Sustainable architectural conservation is the process of maintaining architectural and heritage buildings and elements while seeking to extend and prolong their existence, or to keep them as monuments of humanity’s built heritage which dates back to earlier times. With the rise of the idea of historic and heritage buildings conservation in the 18th and 19th centuries, architects generally adopted the restoration approach as a mechanism for the maintenance and preservation of those buildings. With the development of concepts in the field of conservation, this concept was shifted gradually in to sustainable conservation which includes the process of maintaining and preserving the establishment along with taking into consideration the realization of its values, its relation to its urban fabric and the characteristics of the society where it is located and its connectedness to it.
Conservation of the built heritage began to shift gradually form including mainly the goal of protecting monumental or individual historic buildings, to a comprehensive realization and appreciation of the built urban environment which in addition to the conservation of historic buildings, it usually includes other aspects like the conservation of outstanding traditional buildings, heritage urban fabric, a particular pattern or architectural style of an alley or heritage street and the architectural spatial relationships between buildings and neighbouring outside spaces.
The conservation process developed and turned from being a group of reflexive interactive processes focusing on avoiding any change in the historical structure, into adaptable flexible processes which contribute in helping the society to understand and recognize its historical environment and thus to control and manage the process of transformation and change in the best available way. Hence, the process of conservation is no longer limited to the physical interventions, as for example the processes of interpreting and setting the sustainable use of the place and making the decision about the appropriate reuse of the heritage building or the historical site are the best mechanisms for its conservation and preservation.
The process of architectural conservation includes multiple and different policies and mechanisms which are based mainly on the level of practical intervention on the building in question. Accordingly, the levels of interventions vary from one another, depending on the amount of change and transformation need to be applied on the original building which often prefers the lowest level of the required and necessary intervention, in order to minimize the extent of change and modification applied on the original building.
Conservation policies are divided mainly into two parts: “Preventive Conservation” and “Curative Conservation”:
-Preventive Conservation: also called indirect Conservation. It includes all preventive and proactive processes
which prevent or delay the deterioration and collapse of the historic building. It includes also indirect activities which are physically and practically non-affective on the building. It also includes the documentation, registration, examinations, and periodic surveys of the building and the determination of the effects of pollution and other damages that may affect the building. Moreover, it aims at raising the heritage and economic value of the building.
-Curative Conservation: also known as direct conservation; includes effective interventions according to the following levels:
• Protection: includes all maintenance procedures and simple interventions which contribute to the protection of the building and delay the deterioration speed of its current architectural and functional levels such as cleaning, repainting, removing the stuck plants on the building and controlling any source of damage.
• Preservation: preserving and maintaining the current image of the building while preventing and minimizing the effects of its deteriorating and collapsing factors and protecting it from the anticipated future damage. It includes renovating and repairing all damages resulted from the factors affecting the building. This is in order to keep their historical and architectural values as they are.
• Consolidation: strengthening and enhancing the structural frame of the heritage building through the physical addition of retaining and supporting materials to ensure the durability and safety of the structure. Also, this is to prevent the deterioration of its structural condition which might lead to the loss or collapse of the building, without affecting the historical and heritage elements values.
• Restoration: the process of revving and preserving the building as it is, and restoring it back to its original condition when it was first established or to its condition at a specific previous point in time. It includes, for example, the removal of unknown elements, cleaning works, previous replacing works of desolated parts with new ones while distinguishing them from the old parts. It also includes reassembling and reinstalling the collapsed building through collecting its scattered parts (especially the stone ones) while merging them with new materials, when necessary, on the basis of authentic historical evidence and documents.
• Rehabilitation: includes all the procedures and interventions that aim at reviving the building functionally whether to the same previous function or any suitable function which is compatible with the original function of the building. This is through applying the necessary modifications, changes, alterations and additions which are required to adopt the proposed function based on extensive and comprehensive studies, without affecting the values and the conditions of the building’s different elements. This policy includes the adaptive reuse which aims at adopting an appropriate and suitable new function for the site or the historical building which promotes its cultural, social and economic values.
• Replication and Reproduction: it is the process of making a replica or replicas of an element or part of a historic building because it was damaged or because there will be an environmental threat if it is kept in its original location. Thus, it is replaced with a manufactured replica to keep the unity of the theme of the building or site, while retaining the original part within a protected environment like museums for instance.
• Reconstruction: the process of reconstructing an element or a historic building that was demolished or collapsed as a result of natural disasters or wars, by using modern materials based on authentic documents. It also includes the process of re-establishing a historic building and moving it from its original location to another in order to protect it from the dangers and threats of the natural and environmental factors. This term is currently used in the re-establishment of historic sites and heritage buildings digitally through a re-representation using 3D modelling software which creates the space and environment of the virtual reality.
Nowadays, the concept of Sustainable Conservation is not limited to archaeological sites and historic and individual buildings only. However, various conservation mechanisms are usually employed to protect and maintain all established buildings whether they are historical, traditional or modern, aiming at protecting the resources economically and the urban fabric environmentally, and the characteristics of the society culturally, which usually require adopting the various sustainable conservation policies.
