Whether it involves rooftops, façades or hybrid systems, green building solutions offer a wide range of benefits. Beyond their aesthetic appeal, they play a key role in tackling urban heat islands, managing stormwater and bringing nature back into cities. They also help protect buildings themselves and offer proven benefits for health and well-being. The sector is expected to continue growing in the coming years, with estimated annual growth of 5%.

Three main types of greening

Greening generally applies to rooftops and façades but recent progress has focused on hybrid concepts combining vegetation and solar energy.

For rooftops, greening can be extensive with light and thin vegetation layers (4 to 12 cm) mainly using sedum and grasses, semi-intensive with a thicker substrate (12 to 30 cm) allowing the addition of flowering perennials, or intensive with a substrate over 30 cm which can support shrubs and even small trees, creating real rooftop gardens or hanging gardens.

Green façades are usually based on climbing plants growing from the base of a wall (such as ivy or Virginia creeper) or on above-ground systems like hydroponic green walls where a planting medium is attached to the wall.

Other emerging solutions combine greening and renewable energy, such as bio-solar rooftops.

Key criteria for choosing the right system

Choosing a greening system depends on several factors such as the supporting structure, geographical location, orientation, slope and access to the roof, along with the desired visual effect. The roof’s load-bearing capacity determines the thickness of the substrate that can be used, from the lightest (extensive systems) to the heaviest (intensive systems).

While installation is not particularly complex, regular maintenance is essential to ensure plant health, preserve technical performance and maintain aesthetic value.

Multiple benefits

Green rooftops and façades help reduce urban heat islands and improve thermal comfort. The evapotranspiration of plants lowers temperatures around the system. Plants also absorb solar radiation, which can lead to a temperature drop of 3 to 5°C. In addition, green buildings reduce heat storage by urban surfaces, which is especially valuable during heatwaves like the one in June 2025.

They also help manage rainwater by storing rainfall and regulating runoff, which reduces the amount of water discharged into stormwater systems and can help lower flood risks. Installing a green system contributes to creating a living ecosystem of flora, fauna (pollinators like bees and butterflies, birds, invertebrates) and soil microorganisms, all of which help bring biodiversity back to urban areas.
Vegetated buildings are also better protected, especially in terms of waterproofing, which improves the building’s lifespan and offers additional protection against pollution, UV rays, heat and humidity.
More broadly, green buildings have many positive effects on public health and well-being. They help clean the air by capturing pollutants like fine particles, produce oxygen through photosynthesis, absorb CO2, provide thermal insulation in both summer and winter (thus reducing energy consumption) and also offer acoustic insulation. They create calming environments, often described as anti-stress, and may even become spaces for relaxation or social interaction, such as rooftops converted into terraces.
Another advantage, less frequently mentioned, is that greening a building generally increases its real estate value.

A growing trend: combining greening and solar energy
Greening and solar panels are often seen as competing options for roof renovation, but they are actually compatible and can even enhance one another.

Adivet defines a biosolar roof as one that combines vegetation and photovoltaic or solar thermal panels on the same surface, one above the other, to deliver the benefits of both systems. This combination can create positive synergies such as optimizing available space, increasing energy output by an average of 2 to 5% due to plant evapotranspiration cooling the underside of the panels, and enriching biodiversity thanks to the shaded areas created by the solar modules. Importantly, the solar panels are not placed directly on the roof but are installed on the planting substrate.

Already well developed in Germany, Switzerland and Austria, biosolar roofs are starting to move beyond the experimental stage in France. They meet multiple new requirements to green rooftops or install renewable energy systems in new buildings, extensions or major renovations. These rules stem from the Climate and Resilience Act (2021), the Renewable Energy Acceleration Act (APER, 2023) and related decrees from December 2023. They apply to industrial and commercial buildings, warehouses, hangars used for business purposes, offices and, since January 2025, also to hospitals, cultural, sports and recreational buildings, and public administration and education facilities. The required rooftop coverage is at least 30% today, increasing to 40% in 2026 and 50% in 2027. These hybrid solutions also align with RE2020 (building energy performance and summer comfort during heatwaves), the tertiary decree (energy use reduction targets) and local planning regulations (PLU, PLUi).

In France, several players now offer biosolar roofing solutions, including Vegetek (pilot project on the Icade business park roof in Paris Orly-Rungis), Ecovégétal (Heliovert Eco system) and Le Prieuré (Oasis BioSolar hydro biosolar system installed on the Olympic Village for the Paris 2024 Games).

Reflecting the growing momentum in France, Adivet held a half-day event in mid-June dedicated to biosolar roofing to present the technology, its benefits and its role in local urban planning strategies. This was also the occasion to launch Adivet’s Biosolar Roof Guide, produced in collaboration with the Photovoltaic Industry Group (GMPV). The guide gives an overview of available solutions, the respective benefits of greening and solar energy (PV or thermal) and their combination, key points in design and implementation, specific features related to renovation, the regulatory and technical framework, as well as liability and insurance considerations.