanistica Informazioni, n. 74 (1982) 23. Thurstain-Goodwin, M: Data surfaces for a new policy geography in Longley, P.A. and Batty, M. Advanced Spatial Analysis, The CASA book of GIS, ESRI Press, Redland (2003) 24. Voogd, H.: Prescriptive analysis in planning. In: Environment and Planning B: Planning and Design 12 (3), pp. 303 – 312 (1985)