In the transition toward a low-greenhouse gas emission energy system, retrofitting the building sector is a strategy to maximize energy e!ciency. While optimizing building energy system is well-established in the literature, the socioeconomic aspects are often overlooked, leading to impractical optimal configurations. This thesis adopts a multi-actor modeling approach, optimizing the energy system of an energy community using a game-theory framework. Instead of assuming a universal decisionmaker, this work models the energy system from the perspective of various stakeholders, aiming to enhance the adoption of energy retrofit measures under di"erent policy frameworks. The methodology is been applied to a case study of an energy community in Switzerland. After demonstrating the local effectiveness of policies, the results are extrapolated to a national scale. The findings highlight the critical role of a Community Energy Manager, who coordinates energy flows within the community and should operate as a non-profit entity. Additionally, subsidies exclusively allocated to property owners undertaking energy retrofits have been proven e"ective in incentivizing further investment. Providing 3.1 BCHF/yr in subsidies results in a 48% refurbishment of living spaces, triggering 1.2 BCHF in owner investments. Further subsidies of up to 27.6 BCHF/yr can only stimulate an additional 2.8 BCHF in investments. Beyond this level no more investment can be triggered. Although the results are consistent with the funds required to implement existing policies in Geneva, the budget is overestimated compared to current policies in other cantons. This discrepancy arises because the proposed policy lacks enforcement regulations, which could reduce the need for subsidies by ensuring broader compliance with energy retrofitting requirements.