The energy renovation of the existing building stock is a crucial strategy to achieve environmental targets at national and EU levels, as demonstrated by current energy uses and potential energy savings in the construction sector. The retrofit of school buildings in Italy is relevant because of the poor energy performance of the stock, as well as for its high social value. The Tito Maccio Plauto school in Cesena went through a deep energy retrofit process in the framework of the "School of the Future" EU Project. This paper documents all the phases of the process: the initial energy and indoor environment assessment; the design phase supported by detailed calculation analysis; the two years monitoring phase after the conclusion of the renovation works. The energy monitoring demonstrated a factor 4 reduction of space heating, final and primary energy, as well as the electricity neutrality achieved after the retrofit. Also the indoor environmental quality was addressed in this study by means of instrumental monitoring of indoor parameters and subjective analyses, carried out by a dedicated questionnaire. These additional actions demonstrated the positive impact of the implemented measures on thermal comfort and indoor air quality, as well as other co-benefits. (C) 2016 Elsevier B.V. All rights reserved.