Irina Susorova, Senior Energy Services Engineer · Hargis Engineers and Payam Bahrami, Vice President at Optim Design Inc.
What is the history of vertical vegetation?
For centuries, vertical vegetation was used in building construction to shade building walls and atriums, to shield buildings from wind, and to cultivate agricultural plants. Many countries with hot climates carry on the tradition to grow vines along building perimeters and above atria to shade the facade from excessive sun exposure and to cool the air.
In castles and palaces of medieval Europe, it was also common to grow ornamental plants and fruit tree espaliers along the walls of internal courtyards to provide shade and to grow fruits and vegetables in limited horizontal space. In the building practices of the Vikings, building roofs and facades were clad with turf, a top layer of soil consisting of grass and roots. Such turfclad facades were well-insulated against severe cold weather conditions.
A similar building practice was spread throughout the Northern Midwest prairies of the United States and Canada, where the first pioneers built houses from sod, stacking layers of prairie topsoil on top of each other to form building walls. Although sod provided great insulation, it was not a good structural material due to its susceptibility to water damage from rain – the main reason why there are so few remaining examples of sod houses.
How the modern adaptation of vertical vegetation did began?
The energy consciousness and sustainability movement at the end of the twentieth century brought a new wave of interest in using vertical vegetation in building construction. In recent years, building designers have been promoting the integration of plants into building envelopes. Although green roofs covered with layers of vegetation have long been prominent features of buildings in many cities, green walls that integrate plants into buildings’ vertical elements are still a relatively new feature in contemporary architecture.
Such facade-integrated vegetation systems can be added to existing exterior walls or incorporated as a part of the exterior wall assembly in new construction. Green walls, which include green facades, living walls, vertical gardens, hanging gardens, bioshaders, and biofacades, are becoming important devices for building designers who include them into facades of commercial, residential, and public buildings with great imagination. In addition to their striking visual effect, green walls increase building energy efficiency by reducing energy consumption, mitigating the urban heat island effect, and creating natural habitat areas in cities.
What is a Green Façade?
A green facade is a system of steel, wood, or plastic trellises externally attached to a building facade where plants are supported by horizontal, vertical, or diagonal trellis members. Climbing plants and vines used in green facades grow from planters located on the ground or at some intervals along the facade height. Green facades can be two-dimensional, formed by cables, ropes, and meshes, or three-dimensional, formed by rigid frames and cages.
What is a Living Wall?
A living wall is a system in which vegetation is not only attached to a building façade but is fully integrated into the façade construction where plants and planting media are both placed on the vertical surface of exterior walls. Plants are pregrown in containers on the ground or grown directly in planting media on exterior walls. Typically, living walls are separated from the facade surface by a layer of waterproof membrane intended to protect the rest of the facade construction from unwanted moisture. Living walls have built-in horizontal or vertical automated drip irrigation systems installed behind planting media, which can be accompanied by rain sensors. There are multiple variations of living walls including vegetated mats, hanging pockets, and modular systems.