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Preventive and planned conservation![]()
Preventive conservation applied to built heritage: A working definition and influencing factors
A. Vandesande & K. Van Balen
Raymond Lemaire International Centre for Conservation and Department of Civil Engineering, KU Leuven, Heverlee, Belgium
ABSTRACT: Preventive conservation of built heritage is increasingly of interest to academic research and professionals in the sector, with promising examples that demonstrate the viability of this approach. Accordingly, there is ample data and material from different research fields, with scopes and focus. Nevertheless, a general overview or commonly held delineation is not yet developed. The aim of this paper is to develop a working definition for preventive conservation of built heritage. The research consists of an inductive analysis based on evidence originating from existing research within the UNESCO Chair on preventive conservation, monitoring and maintenance of monuments and sites (PRECOM3OS) network, literature on general building maintenance and short descriptive case studies, while using influencing factors of preventive conservation practice and implementation as a proxy. The proposed working definition of preventive conservation starts from condition-based maintenance with a monitoring system, which is the least destructive of all interventions which inevitably occur in the built heritage conservation process. While this preventive conservation approach has several benefits, its practice and implementation are characterised by different influencing factors, i.e. the available knowledge and know-how as well as financial, environmental and social factors.
1 INTRODUCTION
Preventive conservation has a long tradition in the fields of museology and archaeology, respectively as a conceptual approach to rapidly safeguard and document archaeological heritage on a site at risk and a practical risk management approach that assures optimum preservation conditions for movable heritage (Van Balen 2011). However, when considering the scope of built heritage, interventions are not limited to immediate response actions and the surrounding environment cannot be controlled. Research and practices related to preventive conservation approaches dealing specifically with built heritage were triggered during the last 3 decades. The topic became increasingly endorsed within international and European policies, as can be observed in the international soft law overview in relation to preventive conservation which was initiated by Cebron Lipovec and Van Balen (2008). A more in-depth research has been conducted by Pickard (2013) who examined the different resolutions, recommendations and provisions in cultural heritage conventions adopted under the auspices of the Council of Europe. These developments are also reflected in different EU-funded research projects and by international organisations that started implementing a pro-active approach towards monitoring and maintenance, such as the World Monument Fund with the Watch programme and UNESCO with the Reactive Monitoring and Periodic Reporting mechanisms. Within these developments, special notice should made of the 2008 FP7 project SPRECOMAH, or Seminars on PREventive COnservation and Monitoring of the Architectural Heritage. In 2009 this resulted in the establishment of the UNESCO Chair on preventive conservation, monitoring and maintenance of monuments and sites (PRECOM3OS) at the Raymond Lemaire International Centre for Conservation (University of Leuven) in collaboration with Monumentenwacht Vlaanderen and the University of Cuenca in Ecuador. The aim of the collaboration is identifying research and educational activities in the field of preventive conservation, as well as developing new tools and techniques to improve preventive preservation strategies while considering a variety of cultural and social contexts.
As outlined at the PRECOM3OS UNESCO chair conference of 2012 (Van Balen and Vandesande 2013), built heritage preservation approaches are mainly focused on curative conservation and restorative treatments, which do not always result in the removal of causative factors. Once conserved, the historic structure can return to an environment leading to further deterioration, likely requiring future interventions, and establishing a reactive pattern of treatment. In contrast, preventive conservation approaches are more effective in maintaining heritage integrity and more cost-effective within a long-term perspective. Thereby the main benefits of a preventive conservation approach for built heritage are considered the cost-effectiveness for built heritage owner-managers (Forster and Kayan 2009), the quality protection of built heritage, the prolongation of the physical service life of buildings and building parts (Vandesande et al. 2014) and the empowerment of local communities in dealing with heritage (Della Torre 2010) and the exploitation of their services in heritage management.
Parallel to these developments, preventive conservation of built heritage also became of interest to academic research outside the PRECOM3OS network (to name some: Myrbakk and Myrbakk 2001, Lloyd and Staniforth 2000, Abdul-Rashid and Ahmad 2011) and promising examples that demonstrate the viability of this approach can be identified. Accordingly, there is ample data and material from different research fields, with scopes and focus. Nevertheless, a general overview or commonly held delineation is not yet developed. The aim of this research is to develop a working definition for preventive conservation of built heritage and define the factors that influence preventive conservation practice and implementation. The research consists of an inductive analysis based on evidence originating from existing research within the PRECOM3OS UNESCO Chair network, literature on general building maintenance and short descriptive case studies, while using influencing factors of preventive conservation practice and implementation as a proxy. The research process entailed critically interpreting the different data sources, categorising and coding the outcomes into larger thematic patterns and verify the results in a larger context in order to facilitate new theory building on preventive conservation.
2 PREVENTIVE AND PLANNED CONSERVATION: A WORKING DEFINITION
The results the research process are structured according to the preventive conservation framework developed by the PRECOM3OS UNESCO Chair, which starts from 3 classes of preventive conservation for built heritage based on the classification of disease prevention in medicine (Gordon 1983):
ā Primary prevention: avoid the causes of the unwanted effect (damage);
ā Secondary prevention: condition-assessments and monitoring to enable early detection unwanted effects (damage) and respective symptoms;
ā Tertiary prevention: avoiding further spread of the unwanted effect (damage) and the formation of new unwanted (side) effects (damage).
2.1 Maintenance: Avoid the causes of the unwanted effect
āThe successful preservation of an historic building, complex or city depends on its continued use and the daily care and maintenanceā (DāAyala and Fodde 2008: xv). Maintenance is a widely applied strategy, also in different sectors and disciplines and with a wide variety of definitions, scope and characteristics. Over the past decades, its application has considerably evolved due to an increased maintenance need for a variety of assets and properties with complex designs, new maintenance techniques and changing views on strategies, organisation and expectations (Moubray 1997). These shifts in strategies are reflected in the actual scope and definition of maintenance. The technical committee CEN/TC 319 working on āmaintenanceā within the European Committee for Standardization (CEN), brings together the contributions and needs of the specific sectors in relation to the more general maintenance discipline. The different CEN/TC 319 subcommittees, including i.a. terminology, risk based inspection framework (RBIF), quality assurance requirements for maintenance operations, maintenance process, maintenance performance and indicators and maintenance of buildings, have developed a series of āhorizontalā standards applicable to different sectors and have links with other European and international committees that deal with issues related to maintenance, such as facility and asset management (Talamo and Bonaomi 2015). The CEN-EN 13306 (2010) standard on terminology defines maintenance as the ācombination of all technical, administrative and managerial actions during the life cycle of an item intended to retain it in, or restore it to, a state in which it can perform the required functionā. Furthermore, this European Standard specifies generic terms and subdivisions of maintenance. Specifically, preventive maintenance strategies have a long scientific research tradition and a large applicability in different sectors. They are generally defined as regular maintenance actions at predetermined intervals, or according to prescribed criteria, performed on equipment and infrastructures to reduce probability of failure or degradation an extend their life-span (Lewis 1991, Sullivan et al. 2004).
Image 1. Overview of maintenance as defined by CEN ā EN 13306 (2010), based on Lind and Muyingo (2012).
Maintenance strategies can vary greatly depending on the context of the maintenance operation (Ahire et al.2000). For building maintenance, several factors that determine this context e.g. geographical spread, range of environmental exposures, structural complexity, any deterioration in condition and the number of people involved in its management (Bartholomew-Biggs et al. 2006). Choosing appropriate maintenance strategies based on allocation of resources and defined maintenance standards is an important step in the building maintenance operation process (Lee and Scott 2009).
Approaches and arguments for selecting specific strategies are ample (Horner et al. 1997). For each strategy, different management and organisational problems can observed which result from a lack of understanding between maintenance personnel and managing directors who criticise the inefficiency of maintenance implementation (Zavadskas et al. 2010). In the face of decreasing maintenance resources, technology is increasingly a tool to assist personnel and enhance the quality and efficiency of maintenance (Lee and Wang 2008). In practice, the building maintenance strategy choice depends on available resources in combination with common factors, i.a. building characteristics, owner-managers, technical, administrative and political factors (El-Haram and Horner 2002).
Although this overview provides an insight on the possible maintenance strategies for buildings, the two related ideas of standardisation and a common approach are debatable in context of built heritage. Standardisation is applicable to specific technologies, i.a. geometric measurements and Non-Destructive Tests (NDTs), but standardised approaches and strategies to understand and maintain historic structures do not align with the specificities of historic interventions and additions on a building, local building technologies and cultural context. Rather a general rationale can be put forth, i.e. the most effective general maintenance strategy consists of a broad and flexible approach involving economic, social, cultural and technical considerations. Within this general rationale, āas little as necessary, as much as possibleā has become a commonly expressed maxim in regard to maintaining built heritage (Dann and Wood 2004). This observation essentially illustrates that built heritage strategies should not just be based on corrective or preventive maintenance but minimum interventions. Whereas some activities within the scheduled maintenance process are by definition redundant (Horner et al. 1997), regular and periodic condition surveys are identified to be more effective in pinpointing potential defects as early as possible and reducing the number of unnecessary interventions (Miele 2005, Dann and Worthing 2005, Gardāner 2000). Considering that historic structures themselves are the most important knowledge source about historic materials and construction techniques, these minimum interventions are essential to guarantee quality protection within the built heritage sector.
2.2 Monitoring: Enable early detection unwanted effects
Achieving an effective maintenance strategy for built heritage necessitates comprehensive data on the nature and condition of buildings (Wordsworth 2001). However, considering that āminimal intervention can only work by utilising regular inspectionā (Feilden 2003: 236), this does not imply single condition assessments. Since the 1990s, a pro-active approach towards monitoring has indeed become an important development in conservation field. āThis emphasis is the reflection of the growing commitment to improving managemen...
