Climate change presents new challenges to condition monitoring in historic buildings: a case study on the Jusélius Mausoleum in Finland

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View to the vestibule. Over the entrance is the Cosmos fresco and a mosaic with text ”Refrigera illos in logo viridi super aqvas refectionis in paradiso deliciarum”.  Image courtesy of the authors

By Tiina Sonninen and Kirsi Varkemaa

The mausoleum of Sigrid Jusélius is a significant cultural site in Pori, located in Western Finland. The mausoleum, built in 1901-03, is a masterpiece of the arts and crafts era in Finland. The combination of sandstone exterior, interior marble structures and richly decorated surfaces with frescos has made it challenging to preserve. Only a few years after the building was finished, the original frescos were destroyed due to excess moisture and were later repainted. The Sigrid Jusélius Foundation, which owns and looks after the building, has recently invested in the most modern technology to continuously monitor humidity and temperature to keep this exceptional building in good condition. New problems include increased autumn storms, heavy showers and strong winds pushing rainwater into the sandstone structure.

The Sigrid Jusélius Mausoleum was commissioned by Fritz Arthur Jusélius (1855-1930), a prosperous local industrialist. He had two daughters with his first wife, Blenda Theresia Moliis. Their first-born died a few months after her birth, and their second child, Sigrid Maria, born in 1887, died of tuberculosis at the age of 11.

Soon after Sigrid’s death, her mourning father visited the Turku cathedral, and it is assumed that this visit gave him the idea to build a chapel in memory of his daughter Sigrid. Soon after this visit, he contacted Josef Stenbäck (1854-1929), a well-known architect, to discuss the idea.

The mausoleum project was a difficult challenge for Stenbäck. Jusélius was openly dissatisfied with Stenbäcks´ plans, and he took an active role in choosing construction materials and planning interior decorations. Stenbäck, who wanted to complete the project, invited the famous Finnish painter, Akseli Gallen-Kallela (1865-1931), to help him in interior design.


After difficulties, the mausoleum was constructed at the Käppärä cemetery in Pori. The beautiful building, shaped like a lantern, is representative of the neo-Gothic style. The octagonal structure is adjoined on the east side by a small vestibule and on the west side by a semi-circular chancel. The vaults and walls in the central section are supported by buttresses, and the high windows are topped by triangular pediments. The base was built of Finnish grey granite and the exterior walls are made of yellow sandstone from the nearby seaside.

Akseli Gallen-Kallela painted the frescos on the interior walls and ceiling in 1901-1902. He had studied fresco painting in Italy in the 1890s, and after returning to Finland, he further experimented with the technique and received two important commissions for frescos, one for the mausoleum, the other for the Finnish pavilion at the 1900 World Exposition in Paris. Both projects were turning points in his career.

The frescos in the mausoleum represent naturalistic folklore and symbolism and summarize Gallen-Kallela’s monumental works in the national romantic style. The themes of the paintings come from the Kalevala (Finnish epic poetry) tradition and the Bible, but they also show references to theosophy and occultism. Together with the mausoleum, they form a unique entity in Finnish art history.


Unfortunately, an unheated and unventilated building made of porous sandstone in the rough Finnish climate turned out to be a fatal location for the frescos, and deterioration started as early as 1904. Moisture penetrated the sandstone walls, dissolving salts in the plaster. As sandstone absorbed sea salts, the water-soluble salts passed through the frescos and crystallized on the surface.

Restoration started in 1912, and ventilation ducts were built in 1916-17. However, this was too late for the frescos. They were so weathered that in 1925 they were replaced with bronze reliefs by the sculptor Emil Cedercreutz (1879–1949).

In 1930, after Fritz Jusélius’ death, the Sigrid Jusélius Foundation started to look after the building. They were concerned with a severe crack in the wall and decided to support the foundation, repair the sewage pipes and concrete wall, as well as insulate the sandstone walls. During these repairs, a fire started from the heating stoves. The whole building suffered considerable damage and the Foundation decided to rebuild the mausoleum. The façade was changed to Swedish sandstone, and new central heating was installed. The frescos were re-painted in the late 1930’s by Jorma Gallen-Kallela, the son of Akseli Gallen-Kallela, based on his father’s sketches and studies.

The frescos have now survived for more than 80 years since repainting. The mausoleum is a major sight in the Pori area, and now it is open for visitors year-round. It is on the list of nationally significant sites in Finland, and is well cared for by the Sigrid Jusélius Foundation. From 1985 to 2005, the mausoleum’s environmental conditions were monitored by Ars Longa Ltd, and have been monitored since 2006 by Konservointi T. Sonninen Ltd.


Preserving the sandstone structure and the frescoes requires steady temperature and humidity. In addition to moisture absorbed through the porous sandstone walls, excessive humidity can also occur due to too many visitors especially during the winter season. There is a constant threat of water condensation and subsequent run-off marks on the frescos.

In recent years, an additional challenge has been the increasing rainfall. Last year, in connection with a heavy rain in August, water flooded inside the building. To prevent this from happening in the future, the stained glass windows will be examined, and any deteriorated seams on the façade's sandstone masonry will be repaired to keep the structures and frescos safe.

In addition to repairs, the Jusélius Foundation has invested in the most modern technology to ensure that future generations can also visit this remarkable building. A few years ago the heating system was renovated, the building was connected to the district heating system and temperature sensors were added to control the indoor temperature. The next major repair will be the renewal of the electrical system. This summer the condition monitoring was changed from traditional thermohygrometers to Vaisala’s viewLinc continuous condition monitoring system.


The change is a significant step forward. The viewLinc system keeps track of the conditions around the year and around the clock. Thanks to this system, the conservator, the key people in the foundation and the maintenance team can get accurate information about conditions in the mausoleum remotely—anywhere, anytime. The viewLinc software that enables the reading of measurements from the loggers in the mausoleum is installed on a server. After logging in, users can access the accumulated condition data with a regular browser on their PC or phone. The system sends an alert if there are changes in circumstances that exceed the designated reference values. This allows care takers to make immediate changes to the heating and air conditioning settings if needed.

The measurements accumulate in the database and can be revisited later as needed. For instance, it is possible to study how the combination of visitor numbers and weather affect the conditions in the mausoleum. On very rainy and snowy days, people bring in moisture on their clothes and umbrellas. The data recorded from such days can be used to examine whether this raises the humidity inside the mausoleum too much and whether it is necessary to limit the number of visitors during certain weather conditions. This is even more important as the amount of rain and number of rainy days have increased in Finland in recent years. The system is flexible and allows for different settings depending on what kind of data is needed. The users can also receive automatic email reports on the measurement at a certain interval.


Heinämies, K. 2001. Sigrid Jusélius Foundation.

For more information, visit the Sigrid Jusélius Foundation website: which also includes a video about the Mausoleum. Learn more about Vaisala and their viewLinc monitoring system here:


Tiina Sonninen, a Fellow of IIC, has been an IIC member since 1987. She specializes in the conservation of wall paintings and historic building surfaces. Tiina works as a consultant on nationally significant buildings and sites across Finland. She is trained as a conservator, has an MA in art history and is writing a dissertation at the University of Helsinki on the materials and techniques of wall paintings in medieval churches in Finland. Tiina is also a member of the design team awarded the highly respected Finlandia prize for architecture in 2019 (

Kirsi Varkemaa is a communications professional with experience from various fields. She loves to write about art and technology, and it is a treat for her to combine both in one story. Based in Helsinki, Finland, Kirsi works at Paja Communications, a boutique communications agency she co-founded in 2013.

(See the entire article in the August-September 2020 "News in Conservation" Issue 79, p. 10-14) Sign up in the footer of this page to receive News in Conservation in your inbox, along with news from IIC.

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The mausoleum of Sigrid Jusélius is a significant cultural site in Pori, located in Western Finland. The mausoleum, built in 1901-03, is a masterpiece of the arts and crafts era in Finland. Only a few years after the building was finished, the original frescos were destroyed due to excess moisture and were later repainted. New problems include increased autumn storms, heavy showers and strong winds pushing rainwater into the sandstone structure.
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