In recent decades, the intervention on existing buildings has recorded increasing interest, involving widespread construction, an integral part of the urban fabric of cities as well as smaller towns. The contribution illustrates the need to adapt historic buildings in the face of attention to rural and marginal areas that have emerged most today with the Covid-19 pandemic. The relationship between the energy efficiency process, the conservation needs, and the adaptation of use and management of the built heritage is highlighted. This reflection considers the evolution of the real estate market by analyzing the regulatory tools on energy retrofit and fiscal strategies in response to the current crisis.