The optimisation of energy and the reduction of the impact on the greenhouse effect combine the use of the thermal inertia of the subsoil, renewable energies (solar, Canadian wells, geothermal, etc.) and vegetation for the roof or walls. With regard to effluents, ecological treatment aims to reduce energy consumption, better integrate into the landscape and possibly contribute to the development of biodiversity. This is often based on the principle of phytoremediation by plants with a view to the circular economy.