PSI - Issue 29

Alessandro Miglioli et al. / Procedia Structural Integrity 29 (2020) 118–125 Mignoli et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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1. Introduction In Europe, the building sector is responsible for over 36% of total energy consumption and around a third of greenhouse gas emissions, according to IEA (2018). Themajority of suchbuildings arepre-1990 and a quarter of the existingbuilding stock is composedof historical buildings, as indicated byBuda andMauri (2019). Nomenclature AHU Air HandlingUnit GW Groundwaterwithdrawal/rejection wells GHX Geothermal heat exchangers HP Hea t Pump HVAC Hea ting, Ventila tionandAir Conditioning VAV Variable AirVolume New buildings reached a considerable improvement toward the nearly Zero Energy Building (nZEB) standards thanks to theEuropean regulatory framework, in particular Directive2002/91 andDirective 2010/31. On thecontrary existing and historical buildings still have very high energy consumption. The problem of rela tively low indoor comfort conditions for occupants and in some cases with unacceptable indoor environmental conditions for the conservationof their artworks were stressed by Pigliautile et a l. (2019). According to Ira ti et a l. (2016), around110 million of the existing building require deep renovation. These particular buildings need ta ilored and feasible solutions, through retrofit interventions which take into account the architectural constraints and t hehistoric physical integrity of the cultural heritage, as described in the CENstandard (2017). In such framework, a topic increasingly addressed in the litera ture during the last decade is rela ted to the heating of historical buildings characterized by very huge air volumes and high thermal mass, as churches, which implies a significant thermal power and energy demand for heating. Among them, the most adopted solutions are represented by a ll-a ir system, the infrared heaters and the pew-based heating (Aste et a l. (2017)). While the first two solutions implies high energy consumptionanddrawbacks rela ted to the preservationconstrains, as underlined respectively by Aste et a l. (2016) and Camuffo (2006), the last one seems to be the most innovative one. Pew-based heating system were firstly investiga ted byCamuffoet a l. (2010) as a novel technical solution for local thermal comfort. The authors demonstrated that integrating electric heating foil properly installed as under-seat, under-kneeler and hand-warmer elements can ensure optimal comfort level while minimizing the negative influence on the church and its artworks. Neilen et a l. (2004) obtained significant energy savings can be obtained, typically higher than 70% in comparison with on-demanda ll-air systems. Other advanced solutions for the thermal needs of historical buildings are reported in the litera ture, as the combination of a wa ter-condensed hea t pump (HP), demand-controlled ventila tion and trigenera tion system presented by Schibuola et a l. (2018), respecting preservation orders and constraints defined by authorities. In such a scenario, the present work represents the prosecution of previous research presentedby Leonforte et al. (2019) and is carried out on thesamecase-study, the Armoury hall a t thePa lazzo Ducale in Mantua. The assessment of the energy andeconomic impact of differentHVACsolutions for the musealization of thearmouryhall is presented, providingguidelines of intervention for thepresent and also analogous cases. 2. Case study andmethod The space object of the retrofit intervention is the armoury hall of the PalazzodelCapitano, built in the13 th century, which is part of themuseumcomplexof the PalazzoDucale in Mantua. Thearmouryhall is a single rectangular space tha t covers anarea of about 1000m 2 (66x15m)with a maximumheight of 11m, for a total volume of around9700m 3 . Externalwa lls aremadeby solid bricksand their thickness varies from70 to80cm. Thefloor and the roof arerealized with wooden structures. Thirteen double lancet windows, composedof single glasses and wooden frames, illuminate the indoor space. Currently, the armoury hall is empty, and no system forHVAC is insta lled. In 2018 the restoration project of the ha ll has been planned to make this space available for art exhibitions and cultural events. The