Okay, to be honest, this is mainly true in the summer when greened areas on the house prevent sun exposure to the building, reducing heat in the home. Thermal insulation in the winter and reduction in heating costs is really only likely in buildings thickly covered on all sides with ivy, with a maximum cost reduction of 5-10%.
We usually think of thermal insulation as our friend during cold winters, providing insulating layers to keep our house warm and reduce heating costs. But insulation is also needed in the summer when walls and interiors heat up excessively in strong sunlight. Plant life on the facade acts as a natural insulator, absorbing the sun's rays before they reach the facade. This is especially true in non-insulated homes where the greening can replace air conditioning and save expenses. Facade cooling with plants saves electricity costs and contributes actively to climate protection!