Shadow accounting is conceptualized as a complementary framework to conventional functional accounting, aimed at disclosing concealed information regarding firms’ environmental performance, energy consumption, and social responsibilities—areas not mandatorily reported under prevailing accounting standards. By facilitating voluntary and systematic disclosure to stakeholders, shadow accounting enhances transparency and provides a more robust foundation for assessing organizational sustainability and operational efficiency. In capital markets, its outputs can inform the implementation of decentralized energy systems through structured reporting of energy consumption data, thereby supporting equitable resource distribution and reducing reliance on centralized energy infrastructures. This study adopts a mixed methods design. In the qualitative phase, phenomenological analysis and PRISMA-based content screening were employed to identify the dimensions of shadow accounting outcomes and the capacities required for decentralized energy system implementation, forming the basis for an intuitionistic fuzzy analysis in the quantitative phase. The phenomenological findings yielded 282 open codes, which were synthesized into 32 thematic propositions and four categories of outcomes: sustainability, risk-related, intangible capital, and competitive outcomes. The PRISMA process identified four key capacities for decentralized energy implementation: supply chain integration, reduction of production overhead, reduction of maintenance and repair costs, and expansion of intergenerational rights compliance. Results of the intuitionistic fuzzy analysis indicate that expansion of intergenerational rights compliance is the most significantly influenced capacity, primarily driven by sustainability-related outcomes within the shadow accounting framework.