Life cycle cost assessment of a positive energy district featuring a 5th-generation heating and cooling network: An Italian residential and light commercial case study

Districts are drawing broad interest as they represent areas where various components and energy networks are integrated, opening up new opportunities for achieving climate neutrality goals that single buildings might not accomplish alone. Moreover, the focus on assessing performance has evolved from nearly zero-energy buildings to more stringent concepts, such as achieving positive energy outcomes and zero climate emission targets. In this context, 5th-generation district heating and cooling networks, which balance heating and cooling (providing them simultaneously) as a central design principle and key to their energy efficiency, can be effective in reducing climate emissions and costs. To this end, the authors show and describe the life cycle cost of two district system technologies compared with two other individual energy solutions. The comparison was applied in a new urban district that will be built in Bologna, Italy (41,400 m2 of heated/cooled floor surface area). The outcomes achieved show that the individual water source system is the most convenient solution (but often not feasible due to the large amount of wells required), resulting in 459 € / m2, followed by the 5th-generation district heating and cooling network (from 501 to 555 € / m2), and individual air-source system (582 € / m2). The benefit of exporting electricity ranges from 22 to 24 (considering the minimum power foreseen by the Italian legislative in force) to 281 (assuming a positive energy district configuration) € / m2. The shadow costs (environmental externality costs) influence the outcome, but they do not drive the decision-making process.