Evaluation of the Sustainability of Energy Retrofit Interventions on the Historical Heritage: A Case Study in the City of Matera, Italy Valeria Selicati 1* , Nicola Cardinale 1 , Michele Dassisti 2 1 Department of European and Mediterranean Cultures, University of Basilicata, Via Lanera, 75100 Matera, Italy 2 Department of Mechanics Management and Mathematics, Polytechnic of Bari, Viale Japigia 182, 70126 Bari, Italy Corresponding Author Email: valeria.selicati@unibas.it https://doi.org/10.18280/ijht.380103 ABSTRACT Received: 19 November 2019 Accepted: 17 February 2020 For some years now the regulations in the sustainability field oriented the practitioners towards an increasing restraint concerning energy necessities, to reconsider the weight in terms of energy and environmental impacts associated with different phases of their life cycle. Among the reliable models to carry out the valuation, the Life Cycle Assessment remains a useful tool that determine the most impactful stages of the life cycle of any process and, thus, its environmental performances. This paper aims to develop and complete previous analyses on sustainability led on the historical heritage of the city of Matera, highlighting all the issues that are still unresolved and the possible solutions to be undertaken. Deep considerations on sustainability and its peculiarities are carried out. A reported analysis of literature and a description of the methods and tools used in the case study are shown. The case study consists in performing the LCA using SimaPro software, based on the assumptions aimed to the energetic retrofit for “Palazzo del Sedile”, an historical building located in Matera, Italy. In this section, three methods of assessment are largely described, the choice has been made due to their significance in expressing the environmental effects from three very different perspectives. Keywords: energy retrofit, impact assessment, life cycle assessment, sustainability, historical buildings 1. INTRODUCTION Starting from the work carried out and published in the proceedings of the AIGE IIETA Congress on TI-IJES on June 2019 [1], the following text is an extension and completion of the considerations and the analysis implemented in the paper. In the European Union the construction industry is responsible for about 42% of the final energy consumption and 50% of raw materials, produces approximately 35% of greenhouse gas emissions and 50% of waste [2, 3]. In this context, the Directive n. 2010/31/EU on building energy performance (EPBD recast), the European Union "is committed to develop a sustainable energy system, competitive, secure and decarbonized by 2050"; in particular, the Directive provides that by 31 December 2020 all new buildings must be "nearly zero energy buildings" [4]. The construction sector plays a prominent role and it responsible for the highest impact on the environment in terms of consumption of resources, energy consumption, emissions and wastes. Also in the latest review of the Directive (July 2018) [5] it is evident that each UE member has the task of identifying a long-term strategy to support the renovation of residential and non-residential buildings, both public and private, in order to achieve a decarbonized and energy efficient real estate stock by 2050, facilitating the cost-effective transformation of existing buildings into nearly zero energy buildings , which is interpreted into the need to implement solutions that reduce energy needs and wastes especially in the use phase [6]. A first mention of the importance of the energy diagnosis relating to historical buildings was set up by the AiCARR (Italian association for air conditioning heating and refrigeration), which in February 2014 published a guide. For the evaluation and improvement of the energy performance of historic buildings, in accordance to the recent legislation [7]. After the widespread consolidation of energy efficiency, the interest of the market and the operators switched to environmental sustainability. The demand for reliable indicators easy to use for environmental assessment of buildings has led in recent years to the development of several tools with very different approaches. In particular, the first approach, voluntary, led to the definition of a multi-criteria rating systems (Green Building Rating Systems) that attach to each criterion a score, according to its performance. The scores are based on a weak sustainability where the final evaluation comes out from the idea that lower environmental performance achieved in a category can be offset by better environmental performance achieved in another category. The regulatory path, however, is based on a Life Cycle Thinking approach, i.e. the quantification of synthetic environmental indicators using the Life Cycle Assessment method, internationally recognized as a method to evaluate the environmental profile of products, encoded within international regulations and promoted by European International Journal of Heat and Technology Vol. 38, No. 1, March, 2020, pp. 17-27 Journal homepage: http://iieta.org/journals/ijht 17