## 1 Introduction  
Environmental sustainability is now one of the cornerstones for every sector; in fact the concepts of maintaining resources and environmental balance are of fundamental importance for the development of a process capable of combining the various economic activities in respect of the environment, thanks to the implementation of measures and production processes compatible with the biosphere's ability to renew itself and absorb the effects of human activities [1, 2, 3]. In September 2015, the UN member states approved the 2030 Agenda for sustainable development and, within the framework of the United Nations Framework Convention on Climate Change, the \"Paris Agreement\" was approved, which focuses its attention on the impact that economic activities have on climate change [4, 5]. In December 2019, the European Commission presented the \"European Green Deal\" [6, 7] as a programme of reforms and measures aimed at avoiding a disastrous future characterised by global warming, climate change and pollution, within which the principles of the 2030 Agenda and those of the Paris Agreement systematically converge [8]. The cornerstone of the Green Deal is the proposed law on climate change, which appears to be a very broad and ambitious plan that aims to achieve \"climate neutrality\", by reducing emissions by 55% by 2050 [9]. The economic sectors and activities affected by the reforms of the international Green Deal agreement are many; they include any economic activity capable of producing an impact on the environment and climate. In light of the objectives set by the European Green Deal [10], it has become of fundamental importance to direct the measures of economic activities towards projects and activities to support the ecological transition and the circular economy. In this regard, the EU Regulation on Taxonomy 2020/852 of the European Parliament and of the Council of 18 June 2020 and entered into force on 12 July 2020, is a reference regulatory framework consisting of documents of various kinds to encourage sustainable investments. The basic principle of the Taxonomy is called the DNSH principle \"Do Not Significant Harm\", which aims to assess whether a measure could have a negative impact on the six environmental objectives defined by the EU Taxonomy Regulation. The criteria on which the DNSH principle is based are aimed at climate change mitigation, a principle according to which an economic activity must not lead to significant greenhouse gas emissions (GHG); at climate change adaptation, for which it must not cause a major negative impact on the current and future climate, on the activity itself or on people or on nature or property; at the sustainable use and protection of water and marine resources, whereby an economic activity must not damage the good state of water bodies (surface, underground or marine) and cause qualitative deterioration or reduction of ecological potential. Particular attention is paid to the circular economy [11], avoiding the consequences of significant inefficiencies in the use of recovered or recycled materials, increases in the direct or indirect use of natural resources and a significant increase in waste, their incineration or disposal, causing significant environmental damage in the long term. Each activity must be aimed at preventing and reducing pollution, not leading to an increase in emissions of pollutants into the air, water or soil and each activity must protect and restore biodiversity without harming the good status and resilience of ecosystems or the conservation status of habitats and species, including those of Union interest. The importance of the DNSH Principle is in the context of the interventions of the National Recovery and Resilience Plan (PNRR) [5] which specifically identifies the measures in line with the principles of the \"NextGeneration EU\" program [6] and stipulates that the interventions are aimed at achieving the objectives of the European Green Deal.