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Article

The Threat of Moisture in the Partitions of Unheated and Heated Wooden Historic Churches in Poland

by
Grzegorz Nawalany
1,
Małgorzata Michalik
1,*,
Paweł Sokołowski
1,
Elżbieta Michalik
2 and
Zbigniew Lofek
3
1
Department of Rural Building, Faculty of Environmental Engineering, University of Agriculture in Krakow, al. Mickiewicza 24/28, 30-059 Krakow, Poland
2
Independent Researcher, 33-333 Ptaszkowa, Poland
3
Independent Researcher, ul. Kwiatowa 11, 34-100 Radocza, Poland
*
Author to whom correspondence should be addressed.
Sustainability 2025, 17(7), 2941; https://doi.org/10.3390/su17072941
Submission received: 6 February 2025 / Revised: 10 March 2025 / Accepted: 25 March 2025 / Published: 26 March 2025
(This article belongs to the Section Tourism, Culture, and Heritage)
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Abstract

:
This paper presents experimental studies of the formation of thermal and humidity conditions in two wooden historic churches in southern Poland. The environmental and cultural changes taking shape are creating the need to modernize existing buildings to sustainable standards. The modernization of historic religious buildings is complicated by restrictions on the intrusion of vertical partitions, which are often covered with valuable wall paintings. The paper focuses on the important aspect of preserving historically valuable buildings in good condition and assessing the threat posed by vapor condensation on the surface of the partitions. The studied buildings differ in terms of their uses and heating systems. Building A is unheated, while building B is equipped with a heating system. The scope of the study includes continuous measurements of the temperature and relative humidity of the indoor air inside and outside the studied churches. The work presents a detailed analysis and comparison of the formation of thermal and humidity conditions inside the churches. A computational model of the buildings was created, and then a computational simulation of the risk of water vapor condensation on the surface of the external walls was carried out. The analysis presents the influence of the external climate on the formation of the thermo-humidity conditions inside the buildings, especially in the unheated church. Also shown is the effect of the temporary heating of the church on ensuring the optimal heat and moisture conditions for historic wooden buildings. The analysis shows that turning on the heating only during the use of the church slightly improves the thermal and humidity conditions compared to the unheated church. Additionally, the analysis shows that the occasional use of the unheated church contributes to significant cooling of the church (even to −8.4 °C in the winter half year). Another conclusion that the computational analysis reveals is that water vapor condensation on the surface of the external walls is impossible. However, the difference between the air temperature in the church and the dew point temperature, specifically in the unheated church, is 1.6 °C. Therefore, at lower outside air temperatures, there may be a risk of water vapor condensation.

1. Introduction

Microclimate studies in historic buildings have become the subject of many studies in recent decades. The complexity of factors influencing the formation of the microclimate inside a historic church and the limited possibilities of interfering with the structures and equipment of historic buildings have led to an increase in the interest in research on such buildings [1,2,3]. The renovation of historically valuable buildings is complex and subject to stringent regulations, and any intervention in vertical partitions can be challenging. The exterior walls often represent architecturally significant volumes, while the interior walls are usually covered with wall paintings [4,5,6]. The preservation of historic objects in continuous use and the prevention of their abandonment is one of the most effective methods for maintaining the good condition of historic sites. Efforts regarding the energy modernization of such objects should align with conservation activities [1,7]. Depending on the type of historic building and its equipment, it is necessary to meet the requirements regarding the permissible range of the temperature and relative humidity of the indoor air suitable for storing works of art. It is also important to ensure thermal comfort conditions for the users of such facilities [8,9].
Inappropriate thermal and humidity conditions can adversely affect the preservation of historic objects, contributing to chemical, physical, and biological degradation. Large and rapid fluctuations in the indoor relative humidity are particularly dangerous for wooden structures due to the hygroscopic nature of the material, but they can also lead to the fading of dyes and the formation of deformations. Therefore, thermal and moisture phenomena play a significant role in maintaining the durability of the structural elements and valuable artifacts located inside the building [10,11,12]. The condensation of water vapor, in addition to its harmful effects on equipment, also contributes to a reduction in thermal resistance, which can lead to an increase in the heat flow passing through the partitions. Therefore, it is important that the surface temperature of the partitions is higher than the dew point temperature [13]. The use of ventilation and heating systems is essential for maintaining the appropriate thermal and humidity conditions in the building. However, most historic buildings do not have mechanical ventilation, and air exchange occurs only through leaks and open windows or doors [11,14,15]. Historic churches are often unheated or heated periodically. In unheated buildings, the external conditions play a significant role in shaping the indoor microclimate. During services, the number of people participating in the services also has a considerable impact. Consequently, changes in the usage of such a building, especially if services are held very infrequently, only a few times a year, can negatively affect the preservation of valuable, historically significant exhibits that are part of the building’s equipment. The application of appropriate heating in churches can contribute to periodic decreases in the relative humidity of the indoor air. At the same time, the risk of mold and fungi is lower in heated buildings compared to unheated churches [16,17,18]. Sudden changes in air temperature in historic buildings can affect the humidity levels in the building envelopes, as well as in works of art. Painted wooden objects are acclimatized to the environment in which they have been stored for years. Studies show that the safe range for relative humidity levels for historic objects is 50 ± 5%, while the safe air temperature range is 20 ± 5 °C. It should be emphasized that sudden fluctuations in the temperature and relative humidity of the indoor air are very detrimental phenomena, as they can cause changes in the structures of the materials [19,20].
The use of numerical models is a widely employed tool for analyzing the development of thermal and moisture conditions in various types of buildings, ranging from residential to agricultural, as well as in historic buildings [10,18,21,22]. For studies on the formation of thermal and moisture conditions in historic buildings, dynamic simulations are recommended, as they allow for the assessment of responses to changes in the external environment and the potential for optimizing HVAC system simulations. Due to the complexity of the geometry of such structures, lack of access to documentation, and changes made over the years, simulating the thermal and moisture conditions can be challenging [2,3,10]. To obtain the most accurate results, actual measurements are essential for the proper validation and calibration of the model.
This paper presents an analysis of the formation of thermal and humidity conditions in two historic wooden churches located in southern Poland. One of the churches is unheated, while the other is equipped with a heating system. The main aim of the study was to conduct a comparative analysis of the development of the thermal and humidity conditions in the unheated and heated wooden churches. The results were used to build a geometric model and numerical analysis, which, after validation, can be used for broader analysis and the development of recommendations and standards for historic wooden buildings under different types of use. The paper presents a numerical analysis of the possibility of water vapor condensation on the surface of the partitions. In addition, a biological risk analysis based on Sedlbauer isopleths is presented.

2. Materials and Methods

2.1. Research Objects

The research was conducted in two wooden churches located in southern Poland. Both temples were built in the 14th century in the Gothic tradition. The churches are wooden, constructed using the log cabin technique, and oriented. The sacristies and the presbyteries are covered with flat ceilings, while the naves feature ceilings with braces. The main difference between the studied objects is the way the buildings are used and the presence or absence of heating during the winter season. In one of the studied churches (building A), there is no installed heating system; this facility serves as an auxiliary church (Figure 1). On the other hand, the second studied church (building B) is continuously used for services and heated during the winter; it is equipped with an electric heating system consisting of seven wall electric radiators from Warmtec, with a power of 2500 W and a temperature regulation in the range of 6–30 °C (Figure 2).

2.2. Measuring Apparatus

In the studied facilities, from 1 May 2018 to 1 May 2019, continuous measurements of the temperature and relative humidity of the indoor and outdoor air were conducted at intervals of 10 min. The air temperature measurements inside and outside the facilities were carried out using PT-100 sensors, with an accuracy of ±0.1 °C and a measurement error of ±0.1 °C. For measuring the relative humidity of the indoor and outdoor air, a DTH22 sensor was used, with a measurement range of 0–100% and an accuracy of 2%.
The distribution of the measuring points in both churches is shown in Figure 3 and Figure 4. One sensor was installed in the presbytery, marked with the symbol “I”, at a height of 1.8 m. One sensor was placed by each of the side altars (in the nave), marked with the symbols “II” and “III,” also at a height of 1.8 m, and another was installed in the choir, marked with the letter “IV”, at a height of 4.0 m. Additionally, an external measuring station was installed to monitor the external parameters (temperature and relative humidity of the outside air, wind speed and direction, and solar radiation intensity), marked with the symbol “V”.
The obtained measurement results were used to analyze and compare the development of the temperature and relative humidity in the indoor air of the heated and unheated wooden historic churches. The evaluation of the formation of thermo-humidity conditions was based on the PN EN 15757 (Conservation of Cultural Property—Specifications for Temperature and Relative Humidity to Limit Climate-Induced Me-chanical Damage in Organic Hygroscopic Materials) [23] standard, which introduces the concept of historical climate, to which the interior of a building is acclimatized. However, when there is a change in the use of a historic building, there is a change in the fluctuation in the temperature and relative humidity of the indoor air. Accordingly, the range of temperatures and relative humidity values accepted in the literature as optimal for museum facilities was appended to the evaluation. The required temperature ranges for such facilities are 20 ± 5 °C, and 50 ± 15% for the relative humidity inside the building [19,20,23,24,25]. Additionally, this study allowed for a numerical analysis of the risk of condensation of water vapor on the external wall surfaces of the churches.

2.3. Numerical Analysis

Based on the method of elementary balances (MEB), a numerical analysis was carried out using the WUFIplus® (Version 3.5) computer program. Using the collected data, a geometric model of the churches was created in the program, reflecting the actual data (Figure 5). The resulting model was divided into balance differential elements. This program allows for calculations under non-stationary conditions. The heat flow through the analyzed area was calculated in a non-stationary framework, assuming a time interval of Δτ:
ΔQ = Δτ⋅(Φixiyiz,ix+1iyiz + Φixiyiz,ix−1iyiz + Φixiyiz,ixiyiz+1 + Φixiyiz,ixiyiz-1 + Φixiyiz,ixiy+1iz + Φixiyiz,ixiy−1iz)
where
i—the number of element;
Φixiyiz, …—the heat flux flowing between the element ix iy iz and the adjacent elements [W].
Sustainability 17 02941 g005
Figure 5. Geometric model: (a) building A, (b) building B in WUFIplus® program.
Figure 5. Geometric model: (a) building A, (b) building B in WUFIplus® program.
Sustainability 17 02941 g005
The properly prepared, validated, and calibrated church models allowed for the calculation of the risk of water vapor condensation. The model was statistically tested. The Spearman rank test (α = 0.05) showed a strong correlation of the data, while the Kruskal–Wallis test (α = 0.05) indicated no statistically significant differences. The accuracy of the calibration of the computational model was assessed using the FEMP 3.0, IPMVP, and ASHRAE G 14-2014 criteria [10,26,27,28,29,30].

3. Results and Analysis

3.1. Comparison of Development of Temperature and Relative Air Humidity in Studied Objects

The courses of the temperature and relative humidity of the outside air in the period under study are presented in Figure 6. The outside air temperature reached a maximum of 33.2 °C, while the minimum was −17.2 °C. The values of the relative humidity were in the range of 17–100%. The courses of the temperature and relative humidity of the outside air in the surroundings of both churches under study were similar.
An analysis of the formation of the temperature and relative humidity of the internal air was carried out in the presbytery and two measurement locations in the main nave. The course of the temperature and relative humidity of the internal air in the presbytery is presented in Figure 7 and Figure 8. In the months with the heating system turned off (May–October), the temperature and relative humidity of the internal air reached similar values in both buildings tested, ranging from 6.8 to 24.2 °C and 56.6 to 88.1% in building A, and in building B 9.3–26.8 °C and 40.7–87.1%. In this period, the greatest influence on the formation of the thermal and humidity conditions was the external climate, especially at the time when services were not held. In the months with lower air temperatures (November–April), a higher air temperature was noticeable inside building B (in the range of 2.9 to 26.6 °C). This was caused by the activation of the heating system in the building. The air temperature in building B was even 20 °C higher compared to the air temperature in building A. Additionally, the use of the heating system in building B caused a decrease in humidity by up to 53% compared to the conditions in building A. The air temperature in building A was maintained in the range of −7.4 to 24.2 °C, while in building B, it was 2.9 to 26.8 °C. The range of required values was met only in the summer months (with higher outside air temperatures). However, in the winter months, the requirements were not met in either building. Nevertheless, the use of the heating system reduced the relative humidity of the air inside the heated building. In the period from December to early May, when the heating system was activated in building B, the relative humidity of the air inside the building was in the range of 35–65%. In the summer months, however, it reached values from 48 to 87%. In building A, on the other hand, throughout the entire analyzed period, it was in the range of 59–91%, and therefore above the required values. The air temperature amplitude in building A was a maximum of 7.2 °C in November, and the relative humidity was 17.6% in January. In building B, however, the daily air temperature fluctuations did not exceed 6.9 °C in April, and the relative humidity went up to 19.6%, also in April.
The course of the temperature and relative humidity of the indoor air in the nave (on both sides of the building) is presented in Figure 9, Figure 10, Figure 11 and Figure 12, along with the required range of values. Similar to the presbytery, the required range of indoor air temperatures of 15–25 °C was only met at the beginning of the analyzed period, in the months of July to September, in both investigated buildings. During the remaining analyzed period, the indoor air temperature in the churches dropped below the required values. In building A (the unheated church), the indoor air temperature from October to May ranged from −8.3 to 20.7 °C on the northern side of the church (point II) and from −8.4 to 21.6 °C on the southern side. In the heated church, the temperature ranged from 2.9 to 19.5 °C at point II and from −0.3 to 20.5 °C at point III. Consequently, the heating in the church did not contribute to improving the thermal conditions concerning the required air temperature that should prevail in historic buildings; however, it did improve the humidity conditions during the heating period. From December to April, the relative humidity in building B ranged from 37 to 77% at point II and from 35 to 79% at point III, while in building A, it remained between 57 and 91% at point II and 35 and 91% at point III. The amplitude of the temperature and the relative humidity of the air in the nave of building A was a maximum of 9.5 °C in November and 28.2% in August. In building B, it was 7.8 °C in April and 22.1% in December.
The analysis of the results showed that the heating system implemented only had an impact on improving the thermal conditions considering the thermal comfort of the participants in the services. The requirements that should be maintained in a museum facility equipped with valuable artifacts and polychromes fall within the range of 15–25 °C. As can be inferred from the above results, regardless of whether the church was heated or not, these requirements were not met, particularly during the periods characterized by low outdoor air temperatures. The situation was different when it came to the relative humidity of the air inside the church. The activation of the heating system allowed for a reduction in the internal relative humidity to the required range of 35–65%, compared to the unheated facility, where the range of relative humidity values inside the church remained above the required range.
Figure 13 and Figure 14 show the biological risk based on Sedlbauer isopleths. The model and isopleth define the conditions for mold growth depending on the heat and humidity conditions [31,32,33].
The analysis showed that the conditions for mold germination were present in both studied buildings. There was a greater biological threat in building A, which had no heating system. However, as noted in Figure 14, the heating system did not contribute to negating the possibility of mold growth. Therefore, the relative humidity level and indoor air temperature were not under constant control so as to eliminate the biological risk.
Figure 15 and Figure 16 present the course of the temperature and relative humidity of the air inside the studied buildings on a day when services were held in July.
In building A, there was one service held on the analyzed day, while in building B, there were three. In building B, due to the regularly occurring services and consequently greater exchange of indoor and outdoor air, the impact of the services on the formation of the thermal and humidity conditions was smaller compared to building A. The temperature increase during the service was 1.5 °C. In contrast, in building A, due to the occasional nature of the services, the presence of people, and the increased air exchange through the open doors at that time, there was a greater variation in the thermal and humidity conditions. The air temperature rose by approximately 3.5 °C during the service.
Figure 17 and Figure 18 show the course of the temperature and relative humidity of the air inside the studied buildings on a day when services took place in January.
On the analyzed day, one service was held in building A. The temperature and relative humidity inside were similar at each analyzed point. An increase in the temperature and relative humidity was noticeable only during the service (Δθ of 7 °C and ΔRH of 10%), and was related to the presence of people in the church. After the service ended, the temperature and relative humidity in the building dropped quite rapidly. In contrast, building B held three services on the analyzed day. In building B, there were noticeable variations in the temperature and humidity at the different measurement points. This was related to the heating system being in operation and the distance of the measurement points from the heat source. The increase in the indoor air temperature during the service in building B was lower (approximately 2 °C) compared to building A. This was related not only to the building’s heating system, but also to the higher frequency of the services. The occasional use of building A led to significant cooling of the church, even down to −8.4 °C. It can be observed that a higher frequency of services limited the excessive cooling of the building, thus achieving thermal and humidity conditions closer to those required. The uneven distribution of temperature and relative humidity inside building B is an unfavorable phenomenon for the preservation of historic objects. Simultaneously, there were significant variations in the temperature and humidity, which can cause different changes and deformations in works of art depending on their locations within the building.
Figure 19 and Figure 20 show the percentage shares of the days with optimal values of temperature and relative humidity in the church.
The recommended values for both temperature and relative humidity were met for a greater number of days in building B. The recommended air temperature value (20 ± 5 °C) was achieved in building B for approximately 46% of the monitored period, while the relative humidity (50 ± 10%) was met for about 72%. In contrast, in building A, the air temperature reached the recommended values for 35% of the monitored period, and the relative humidity for about 3%.
The recommended air temperature values (20 ± 5 °C) were met for 71% of the time from May to October and only 2% of the time from November to April in building A. In building B, the recommended temperature range was achieved for 84% of the time from May to October and only 9% of the time from November to April. The recommended relative humidity range (50 ± 10%) was met for 10% of the time from May to October and only 1% of the time from November to April in building A. In building B, the recommended relative humidity range was achieved for 53% of the time from May to October and for 96% of the time from November to April. Consequently, better humidity conditions prevailed in building B. The activation of the heating allowed for the maintenance of the recommended relative humidity values for most of the analyzed period. Building B is a church that is in regular use, while building A serves as an auxiliary church. The higher number of services, and consequently the greater number of people visiting the church, contributed to a greater exchange of the indoor air with the outside, leading to greater thermal and humidity variability.

3.2. Numerical Analysis of the Risk of Water Vapor Condensation

The conducted analysis of the thermal and humidity conditions in both studied buildings showed that, regarding the indoor air temperatures within the churches, the thermal requirements were not met. However, the application of heating in building B contributed to maintaining the required values of the relative humidity of the indoor air from October to May (during this time, the heating system was activated). In building A, on the other hand, the humidity exceeded the required range. Consequently, an analysis was conducted on the possibility of the condensation of water vapor on the surfaces of the internal walls. The course of the air temperature and dew point temperature in buildings A and B is presented in Figure 21 and Figure 22.
The conducted research showed no risk of condensation of water vapor on the surface of the walls in both analyzed buildings. However, it should be noted that the surface temperature of the walls inside the unheated building reached values ranging from 1.6 to 10.4 °C higher than the dew point temperature. In the heated church, the surface temperature of the walls was 4.5 to 22.1 °C higher. Therefore, considering the similar material and structural solutions of both buildings, it should be noted that the use of heating may contribute to improving the humidity conditions in the facility and reducing the risk of condensation of water vapor on the surface of the walls. However, it is important to point out that the measured and used climatic data for the calculations assumed a mild winter. At lower external air temperatures (below −10 °C), particularly in the unheated building, there would be a concentration of water vapor on the surfaces of the external walls.

4. Discussion

The requirements for the thermal comfort of people and the preservation of historic buildings in good condition are varied, as has been emphasized in many publications [9,34,35]. However, as Varas-Muriel and Fort (2018) [36] point out, the latter thermal and humidity requirements should prevail in historic buildings, as their protection should be more important than the requirements for human comfort. As presented in this publication, however, the application of heating contributed to improving the thermal conditions for participants of the services, while the thermal requirements considered optimal for historic buildings were not met. On the other hand, the heating system helped to achieve the required relative humidity values compared to the unheated church. As Maroy et al. (2015) [19] note, the maximum relative humidity at which the biological degradation of wooden structures does not occur is 75%. This value was exceeded in the analyzed unheated church, which may contribute to the destruction and damage of wooden objects. Continuous fluctuations in the temperature and relative humidity of the outside air effect constant changes in the thermal conductivity of building materials. High air temperatures contribute to the raising of the temperature of the partitions, which reduces the risk of condensation. However, if the occurrence of high air temperatures is combined with the operation of dehumidification systems, it leads to a greater risk of condensation due to the increasing difference between the air temperatures outside and inside the building [37,38,39].
For the analysis of the development of the thermal and humidity conditions in the churches studied, the ranges of 20 ± 5 °C for the air temperature and 50 ± 15% for the relative air humidity were assumed as the optimal conditions. However, as Aste et al. (2019) [40] point out, the thermal and humidity requirements for wood should be more restrictive—for the air temperature, within the range of 19–24 °C, and for the relative air humidity 50–60%. Daily fluctuations in the air temperature should not exceed 1.5 °C, and in the relative air humidity 4%. Despite taking into account wider ranges in the analysis, the requirements for both buildings were not met. Similar situations occurred in the studies presented in the following works, in particular during services, at which times the momentary fluctuations in the relative humidity exceeded 10%. The studies by Aste et al. (2019) [40] also show that the air temperature inside the building was higher than required, and the relative humidity values often remain at the upper limit. The authors note that daily air temperature fluctuations of around 1.5 °C should not pose a threat to wooden materials. However, in the studied buildings, the daily temperature and relative humidity fluctuations inside the churches reach values higher than 1.5 °C and 4%, and amount to 9.5 °C and 28.2% in the unheated building and 7.8 °C and 22.1% in the heated building.
The research by Nawalany et al. (2021) [9] showed that the air temperature in the unheated church under study drops below 0 °C, which is why the authors suggest using periodic church heating. However, as noted by Muñoz-González et al. (2018) [41], in contrast to churches located in northern Europe, Spanish churches show a lower demand for heating in winter, with a higher demand for cooling and drying in spring and summer, due to the Mediterranean climate characterized by a high outside air temperature and relative humidity. As noted by Zhang et al. (2022) [42], the use of an appropriate heating system and appropriate control of the heating mode can contribute to reducing energy consumption by 3.7%. Various heating systems are used to heat churches: blowers, convector heating devices, or pew heating. In order to ensure the thermal comfort of participants and at the same time reduce the occurrence of large fluctuations in the temperature and relative humidity inside historic buildings, many researchers suggest using heated pews. These allow for heating the zone where people gather without causing large changes in the temperature and relative humidity [42,43,44,45]. In the examined church, seven electric heaters are used for heating, which improved the humidity conditions in the building, but the thermal requirements that should prevail in a museum building were not met. This is related to the control of the heating in the church, which is mainly focused on improving the thermal comfort of the people participating in the services.
In the winter months, the high moisture content in the air is a significant problem, and the excess moisture can contribute not only to the accumulation of moisture in the partitions, but also to the biological hazard of mold growth [46,47,48]. In the case of building A, which has no heating system, the dehumidification of the building should be considered during the winter season. The lack of a heating system and the high humidity outside worsen the humidity conditions inside the building [38,39].
Historic buildings demand the required conditions of an indoor microclimate. Fluctuations in the relative humidity contribute to the possibility of mold growth, and also to the destruction of hygroscopic materials [8,9,34,49]. Historic religious buildings should meet the conditions for museum buildings, which are characterized by similar specifics of use. In both cases, the thermal comfort of visitors is different from the microclimate stipulated for museum buildings, and in addition, visitors can effect fluctuations in the interior microclimate. Therefore, the study of microclimates in museum buildings is extremely important [8,35,50].

5. Summary and Conclusions

The conducted research allowed for the analysis of the formation of thermal and humidity conditions in wooden historic buildings. The analysis showed that the temporary use of heating, only during the use of the church, only slightly improves the thermal and humidity conditions in the historic interior compared to an unheated church. The use of heating is only intended to improve the comfort of the participants, and not to improve the conditions resulting in the preservation of historically valuable buildings in good condition.
The daily fluctuations in the air temperature inside the unheated church amounted to a maximum of 9.5 °C, and in the relative humidity 28.2%. In the heated building, these values were lower, and amounted to 7.8 °C and 22.1%. The high daily fluctuations in the temperature and relative humidity could contribute to the destruction of the wooden structures and equipment.
The use of heating in the church resulted in lower values of the relative humidity of the internal air compared to the unheated building. Starting the heating in the winter half year allowed for the maintenance of a relative humidity in the required range of 35–65%, while in the unheated building, the relative humidity remained above 65%.
In both analyzed buildings, there was no risk of water vapor condensation on the surface of the walls inside. However, the differences between the dew point temperature and the temperature of the wall surfaces were lower in the unheated building.
The conducted research allowed us to compare the formation of the thermal and humidity conditions in the unheated and heated wooden churches. This study may allow for the conduct of a broader (numerical) analysis in order to find the best heating system for wooden historic buildings, which will allow the maintenance of the recommended values of the temperature and relative humidity of the internal air.

Author Contributions

Conceptualization, G.N., P.S. and M.M.; methodology, G.N., P.S. and M.M.; software, P.S. and M.M.; validation, P.S. and M.M.; formal analysis, G.N., P.S. and M.M.; investigation, G.N. and P.S.; resources, G.N.; data curation, M.M. and Z.L.; writing—original draft preparation, G.N., M.M., P.S. and E.M.; writing—review and editing, G.N., M.M., P.S. and E.M.; visualization, P.S. and M.M. and G.N.; supervision, G.N. and P.S. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by the Faculty of Environmental Engineering, University of Agriculture in Krakow, through the project “Subvention 030001-D014 Environmental Engineering, Mining, and Energy”.

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

Data are contained within the article.

Conflicts of Interest

The authors declare no conflicts of interest.

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Figure 1. Unheated wooden church; (a) southern facade, (b) interior of church.
Figure 1. Unheated wooden church; (a) southern facade, (b) interior of church.
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Figure 2. Heated wooden church; (a) southern facade, (b) interior of church.
Figure 2. Heated wooden church; (a) southern facade, (b) interior of church.
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Figure 3. Location of measurement points: (a) plan, (b) section, building A.
Figure 3. Location of measurement points: (a) plan, (b) section, building A.
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Figure 4. Location of measurement points: (a) plan, (b) section, building B.
Figure 4. Location of measurement points: (a) plan, (b) section, building B.
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Figure 6. Temperature and relative humidity of outside air, unheated church.
Figure 6. Temperature and relative humidity of outside air, unheated church.
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Figure 7. The indoor air temperature: θI_A at measurement point I in building A; θI_B at measurement point I in building B.
Figure 7. The indoor air temperature: θI_A at measurement point I in building A; θI_B at measurement point I in building B.
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Figure 8. The relative humidity of the indoor air: RH_I_A at measurement point I in building A, and RH_I_B at measurement point I in building B.
Figure 8. The relative humidity of the indoor air: RH_I_A at measurement point I in building A, and RH_I_B at measurement point I in building B.
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Figure 9. Indoor air temperature: θII_A at measurement point II in building A, and θII_B at measurement point II in building B.
Figure 9. Indoor air temperature: θII_A at measurement point II in building A, and θII_B at measurement point II in building B.
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Figure 10. Relative humidity of indoor air: RH_II_A at measurement point II in building A; RH_II_B at measurement point II in building B.
Figure 10. Relative humidity of indoor air: RH_II_A at measurement point II in building A; RH_II_B at measurement point II in building B.
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Figure 11. Indoor air temperature: θIII_A at measurement point III in building A; θIII_B at measurement point III in building B.
Figure 11. Indoor air temperature: θIII_A at measurement point III in building A; θIII_B at measurement point III in building B.
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Figure 12. Relative humidity of indoor air: RH_III_A at measurement point III in building A; RH_III_B at measurement point III in building B.
Figure 12. Relative humidity of indoor air: RH_III_A at measurement point III in building A; RH_III_B at measurement point III in building B.
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Figure 13. Sedlbauer isopleth model for predicting mold growth in building A.
Figure 13. Sedlbauer isopleth model for predicting mold growth in building A.
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Figure 14. Sedlbauer isopleth model for predicting mold growth in building B.
Figure 14. Sedlbauer isopleth model for predicting mold growth in building B.
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Figure 15. The course of the (a) temperature and (b) relative humidity of the indoor air in building A on 1 July 2018.
Figure 15. The course of the (a) temperature and (b) relative humidity of the indoor air in building A on 1 July 2018.
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Figure 16. Course of (a) temperature (b) relative humidity of indoor air in building B on 1 July 2018.
Figure 16. Course of (a) temperature (b) relative humidity of indoor air in building B on 1 July 2018.
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Figure 17. Course of (a) temperature, (b) relative humidity of indoor air in building A on 22 January 2019.
Figure 17. Course of (a) temperature, (b) relative humidity of indoor air in building A on 22 January 2019.
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Figure 18. Course of (a) temperature, (b) relative humidity of indoor air in building B on January 22, 2019.
Figure 18. Course of (a) temperature, (b) relative humidity of indoor air in building B on January 22, 2019.
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Figure 19. Meeting of recommended indoor air temperature values in buildings A and B.
Figure 19. Meeting of recommended indoor air temperature values in buildings A and B.
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Figure 20. Meeting of recommended values for relative humidity of indoor air in buildings A and B.
Figure 20. Meeting of recommended values for relative humidity of indoor air in buildings A and B.
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Figure 21. The indoor air temperature, θi, and the dew point temperature, DP, in building A.
Figure 21. The indoor air temperature, θi, and the dew point temperature, DP, in building A.
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Figure 22. The indoor air temperature, θi, and the dew point temperature, DP, in building B.
Figure 22. The indoor air temperature, θi, and the dew point temperature, DP, in building B.
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MDPI and ACS Style

Nawalany, G.; Michalik, M.; Sokołowski, P.; Michalik, E.; Lofek, Z. The Threat of Moisture in the Partitions of Unheated and Heated Wooden Historic Churches in Poland. Sustainability 2025, 17, 2941. https://doi.org/10.3390/su17072941

AMA Style

Nawalany G, Michalik M, Sokołowski P, Michalik E, Lofek Z. The Threat of Moisture in the Partitions of Unheated and Heated Wooden Historic Churches in Poland. Sustainability. 2025; 17(7):2941. https://doi.org/10.3390/su17072941

Chicago/Turabian Style

Nawalany, Grzegorz, Małgorzata Michalik, Paweł Sokołowski, Elżbieta Michalik, and Zbigniew Lofek. 2025. "The Threat of Moisture in the Partitions of Unheated and Heated Wooden Historic Churches in Poland" Sustainability 17, no. 7: 2941. https://doi.org/10.3390/su17072941

APA Style

Nawalany, G., Michalik, M., Sokołowski, P., Michalik, E., & Lofek, Z. (2025). The Threat of Moisture in the Partitions of Unheated and Heated Wooden Historic Churches in Poland. Sustainability, 17(7), 2941. https://doi.org/10.3390/su17072941

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