The building sector plays a crucial role in the advocated transition towards a carbon-free economy, and thus the zero-carbon building concept is taking hold. The paper focuses on the issue of existing hotels, with the aim of investigating the possibility of meeting the ambitious zero-carbon targets for this category of buildings, in which guests' comfort and satisfaction is the core business. A reference hotel and different retrofit scenarios are assessed in two Italian climatic zones. Models are evaluated with a multi-objective approach, by introducing a set of hotel-related Key Performance Indicators (KPIs), to evaluate the simulated models on three main dimensions: thermal comfort, energy and environmental impacts. The obtained results have emphasized the difficulty to achieve the zero-carbon targets, due to the high energy consumptions caused by the comfort-based nature of hotels and of the space constraints for on-site renewable sources. These outcomes help highlighting the need to shift the focus from single building to district or city scale, proving that the zero-carbon building definition must go hand-in-hand with the Post-Carbon City concept. (C) 2020 Elsevier Ltd. All rights reserved.