Analysing the Main Standards for Climate-Induced Mechanical Risk in Heritage Wooden Structures: The Case of the Ringebu and Heddal Stave Churches (Norway)

Abstract

Studying, controlling and extrapolating the indoor microclimate of historical buildings have always been at the forefront among numerous preventive conservation strategies, especially in case of buildings made of organic hygroscopic materials, e.g., wood. The variations and fluctuations of the microclimatic variables, namely temperature (T) and relative humidity (RH), could have a detrimental effect on the mechanical properties of wooden objects, works of art and structures. For this reason, through the years, several guidelines have been provided by standards and protocols about the optimal microclimatic conditions that should be ensured to avoid the decay and the eventual catastrophic failure of heritage objects and buildings. In this work, two historical buildings entirely made of Scots pine wood have been analysed: the Ringebu and Heddal stave churches (Norway). These churches store several wooden medieval statues and paintings that are also susceptible to the effects of the microclimate. For this reason, the timeseries of the indoor relative humidity of the two churches have been analysed, in the framework of the indications provided by the standards. The criticalities of the existing protocols have been pointed out, emphasizing the need for systematically and periodically updated specifications, tailorable to a given case study of concern, without forgetting the ever-present needs of energy- and money-saving approaches.

Sustainable management of heritage buildings in long-term perspective (SyMBoL): current knowledge and further research needs

“…Damage functions and RAT may closely link environmental monitored or simulated data with the condition of objects in collections or inside HHB. The potentiality in the use of this novel RAT (Bertolin et al, 2021a) was tested using (1) real monitored microclimate data measured with thermo-hygrometers in Heddal and Ringebu (Califano et al, 2022a(Califano et al, , 2022b(Califano et al, , 2023 and ( 2) machine learning algorithms applied to analyse climate-induced risk of mechanical decay on valuable heritage objects kept indoors. In this framework, NTNU contributed (Califano et al, 2022a(Califano et al, , 2022b to analyse the several existing guidelines provided by standards and protocols about the optimal microclimatic conditions that should avoid decay.…”

“…, 2022a, 2022b, 2023) and (2) machine learning algorithms applied to analyse climate-induced risk of mechanical decay on valuable heritage objects kept indoors. In this framework, NTNU contributed (Califano et al. , 2022a, 2022b) to analyse the several existing guidelines provided by standards and protocols about the optimal microclimatic conditions that should avoid decay.…”

“…The potentiality in the use of this novel RAT (Bertolin et al. , 2021a) was tested using (1) real monitored microclimate data measured with thermo-hygrometers in Heddal and Ringebu (Califano et al. , 2022a, 2022b, 2023) and (2) machine learning algorithms applied to analyse climate-induced risk of mechanical decay on valuable heritage objects kept indoors.…”

Potential of frost damage of off-ground foundation stones in Norwegian Stave Churches since 1950 using land surface temperature

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Figure 4 Difference between the outdoor daily mean air temperature and surface temperature (ST) at the Heddal Stave church's location. The Air temperature data were collected outside of the stave church building envelope with a datalogger DL175H1 within the framework of the Symbol project (2018-2022), see Califano et al 2022a and 2022b [42] , [43] . ST data are those analyzed in this contribution.

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“…The differences are calculated as differences between the daily mean air temperature – as monitored outside the church using a Testo 175H1 data logger - and the datasets obtained from GLDAS-2.1 over the grid of 0.25° x 0.25°. For details on the monitoring campaign conducted in Heddal (see Califano et al 2022a and 2022b [42] , [43] ).…”