What is a Green Facade
To “green” building envelopes is currently one of the most promising ways to provide energy savings in buildings and to contribute to the urban heat island effect mitigation. The shadow effect supplied by plants is the most significant parameter for this purpose. One way to characterize the potential shadow effect of greenery is to calculate the facade foliar density by means of the leaf area index (LAI). As LAI is commonly used in horizontal crops, their use in vertical greenery systems (VGS) has generated dispersion and uncertainty in previous studies both in terms of methodologies and results obtained. In addition, a lack of data relating to the influence of the facade orientation in the final contribution of vertical greenery to the energy savings has been observed in previous studies.
This study aims at establishing a common and easy way to measure LAI and to lick it to the energy savings provided by VGS. Moreover, the energy savings achieved as well as the influence of facade orientation on the final thermal behavior of two different VGS, a double-skin green facade and a green wall, was studied.
Climbing plants can assign directly to the surface of a building, or they can be supported on a structure sovereign of the building. The use of climbers that anchor themselves to a structure by twining stems or twining coils enables a green facade to be installed in front of solid walls or some other structure, to create a divider, privacy screen or sunshade. The degree of the mass of the facade coverage can be managed to suit the required function. For example, a facade designed to gloom a building wall would ideally have greater greenery density than a screen installed near a window that is designed to allow at least some degree of views to the environment beyond the facade.
Green facades are often installed because they provide an eye-catching look to a building wall, or they may be used to block out a view, or to afford shade for a building. Green facades can create a cooler microclimate instantly end-to-end to a building, primarily through direct shielding of the building facade, but also from cooling from plant flora (transpiration of water through the leaves), and evaporative loss of water from the growing standard. All climbing plants will provide some retaining of storm-water, shading of the building, protection of its surface, and capture of airborne particulate matter and unstable gaseous pollutants. These benefits will be greater for classic species that retain foliage cover year-round.
For multi-level facades, mainly at height, wind can create major problems for plant attachment. In these settings, twining climbers are ideal over plants that adhere directly to the building facade as the snaking stems attach strongly around vertical and horizontal funds. Shrubbery may still be stripped under extreme wind conditions, so foliage type and size should be matched to the level of revelation and likely wind meters at the site. In general, the higher the planting on a building, the riskier the growing conditions are likely to be. Other factors of importance in multi-level facade design include urn box design (volume, substrate, drainage), maintenance access and irrigation structure design.
Present-day architecture is increasingly focusing on vertical greening systems as a means to reestablish the environmental integrity of urban areas, biodiversity and sustainability. Vertical greening is the activity of greening the building covering with all forms of vegetated wall surfaces as with plants either fixed into the ground, in the wall itself or in modular panels attached to the façade. Vertical green can be categorized as façade greening or living wall systems according to the mounting method employed. The plant choice affects the aesthetical and practical aspects of a greened façade and many parameters have to be taken into account when picking plant species for vertical greening systems. These parameters include the subsidiary system type, microclimatic benefits, maintenance needs, biomass production, climate type, and environmental strictures, façade way and limits within the urban area.
Benefits of vertical greening systems
Applying vertical greening systems on both new and existing buildings can offer multiple environmental benefits and a sustainable method in terms of, nutrients and water management and effective safeguarding of edifices.
The ecological and environmental assistance of green roofs include the perfection of air quality, the reduction of pollution, increased biodiversity and reduction of the heat island outcome in urban areas. Plant’s leaves collect and absorb fine dust particles and transform the carbon dioxide made by traffic & heating into carbon hydrates and oxygen. The reduction of the heat island effect in urban areas befalls thanks to the lower amount of heat re-radiated by greened façades and humidity affected by the evapotranspiration caused by plants as compared to artificial surfaces. This process also allows indirectly saving extensive energy supplied to the building as the plants and the growing medium provide insulation and shade which can reduce energy needed for cooling, expressly in the Mediterranean area.
Vertical greening systems can mend biodiversity as they create a habitat for microbes and also for smaller animals such as bees, bats, birds, etc. Green façades function in this context as a food source (insects) and as nesting or breeding prospect.
In addition the above-mentioned benefits, green roofs and walls also provide economic benefits. Those relate to the real estate market, greater resilience of buildings, and a better psychosomatic state of citizens.
The presence of vegetation in urban areas might affect the economic value of buildings, increase property or rental prices due to the improved visual aspects. Both green roofs and vertical greening structures reduce the frequency of maintenance interventions thanks to a shielding action of leaves against negative effects of UV rays, temperature vacillations, acid rain and air pollution on the fundamental surfaces.
Still, vegetation and green areas are scarce in modern urban environments, where impervious surfaces i.e. traditional building materials, asphalt roads, etc. may cover more than 75% of the entire area. It’s prudent that most of the cities’ surfaces are green because some of the environmental benefits of greening the building envelope only work if a huge surface in the given area is greened.
The greening systems’ design needs to take into account many aspects including the integration with the building envelope, a sustainable substantial choice, the environmental impact, and the relationship between the growing medium and the vegetation, the economics related to costs and budding savings due to the possible reduction of energy required for heating and cooling.