Conservation and restoration of immovable cultural property
Conservation and restoration of immovable cultural property describes the process through which the material, historical, and design integrity of any immovable cultural property are prolonged through carefully planned interventions. The individual engaged in this pursuit is known as an architectural conservator-restorer. Decisions of when and how to engage in an intervention are critical to the ultimate conservation-restoration of cultural heritage. Ultimately, the decision is value based: a combination of artistic, contextual, and informational values is normally considered. In some cases, a decision to not intervene may be the most appropriate choice . Definitions. Narrow definition. The Conservation Architect must consider factors that deal with issues of prolonging the life and preserving the integrity of architectural character, such as form and style, and/or its constituent materials, such as stone, brick, glass, metal, and wood. In this sense, the term refers to the "professional use of a combination of science, art, craft, and technology as a preservation tool" and is allied with – and often equated to – its parent fields, of historic environment conservation and art conservation. Broad definition. In addition to the design and art/science definition described above, architectural conservation also refers to  issues of identification, policy, regulation, and advocacy associated with the entirety of the cultural and built environment. This broader scope recognizes that society has mechanisms to identify and value historic cultural resources, create laws to protect these resources, and develop policies and management plans for interpretation, protection, and education. Typically this process operates as a specialized aspect of a society's planning system, and its practitioners are termed built or historic environment conservation professionals. Functional definition. Architectural conservation is the process by which individuals or groups attempt to protect valued buildings from unwanted change. History of the architectural conservation movement . As a movement, architectural conservation in general, and the preservation of ancient structures specifically, gained momentum during the 18th and 19th centuries. It was a response to Modernism and its corresponding architectural perspective, which eschewed sentimental attachment to old buildings and structures in favor of technological and architectural progress and change. Prior to this time most of the ancient buildings that were still standing had only survived because they either had significant cultural or religious import, or they had yet to be discovered. The growth of the architectural conservation movement took place at a time of significant archaeological discovery and  scientific advancement. Those educated in the field began to see various examples of architecture as either being "correct" or "incorrect". Because of this, two schools of thought began to emerge within the field of building conservation. Preservation/Conservation were used interchangeably to refer to the architectural school of thought that either encouraged measures that would protect and maintain buildings in their current state, or would prevent further damage and deterioration to them. This school of thought saw the original design of old buildings as correct in and of themselves. Two of the main proponents of preservation and conservation in the  19th century were art critic John Ruskin and artist William Morris. Restoration was the conservationist school of thought that believed historic buildings could be improved, and sometimes even completed, using current day materials, design, and techniques. In this way it is very similar to the Modernist architectural theory, except it does not advocate the destruction of ancient structures. One of the most ardent supporters of this school of thought in the 19th century was the French architect Eugène Viollet-le-Duc. Victorian restoration of medieval churches was widespread in England and elsewhere, with results that were deplored at the time  by William Morris and are now widely regretted. Current treatments. The Department of the Interior of the United States defined the following treatment approaches to architectural conservation: Other nations recognize some or all of these as potential treatments for historic structures. Canada recognizes preservation, rehabilitation, and restoration. The Burra Charter, for Australia, identifies preservation, restoration, and reconstruction. Common architectural conservation/preservation problems. The earliest building materials used by ancient peoples, such as wood and mud, were organic. Organic materials were used because they were plentiful and renewable. Unfortunately, the organic materials used were also very susceptible to the two most  significant impediments to preservation and conservation: the elements and life (both human and animal). Over time inorganic materials like brick, stone, metal, concrete, and terra cotta began to be used by ancient people instead of organic ones, due to their durability. In fact, we know that these materials are durable because many ancient structures that are composed of them, even some built as far back as the Bronze Age, like Egypt's Great Pyramids, still stand today. Ancient buildings such as the Egyptian pyramids, the Roman Colosseum, and the Parthenon face common preservation issues. The most prominent factors affecting these  structures are the environment, pollution, and tourism. As the Earth's climate patterns change, so too do the environmental conditions governing these buildings. For example, the Colosseum has already faced lightning, fire, and earthquakes. The changing climate increases the accumulation of salt crystals on the outside of monuments like the Colosseum and the Parthenon. This phenomenon increases the deterioration of these buildings. The salt crystals further contribute to the black effect that man-made pollution has on these buildings. The Parthenon is especially exposed and many of the remaining marbles are eroding to the point that they may no longer  be identifiable. The pollution from corrosive agents in the air has also attributed to this deterioration. The third factor affecting ancient building conservation is tourism. While tourism provides both economical and cultural benefits, it can also be destructive. The Egyptian tomb of Seti the 1st is currently off limits to the public due to the deterioration that has been caused by tourists. The pyramids in Giza have also encountered problems due to large numbers of tourists; more tourists mean greater humidity and water presence, which can lead to erosion. All of the above factors complicate the conservation options available to  treat these buildings. Conservation process. Assessment. The first step in any building conservation project is a sensitive assessment of its history and merits. As noted architect Donald Insall states, "Every building has its own biography. A knowledge of the whole life of a building brings an essential understanding of its features and its problems. He gives the Parthenon in Athens as an example; built between 447 and 432 BCE to serve as a temple dedicated to the goddess Athena, its purpose over time changed to Christian church, mosque, and powder magazine before it became one of the most famous tourist  attractions in the world. Once the assessment is complete, the next step is a thorough measured survey with a tape, rod and level. Modern measuring techniques, such as photogrammetry (the use of aerial photographs to make maps and surveys) and stereophotogrammetry, are also used today to increase accuracy. Once the measurements are complete, there is an analysis of the structural stability of the building and its living pattern of movement. No building is permanently still; soil and wind can affect building stability and need to be documented. Finally, the architect or surveyor tests the electrical connections, plumbing, and other utilities  present in the building (this is more for historic and re-purposed buildings). For both ancient and historic buildings, lightning conductors and fire-fighting equipment are checked to make sure they can provide sufficient protection. At the end of this assessment process, the conservator will analyze all the collected data and decide on a conservation plan based on available funding sources.. Treatment. The phrase covers a wide span of activities, from the cleaning of the interior or exterior of a building — as took place at St Paul's Cathedral in London — to the rebuilding of damaged or derelict buildings, such  as the restoration of the Windsor Great Hall in Windsor Castle after a destructive fire in 1992. The 1985–1989 removal of 38 layers of paint and the cleaning and repair of the exterior sandstone walls of the White House in the United States are an example of building restoration. Buildings are structures which have, from time to time, particular purposes. They require ongoing maintenance to prevent them falling into disrepair as a result of the ravages of time and use. Building restoration can be thought of as that set of activities which are greater than year-to-year maintenance, but  which by retaining the building are less than a demolition and the construction of a new building. Not all building conservation seeks to follow the original design of the building. It is reasonably commonplace for the shell of a building — its external walls — to be retained whilst an entirely new building is constructed within. This approach is also referred to as adaptive reuse. Although techniques of architectural conservation are improving, the action of cleaning or repairing buildings can, with hindsight, be seen to cause problems that at the time were unforeseen. A good example is the unrestrained use of sandblasting  to clean smog deposits from soft-stoned buildings — a technique employed in the UK in the 1960s and 1970s — which has damaged the external faces of stonework to the extent that in some cases, later, the stonework has needed to be replaced. Contemporary building codes recognize such problems, and (it is to be hoped) mitigate poor outcomes. Case example: Ancient stone structures. Most ancient buildings are constructed of stone and have survived from antiquity as a result of the stability of this building material. However, stone can deteriorate rapidly without protection, particularly in our modern era of pollution and climate  change. Public awareness and outreach to promote architectural conservation. There are many organizations that work to raise public awareness of the necessity to preserve ancient and historic buildings and areas, across communities, users and government. In addition to promoting the cultural value of these buildings, and encouraging appropriate policies and strategies for conservation, the organizations can help in raising the required funding to implement conservation initiatives and plans, and often serve as a link between the community and local/federal governments to advance conservation projects. A brief list of architectural conservation organizations is below: Restoration. Building Restoration describes a particular  treatment approach and philosophy within the field of architectural conservation and historic preservation. It emphasizes the preservation of structures such as historic sites, houses, monuments, and other significant properties through careful maintenance and upkeep. Restoration aims to create accurate depictions of these locations and protect them against deterioration that could make them inaccessible or unrecognizable in the future. Overview. In the field of historic preservation, building restoration is the action or process of accurately revealing, recovering or representing the state of a historic building, as it appeared at a particular period in its history, while protecting its heritage value. Restoration  work may be performed to reverse decay, or alterations made to the buildings. Since Historic Building Conservation is more about fostering a deep appreciation for these famous structures and learning more about why they exist, rather than just keeping historic structures standing tall and looking as beautiful as ever, true historic building preservation aims for a high level of authenticity, accurately replicating historic materials and techniques as much as possible, ideally using modern techniques only in a concealed manner where they will not compromise the historic character of the structure's appearance. For instance a restoration might involve the replacement  of outdated heating and cooling systems with newer ones, or the installation of climate controls that never existed at the time of building after careful study. Tsarskoye Selo, the complex of former royal palaces outside St Petersburg in Russia is an example of this sort of work. Exterior and interior paint colors present similar problems over time. Air pollution, acid rain, and sun take a toll, and often many layers of different paint exist. Historic paint analysis of old paint layers now allow a corresponding chemical recipe and color to be re-produced. But this is often only a beginning  as many of the original materials are either unstable or in many cases environmentally unsound. Many eighteenth century greens were made with arsenic and lead, materials no longer allowed in paints. Another problem occurs when the original pigment came from a material no longer available. For example, in the early to mid-19th century, some browns were produced from bits of ground mummies. In cases like this the standards allow other materials with similar appearance to be used and organizations like Britain's National Trust for Places of Historic Interest or Natural Beauty will work with a historic paint color re -creator s to replicate the antique paints in durable, stable, and environmentally safe materials. In the United States the National Trust for Historic Preservation is a helpful resource. The polychrome painted interiors of the Vermont State House and Boston Public Library are examples of this type of heritage restoration. Types of Treatment. Historical conservation is the "preservation and repair of archaeological, historical, and cultural sites and artifacts". When dealing with building conservation, there are four primary types of treatment, or ways in which a property can be managed. Each one has their own objectives and limitations. The next two treatments  are a subset of preservation with some variation to account for the different requirements of the building and the needs of the institution. Reasonings for Restoration. The reasons to restore a building most frequently fall into five main categories. Value - Buildings hold intrinsic value not only in the history of the building, how it was used, but also how it was built. Historic buildings, notably pre-WWII, are built with higher quality materials and built under different standards than modern buildings. Architectural Design - Buildings have personalities, specific architectural elements that make the building unique and more valuable. Saving these unique  traits within original building are ideal. Sustainability - Restoring a building for another purpose than its original intent is called adaptive reuse. Financially, businesses are better off restoring a building and adapting it for modern use than constructing a new site. The buildings are often built to better standards and as mentioned above have unique architectural elements that can increase business. Cultural Significance - One of the most important reasons that a site is restored is because of its cultural significance. Certain sites are tied to a nation’s identity making the site more valuable for what it provides to the culture  than if it were demolished. According to Building Talk, “the renovation of heritage buildings is essential to the permanent residence of history and culture in the nation’s psyche.” One Chance Rule - When a building is demolished what is lost cannot be measured. The site could hold a one of a kind design element or a historically significant past currently unknown. The One Chance Rule is guided by the idea that there is only one chance to restore a site and missing that opportunity could destroy a site of unknown significance. Although rare, there are times when a site  would be demolished or reconstruction is chosen over restoration. This decision is made primarily when the resources to restore the site are unavailable. The challenge to reconstruction is that there is an element of conjecture in the process that can easily alter the site unintentionally. Another reason not to restore a building is the value and knowledge that can be gained from the material remaining within the building. The Society for the Protection of Ancient Buildings has a unique approach to the preservation of historic buildings, which focuses on the materials that were used in the building's construction and  what knowledge can be learned from the remaining material. Standards of Restoration. One of the biggest challenges to building restoration is that each country has their own terminology, standards, regulations and oversights which impact every restoration process. As a result, there are no international set of standards. Conservators often follow best practices in the restoration approach. Every restoration project will adhere to the standard that the property is to be used as it was originally intended. This standard will guide all other decisions in the restoration process. This would include which materials are selected, to methods of construction, and finishing  touches to the building such as fixtures. The property being restored is considered a record of its time. Any work undertaken will only be to restore the site to the specified time period and no removal of those historical elements will be made, however this does not exclude removing elements not historically accurate to the site. Best practices are as follows: Cultural Heritage Sites Cultural Heritage is the physical and emotional reflection of a society, their legacy, and what they value. Tangible or physical representations include the material of the culture, locations of cultural significance, and the community associated with  the culture. Intangible representations include oral stories, traditions, and the emotional connection to the cultural ancestors. The conservation and restoration of cultural heritage sites pose different challenges and often follow different guidelines because of designation of a heritage site. The United Nations Educational, Scientific and Cultural Organization (UNESCO) is a guiding resource in the conservation of cultural heritage sites. UNESCO's mission is to identify, protect, and preserve World Heritage Sites. The World Heritage List is constantly evolving as new sites of cultural significance are added. Another great resource for restoration of cultural heritage sites is the World Monuments Fund , which focuses on working with local groups around the world providing support for restoration, preservation, and stewardship. Restoration of Historic Buildings Restoration of historic buildings varies from country to country, just as with cultural heritage sites and other building restoration projects. Before any work is done on a historic building, conservator-restorers should consult local requirements. Best practices listed above still apply. One example of restoration of historic buildings is the work conducted by the National Park Service which owns and maintains thousands of historic buildings and has been a leader in historic preservation for over 100 years. The standards  were developed in 1975 and updated in 1992. The standards deal with the "...materials, features, finishes, spaces, and spatial relationships..." of historic buildings and are divided into preservation, rehabilitating, restoration and reconstruction. Agents of Deterioration. As buildings can sustain various forms of damage and deterioration over time, understanding the cause of this damage and finding the best way to treat and prevent it is an important aspect to building restoration. The Agents of Deterioration are the ten primary sources of damage to heritage objects and buildings comprised in a comprehensive list by the Canadian Conservation Institute. The Agents are physical  forces, fire, pests, light (ultraviolet and infrared), incorrect relative humidity, thieves and vandals, water, pollutants, incorrect temperature and the dissociation of objects. While each of the ten agents can affect a historic building, some agents cause more common types of damage that may be addressed through building restoration.