This paper is built on the following research questions: (i) What are the direct/indirect relationships between Sustainable Development Goal 11 (SDG11) and sustainability protocols? (ii) Could the sustainability protocols constitute a solution towards the achievement of SDG11? We underline that, on the one hand, the SDGs are guidelines to support the development of sustainable policies and thus address all elements that may affect them, and on the other hand, sustainability protocols are assessment tools to promote sustainability-conscious design while remaining focused on the built environment. In the Italian regulatory context, the paper highlights how this difference in terms of focus and scale means that they only overlap and mutually reinforce each other with regard to certain aspects, more related to energy and air pollution issues and less to the social aspects of sustainability. Even if there is not always a direct relationship between the evaluation criteria of the protocols and the indicators of SDG11, it is possible to conclude that the sustainability protocols can facilitate the achievement of the SDG11 targets, acting as a key for the implementation of sustainable cities and helping in structuring the process leading to sustainability in a broader framework.

This paper explores the enhancement of adaptive reuse (AR) of buildings through the lens of the sustainability protocols within the context of circular economy (CE) in Italy. Cities and the built environment can play a key role in the transition to a CE, especially considering the documented negative global impact due to resource consumption and waste generation. This is recognised among the principles of circularity defined by the European Commission towards a general strategy for a sustainable built environment, which encourages initiatives of building reuse and land consumption reduction. It has been proven that the AR of vacant buildings can bring environmental, social, and economic benefits towards an urban strategy based on CE principles by generating useful values to support innovative development dynamics. In this perspective, the sustainability protocols can be identified as useful tools to pursue strategies for spreading the culture of sustainable build environment. Considering the huge vacant Italian architectural heritage, this paper aims to analyze how the most widely used sustainability protocols in the Italian context currently address the enhancement of the reuse of buildings, to improve environmental, social, and economic quality in the built environment. We discuss the results highlighting how and which sustainability protocols better intercept these issues, providing grounds for future development.