We report on modeling work that shows how the market, technology, civil society and the state govern the diffusion of energy-efficient renovations in Switzerland’s stock of residential, multifamily buildings. The particular focus of this chapter is on the policy implications that we drew from an extensive System Dynamics modeling study. We conclude that energy efficiency is important, yet not sufficient in order to reach ambitious emission reduction goals. In addition to promoting energy efficiency, Switzerland should aim for a widespread decarbonization of heating systems. We discuss what kind of instruments can be used to address various policy levers in order to accelerate the diffusion of energyefficient renovations. We propose two regulations that could serve as a framework for ambitious long-term decarbonization efforts. Finally, we propose a service innovation that could assist building owners in complying with the ambitious regulations required.