Energy and Microclimate Simulation in a Heritage Building: Further Studies on the Malatestiana Library

energies

Article Energy and Microclimate Simulation in a Heritage Building: Further Studies on the Malatestiana Library

Lamberto Tronchin 1,*,† ID and Kristian Fabbri 2,†

1 Department of Industrial Engineering, University of Bologna, Viale del Risorgimento 2, 40129 Bologna, Italy 2 Department of Architecture, University of Bologna, Viale Europa 596, 47521 Cesena, Italy; [email protected] * Correspondence: [email protected]; Tel.: +39-051-209-0542; Fax: +39-051-209-3296 † These authors contributed equally to this work.

Received: 6 September 2017; Accepted: 6 October 2017; Published: 16 October 2017

Abstract: Historical and heritage (especially UNESCO) buildings need a specific, peculiar approach regarding energy performance, energy behavior, and indoor microclimate. Comparing a new building with a historical (UNESCO) building, it is evident that the degrees of freedom for implementing energy efficiency in historical buildings are strongly limited. Several constraints about the materials, the geometry, and the structures do not allow a comprehensive enhancement of energy performance or microclimate parameters. In this paper, we describe an energy building performance criterion adopted in order to find out the energy behavior in the Malatestiana Library. The challenge consists of optimizing energy efficiency and microclimate as well as a full preservation of ancient manuscripts. The study adopts Google Sketchup software to model three-dimensional (3D) buildings, and IESVE software to simulate an indoor microclimate. Software building models allow for the evaluation of different types of natural ventilation and section forms, e.g., original, without attic, and without ground floor. The results of the software modeling allow for a comparison of several building use modality effects and the effect of the presence of an attic and ground floor on indoor microclimate parameters in order to conserve and preserve ancient manuscripts.

Keywords: building simulation; heritage building; indoor microclimate; Malatestiana Library

1. Introduction: Energy Building Simulation in a Heritage Site Historical buildings, especially heritage buildings, have specific characteristics regarding building energy performance behavior and modeling. On one hand, these building are generally excluded from minimum energy requirement obligations and energy performance certification (e.g., Directive 2010/31/UE of the European Parliament and of the Council of 19 May 2010 on the energy performance of buildings (recast) excludes heritage buildings). On the other, heritage buildings have several kinds of use: museums, the building as a museum itself, archives, offices, dwellings, etc. Moreover, the use of these buildings requires the maintenance of a comfortable indoor microclimate for its users, guaranteed by Heating, Ventilation, and/or Air-Conditioning (HVAC) systems. The main questions concern:

(a) how to insert HVAC systems in historic buildings; (b) how to reduce energy consumption and energy costs, which have an economical incidence on heritage bills, as described by in F. Ascione [1]; (c) the study of building behavior in order to: (i) control the indoor microclimate level to guarantee building and artifact conservation;

Energies 2017, 10, 1621; doi:10.3390/en10101621 www.mdpi.com/journal/energies Energies 2017, 10, 1621 2 of 14

(ii) guarantee an indoor microclimate level to satisfy user comfort; (iii) improve HVAC system management in order to satisfy the above two points.

Historical buildings have another peculiarity: they were built before the invention of modern technical HVAC systems and were previously heated by braziers, a fireplace, or stove. Moreover, it would be interesting to study the architectural solutions that allowed the building to be used in the past. For this reason, it is worthy of interest to analyze the effects of different architectural solutions on the energy behavior, indoor microclimate, and preservation of the materials hosted in these important structures. Building Performance Simulation (BPS) by dynamic software, e.g., EnergyPlus, Trynsis, and ESPr, allow for the calculation and study of an indoor microclimate and how it is influenced by boundary conditions: outdoor climate, user and human behavior, HVAC systems, heating load, etc. A comparison between indoor microclimate in an actual building configuration and a historic (in the past) configuration shows any deficiency that depends on historical buildings and that depends on “modern use”, e.g., with plant or new modern standards. In order to make the above comparison, the building must be a “patient zero”; in other words, a heritage building in which nothing has changed since the time it was built, and, if possible, has conserved its inside use and artifacts. This paper describes an indoor microclimate simulation of a “zero patient” building: the Malatestiana Library located in Cesena, in central northern Italy. The goal of this study is to find, through Building Energy Performance (BEP) Simulation, how indoor microclimate air perfectly conserves wooden desks and parchments without any HVAC system. The first problem of the BEP simulation of heritage buildings is geometrical and thermo-physics modeling, as well as HVAC modeling if the building has a HVAC system. Scientific literature reports some research on the subject, but with a different kind of approach. The focus of the Balocco [2] study concerns a problem of HVAC systems’ effect in heritage buildings, or, in other words, the suitable air-conditioning plant design in the case of heritage buildings, and their influence on thermo-physics behavior. The research is on the Hall of the Five Hundred di Palazzo Vecchio in Florence, in which the authors compare several HVAC configurations and Computer Fluid Dynamics (CFD) software results. Also, the studies of D’Agostino [3] and Corgnati [4] deal with the CFD simulation of heritage buildings, but in this case, buildings without HVAC systems. Other research addresses particular problems of heritage buildings, such as air humidity effect or humidity transfer through walls, as described in D’Agostino’s work [5,6] on heritage church buildings without HVAC systems, and Bernardi’s research [7] that describes the indoor microclimate in another church. The goals of these studies are the microclimate’s effect on walls, or inside walls, with “mass transfer phenomenon”, and are not about indoor air microclimate. An article by Samek [8] studies the indoor air microclimate of a church building, monitoring the effect of overhead electric radiant heaters. Further possibilities could be analyzing the building by exergy methods or multiscale analysis as in Fabbri and Tronchin’s works [9,10]. The study of the indoor microclimate in heritage buildings as regards buildings with HVAC systems, and the effect of these on original buildings, is described in Camuffo [11] for energy retrofit [12,13], and, in particular, museum buildings [14,15]. From a BEP simulation point of view, historic buildings are the same as all buildings; it is possible to know the geometry, while it is difficult to know the material thermo-physics parameter. In any case, it is possible to accurately simulate an indoor air microclimate; furthermore, it is possible to evaluate the range of variations of two parameters that have a main influence on artifacts: air temperature and relative humidity, which in turn are influenced by indoor air ventilation (air velocity and turbulence).

2. Aims of the Research The aim of the research here presented consists of verifying the use of numerical models and existing tools (i.e., SkecthUp and IESVE) in the modeling of Heritage Buildings. More precisely, Energies 2017, 10, 1621 3 of 14 the most important task consists in verifying the amount of the inﬂuence of architectural conﬁgurations

(withEnergies or without 2017, 10 the, 1621 roof, first floor, etc.) on the indoor microclimate thermal parameters. Although3 of 14 a moreEnergies detailed 2017 evaluation, 10, 1621 of the thermo-physics parameter could be obtained by means of the validation3 of 14 validation of the numerical model, a comparison of different architectural scenarios does not require of thevalidation numerical of the model, numerical a comparison model, a comparison of different of architectural different architectural scenarios scenarios does not does require not require a specific a specific validation, because the research aims to compare the differences and not the absolute validation,a specific because validation, the research because aimsthe research to compare aims theto compare differences the anddifferences not the and absolute not the values. absolute values. values. 3. The UNESCO Site 3. The UNESCO Site In3. The this UNESCO research, Site we will demonstrate the criterion for modeling a historical building with a In this research, we will demonstrate the criterion for modeling a historical building with a dynamic model.In this research, Our aim we is towill study demonstrate the indoor the microclimatecriterion for modeling behavior a of historical the Malatestiana building with Library a in dynamic model. Our aim is to study the indoor microclimate behavior of the Malatestiana Library in dynamic model. Our aim is to study the indoor microclimate behavior of the Malatestiana Library in CesenaCesena (Figures (Figures1 and 1 2and). 2). Cesena (Figures 1 and 2).

Figure 1. The Malatestiana Library, Cesena: interior view. FigureFigure 1. 1.The The Malatestiana Malatestiana Library, Cesena: Cesena: interior interior view. view.

Figure 2. The Malatestiana Library, Cesena_ external view. Figure 2. The Malatestiana Library, Cesena_ external view. Figure 2. The Malatestiana Library, Cesena_ external view. In the following, Google Sketchup [16] was utilized in order to realize a three-dimensional (3D) In the following, Google Sketchup [16] was utilized in order to realize a three-dimensional (3D) virtual model. Also used was the software IESVE [17], which has been applied in several research Invirtual the following,model. Also Google used was Sketchup the software [16] wasIESVE utilized [17], which in order has tobeen realize applied a three-dimensional in several research (3D) papers, such as Said [18], which describes a long-term monitoring of the hygrothermal performance papers, such as Said [18], which describes a long-term monitoring of the hygrothermal performance virtualof model.the building Also envelope used was of the a heritage software building IESVE in [17 Ottawa,], which and has in been the appliedGuidelines in of several Historical research of the building envelope of a heritage building in Ottawa, and in the Guidelines of Historical papers,Scotland, such as where Said century [18], which villa describesmodeling awith long-term IESVE is monitoring described. In of these the hygrothermal case studies, the performance software of Scotland, where century villa modeling with IESVE is described. In these case studies, the software the buildingmodeling envelope adopts a dynamic of a heritage model. building The goal inof Ottawa,this paper and is to in know the Guidelineshow the building of Historical geometry Scotland,and modeling adopts a dynamic model. The goal of this paper is to know how the building geometry and wherearchitectural century villa section modeling of Malatestiana with IESVE Library is described. influences Inits these indoor case microclimate. studies, the In software this particular modeling architectural section of Malatestiana Library influences its indoor microclimate. In this particular adoptscase, a dynamic our aim is model. to evaluate The goalthe roof of this and paper “attic isinfluence”. to know how the building geometry and architectural case, our aim is to evaluate the roof and “attic influence”. The Malatestiana Library can be modeled as a parallelepiped, about 40 m × 10 m × 4 m (height), section ofThe Malatestiana Malatestiana Library Library inﬂuences can be modeled its indoor as a parallelepiped, microclimate. about In this 40 particular m × 10 m × case, 4 m (height), our aim is to below which there is a space with the same dimensions but 8 m high, and above a 4 m high attic and evaluatebelow the which roof there and “atticis a space inﬂuence”. with the same dimensions but 8 m high, and above a 4 m high attic and approximately 1.5 m of roof gutter line (Figure 3). The attic reduces solar radiation and solar gain in Theapproximately Malatestiana 1.5 m Library of roof cangutter be line modeled (Figure as 3). a The parallelepiped, attic reduces aboutsolar radiation 40 m × and10 m solar× 4 gain m (height), in the summer period and provides insulation during the winter period. In this paper, we study the belowthe which summer there period is a spaceand provides with the insulation same dimensions during the butwinter 8 m period. high, andIn this above paper, a 4 we m highstudyattic the and effect of the attic on the indoor microclimate, and furthermore building modeling and dynamic effect of the attic on the indoor microclimate, and furthermore building modeling and dynamic approximatelysimulation with 1.5 m BEP of roofsoftware, gutter such line as (FigureIESVE, 3and). The how attic it can reduces be useful solar for this radiation kind of andresearch. solar gain in the summersimulation period with and BEP providessoftware, insulationsuch as IESVE, during and thehow winter it can be period. useful In for this this paper, kind of we research. study the effect

Energies 2017, 10, 1621 4 of 14 of the attic on the indoor microclimate, and furthermore building modeling and dynamic simulation Energies 2017, 10, 1621 4 of 14 with BEP software, such as IESVE, and how it can be useful for this kind of research.

Figure 3. The model of the Malatestiana Library. Figure 3. The model of the Malatestiana Library. 4. Methodology: Introduction 4. Methodology: Introduction As reported earlier, the work here presented does not contain a validation of the numerical Asmodel, reported because earlier, it is not the necessary. work here The presented main purpose does notof the contain work aconsists validation in comparing of the numerical the role in model, becauseenergy it is behaviour not necessary. of different The architectural main purpose solutions of the in work historical consists buildings, in comparing rather than the investigating role in energy behaviourseveral of different different solutions architectural for optimising solutions microcli in historicalmate and buildings, energy efficiency rather than in investigatingthe Malatestiana several Library. different solutions for optimising microclimate and energy efficiency in the Malatestiana Library. The parameters here considered during the research are those which describe the indoor The parameters here considered during the research are those which describe the indoor microclimate and were previously introduced, i.e., the indoor air temperature (°C),◦ which allows us microclimateto determine and the were indoor/outdoor previously introduced,heating exchanges; i.e., the the indoor relative air humidity temperature (RH) (%), ( C), which which is strongly allows us to determineinfluenced the indoor/outdoorby the indoor air heatingtemperature; exchanges; the air velocity the relative (m/s), humidity which allows (RH) us (%), to determine which is stronglythe influencedconvective by thefluxes indoor and air movements temperature; of thefine airparticulate velocity (m/s),matter which(PM10/PM2.5). allows usMoreover, to determine air the convectivetemperature fluxes and movementsrelative humidity of fine are particulate quite im matterportant (PM10/PM2.5).for a proper preservation Moreover, airof temperatureancient and relativemanuscripts, humidity such as are ancient quite books. important for a proper preservation of ancient manuscripts, such as ancient books.The numerical simulation does not require special equipment: a normal notebook having an TheIntel numericali3 Processor simulation and 1 Gb of does random not require access specialmemory equipment: (RAM), allows a normal one to notebookperform a havingsimulation an Intel with Google Sketchup IESVE. i3 Processor and 1 Gb of random access memory (RAM), allows one to perform a simulation with Google4.1. Sketchup Adoption of IESVE. Sketchup Model 4.1. AdoptionThe offirst Sketchup step in Modelstudying an indoor microclimate, with and without an attic, is to model the building. We decided to use IESVE software and to construct the 3D model with Google Sketchup The(Figure first 4).step in studying an indoor microclimate, with and without an attic, is to model the building.The We decidedstudies of to Ellis use IESVE[19] and software Attia [20] and adopted to construct Google the Sketchup 3D model to withevaluate Google building Sketchup (Figureperformance4). with Energyplus. The geometric precision of the 3D modeling should be good enough, Thebut in studies order to of study Ellis [an19 ]indoor and Attia microclimate [20] adopted it is preferable Google Sketchup to develop to a evaluate “lightweight” building file to performance speed with Energyplus.up the interface The model, geometric the calculations, precision and of the the 3D simulation modeling results. should Sketchup be good has enough, some advantages: but in order to studya ansimplified indoor microclimateand intuitive design, it is preferable a parametric to develop system ato “lightweight” define a two-dimensional file to speed (2D) up theand interface 3D architectural form, the adoption of intuitive 3D modeling with extrusion with a push and pull model, the calculations, and the simulation results. Sketchup has some advantages: a simplified command and a Boolean data-type command. Furthermore, it allows users to define geographic and intuitive design, a parametric system to define a two-dimensional (2D) and 3D architectural form, the adoption of intuitive 3D modeling with extrusion with a push and pull command and Energies 2017, 10, 1621 5 of 14 a Boolean data-type command. Furthermore, it allows users to define geographic coordinates (GeographicEnergies Information 2017, 10, 1621 System, GIS) with latitude and longitude, so as to simulate solar5 of 14 and shade surfaces. Google Sketchup has a plug-in to the BPS IESVE software. coordinates (Geographic Information System, GIS) with latitude and longitude, so as to simulate solar The IESVEand shade software surfaces. is Google capable Sketchup of simulating has a plug-in energy to the BPS and IESVE microclimate software. behavior when interfaced with the EnergyplusThe IESVE “engine”.software is capable The of tasks simulating and en commandsergy and microclimate of IESVE behavior allow when users interfaced to carry out simulationswith for: the energy Energyplus building “engine”. performance, The tasks Computerand commands Fluid of DynamicsIESVE allow (CFD),users to heating, carry out ventilation, air-conditioningsimulations plants, for: energy human building comfort, performance, and environmental Computer Fluid Dynami impact.cs (CFD), heating, ventilation, air-conditioning plants, human comfort, and environmental impact.

Figure 4. The three-dimensional (3D) Model of the Library. Figure 4. The three-dimensional (3D) Model of the Library. 4.2. The Modeling 4.2. The ModelingThe 3D model was realized using Google Sketchup. The Malatestiana Library was divided into three zones, from the top: The 3D model was realized using Google Sketchup. The Malatestiana Library was divided into - three zones, fromAn attic, the which top: is not used, - A library with windows, a cross volt, and a barrel vault, - An attic,- A which space under is not the used, library, which is currently an archaeological museum as shown in Figure 3. - A libraryThe with 3D windows,model is a “wireframe a cross volt, model” and of a the barrel building’s vault, geometry, and all the thermo-physics information of the walls and structure are inserted with IESVE. - A space under the library, which is currently an archaeological museum as shown in Figure3. Furthermore, IESVE allows users to insert all climate and location data with APlocated selection The 3D(selection model wizard). is a “wireframe The climate data model” file has of two the file building’s extensions: the geometry, FTW by IESVE and and all the EPW thermo-physics by Energy plus and the U.S. Department of Energy (DOE) file extensions. We adopt a 10-min step for informationthe of climate the walls data, this and step structure is enough are in the inserted case of withbuilding IESVE. simulations. The CFD command allows Furthermore,users to model IESVE the allowsair flow, usersair velocity, to insert and temperature all climate distribution. and location The data CFD withreveals APlocated indoor air selection (selectionbehavior wizard). in Therelation climate to space data distribution file has, building two file use, extensions: and window the opening FTW time. by IESVE and the EPW by Energy plus and the U.S. Department of Energy (DOE) file extensions. We adopt a 10-min step for the 4.3. The Malatestiana Library climate data, this step is enough in the case of building simulations. The CFD command allows users The object of study is the Malatestiana Library, located in Cesena (center-north Italy), the only to model the air flow, air velocity, and temperature distribution. The CFD reveals indoor air behavior medieval library that has not undergone any changes since it was built in 1452 by Novello Malatesta in relationdei to Malatesti space distribution, Prince. The Malatestiana building Library use, and of Malatesta window Novello opening is on time. UNESCO’s Memory of the World list (Memoire du Monde’ Register) [21,22]. The aim of the UNESCO Memory of the World list, 4.3. The Malatestianaset up in 1992, Library is to preserve and make a Uniqueness Document for Human History. In 2005, UNESCO identified the Malatestiana Library as a “Unicum library”, the first one in Italy and in the The objectWorld. ofIt includes study isthe the same Malatestiana building, same Library, wooden locateddesks, and in same Cesena manuscripts (center-north from 1452 Italy), until the only medieval librarytoday. Furthermore, that has not it has undergone been used anyas a public changes library since until it today, was builtnot just in a 1452 museum. by Novello For these Malatesta dei Malatestireasons, Prince. we would The like Malatestiana to know how Library this perfect of conservation Malatesta of Novello wooden isdesks on and UNESCO’s manuscripts Memory was of the World listpossible (Memoire through du almost Monde’ 600 years Register) without [21 any,22 HVAC]. The system. aim of the UNESCO Memory of the World list, set up in 1992, is to preserve and make a Uniqueness Document for Human History. In 2005, UNESCO identified the Malatestiana Library as a “Unicum library”, the first one in Italy and in the World. It includes the same building, same wooden desks, and same manuscripts from 1452 until today. Furthermore, it has been used as a public library until today, not just a museum. For these reasons, we would like to know how this perfect conservation of wooden desks and manuscripts was possible through almost 600 years without any HVAC system. Energies 2017, 10, 1621 6 of 14

The Malatestiana Library was the ﬁrst Italian civic library. Commissioned by the Lord of Cesena, Novello Malatesta, the works were directed by Matteo Nuti from Fano (probably a pupil of L. B. Alberti), lasted from 1447 to 1452, and were completed with furniture and manuscripts in 1454. The aula has a basilica shape with three naves, which are divided by ten rows of white, local stone columns. The central nave is higher (6.30 m) than the aisles (4.10); the span is eleven for each aisle, pole vaulted. The central nave is barrel vaulted and ends with a rose, under which is the gravestone of Novello Malatesta. The ﬁttings are composed of 58 desks; light comes in through 44 windows. The building has three levels, the lower and the upper working exclusively to ensure the best conditions for conserving the books in the middle one. The room in which books (better still, manuscripts) are conserved has:

- a large number of windows (light, exchange of air); and - the minimum amount of wooden structures (just the windows and the desks, no wooden beams or planks), to avoid ﬁre risks.

The ﬁttings are composed of desks made of larch wood (one of the less inﬂammable types of wood). Also, from a structural point of view, the building is absolutely singular, with a strong resistance to earthquakes:

- the particular internal structure, with a large two-naves lower level, is barrel vaulted; - a three-naves middle level, really light in its structures, is superimposed over the two lower level naves; - a totally free third level has large trusses, the bonds of which are very far from the superior part of the vault; - tie rods at every level, linking together all the internal and external structures, pillars, columns, and walls.

This library has preserved its structure, fittings, and codices for more than 550 years since its opening. The thickness of the external walls reduces the heating flow through the walls in order to improve thermal inertia. The internal environment is constituted by an area of 40.87 × 10.47 m on the map (nearly a surface of 427 m2) and a height of 4.10 m in the lateral vaults and 6.30 m in the central vault, for a total indoor volume of around 1974 m3. The room has a wooden door of 1.55 × 2.33 m with double locks and side openings, each one of 0.855 × 1.28 m, separated from the inside by a bar which allows air to flow from the inside of the Malatestiana Library to other rooms of a new building, which is used for museums and civic libraries. The inside environment has no plant system, if we exclude the fire alarm and burglar alarm, to be found on the smaller walls of the Library. The plutea and manuscripts are displayed according to the wishes of Novello Malatesta. On the longer sides, there are 22 windows on each side, measuring 0.66 × 1.20 m (0.79 m2), which are without hermetic wooden frames and have simple glass panes. Externally, they are protected by a grill to avoid the entrance of birds and by an electrostatic system to repel pigeons. The Malatestiana Library environment is enclosed between two air spaces.

(a) Underneath there exists a large vault place, actually used as an archaeological museum. The space is 5.30 m high; therefore, the level of access to the library is 5.70 m from the ground, so the indoor environment of the library is not influenced by ground temperature variation and other correlated phenomena (rising humidity, flooding, etc.). (b) Above there is an attic (Figure5), a space at present not in use, its maximum height is 2.70 m, and it has an outside ventilated opening (without window or frame) with wooden roofing, a truss covering, secondary beams, small beams, and earthenware tiles.

The attic reduces the solar radiation effect on the library’s ceiling, because there is not any continuity in heat transmission, by irradiation, which strikes the outside rooﬁng going towards the Energies 2017, 10, 1621 7 of 14 environment inside the Library. The air-ventilated attic guarantees the convective exchange of air inside the room, in order to avoid all overheating and air stratiﬁcation phenomenon. Energies 2017, 10, 1621 7 of 14

Figure 5. The attic on the top of the Library. Figure 5. The attic on the top of the Library. The indoor section of the library is separated from direct contact: The indoor(a) from section the ground of the level library and other is separatedrooms (the space from occupied direct by contact: the archaeological museum is not air conditioned) and so it is isolated from thermal exchanges; and (a) from(b) the from ground incident level solar and radiation, other rooms direct or (the diffused space on occupied the attic floor, by thebecause archaeological it is not involved museum in is not air conditioned)these energetic and soexchanges it is isolated due to the from air volume thermal of the exchanges; attic (also, andin this case, there are not any HVAC plants) and the air has the same outdoor temperature. (b) from incident solar radiation, direct or diffused on the attic floor, because it is not involved in The attic, over the library, has the same geometry and structure with brick wall. The total surface these energetic exchanges due to the air volume of the attic (also, in this case, there are not any is 427 m2, with three windows, of 0.48 m2, without frame, for each longitudinal side. The roof structure HVACis a plants) wooden andtruss,the with air wood has splines the same and brick outdoor tiles. The temperature. roof does not have any insulation. The ridge is 15.60 m above the ground floor. The attic’s volume is 1386 m3. The attic,The over space the library,under the has library the samehouses geometrythe Archaeological and structure Museum, with where brick the wall.San Francesco The total surface is 427 m2, withConvent three refectory windows, once stood. of 0.48 It ha ms2 ,the without same geometry frame, as for the each library longitudinal (obvious) with side. a volume The roof of structure is a wooden2142 truss, m3. The with structure wood is splinesa brick wall, and column, brick and tiles. barrel The vault. roof The does ground not havefloor has any two insulation. naïves with The ridge a cross vault, a central nave, and two lateral aisles with a cross vault of the upper Malatestiana is 15.60 m above the ground floor. The attic’s volume is 1386 m3. Library. The ground floor has seven windows on one sidewall and six on the other, with wooden The spaceframes under and glass. the The library access houses door is thewooden, Archaeological and all windows Museum, have wrought-iron where the gratings. San Francesco Convent refectory onceThe stood. indoor It library has thevolume same is protected geometry from as th thee effects library produced (obvious) by the horizontal with a volumecomponent of 2142 m3. The structureof solar is radiation; a brick so, wall, only column,the vertical and wallsbarrel are exposed vault. to the The east, ground the south floorand the has west two according naïves with a to the solar diagram. The area occupied by the vertical walls is less than that occupied by the cross vault, a central nave, and two lateral aisles with a cross vault of the upper Malatestiana Library. horizontal elements of the roofing and flooring. Therefore, the effects of direct solar irradiation on The groundthe floor vertical has walls seven and the windows incidental on heat one transmission sidewall from and outside six on tothe inside other, are reduced. with wooden In any case, frames and glass. Thethe access heat flow door by is solar wooden, irradiation and depends all windows on wall thermal have wrought-iron displacement due gratings. to the thermo-physics The indoorand thermal library capacity volume of the is protectedwalls. The manuscripts from the effects conserved produced in the library by the are horizontal monitored componentand of controlled and subject to periodic assessment, and if necessary, conservation. The manuscripts, solar radiation; so, only the vertical walls are exposed to the east, the south and the west according to reproduced and available in digital format, can be consulted in exceptional cases by historians; in the solar diagram.such cases, The the requested area occupied manuscript by theis removed vertical from walls the library is less by than the thatlibrarian occupied and consulted by the in horizontal elements of the roofing and flooring. Therefore, the effects of direct solar irradiation on the vertical walls and the incidental heat transmission from outside to inside are reduced. In any case, the heat

ﬂow by solar irradiation depends on wall thermal displacement due to the thermo-physics and thermal capacity of the walls. The manuscripts conserved in the library are monitored and controlled and subject to periodic assessment, and if necessary, conservation. The manuscripts, reproduced and available in digital format, can be consulted in exceptional cases by historians; in such cases, the requested manuscript is removed from the library by the librarian and consulted in another part Energies 2017, 10, 1621 8 of 14 of the library. The Malatestiana Library was the object of indoor microclimate monitoring during 2013 research; the results were published in Fabbri [23].

5. The Scenarios As mentioned earlier, the Malatestiana Library was modeled by means of IESVE; the input data concern geometry, the thermo-physics parameter, window opening, and climate data. The output data of the simulation are:

- indoor air temperature (◦C); - indoor relative humidity (%); - air velocity (m/s); - occupant Predicted Mean Vote (PMV).

The aims of the study are to evaluate the natural ventilation incidence with different kinds of window opening times. The building energy performance simulation interests the entire building, ground ﬂoor, library, and attic, but the results are only for the library. The scenarios carried out are the following:

(1) with all 44 windows closed, for all days during the year; (2) with six windows open 2 h per day. In this case, we consider three windows opened for each side, from 7 a.m. to 9 a.m. The library caretaker conﬁrmed that these are “as usual” scenarios. In this case, we have new air ventilation from outdoor climate data; (3) with six windows open 12 h per day. In this case, the building simulation considers three windows open from 7 a.m. to 7 p.m. In this case, the outdoor climate has a greater incidence on the indoor air.

We do not consider other kinds of window opening scenarios, because the above cases include the majority of cases, e.g., the caretaker advised us that all 44 windows are never opened, and windows are never open all day, not even in summer. The second typology of scenario concerns a building section configuration, in other words, we would like to know the ground floor’s and the attic’s influence on the library’s indoor microclimate. The three scenarios are:

(a) the actual building, with six windows open 2 h per day; (b) the building without the attic, with six windows open 2 h per day, in order to evaluate solar irradiation’s influence; (c) the building without the ground floor, with six windows open 2 h per day, to evaluate the basement terrain’s influence.

6. Results and Discussion The results of the BPSs show different indoor air behaviors based on the boundary conditions. We will report each case with comments. In Case 1, the simulation shows that the average indoor air temperature is 17.77 ◦C, whereas the RH is 45.37%; furthermore, during the period March–July, the average air temperature is 20.91 ◦C and the RH is 55.60%. Following Italian Law, by Italian Ministry of Cultural Heritage and Tourism (MIBAC) (MIBAC, 1998, “Atto di indirizzo” Dlgs 112/1998 art.150 comma 6, pg.144), the standard range values in the case of manuscripts deﬁne the range values of temperature and RH, of an indoor air microclimate, as between 13 and 18 ◦C (to an extent to 20 ◦C) and an RH of between 55 and 66%. The IESVE simulation shows that the indoor air of the Library is above the standard range values. The peak temperature, during summer time, is 27 ◦C, and the temperature is over 25 ◦C only for one week in a year. Energies 2017, 10, 1621 9 of 14

The CFD analysis needs only to simulate a specific day and schedule. We decided to simulate on the hottest day, which is defined by IESVE as 8 July at 12:00 p.m. The result of the simulation is that the temperature is homogeneous inside the library, with an average value of 21 ◦C. The air velocity is zero m/s, because the windows are closed all day. ◦ ◦ EnergiesIn Case 2017 2,, the10, 1621 simulation shows that the average indoor air temperature is 17.05 C, only9 −of 0.7214 C less than Case 1, and the RH value is 69.26%, 13.66% more than Case 1. This is because the indoor air has a naturalIn Case ventilation 2, the simulation with the shows outdoor that the air, average that has indoor more air moisture, temperature especially is 17.05 °C, in only winter −0.72 and on rainy°C days, less than than Case the 1, inside and the air. RH The value IESVE is 69.26%, simulation 13.66% shows more than a longer Case 1. duration, This is because compared the indoor to Case 1, air has a natural ventilation with the outdoor air, that has more moisture, especially in winter and on in a period when the air temperature and RH are within the standard range values defined by MICAB. rainy days, than the inside air. The IESVE simulation shows a longer duration, compared to Case 1, The peak temperature during summer time is 27 ◦C, and the temperature is over 25 ◦C only for one in a period when the air temperature and RH are within the standard range values defined by weekMICAB. in July. The The peak RH temperature value changes during every summer day andtime allis 27 year, °C, and but the the temperature air is never is very over dry25 °C (RH only lower thanfor 40%). one week in July. The RH value changes every day and all year, but the air is never very dry (RH lowerThe CFD than analysis40%). shows a peak indoor air velocity on 15 October at 7:00 a.m. The indoor air temperatureThe isCFD 16 ◦analysisC and theshows air velocitya peak indoor increases air veloci nearty the on windows15 October (Figure at 7:006 a.m.). The indoor air temperatureIn Case 3, the is 16 simulation °C and the shows air velocity that the increases average near indoor the windows air temperature (Figure 6). is 18.12 ◦C, only +0.35 ◦C less thanIn Case Case 1, 3, but the more simulation than +1 shows◦C higher that the than average Case indoor 2. The air RH temperature average value is 18.12 is 70.33%,°C, only nearly+0.35 the same°C RH less as than in Case Case 2, 1, but but more more than than +14.73%+1 °C higher in relation than Case to Case2. The 1, RH the average driest case. value Window is 70.33%, opening nearly and the same RH as in Case 2, but more than +14.73% in relation to Case 1, the driest case. Window indoor/outdoor air natural ventilation should be a problem in order to guarantee indoor air standard opening and indoor/outdoor air natural ventilation should be a problem in order to guarantee indoor range values following the MIBAC law. These results show how window opening and maintenance air standard range values following the MIBAC law. These results show how window opening and care,maintenance by the library care, caretaker, by the library have caretaker, a positive have influence a positive on influence manuscript on manuscript and artifact and conservation. artifact The CFDconservation. analysis The shows CFD a analysis peak indoor shows aira peak velocity indoor on air 2 Decembervelocity on 2 at December 7:00 a.m. at 7:00 a.m. The IESVEThe IESVE simulation simulation shows shows a a longer longer duration,duration, compared compared to to Case Case 1, the 1, the same same as Case as Case 2, in 2,a period in a period whenwhen air temperatureair temperature and and RH RH are are within within thethe standardstandard range range values values defined defined by MICAB. by MICAB. The peak The peak temperaturetemperature during during summer summer time time is is 27 27◦ °C,C, andand the temp temperatureerature is isover over 25 °C 25 only◦C only for one for week one weekin July. in July. TheThe RH RH values values change change during during the the dayday andand during the the year; year; furthermore, furthermore, there there are more are more cases cases presentingpresenting an RHan RH greater greater than than 70% 70% compared compared to Case 2. 2. The The CFD CFD simulation simulation (Figure (Figure 7) shows7) shows an an average temperature of 15 °C, and air velocity increases near windows and in the middle of the center average temperature of 15 ◦C, and air velocity increases near windows and in the middle of the center nave of the library. nave of the library.

FigureFigure 6. 6.Indoor Indoor air air velocityvelocity in in the the middle middle ofof central central nave. nave.

Energies 2017, 10, 1621 10 of 14 EnergiesEnergies2017, 10 2017, 1621, 10, 1621 10 of 1410 of 14

FigureFigure 7. 7.Indoor Indoor air air velocityvelocity in in the the middle middle near near the the windows. windows. Figure 7. Indoor air velocity in the middle near the windows. TheThe second second part part of of the the study study regards regards thethe architectural form form ofof the the building: building: The second part of the study regards the architectural form of the building: (a) the actual architectural section, compared with: (a) the actual architectural section, compared with: (b)(a) withoutthe actual the architectural attic, and section, compared with: (b) without the attic, and (c)(b) withoutwithout the the ground attic, and floor museum. (c) without(c) without the groundthe ground ﬂoor floor museum. museum. Figure 8 shows a conceptual scheme of the three simulations. FigureFigure8 shows 8 shows a conceptual a conceptual scheme scheme of of the the three three simulations. simulations.

Figure 8. Conceptual scheme of the further simulations. (a) actual architectural section, Figure(bFigure) 8.simulationConceptual 8. Conceptual without scheme roof, schemeof (c) the simulation furtherof the withoutsimulations.further air simulations. space (a) actualof the ground( architecturala) actual floor architectural section; (b )section, simulation without(b) roof;simulation (c) simulation without roof, without (c) simulation air space without of the air ground space floor.of the ground floor These simulations consider windows opening 2 h per day, which represent the actual use and maintenanceThese simulations of the buildings. consider We windows consider openingthe case (a),2 h theper buildingday, which with represent the original the actual architectural use and section,Thesemaintenance simulationsas our ofbaseline the buildings. consider (Case 2). windowsWe consider opening the case 2 (a), h perthe day,building which with represent the original the architectural actual use and maintenancesection,In Figure as of our the 8b, baseline buildings. solar radiation (Case We 2). is consider directly on the the case library’s (a), the roof, building so the indoor with theair has original an increase architectural of section,solar as energy.In our Figure baseline The 8b, results solar (Case radiationof the 2). IESVE is directly simulation on the show library’s a longer roof, duration so the indoorof standard air has range an increase values of of airInsolar Figuretemperature energy.8b, solarThe and results radiation RH. ofThe the ispeakIESVE directly temperature, simulation on the show library’sduring a longer summer roof, duration so time, the indoorofis standard nearly air 27 hasrange °C, an valuesbut increase the of of air temperature and RH. The peak temperature, during summer time, is nearly 27 °C, but the solar energy. The results of the IESVE simulation show a longer duration of standard range values of air ◦ temperature and RH. The peak temperature, during summer time, is nearly 27 C, but the temperature is over 25 ◦C only for all of the summer season. In this case, the average annual temperature is 14.13 ◦C, with a gap of −2.92 ◦C, and an annual RH of 39.89%, with a gap of nearly 40% in spite of case (a). In this case, the indoor air should be drier than a building with an attic. Energies 2017, 10, 1621 11 of 14 Energies 2017, 10, 1621 11 of 14 temperature is over 25 °C only for all of the summer season. In this case, the average annual temperaturetemperature isis 14.13 over °C,25 with°C only a gap for of all −2.92 of °C,the andsummer an annual season. RH In of this 39.89%, case, with the aaverage gap of nearlyannual Energies40%temperature2017 in, spite10, 1621 of is case 14.13 (a). °C, In with this case,a gap the of indoor−2.92 °C, air and should an annualbe drier RH than of a39.89%, building with with a angap attic. of nearly 11 of 14 40% Wein spite can supposeof case (a). that In a this configuration case, the indoor without air shouldthe attic be could drier have than aa higherbuilding temperature with an attic. during summer,We canand supposeconsequently that a a configuration lower RH value. without These the facts attic should could cause have a modificationhigher temperature of the indoorduring air’sWesummer, cancondition suppose and consequentlywith that damage a configuration ato lower the manu RH value.scripts’ without These elasticity the facts attic and should could hygroscopicity. cause have a amodification higher temperature of the indoor during summer,air’sThe andcondition result consequently withof the damage IESVE a lower to simulation the RHmanu value. scripts’of the These airelasticity temperature facts and should hygroscopicity. (Figure cause 9) a modificationshows an irregular of the air indoor air’stemperature conditionThe result with distribution of damage the IESVE inside to the simulation the manuscripts’ environment of the elasticity aircompared temperature and to baseline hygroscopicity. (Figure tren 9)ds. shows The CFDan irregular simulation air ofThetemperature air resultvelocity ofdistribution (Figure the IESVE 10) insideshows simulation thean increaseenvironment of theof air air co velocitympared temperature (0.15 to baseline m/s) (Figure in tren the9 ds.middle) showsThe CFDof anthe simulation irregularbuilding air of air velocity (Figure 10) shows an increase of air velocity (0.15 m/s) in the middle of the building temperaturethat probably distribution depends inside on convective the environment and air stratifi comparedcation at to the baseline upper trends.side of the The central CFD simulationnave. In of Figurethat probably 8c, the library’s depends basement on convective is in direct and air contact stratifi withcation the atground. the upper side of the central nave. In air velocity (Figure 10) shows an increase of air velocity (0.15 m/s) in the middle of the building that Figure 8c, the library’s basement is in direct contact with the ground. probably depends on convective and air stratification at the upper side of the central nave. In Figure8c, the library’s basement is in direct contact with the ground.

Figure 9. Distribution maps of the temperature. Figure 9. Distribution maps of the temperature. Figure 9. Distribution maps of the temperature.

FigureFigure 10. 10. DistributionDistribution maps maps of of air air velocity. velocity. Figure 10. Distribution maps of air velocity. The IESVE simulation results show a shorter period of standard range values, by the MIBAC law; moreover, there is an increase in the daily gap difference of indoor air temperature and RH, increasing the damaging effect on the artifacts and manuscripts. In this case, compared with the case (b) without the attic conﬁguration, the results do not show a peak temperature, but the temperature trends are lower than the case (a), actual architectural section. The annual average temperature is 13.37 ◦C, with a gap of −3.68 ◦C, but the average RH value is 70.16%, with a gap of nearly 1.5% in spite of case (a), slightly higher than baseline. In the building without a museum, the average temperature Energies 2017, 10, 1621 12 of 14 is nearly the same as the baseline, but the RH increases, and depends on the effect of the basement which is in direct contact with the ground. In the building without the attic, unlike in a complete building, the annual average temperature increases, depending only on direct solar radiation on the library’s roof top. These results show the importance of BPS applied to heritage buildings, so if we can consider that it is obvious that detaching the library from the basement would reduce water inﬁltrations from the ground, on the contrary, such a large attic has been chosen to reduce the high summer temperatures which damage the artifacts that are stored inside the building.

7. Conclusions A BPS allows us to verify indoor microclimate parameters based on different window and architectural conﬁgurations. Each case study scenario presents a gap compared with a real building. These depend on:

(a) building geometry: in the Google Sketchup software model, we decided to use a simplified model of indoor volume, so we removed an indoor column and a wooden desk, which could play a role in CFD and air velocity, especially to study dust distribution. Furthermore, historical buildings are more difficult to analyze as they have more details and different shapes compared to residential buildings; (b) we did not consider the outdoor context—the neighboring buildings—because they are far from the Malatestiana Library and so have no influence on the radiation or other outdoor data; maybe only the outdoor pavement, in particular the courtyard lawn grass, could have a small influence on the outside temperature.

In this sense, future studies applying Building Performance Software should be improved with geo-location outdoor climate data from a global positioning system (GPS). We would like to improve our studies with GAIAG [24], a Satellite Application Facility for Decision-Making. The company works in remote sensing for the Global Monitoring Environment and Security (GMES) application integrated with the OGC standard (Open Geospatial Consortium standard) in compliance with the INSPIRE European Directive for the management of spatial data. The integration of satellite data would allow us to obtain data input in ﬁle extension WEA, EPW, or CSV code with real geo-related data, with satellite monitoring data. The different kinds of acquirable data allow for the improvement of quality and efﬁciency in Building Energy Performance models. Furthermore, the BEP software:

(i) analyzes indoor CO2 (carbon dioxide) distribution produced by visitors. We decided to not do this simulation because the measurements show still air and library visits are strictly regulated, only a maximum of 20 persons, for 15–20 min, with a maximum of 80–100 visitors per day, with a peak of 3000 visitors/day. Furthermore, visitors can visit only the ﬁrst 3 m of the entrance area; (ii) adopts the HVAC design (or validation), or simulates a HVAC system’s effect (or damage) on the Malatestiana Library. We would like to highlight a fact: HVAC systems are not present because they can modify the indoor microclimate and damage artifacts, manuscripts, and the actual building; (iii) evaluates the predicted mean vote (PMV) and predicted percentage of dissatisﬁed (PPD) of thermal comfort also with a CFD simulation. An interesting study concerns the simulation of the PMV and PPD at the original Malatestiana Library during the XV-XIX century, when the neutral value of the PMV was under a −1.5 ≈ −2 value.

The main difficulty in BPS is to insert all data, which is however simplified by the IESVE interface and Google Sketchup. An advantage is the accuracy of modeling, which allows for the simulation of several conditions, as this present paper demonstrates. The BPS could be adopted to verify a building design or existing building, but another clever use is to use this software as a design tool, in the Energies 2017, 10, 1621 13 of 14 case of new or retrofit buildings, or an investigation tool in the case of heritage buildings. In this research, we do not use the IESVE software with aims to verify; instead, we would like to investigate the architectural sections of buildings and the influence of maintenance on indoor air. A BPS should be implemented in historical and archaeological investigations, e.g., PMV simulation to discover the ancient habits used in the library or perhaps even the type of clothes they wore to read in such buildings. In our research, the BPS has been done following an indoor monitoring campaign, in order to measure the effect on:

(1) building and windows opening management; and (2) building attic and ground ﬂoor inﬂuence on the indoor microclimate of the Malatestiana Library.

The result allows us to understand the indoor environmental role of the architectural section, in order to know if the designer has a role in choosing an environmental control strategy. Following an archaeological study analysis criterion, we observed that several libraries built in the same century have the same architectural sections, e.g., the San Marco Library in Florence (XV century), the Santa Maria Incoronata Library in Milan (XV century), and the Monte Oliveto Library in Asciano, Tuscany (XV century), all have the same architectural section design. These libraries, however, have been modiﬁed over time. The BPS conﬁrms to us that the architectural Renaissance design criterion (proportion, symmetry, golden section, etc.) are not just an “aesthetic criterion”, but they could be compared—with an empirical approach—to a current BPS model in order to discover indoor air environmental behavior. In our opinion, this is the most relevant discovery of this research, because BPSs show a direct and close relation between aesthetics and the environment, and between library architecture and an “ante-literam” environmental design. In conclusion, the BPE model should also be used as an archaeological/architectural tool to discover the environmental design strategies of the past.

Acknowledgments: The authors wish to acknowledge Giulia Angeli for her support during the research. Furthermore, the authors would like to thank the caretakers and the Deputy Director, Paola Errani, who granted access to the Library, and for their kindness, attention, and care shown in the management and conservation of the Malatestiana Library. Author Contributions: The study was designed by Lamberto Tronchin and Kristian Fabbri. Kristian Fabbri performed measurements by means of equipment belonging to Lamberto Tronchin. The simulation, the results, and the analysis were performed, analysed, and checked by Kristian Fabbri and Lamberto Tronchin. All authors have read and approved the final manuscript. Conflicts of Interest: The authors declare no conflict of interest.

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