Every fall, thousands of stone sculptures or fountains are hidden under mostly wooden shelters to protect them from the winter. However, a large number of artistically valuable objects are thus invisible for almost half the year. Instead, passers-by are put off until next spring by stereotypical and aesthetically insignificant wooden crates or textile covers. With transparent protective covers, […]
Every fall, thousands of stone sculptures or fountains are hidden under mostly wooden shelters to protect them from the winter. However, a large number of artistically valuable objects are thus invisible for almost half the year. Instead, passers-by are put off until next spring by stereotypical and aesthetically insignificant wooden crates or textile covers. A research project now aims to make the objects visible all year round with transparent protective covers.
In recent years, more and more transparent enclosures have been purchased for objects in highly frequented locations, for example for the Marienbrunnen fountain in Altötting or the Schönen Brunnen fountain in Schwabach. Such decisions, in favor of urban quality, are of course to be welcomed, but they raise two problems: Firstly, the cost of the steel and glass constructions used here and the logistical effort involved are high. Secondly, transparent enclosures have so far been viewed critically by experts, as the solar input causes a “greenhouse effect” with high temperature and humidity fluctuations. This can put considerable strain on the protected object. So can transparent winter shelters be designed in such a way that they achieve or even exceed the same protective effect as conventional systems at a comparable cost?
Based on this question, a research team from the Fraunhofer Institute for Building Physics (IBP) and the Chair of Design and Building Envelope at the Technical University of Munich (TUM) began developing an enclosure system using transparent membranes in 2013. This should be easy to install, transport and store, be comparatively inexpensive and sufficiently durable and also provide a favorable indoor climate.
Many years of research into the durability of building materials at the Fraunhofer IBP have led to the realization that moisture is predominantly involved in the deterioration of natural and artificial stone. An enclosure should therefore reduce water ingress in the form of precipitation or condensation. Based on these findings, the research project attempted to take a different approach. The approach here is not to create a more constant internal temperature, but to reduce the material moisture of the protected object. The considerations:
In this case, the assumed transparency of the shell not only serves the purpose of making the cultural assets visible even in winter, but also uses the associated solar radiation to dry the monuments. When the sun is shining, moisture is to be dissipated via air exchange, while in less favorable climatic phases, moisture ingress through re-condensation is avoided. Controlled ventilation therefore plays a key role. In this way, year-round visibility and conservation requirements are to be combined in one concept.
This text is an excerpt from the article “Winter blast. Transparent enclosure systems for stone objects” in RESTAURO 7/2016. You will find the full article in RESTAURO from October 10, 2016, which will focus on the topic of stone conservation.












