Retrofit intervention in the second cloister of Sant' Antonio in Polesine in Ferrara follows two themes. On a side, conservative appearance is addressed to maintenance the building formal complexity. On the other, technological innovation aims to integrate plants distribution system and other useful components for the building new use. In particular, the study aims to become a field of research for new building envelope alternatives and multiple air-conditioning systems that can be installed without altering the look of the environments in order to reduce building energy consumption. The intent is to redevelop the complex to give it a new functional and energetic life. The study is an example of energy retrofit of a part of building historical heritage that makes it suitable to new energy saving requirement.