Nature based strategies for urban sustainability: vertical greening systems.

The tropical region covers 1/3 of the world's land mass and is inhabited by 1/3 of the world's population. More than half of the world's population lives in urban areas and rural areas are being transformed into urban areas. In a few decades to come, tropical regions will have more urban areas than rural areas.

Population growth and increasing urbanization have reduced the amount of green space within cities. Urbanization has caused many environmental problems, such as the urban heat island effect (which is the increase in heat generated by cities), global warming and climate change. The contribution of cities and buildings to greenhouse gas emissions and energy consumption accumulates throughout their life cycle from conception to construction, through use and finally demolition.

The building industry has a vital role to play in creating a more sustainable built environment, and out of this understanding come niches categorized as sustainable architecture, green architecture, ecological architecture, climate design, green building, energy efficient buildings, and sustainable real estate development. In this regard, the importance of cultivating urban vegetation is vital. Vertical Greenery System is increasingly recognized as an approach that is environmentally sustainable and capable of mitigating the impacts of climate change in urban areas.

The integration of Vertical Greenery System in urban areas is an effective strategy to mitigate urban heat island impacts, as vegetation provides carbon sequestration potential, shades, reduces urban temperatures, and provides fresh air and oxygen to urban inhabitants in close proximity. In addition, a vertical vegetation system allows passive cooling to be retrofitted into a building when other heating or cooling system options are costly and time-consuming to install.

Vertical Greenery System is a general term that refers to any form of plants growing either on or against wall surfaces that may or may not permanently adhere to the interior wall or facade of a building. Vertical Greenery System is also known by different terminologies such as green space wall, green wall technologies, green facade, green scaffolding, biological walls, garden wall and living walls, among others.

Within the systems for the greening of facades are mainly used climbing or hanging plants that can be attached directly to the wall or use lightweight structures to climb and extend over the wall. The common factor is that the plants grow from the lower part of the system, where they are placed in planters that require a wire or stainless steel mesh structure on which to grow vertically or are planted directly in the ground, these mesh or cable systems for green facades are adaptable to curved surfaces and columns, allowing a customized design. It is also possible to place these planters at different heights to accelerate surface coverage and combine them with hanging plants. Depending on the species of plant used, in some cases it may take years for the vegetation to fully develop until the desired surface is covered.

Living walls, on the other hand, refer to vegetation grown in planters that can be converted into modular systems attached to walls without relying on ground-level rooting space and mechanized irrigation. These modular panel systems are popular and can be in the form of vertical or horizontal felt systems and trays, among others.

Felt or cloth systems are one of the most widespread types of systems and can consist of hydroponic crops or have a substrate. The plant species are planted by cutting the felt in situ or using modules with cavities already prepared. In addition to felt systems, there are different types of modular panel systems and their classification varies according to the type of growing medium used (hydroponic or substrates) and the material of which their structure is made: polyethylene or recycled plastic panels.

Living walls have a greater aesthetic potential because they allow the integration of different plant species. However, the installation, design and maintenance of a green facade is simpler compared to living walls.

Finally, a simple Vertical Greenery System.