Towards sustainable net-zero districts using the extended exergy accounting concept

The net-zero energy concept has attracted increasing attention to facilitate the development of sustainable built environments. Despite promising progress, there is no comprehensive approach that simultaneously considers all technical, economic, environmental, and social parameters. The present study uses the extended exergy accounting concept in the net-zero energy framework to cope with the drawbacks of the existing net-zero definitions. This method weighs all energetic and non-energetic inputs in a single consolidated exergy term, thus making an unbiased comparison of various options possible. The proposed approach is applied to a district in central Iran, and its sensitivity and applicability are compared with the net-zero source energy and exergy methods. The new approach reasonably responds to changes in the energy network and renewable energy system parameters. In the baseline conditions, the new method provides the highest self-consumption index (51.8%) in the investigated case study. Although the net-zero exergy approach generates more renewable energy (two times) than the presented approach, it increases the self-sufficiency index by only 3%. The new approach accounts for the energy load profile while setting up local renewable energy production based on energy network and renewable system efficiency. The developed approach appears to be reliable for developing sustainable net-zero systems.