Net-zero exergoeconomic and exergoenvironmental building as new concepts for developing sustainable built environments

The net-zero energy building concept has gained increasing popularity in recent years to reduce energy consumption and attain a balanced energy budget in buildings over a year. To this end, various net-zero energy building definitions, including net-zero site energy building, net-zero source energy building, net-zero energy costs building, net-zero energy emissions building, and net-zero exergy building, have been proposed and used in the published literature. In the present study, two new net-zero energy building definitions called "net-zero exergoeconomic building" and "net-zero exergoenvironmental building" are presented to complement the insights obtained from the previously proposed definitions for recognizing the most appropriate configurations of net-zero energy building systems. A comprehensive case study is conducted to prove how the proposed definitions can be applied in practice to promote net-zero energy building systems. The developed definitions are applied for a grid-connected office building equipped with a photovoltaic power plant using actual technical, climatic, economic, and environmental data. The case study is solely used as a proof-of-concept to demonstrate the reliability and flexibility of the proposed definitions over the previously developed ones using technical, economic, and environmental metrics. The main concluding remarks derived from the proposed net-zero energy building definitions are compared with those of the previous approaches from technical, economic, and environmental viewpoints to demonstrate their applicability and relevancy to the development of sustainable building systems. The results show that the proposed net-zero exergoeconomic building definition provides more conceptual and practical information on developing sustainable built environments. Overall, the proposed exergy-based approaches are recommended as complements to the current net-zero energy building definitions to help sustainable building design.