Most of the Italian buildings were built during the three decades following the Second World War. However, the National cultural heritage is made up by huge and widespread amount of buildings built at an earlier time that, as a whole, although not always characterized by remarkable monumental and artistic importance, define the specific character and the historical memory of a site. The renovation of these buildings requires dedicated technological solutions, even within energy efficiency improvement scenarios. The public buildings built over seventy years ago, in fact, are amenable to protection constraints (according to the National Code of Cultural Heritage and Landscape) and represent a large part of the entire stock. The subject of this study was the definition of criteria for intervention on school buildings, protected by the Cultural Heritage Code, with the aim of upgrading according to the target nearly Zero Energy Building (nZEB). The tasks required to carry out the study have foreseen the identification of a case-study, based on a survey of school buildings of the Municipality of Milan built over seventy years ago, which is representative of a common historical school building typology. Then, the definition of retrofit measures have been set to meet the nZEB requirements as defined by the National implementation of the EPBD – Recast, while complying with the protection constraints. The energy simulation of the selected school was conducted based on a certified software that adopts the official National calculation procedure. The set of energy simulations have been calibrated starting from the retrofit solutions needed to upgrade the energy performance of the building envelope in consistent with the National nZEB requirements. These have resulted in the insulation of the opaque envelope (ceiling of the unheated basement, floor of the unheated loft under the pitched roof and inner side of the external walls, for compliance with the protection constraints), as well as the placement of new internal windows in addition to the existing ones (the new high energy performance standards for the windows imply frame profiles incompatible with the protection constraints of the facades) and the installation of internal venetian blinds. Satisfying the nZEB requirements referred to building energy systems and energy from renewable sources have included the replacement of existing luminaires with new ones equipped with dimmed LED lamps (activated according to combined occupation and daylight sensors). Meanwhile, in order to address solutions that are compatible with the constraints of protection and replicable elsewhere, the existing gas boiler has been substituted with an air-to-water heat pump, accompanied by the installation of a photovoltaic system integrated on the roof slopes facing the courtyard. The connection to a district heating network has been also considered as a particular alternative, since allows derogation from the "National requirements for thermal-renewables”. Finally, the cost-effectiveness of the various interventions was evaluated, in terms of both Total Annual Cost related to the achieved energy performance and Net Present Value. Results indicate that building envelope measures imply a Pay Back Time up to 21 years, while the building energy systems/renewables measures can extend this value up to 26 years.
|Titolo:||Retrofitting under protection constraints according to the nearly Zero Energy Building (nZEB) target: the case of an Italian cultural heritage’s school building.|
|Autori interni:||FERRARI, SIMONE|
|Data di pubblicazione:||2017|
|Appare nelle tipologie:||04.1 Contributo in Atti di convegno|