Protecting our historic buildings in times of climate change
Museums, palaces and other historic buildings around the world are home to irreplaceable cultural treasures – centuries-old paintings, prized furniture and costly textiles to mention only a few. In northern Europe, mould growth or a higher risk of infestation with pests and insects could put all that into jeopardy, driven by projected increases in precipitation and changing outdoor and indoor temperature up to the year 2100. Meanwhile, south of the 50th degree latitude, the number of tropical nights is set to rise, bringing more periods of intense heat that will increase the demand for cooling. These are only some of the many findings of the EU research project Climate for Culture, which was jointly coordinated by the Fraunhofer Institute for Building Physics IBP.
The project brought together 27 partners from 16 countries in Europe and North Africa. Over a period of five years, a multidisciplinary team of chemists, physicists, meteorologists, oceanographers, conservators, IT specialists, economists, art historians and biologists worked on developing a methodology to reliably assess the impact of changing climate on our cultural heritage, conducted the necessary risk analyses and came up with measures for preserving historic buildings and their collections. "For the first time ever, a high resolution regional climate model was combined with building simulation to study the effects of climate change based on two moderate emission scenarios known technically as A1B and RCP4.5 from the Intergovernmental Panel on Climate Change (IPCC) reports AR4 and the future AR5", says Dr. Johanna Leissner, the overall project coordinator.
After years of intensive research, the main results were now presented at the final conference in Munich on July 9 and 10, 2014 as well as recommendations made for possible adaptation and mitigation measures for preservation. Especially the simulation results has shown that climate change will have negative effects such as an increase of mould growth in the North of Europe or rising sea levels especially in the North Sea. For some regions in Europe less energy for heating will be needed, which seems to be positive. In the context of the two moderate emission scenarios, climate change modeling may lead to specific predictions some of which may be regarded as negative, neutral or positive effects, at least seen from the present perspectives.
High-resolution climate models looking ahead to 2100
For generating information on future indoor climates in buildings and future energy demand for their climatisation, a set of 16 generic building types derived from more than 100 real historic buildings was developed. Temperature (T), relative humidity (RH) levels and fluctuations as the main environmental drivers of the risks for both building envelopes and collections were taken into account. Thus, various climate maps consisting of different climate parameters were created with a spatial resolution of up to 10x10 km grid size and for timeframes spanning the years 1960 – 1990, 2020 – 2050 and 2070 – 2100. Furthermore, damage mechanisms governed by physical, chemical or biological variables, e.g. freeze-thaw cycles, crystallization-dissolution cycles or mould infestation, were considered for generating risk maps. They showed either the risk levels for any of the three time windows (i.e. recent past, near future and far future) or the change in risk from one time window to another (i.e. difference between near future and recent past or difference between far future and recent past). The difference maps show whether a risk characteristic is increasing or decreasing and how much for each location over Europe.
Despite the moderate emission scenarios used the results showed that for example the Northern parts of Europe will suffer from wetter winters leading to higher risks for mould growth, whereas the energy demand for heating will slightly decrease. In the South however, the energy demand for cooling will increase substantially.
Building simulation extended to historic buildings
The data produced by the project partners were entered into a comprehensive database as basis for two hygrothermal simulation programs currently in use - WUFI® Plus and Hambase. WUFI® Plus enables the realistic calculation of the changing hygrothermal performance of multi-layered building components, as well as of the entire building, including heating and ventilation. The project database also contains many further building and component parameters needed by WUFI® Plus to calculate simulations correctly. Previously, it was impossible to show the effects of heat, damp, sunlight and water vapor on the fabric of historic buildings. In contrast to new buildings, where the parameters are already known due to the standardization of components, the same parameters have to be painstakingly measured in old buildings or determined by using average values. In the course of the project, researchers have expanded and modified the simulation programs so that all physical effects can now be mapped as well as the changes that occur when energy and humidity is transported in and out of buildings or individual components. Scientists can also simulate altered conditions in detail, including insulation, waterproofing of the building shell, changed building usage, heating, ventilation, etc., and the way that these changes impact the climate indoors.
This information makes it possible that sustainable concepts to protect historic buildings and their collections can be developed and appropriate modifications suggested.
"It is for the first time that climatic data has been collected on such a scale and fed into hygrothermal simulation models. Two kinds of building simulation tools proved to be suitable for historic buildings. We are particularly pleased to see that Fraunhofer IBP’s WUFI® Plus software is one of the two programs that will now help to protect historic buildings and their collections from the negative impact of climate change in the future", explains Prof. Dr. Klaus Peter Sedlbauer, director of Fraunhofer IBP. "This risk assessment is crucial", says Dr. Ralf Kilian, expert for preventive conservation at Fraunhofer IBP. "With WUFI® Plus, we can use forecasts to simulate the future and predict how indoor climates will evolve. At the same time, we can simulate the effect of proposed measures, and get an idea of whether and how effectively they will work."
Not neglecting costs
Furthermore, the project provides insight into the possible socio-economic impact of climate change, given the importance of cultural heritage to Europe’s economy. To date, attitudes, preferences and values for the protection of heritage assets from future climate impacts have not been investigated. Moreover, there is no comprehensive analysis of economic benefits associated with reducing climate change damages to built heritage interiors.
In this context a questionnaire with 24 questions concerning behavioral, attitudinal, and demographic issues was developed in order to ask museum visitors whether they would be willing to make an additional contribution to maintain cultural heritage. "We carried out visitor surveys in Germany, the UK, Sweden, Italy and Romania and were very pleasantly surprised to see that in all these countries a majority of visitors would be willing to pay additionally 1 to 2 Euros to the entry fee for specific sites and per visit for protection from gradual climate change impacts", says Dr. Johanna Leissner. The visitors were also consulted about their familiarity with climate change and its impact on cultural heritage. "Surprisingly, more than half of the respondents (62 percent) felt somewhat to very familiar with the impact of climate change on cultural heritage site", reports Constanze Fuhrmann, who carried out the survey in Germany at the Cistercian Monastery Bronnbach. But, for about a third of respondents, the enjoyment of the visit could be affected if climate change damages were present.
All results and findings are still being fed into an online software platform which provides a tool for users to obtain validated information about future climate change and its impact on historic buildings and their cultural treasures. Anyone interested can find climate, energy requirement and risk maps, as well as an expert system that provides owners and users of historic buildings with suggestions for specific measures they could introduce to ensure energy-efficient and sustainable air conditioning in these spaces.
More information, including a handbook about energy-efficient climate management and a softSware for digitalizing analog thermo-hygrograph data, can be found soon on the project website: www.climateforculture.eu. Detailed research findings will be made available to the public at the end of the year.