In a previous post the social and economic importance of heritage conservation were already described. Also we promised that on successive posts we will go into more detail describing the three main aspects that need to be monitored to ensure such conservation. Refreshing your memory, they were:
Relative humidity and temperature.
Lighting (natural and artificial).
Contaminants.
As promised is debt, in this post we will focus on the first point (be patient, we will talk about others further on), which makes us to face the heritage “bad boys”. Relative humidity and temperature are very damaging in the effects they can cause on the materials of which historic buildings are made of. Taking advantage of Physics, relative humidity is a very useful indicator of the water content in the air (vapour), and, on the other hand, temperature indicates the level of kinetic energy (movement) of the molecules of the air.
Both parameters vary according to the local meteorological conditions, the human actions and the conservation state of the historical buildings. This means that the atmosphere surrounding the historical buildings consist of a greater or lesser amount of water vapour at a certain temperature, definitely influencing the physical & chemical stability of the materials of which they are built on, or even of which the objects inside are composed.
In this sense, it is not negligible the effect caused by people, not only by our increasingly demanding comfort requirements, but by the number of visitors. We can influence the relative humidity and the temperature in such a way that inadequate values are reached. The effects of people are added to those of the local climate (more or less wet or warm), to the assets by itself (watertightness and ventilation capacity), to the derivatives of the proximity of heat sources (heating, sunny glass surfaces, old artificial lighting systems), the proximity of cold sources (external walls or air conditioning systems), as well as sources of humidity (leaks and floods).
The main factor to be controlled because the risk of direct deterioration that could originate is just humidity. The amount of water vapour in the air results in dimensional changes such as the well-known expansion and contraction of wood, making fractures and cracks when strong fluctuations happen. In addition, extreme relative humidity values cause softening or drying of organic materials such as adhesives and binders. But it also affects the stability of inorganic materials, such as metals, accelerating the corrosion processes, especially in the presence of salts. In poorly ventilation and dirty conditions, high values of relative humidity will cause the proliferation of living organisms causing biodeterioration (from microorganisms to rodents … Disgusting!). Even health problems as shown in the image.
Conversely, the temperature accelerates the chemical reactions and favours the biological activity. It contributes to the softening of waxes and adhesives and the loss of adhesion between different materials, such as enamels.
Perhaps reading all this causes some discomfort (and even itching …). But, what can we do to prevent these adverse effects? The answer is as simple as reasonable: just avoiding too high or too low levels of temperature and relative humidity, ensuring the highest possible stability
Following the indications of the IPCE (Spanish Cultural Heritage Institute, dependent on the Ministry of Culture), which establishes the National Preventive Conservation Plan (PNCP), the evaluation of risks derived from the microclimatic factors of which we are talking about, three aspects must be monitored:
Extreme levels of relative humidity and air temperature.
The magnitude and speed of fluctuations in relative humidity and air temperature.
The proximity of sources of humidity and heating or cooling emission sources.
A wide range of sensors is available on the market to monitor temperature and humidity, either continuously or timely (see image). Indeed, it is necessary to know how to properly treat, interpret and integrate the data they provide.
What is not so frequent is using alternative methods to evaluate the effects of moisture on the materials of the built heritage. Even before these appear and the remedy is worse than the disease. CARTIF is a pioneer in the use of laser scanners to make this assessment. A recent article published in the prestigious international journal Studies in Conservation, together with the developments carried out for the European research project INCEPTION show that while 3D documenting a historical building, the level of humidity present in a known type of material could be registered in parallel. A trustworthy 2×1 to take into account in the minimum conservation expenditure times we live in. The cloister of the Cathedral of Ciudad Rodrigo (Salamanca, Spain) has been the choice for on-site validations.
An important example that gives account of the scope of applied research in cultural heritage by a technology centre within a sector where it still takes more than expected that not so new technologies to be of daily use.
Let me remind you that Europe features the most diverse, rich and numerous cultural heritage around the world. 609 million tourists visited the “old continent” by 2015 (29 million in 2014) according to the World Tourism Organization, and, although it is somewhat pretentious, it is suggested that 37% of these tourists are cultural tourists, a figure that grows by 15% each year. This “curious specie” wanders around the cities getting the urgent need to visit the built heritage and being actively involved in cultural events.
I agree on speaking about cultural heritage as a touristic resource is disappointing when heritage is properly identified as integrator item and a completely intangible social identifier, but also certainly is an economic resource and just making cash its sustainability is ensured. This is the way to fix and create thousands of jobs, which in turn reinforce the character of social backbone that heritage is by itself, even allowing to improve the citizens’ quality of life.
Because of this the public sector comes boosting the creation of more and more cultural attractions with the built heritage as backdrop. Cultural tourism is perceived as the main source for funding heritage preservation: tourists generate the resources needed for maintenance and restoration. Let’s see if this is really so in the coming years, since the Richards report, ensures there is a much higher offer than real demand right now.
Making sure the protection and the preservation of our built heritage is, today, more urgent than ever. Not only as “prey” of cultural tourism, and not only as a brand of territory (including citizens), but because of their vulnerability to pollution, climate change and socio-economic pressures. We all get sick from time to time and we know it is always better to prevent than cure. The same happens to the built heritage: it is as much desirable as important to have automated systems that continuously tell us how the built heritage is, preventing “ills” just before they are such as expensive as irreparable. It is somewhat comparable to doctor’s auscultation, but what do we need listening to? In the technical jargon we say “monitoring” and many types of sensors are used to, but three aspects are mainly registered:
The temperature and relative humidity. Both are always linked (in fact they are inverse). Any kind of heritage building has greater or lesser water content in the air at a given temperature, having a decisive influence on the physical-chemical stability of the materials they are made of. Inadequate conditions of temperature and humidity produce deformation and rupture; rust and corrosion; as well as bio-deterioration (emergence of organisms).
Natural and artificial lighting. the Sun, or electric sources are electromagnetic radiation mainly covering the ultraviolet (UV), visible (VIS) and infrared (IR) ranges. Together they cause photo-degradation (discoloration) and temperature increases, especially in the case of organic materials (paintings, textiles, books and documents).
Pollutants. The air composition and quality are altered by compounds that mostly come from the use of fossil fuels (road traffic, heating of buildings and industrial activities). These compounds are able to make chemical reactions that affect the materials causing corrosion; spots and coatings; and also bio-deterioration.
These parameters will be particularly broken in subsequent posts.
In any case, the role of technological centres as CARTIF is decisive to take step forward in the technical developments required so that monitoring can be done affordably and fully compatible with the aesthetics and functionality of the building. Relevant international projects on this regard where CARTIF is playing a major role are:
After Italy and recently China, Spain is the country that holds the largest number of human heritage sites. We are also a first order world tourist destination, with a yearly increasing cultural component. Playing at home, Castilla y León accounts for 60% of the Spanish heritage… Do we take the fingers out?
Have you ever thought on the importance of the monuments close to you?. Do you happen to know they really are a source of employment and local development?. Here you are a few lines to explain it, and also to make you understand how the applied RTD is effectively contributing to the study, protection, conservation, refurbishment and reuse of cultural heritage.
Since 1999, with the Florence Conference, and later with the World Bank and the UNESCO reports, cultural heritage is considered a rightful source of socio-economic development for the countries. It is really a form of capital that the economist David Throsby noted as ‘cultural capital’, i.e. an asset with specific key features (the economic value is added to the cultural value -primordial, symbolic, intangible-).
Europe is the region that counts with the most important and the richest cultural heritage all over the world. This contributes to attract millions of tourists every year. Obviously it helps to create jobs and enhances the quality of life of European citizens while reinforcing a common shared identity.
The European Union Treaty (Article 167) specifies that safeguarding cultural heritage (moveable and immoveable) must be treated as a priority for the EU and is the legal basis for protection initiatives including research on cultural heritage. Besides, UNESCO expressly states that “the protection of cultural heritage, as an expression of living culture, contributes to the development of societies and the building of peace”.
The protection and preservation of important monuments and sites is more pressing than ever as cultural heritage is exposed to pollution, climate change and socio-economic pressures. According to specialists in the field, the activities oriented to ensure the sustainability of heritage are proving to have a major impact boosting the local economy and attracting foreign capital (because of related cultural tourism).
The following figures emerging from the EVoCH Platform within CARTIF is a founding member, will take you on the way of we are talking about:
The recognition of the importance of the mentioned aspects leads cultural heritage to be considered into specific RTD proposals in the current EU Research and Innovation programme (Horizon 2020). In fact, since 1986 the EU has been supporting research for the preservation of tangible cultural heritage to develop ‘state of the art’ methodologies, tools and products.
During the last years, a few successful results of technology transfer are giving evidence that the most effective and practical way of supporting and developing innovative services, is a collaboration between applied research organizations and enterprises to make these fit ICT tools into their daily work. In CARTIF, we have been working in this field more than 15 years. Some of our projects, INCEPTION, COST Action i2MHB, SHBUILDINGS, RENERPATH or 3D Virtual Restoration of Historical Paintings, have developed the most innovative technologies.
A researcher installs a sensor in Palencia´s cathedral
This means that new technological solutions are really the basis to meet actual demands on the five internationally recognised levels of intervention on cultural heritage: study, protection, conservation, restoration and dissemination. Only in this way, reliable, fast, easy-to-use and affordable tools will be available to shift the very traditional procedures of those levels to the 21st century we are living in.
Consequently stable and high-quality associated skilled jobs will be created, directly related to an intrinsic and non-transferable resource such cultural heritage is by itself.
