Is greening the building envelope economically sustainable? An analysis to evaluate the advantages of economy of scope of vertical greening systems and green roofs

- This paper analyzes the (possible) advantages of economy of scope of green envelopes.
- A cost benefit analysis of vertical greening systems and green roofs was conducted.
- Combining the installation of green roof and vertical greening systems increases the economic sustainability.
- Economic incentives (tax reduction) could reduce personal initial cost allowing a wider diffusion of greening systems to reduce environmental issues of dense urban areas.

A wide replication of green envelopes can be a good opportunity to improve urban environment conditions, as demonstrated by several studies. Greening systems increase also building envelope performances; however their economic sustainability has not been fully investigated. This study evaluates the economic sustainability of two combined greening systems installed on an office building: a vertical greening system and a green roof, and it evaluates the advantages of economy of scope. The Cost-Benefit Analysis on two different combinations of vertical greening and green roofs considers personal benefits and costs over their life cycle. The results demonstrate the advantages of economy of scope, due to the additional benefits coming from the combination of two different systems. The results show that the tax incentives and the combination of green systems can make the installation and the maintenance costs economically sustainable during the life span of a greening system; this could lead to a wider diffusion of greening systems with higher environmental and aesthetic performances.