Cost-optimal control of bidirectional heat and power exchange between a green active building and district utilities

• Nonlinear optimization minimizes cost for a heat and power solar prosumer building. • A full thermal comfort model is integrated within the optimization framework. • Disabling bidirectional energy trading increases total operating costs by 11%. • Operating costs are highly sensitive to feed-in tariff policy. • Solar collectors’ cuts operating costs by 107% and emissions by ∼200%. The growing transition of modern buildings from passive consumers to active prosumers is critical for decarbonizing the built environment. However, optimally managing bi-directional trading of both heat and power presents significant challenges. The existing literature often simplifies the complex thermal dynamics of buildings, particularly those with radiant systems, and does not explicitly account for indoor thermal comfort. This study addresses these gaps by developing a nonlinear optimal control strategy for a green, thermally active office building equipped with photovoltaic-thermal collectors, thermal and electrical storage, and a radiant floor. The main objective is to minimize the net daily operating costs through smart scheduling of storage and bidirectional energy trading with district utilities, while strictly maintaining occupant thermal comfort using a full model of predicted mean vote. Using the interior-point algorithm, the results demonstrate that the proposed strategy effectively captures the complex system dynamics, achieving high self-sufficiency and maintaining favorable comfort levels. Compared to a conventional building without local generation, the prosumer model reduces net operating costs by 107% and indirect CO 2 emissions by 197%. The analysis reveals that bidirectional trading is crucial. Disabling exports increases costs by 11% and compromises comfort. Furthermore, the system’s profitability is highly sensitive to heat export tariffs, with a 21% cost reduction achieved when the feed-in tariff is increased from 50% to 80% of the retail price. Overall, the study highlights the critical role of supportive tariff structures to boost the merits of local production of heat and power.