Building Simulation to Measure Indoor Microclimate in Heritage Buildings
Total Page:16
File Type:pdf, Size:1020Kb
________________________________________________________________________________________________ Building Simulation to Measure Indoor Microclimate in Heritage Buildings 1 1 1 Kristian Fabbri , Marco Pretelli , Anna Bonora 1University of Bologna, Bologna, Italy Abstract materials (e.g. ceramics, papyrus manuscripts) in relation to their nature. Indeed, sometimes, to ensure microclimate The aim of this paper is to describe our Building control on the artefacts, special showcases are provided in Simulation (BS) approach to study indoor microclimate case of higher risks due to decay and use. parameters in heritage buildings. Literature already exists Moreover, nowadays, the indoor microclimate control can over this subject: in the area of museums - Thomson, be provided by HVAC system (Heating Ventilation and Camuffo; this issue has been particularly emphasized, for Air-Conditioning) for the winter/summer air example, by Bernardi; others, as De Guichen, proposed conditioning, if the characteristics of the building and/or specific methodologies for museums. Nevertheless, in our frequency of visitors are such as to justify their on/off opinion, today there isn’t a vision which includes the activation or their implementation. history and the objectives of the architecture. We consider indoor microclimate in heritage buildings as a result of In different contexts, the artworks are housed in several several strategies to guarantee indoor comfort. We named rooms, and they belong to the building and to the visitors’ it “Historic Indoor Microclimate”, and we adopt BS to path. The microclimate of these rooms can be "kept under simulate actual, past and future indoor microclimate. In control" thanks to the technical HVAC. Nevertheless, this paper we show three case studies of Italian historic sometimes the HVAC system is not enough. This kind of buildings: Villa La Petraia, Florence; Villa Barbaro, problems involves also the management of the artworks Maser; Palace of Venaria Reale, Turin, which can clarify borrow for museum expositions. the importance of the application of the BS on cultural In this paper, we propose a new index, the “Heritage heritage. Moreover, the paper proposes an index: Microclimate Risk” (HMR), to define a unique tool to “Heritage Microclimate Risk”, useful to study the indoor evaluate indoor microclimate aggressiveness for building, microclimate aggressiveness. furniture, painting, etc. It permits to evaluate the risk level Introduction to whom the objects are exposed and the level of the human’s comfort, in order to improve it, through the help Nowadays it is becoming increasingly clear the need of a of hypothetical scenarios, realized by the BS. proper management of historic buildings: ensuring the This article, thanks to the experience reported by the case conservation of the cultural heritage and guarantying the thermal comfort of the occupants. The preservation of an studies -Villa La Petraia, Florence; Villa Barbaro, Maser; Palace of Venaria Reale, Turin-, shows how the Building historic building depends largely on its microclimatic conditions. Simulation can be useful to face those mentioned categories of problems: we propose a methodology, based The study of the indoor microclimate of heritage on the use of the virtual BS on cultural heritage, which buildings involves some problems. We are specifically permits to pre-emptively define, throughout a virtual interested about the ones related to the impact on the building model, which actions could aid the preservation artworks (paintings, furniture, frescos, etc.), in relation to of the heritage buildings, avoiding the risk component that specific agents (physical, chemical, biological) which can would be taken working on the physical building. damage them and whose presence, concentration and diffusion. Methods That depends on the characteristics of the indoor The proposed methodology is composed of three phases: microclimate and it’s influenced by the management of 1. Understanding the building, through: artworks – and of the buildings that host them – and the a. archive research: to verify the geometrical, tourists in relation to the relevant artistic path. structural and thermo-physical characteristics of This problem has long been known in scientific literature, the historic building; specific to museums (Thomson, 1986; Camuffo, 1998; b. on-site relief: to obtain the building geometric Bernardi, 2008; Corgnati and Filippi, 2010; D’Agostino, measurement; 2015; Litti, Audenaert and Fabbri 2017; Lucchi 2017) and c. on-site monitoring: to record, using probes, the there exist Standards (UNI 10829 EN 15759-1), which Actual Indoor Microclimate (AIM) identify the range of the values, allowing the preservation characteristics, following the definition of of the individual works (e.g. books, paintings) or Pretelli and Fabbri); ________________________________________________________________________________________________ Proceedings of the 16th IBPSA Conference 4086 Rome, Italy, Sept. 2-4, 2019 https://doi.org/10.26868/25222708.2019.210181 ________________________________________________________________________________________________ 2. Virtual Building modelling and simulation: When the model is validated, the accuracy of the Building a. Building Simulation: construction of a 3D Simulation, with respect to the variables used in Virtual Building model, trough any modelling validation, is confirmed software, and of Virtual Environment model in The thermal characteristics of the models are dynamic conditions (Building Energy automatically calculated by the software once we specify Simulation, CFD), using IES.VE software, to all the construction components (stratigraphy materials reproduce the same characteristics of the case and thickness). study; The environment of an indoor space is affected by the b. Model validation: to validate the model, outdoor climate too. Indeed, on IES.VE, it is necessary to comparing the simulated data to the ones choose the weather file whose data are got from the obtained through the indoor microclimate nearest meteorological station from each case study. campaign; Moreover, it is fundamental setting information about the c. Virtual Scenarios: if the virtual building model geographical location and the HVAC system (set-point, gets validated through the data collected with the daily profile, etc.). In this way it is possible to obtain a microclimate indoor monitoring, the study of the virtual model, which has the same environmental Heritage Microclimate Risk (HMR) can characteristics of the original space of the studied proceed, along with the scenarios of architecture. That permits to realize Building Simulations management and/or modification of the indoor and to assume present, future and past environmental microclimate; scenarios, simulating the state of conservation of the 3. Calculating the Heritage Microclimate Risk (HMR). building, of the artworks and the occupants’ comfort: we The environmental parameters recorded by probes are: can evaluate what could happen changing certain Air Temperature (measured in °C), Relative Humidity materials of the building; the management of the HVAC (measured in %), Illuminance (measured in lux) and system; taking in consideration the Climate Change and Carbon Dioxide (CO2 measured in ppm). its consequences on the specific indoor microclimate; etc. Moreover, the virtual model gives the opportunity to Finally, to calculate the HMR is useful to estimate the simulate other variables, even if not measured by the aggressiveness of the microclimate against the materials probe, such as the distribution of the air velocity in the hosted in a specific indoor microclimate. It is calculated space (to assess any phenomena of turbulence and/or as follows: handling of the dust) and/or water vapour content, and/or 푚푟 퐻푀푅 = ℎ[%] (5) mean radiant temperature and/or natural light distribution ℎ (illuminance). and regarding the single variable(x) The validation process consists in the comparison of the 푚푟ℎ 퐻푀푅 = (푥)[%] (6) measured data -by probes, during the monitoring (푥) ℎ campaign- with the simulated ones -obtained using the where: software IES.VE (Integrated Environmental Solutions)-. mrh is the hourly microclimate risk of the reference The validation parameters are: period; • MBE (Mean Bias Error), h represents the total hours of the reference period. ∑푛 (푀 −푠 ) 푀퐵퐸 = =1 (1) In the case study presented in this paper, the reference ∑푛 푀 =1 period corresponds to the monitoring campaign. Validated if MBE < 10%; The mrh (hourly microclimate risk) is determined by • Coefficient of Variation root-mean-square error 푚푟 = ∑푛 (ℎ푟 > ℎ푟 ) + (ℎ푟 < (RMSE): ℎ 푗=1 (푥) (푥,푠푒푡),푚푖푛 푗 (푥) 2 ℎ푟(푥,푠푒푡),푚푎푥) [h] (7) n (푀−푆) 푗 √훴ⅈ=1[ ̇ ] 푁 Where 퐶푉 (푅푀푆퐸) = 푛 (2) ∑ 푀 =1 “hr(x)” is the heritage risk of the microclimatic variable 푛 (x); Validated if CV (RMSE) < 30%; “hr(x,set),min” is the heritage risk of the microclimatic • Pearson Correlation Coefficient: variable (x) with the minimum set-point, defined as the 휎 푃퐸퐴푅푆푂푁 = 푀푆 (3) lower range established by Standard (UNI 10829, 1999) 휎푀휎푠 or other guidelines; if > 0.7 = strong correlation, “hr(x,set),max” is the heritage risk of the microclimatic if between 0.3 – 0.7 = correlation; variable (x) with the maximum set-point defined as the • Coefficient of determination R2: lower range established by Standard (UNI 10829, 1999) ∑푛 ( ̅)2 or other guidelines; 2 =1 푆−푀 푅 = 푛 2 (4) “j” is the number of hours of the reference period. ∑ (푀−푀̅) =1 Validated if R2 > 0.5 ________________________________________________________________________________________________