Indoor Microclimate effect on heritage buildings: the case ... - BH 2013

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Built Heritage 2013 Monitoring Conservation Management

Indoor Microclimate effect on heritage buildings: the case study of Malatestiana Library Marco Pretelli1, Kristian Fabbri2, Andrea Ugolini3, Andreina Milan3 1 Assistant Professor University of Bologna, Department of Architecture, Cesena (FC), Italy; 2 Adjunct Professor University of Bologna, Department of Architecture, Cesena (FC), Italy; 3 Researcher University of Bologna, Department of Architecture, Cesena (FC), Italy 1. Introduction The aim of all disciplines concerning heritage buildings is preserving them and their contents, studying their decay and damage processes (chemical, physical, biological, mechanical, etc.) and relative causes, developing strategies in order to reduce or prevent them. If we exclude outside building damage factors, like ground humidity, roof seepage or hydraulic system seepage, subsidence, statics or mechanical damage, etc. or earthquakes, we can assert damages depends in first by indoor building factors, strictly connected with indoor microclimate conditions, functions and usage. In this paper, the case study of the Indoor Microclimatic Quality (IMQ),of the Malatestiana Library (building and artifacts) is a priority in spite of human comfort. In case of heritage buildings, like the Malatestiana Library, our opinion is that the main goal of indoor microclimate evaluation and/or monitoring should be to preserve the building and the artifacts, as a first step. As a second step, we can consider user comfort and the building’s function in order to allow visits. In heritage buildings we need to overturn the approach: the “object” (artifact, manuscript, artwork, building etc.) is “more essential” than “people” (visitors, users, janitors, etc.). So the indoor comfort range must be calibrated and adapted in order to privilege the “object’s” range of wellbeing. Our above thesis might appear obvious, but the approach to heritage buildings depends on structural features and inside functions. In several heritage buildings the introduction of HVAC, wiring and other systems was motivated by visitors’ or users’ presence, without considering these systems’ collateral effects on heritage buildings. HVAC systems modify indoor microclimate condition and create a “microclimate stress” for both, artifacts and buildings, that was often not present in the original building. Several studies [K.Fabbri, 2013] [M.Pretelli et al., 2013] discuss the role of technical systems (HVAC, wiring, elevator, etc.) in historical buildings. One of the goals of the present paper is to continue along the same research thread referring to the specific case study of the Malatestiana Library because of its unique status as a “representative sample” of a building that never had HVAC systems. Historic buildings are used according to different levels that range from pure conservation to reuse for specific functions: this can be seen in religious structures, museums, libraries or to such dwellings as villas, etc. Heritage building microclimate is a specific field of research, this is evident in scientific literature as Dario Camuffo [Dario Camuffo,1998], C. Balocco [C.Ballocco et.al, 2010], and in the same way “historic climate” concept defined in Italian Standards UNI described in D.Del Curto [D.Del Curto, 2010]. 1439

Built Heritage 2013 Monitoring Conservation Management

Standards define the range of microclimate condition for several kinds of artifacts (paper, drawings, wood, paintings, plasters, fresco etc.), but they specify that in the case of artifacts preserved, from origin to present outside that range, we must guarantee the historic preservation climate. 2. Aim of the paper In the present paper we describe results of the indoor microclimate monitoring campaign of the Malatestiana Library in Cesena. The Library is an “unicum” in heritage building since 1454, the year of its construction: it has been a library with same wooden plutei and original manuscripts, with no use of fireplaces, stoves or HVAC systems, resulting in an unchanged indoor microclimate. Since the 15th century indoor microclimate control of temperature and RH, has been regulated by opening windows and visitors inflow control. The windows are sometimes open, usually once a day, without microclimate monitoring in order to control indoor temperature and RH variables. Until our recent monitoring campaign, nobody knew the Malatestiana Library microclimate, whose variations depended on the officer and janitors’ “common sense” in opening windows. Malatestiana visitors’ rules limited visitors’ inflow: both in their number and in the spaces available for tours. The first monitoring results allowed a few methodological and scientific considerations to be developed, in order to promote new Malatestiana rules regarding visits and conservation. 3. The study case: Malatestiana Library The Malatestiana Library was built between 1450 and 1545 by Malatesta Novello, lord of Cesena, following a design by Matteo Nuti, an architect born in Fano and a pupil of Leon Battista Alberti. The Library conserves the same plutei and manuscripts since 1454, and in 2005 it entered the category of UNESCO’s “Memoires du Monde” [UNESCO, 2005]. “The Library of Malatesta Novello, the last ancient library dating from immediately before the invention of printing, embodies the very concept of a humanist library”. The Library has a rectangular floor with only one entrance, divided in 3 aisles with a center aisle raised above the others; the space is divided by 20 columns, with capitals and shields, 22 windows per side and 1 rose window on the short wall opposite the entrance. The entrance is located on a short wall connected to the rest of the new library, in the same wall there are 2 windows that are always open.

Fig.2 - Measurement tool

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Built Heritage 2013 Monitoring Conservation Management

Inside the Library 58 wood plutei are present (“pluteo” is a desk or backbench furniture to conserve and read manuscripts) with book holders to consult manuscripts. The Library contains 343 Codex, about 150 from the 15th century directly commissioned by Malatesta Novello, lord of Cesena, while the other manuscripts were collected in the 16th and 17th centuries. Now-a-days manuscripts are consulted in a separate room, with special equipment for reading, examining and restoring manuscripts. The Malatestiana Library is an unique object of study because since the 16th century building, plutei and manuscripts haven’t changed or been restored. The building doesn’t have any technical or plant systems, any heating systems, any stove or fireplace, any wiring or artificial lighting system or any other artificial artifact that might change indoor microclimate. From the 15th century until now indoor microclimate has been controlled only by windows opening. We decided to study and monitor the Malatestiana Library in order to support our thesis: (a) all actions in order to conserve historical building and/or artifact need to take into account the indoor microclimate history, and (b) HVAC, wiring, artificial lighting and other technical system refurbishment in historical and heritage buildings could have negative impact on indoor microclimate and artifacts. In this way the Malatestiana Library is like a “Patient Zero” to compare other heritage buildings’ indoor microclimates. A word of warning: our thesis is not that “heritage buildings without HVAC system are better”, but we affirm that the need for HVAC systems in heritage buildings should be conditioned by the priority of heritage and not human comfort. Thus the HVAC must be designed not to change historic indoor microclimate. We decided to do a monitoring campaign in order to study how indoor microclimate parameters are affected by “keepers praxis” and visitor access. The windows are sometimes opened by keepers, from half an hour to 2 - 4 hours per day, depending on outside weather conditions and on “keeper-commonsense”. The keepers open the 2nd 7th and 17th windows on the right side and 3rd, 12th and 22th on the left side. Opening windows is the only indoor air ventilation system (natural ventilation), except air movement through windows on the entrance wall side. The keepers decide when to open windows and the duration, following a well-established habit: a “keepers praxis” without instrumental monitoring. When we proposed this program to the Malatestiana Library direction the research aims were to understand and standardize these opening practices. Asking for advice the keepers was very interesting and helped us understand some aspects of the Library management and long-time microclimate variations. Visitor rules have existed since the Library became a museum 50 years ago, but we can consider 30 people a day as a maximum inflow over the last 5 centuries. So the Library’s indoor pollutants arrive only via opening windows, often in the morning, and via visitors. We believe that these are the only indoor pollutants since 1454, in this way we consider the current indoor environment the same as the “historic microclimate” of 5 centuries ago. 1441

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4. Research methodologies The first step of the research consists in a continuum monitoring of Malatestiana Library indoor environment. Monitoring campaign regards measurement of the two most important parameters, able to deteriorate the manuscripts and the plutei: Temperature, in °C, and Relative Humidity (RH). The measurement of the trend of the relative humidity (RH) allows us to monitor the variation of the amount of water vapor present in the library, one of the most important parameters influencing the conservation of artefacts, manuscripts and plutei. The factors that affect the amount of absolute humidity and water vapor present in the library are: a) trends of variation of the indoor microclimate, temperature and relative humidity with respect to the weather conditions outside weather; b) the periodic openings of the windows, with the resulting mixture of the

Fig.3 - Trend of Temperature and RH from 19.03.2013 to 30.04.2013 - Peak value correspond to windows opening

Fig.4 - Trend of Air velocity (m/s) from 19.03.2013 to 30.04.2013 - We don’t observe any convective phenomenon

Fig.5 - Diagram Temperature and RH - Indoor Microclimate Quality

1442 Table 1 Comparison between microclimate measure, standard and MIBAC values

Built Heritage 2013 Monitoring Conservation Management

amount of internal and external air. The opening of the windows is carried out according to the rules of common sense, on the part of the keepers in relation to microclimatic conditions outside (i.e., if it rains or there is fog, windows are not opened), for a period of a few hours in the morning. c) the presence of visitors, whose breath increase water vapor in the space close to the entrance. The air volume of the indoor library is treated as HVAC systems for ventilation and microclimate control environments, with the difference that in this case it is not necessary to ensure the conditions for the set-point of 20° indoor and RH 60%-65% and that the conditions of set-point outdoor are those of the outside air. In Malatestiana “Natural Microclimate Machine” with regard to ventilation and RH, control of openings and access of people is equivalent to changing the air performed by an HVAC system. We used Instrument HD - WBGT - PMV HD 32.3 for monitoring campaign In addition to the Instrument HD there is a register (“Report notebook”) in which the keepers have signed the date, time and duration of visits and the opening of the windows, and any other specific operation, as, for instance, cleaning operations. The monitoring is ongoing and it will continue. 5. Monitoring Results and discussion Monitoring campaign started on March 12th 2013 and stopped (in relation to the contents of this paper) on April 30th 2013. Figure 3 shows the data of the probe HD with the trend of the air temperature (Ta in °C) and Relative Humidity (RH in%). The two phenomena are related, as the temperature Ta of the indoor air, the concentration of RH decreases. The peaks, in the top and bottom, are due to the variation of the concentration of RH due to the opening of the windows and of mixing with the outside air. Figure 4 shows the variation of the air velocity (m / s), which varies between 0 m / s and 0.18 m / s as the maximum point, and an average value of about 0.09 m / s. One may conclude that the air is in a condition of quiet and have not been detected spontaneous convective phenomena, and this factor does not affect either the airflow or thermal exchanges, but is positive without any doubt in terms of transport and deposits of dust, also if this aspect is not object of the present study. Figure 5 shows the relationship between air temperatures Ta and RH, identifying the “range of well-being” (indoor Microclimate Quality - IMQ) for goods stored: plutei and manuscripts. The reference range for the artifacts of the Malatestiana Library are between 12 ° C and 20 ° C and RH between 55% - 68%, you can also specify further that among the RH is between 12-14 ° C 60% - 68% and that between 16 ° C - 20 ° C RH is between 55% and 60%. So if the air temperature is greater than the content of water vapor is less, and vice versa, a phenomenon due to the exchange of heat (latent or sensitive). The Table 1 compare range of Malatestiana Library microclimate data measured during our research, with UNI 10289 standard and MIBAC Dlgs 112/1998 values. We can observe that Malatestiana temperature ranges are similar, but RH value are slightly (+5%) greater than standard values. In the specific 1443

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case of the Malatestiana Library the present study is the first methodological survey related to its microclimatic conditions. The past history highlights the fact that neither the conditions of the place, neither the contents retained, have been changed; in addition, the choice in modern times to not change the state of the Library by integrating any plant systems. Figure 6 shows the trend of the difference between the outdoor and indoor RH and the variation of the difference between the indoor and outdoor temperatures. The graph shows some relations between variation of temperature and RH: when the difference between indoor and outdoor air temperature is greater, than the trend RH decreases, while the peaks of decrease or increase of RH, linked to the opening of the windows, correspond to greater variability, in positive and negative relationship between outdoor and indoor temperatures. The graph shows that the variation in outdoor RH is not directly related to the trend of indoor RH. The peaks of humidity variation coincide with the opening of the windows and the duration of the opening itself. Fig.6 - Trend of RH indoor and outdoor and outdoor-indoor temperature gap

1444 Fig.7 - Cumulative Frequency of RH

Built Heritage 2013 Monitoring Conservation Management

In accordance with the standard UNI 10829 the Figures 7 show the cumulative frequency of the indoor air RH during the month of experimentation. The graph shows that less than 2% of the values is below 55% RH, while only 32% RH respects the limits of 60% required by standard. The cumulative frequency shows about 90% of the values is below 65% RH, it can therefore be assumed that this value represents the value “characteristic” for manuscripts of the Malatestiana Library. 6. Conclusions This research moved from the decision to study the microclimate of an extraordinary building, Libreria Malatestiana in Cesena. During the monitoring operations, the keepers and the director started to ask if the way in which they are operating (probably since the beginning of the life of the Library…) is correct: “the choice of opening the windows and the access control, operated according to our “common sense”, guarantees the preservation of the library and of its precious contents?”. The unloading of the data made it possible to deal with the keepers on some of the themes and issues that arise from time in the current management, according to “common sense”, followed for centuries, we guess. The results of the research show that the absence of HVAC systems does not affect the conservation of artifacts; indeed, it seems to be true the opposite; in this case the center of the action this absence seems to have contributed, from the construction of the library, more than 5 centuries ago, to the preservation of the building and its precious contents. The decision to adopt the approach of “Heritage First” and thus ensure the welfare conditions of the artifacts before the people, certainly does not depends on those who analyze the micro-climatic conditions or on those who design HVAC systems. The study allowed us to verify if the choices of building management, adopted in accordance with the logic of “common sense” are correct. In most cases it is believed that the answer to this question is positive, with a few critical remarks. Despite the particularity of the object of study, it is possible to derive some common considerations and other details: (a) the absence of HVAC systems involves a diagram RH/T characteristic of the object, a sort of “signature” of the parameters of the conditions as to ensure the preservation; (b) the feedback of “common sense” should be subject to continuous monitoring and localized as well as the presence of people to monitor the possible occurrence of decay processes and the relationship between environmental degradation, presence of people and microclimatic parameters recorded. In this sense we want to use these results to propose a system of continuous monitoring with multiple probes arranged in the environment, and equipped with wireless systems for the collection and processing of data, so as to: (1) build a historical archive of microclimatic conditions (historic climate archive), maybe with maps of indoor microclimatic conditions (spatial distribution of relative humidity RH, temperature, air velocity, etc..) as in [R.Cataldo. et al. 2005], [K.Gysels 2004], [D.Camuffo. et al,2004]; (2) put a display outside the Library by which predict warning systems for opening and closing windows, access monitoring and alarm systems, if these 1445

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parameters vary in an unusual way; (3) the production of a “Management Protocol” to rule visits and openings of the Malatestiana Library, to be used even in cases in which the custody and/ or visits are entrusted to external parties. This will result in differences in the management of the storage conditions of the Library, object of our monitoring: opening windows and access control. The result of our theoretical research on the microclimate of the Malatestiana Library has been practical suggestions on how we can preserve the architecture and its contents; so we hope to have contributed to the possibility of a longer life of this extraordinary building. Acknowledgements We would like tank Librarian staff and keepers, their point of view and debate has been a relevant starting point of reflection about data results. The authors would like to thank the Keepers and the Deputy Director, Paola Errani, that granted for the availability of the Library, and for their courtesy, attention and care shown in the management and conservation of the Malatestiana Library. References C.Ballocco, Boddi R, 2010, Analysing indoor climate in Italian heritage buildings, published in Indoor environment and preservation, Nardini Editore, Firenze 2010 ISBN 9788840443393, pages 51-64. Camuffo D, Pagan E, Berdardi A, Becherini F, 2004, The impact of heating, lighting and people in re-using historical buildings: a case study, «Journal of Cultural Heritage», Volume 5, Issue 4, October–December 2004, pages 409-416. Cataldo R, De Donno A, De Nunzio G, Leucci G, Nuzzo L, Silviero S, 2005, Integrated methods for analysis of deterioration of cultural heritage: the Crypt of “Cattedrale di Otranto”, «Journal of Cultural Heritage», Volume 6, Issue 1, January–March 2005, pages 29–38. D. Del Curto, 2010, Building climate and cultural heritage safeguard. Instruments and models of investigation, published in Indoor environment and preservation, Nardini Editore, Firenze 2010 ISBN 9788840443393, pages 27-41. Dario Camuffo, 1998, Microclimate for Cultural Heritage, Elsevier Science B.B. Amsterdam. Gysels K, Delalieux F, Deutsch F, Van Grieken R, Camuffo D, Bernardi A, Sturaro G, Busse HJ, Wieser M, 2004, Indoor environment and conservation in the Royal Museum of Fine Arts, Antwerp, Belgium, «Journal of Cultural Heritage», Volume 5, Issue 2, April–June 2004, pages 221–230. K.Fabbri, 2013, Energy incidence of historic building: Leaving no stone unturned, «Journal of Cultural Heritage», Volume 14, Issue 3, Supplement, June 2013, pages e25-e27. M.Pretelli M, A.Ugolini, K.Fabbri, 2013, “Historic plants as monuments” preserving, rethinking and re-using historic plants, «Journal of Cultural Heritage», Volume 14, Issue 3, Supplement, June 2013, pages S38–S43. MiBAC Ministry of Cultural Heritage MIBAC Atto di indirizzo Dlgs 112/98 art.150 comma 6. UNESCO, 2005 - Memory of the World - The Malatesta Novello Library. UNI 10829:1999 Works of art of historical importance - Ambient conditions or the conservation - Measurement and analysis. 1446