Overview
The professional consensus states that any specific vertical covered in vegetation can be considered as a green facade . The most frequently used term in this field however is green wall . Recently, the meaning of the two terms are becoming increasingly separated in the professional literature: green facades refer to/became used for outdoor, whilst green wall for indoor plant walls/walls covered in vegetation. Quick hedges, fences covered with climbing plants, plant support walls and living-pictures are often referred to as “green wall-green facade”. The latter is not covered within the scope of the website, only structures belonging to the concept of “building construction” in a classical sense are examined and described here. Besides the term green walls, many synonyms are also in use for green facades, the most frequent ones are: plant wall, living-wall, vertical garden . Here the expression of green facade will be used.
The architectural use of green facades goes back a long way, at least the use of walls covered with climbing plants. Patrick Blanc , the French botanist, is considered by most to be the father of modern green facades, the actual inventor of the green wall system however is Stanley Hart White, who patented his invention in 1938, the improvement of the “botanic brick”: the building structure and system covered with vegetation. Our company designed and built the first green wall in Hungary in 2003 for the La Espada Argentinian grill restaurant. Although, sadly the restaurant no longer exists, we still continue our greening of vertical surfaces. The exact number of actual implementations in the world is not known, however, looking only at Patrick Blanc’s work, over 50 completed projects are associated with his name. In Hungary, to date, approximately 25 installations have been completed, with only five of them being outdoor structures. The world’s largest – 5324 m2 – built green wall is in Singapore. For further information, interesting facts and current issues click on the following link. more less

Indoors vs outdoors
Many aspects of the two different spaces can be managed on similar principals, however, there are numerous and significant differences. Whilst indoors, the greatest challenge is providing sufficient light, outdoors the hardest task is managing the environmental and climatic effects (especially extremes in temperature). Whilst the indoor climate is more or less consistent (human comfort zone) anywhere in the world, outside we meet extremely variable and seasonal changing (macro, mezo and micro) climatic conditions, which means that no two tasks are ever the same. In line with this, the installation of an indoor green facade is a relatively simple task, given sufficient professional expertise, and with mature globally applicable and not over expensive technologies readily available. For more details on the questions and available solutions regarding the installation of indoor green walls click here. Externally, understanding of a much greater magnitude of complexity is required in order to create green facades that in the end function and provide long-term decoration in accordance with the expectations of the client. Our website focuses on outdoor green facades . more less

Our Mission
We aim to provide professional support primarily for the architectural and landscaping profession who are most familiar with the topic, in the hope that we may contribute to the development of this architectural-landscape tool through increasingly high quality projects. more less

Systems

Climbing without a support structure
All green facade systems have their natural configuration. Plants holding onto trees in the jungle or climbing onto cliffs (epiphytons) can be considered as configurations for plants climbing onto the facade of buildings. The potential climbing height of the trained plants is genetically restricted to a scale (2-20 meters) dependent on the species They require minimal maintenance, however, there is a risk of damage to the facade by the roots or the large foliage mass. The number of plants that can be trained this way is rather limited.One of the most attractive examples in Hungary is on the wall of the headquarters of the Chambers of Hungarian Architects, the Almássy Palace. more less

Climbing with a support system
The training of the plants available in this group requires a support system, which the clinging parts of the plants (tendril, offshoots) can cling to. When designing the framework, engineering considerations are an important factor. The foliage weight of mature plants is difficult to determine in advance as it depends on a number of factors, thus these structures are characteristically significantly oversized. The support structure is typically a trellis, mesh or simple wire; the material is mostly stainless steel or wood. A support system is required if the plants are not able to cling to the wall on their own or the wall is not suitable to receive them. In addition to the static design of the system, the architectural appearance is also important as the majority of usable plants are deciduous, therefore in winter and until full coverage, the support structure itself needs to be aesthetically pleasing. The installation of a high standard stainless steel support system requires thorough technological knowledge and careful planning. The price range of these systems is considerably higher than the previous type, although in return, the range of available plants is much wider. The support system contributes to 98% of the increase in price; any cost increase associated with the plants is minimal. The temporal and spatial growth limits the plants, similarly to the installations without support systems, and has to be kept in mind. more less

Pocket planters
Credited to Patrick Blanc, this is the earliest versCredited to Patrick Blanc, this is the earliest version of systems not requiring soil connection. The system is built by fixing a watertight material (to protect the frame and wall) to a frame that is secured to the façade. One or more felt or textile layers are added with the plants inserted being between layers, into the pockets cut onto the outmost felt layer, and root over time into the material. With this system, although not too costly, technically there is much room for improvement:

1. Then surface of the felt material is not specifically aesthetic, even when new, and after a short time due to mineralisation and algae it may not be viewed as at all attractive. This does not represent a problem as long as the foliage coverage is 100%, however in case of loss of foliage due to any reasons (which is unavoidable in our climate), this surface will show.

2. The material easily tears or is damaged, the changing and replacement of plants (this is also unavoidable) mechanically damages the felt, which can become unsuitable for the task.

3. As the structure is so thin, the damping effect of the system is minimal, thus the root stock serving as the “engine” of the plants is highly exposed; it has to react without any buffer to the environmental changes (winter-summer) and maybe damaged even in milder extremes of weather.

4. Although we can consider the widespread growth of the roots, within the monolithic structure, as an advantage of the system in many applications (monoculture, figurative landscapes, logos, etc.) this is exactly its greatest disadvantage. In mixed plantings where keeping the original planting order of the vegetation and the required visual appearance is markedly close to nature, in theory it does not represent a problem that in the fight for the limited rooting zone some plants overcome others. In this way, the appearance of the surface develops spontaneously, and with time the more aggressive species take over. The variability of the landscape can only be maintained by replacements, which is not tolerated well by the felt medium in the long run.

Having said this, to date, the best known installations (Caixa Forum – Madrid, Musée du Quai Branly – Paris, Athenaeum Hotel - London) were built with such systems; less well known is that the decorative condition of these surfaces can only be maintained by regular significant plant replacements and rather high costs. Besides the premium locations and the indeed beautiful installations referred to, the large number of poorly done, often rather subdued landscapes are typical; this early technology is now being superseded. more less

Container planters
This system is closest to the balcony box planters. In a container green wall system the planters are placed in multiple lines above the each other. The pots may be made of metal, wood, plastic in a wide variety of sizes and designs. It has to be water and weatherproof, thus in respect of the usable material the same questions arise as in the case of modular systems, which are of similar price. The use of hydroculture is also recommended for this technology, and although soil based mediums can be used, all of the previously mentioned disadvantages have to be considered. The best example of this technology is on the Bercsényi street façade of the Allee Shopping Centre in Budapest. more less

Modular
The modular solutions combine the benefits of the pocket and container systems, while trying to eliminate their disadvantages. The material is typically plastic or metal, and the plant growing system is almost exclusively hydroculture. Compared with the previous systems, they provide further technical solutions. The developments in recent years focused mostly on lowering the cost price whilst retaining these beneficial qualities. Today’s research targets almost entirely the creation and perfecting of such systems; the modular systems dominance is continually increasing amongst completed installations. The appearance required after installation can be precisely planned and even 100% coverage can be provided immediately following implementation. Systems of various designs and prices are now available in the market. The green façade system greenwall.pro is also in this group; its final structure emerging by the summer of 2014 after detailed comparative analysis of the market’s leading products, and based on a five year developmental stage with a three year testing period of the final prototype. more less

Urban climate
Today, the beneficial effects of green landscapes on urban climate is a worldwide and thoroughly researched issue, within the scope of this site we have reviewed specific questions regarding the effect of vertical landscapes upon urban climate. The most important aspect is the limited horizontal projection of vertical landscapes, thus the ground-space requirement is minimal. This is especially important in parts of a city, where the construction of traditional landscapes is out of question due to the high ratio of developed areas. They are especially effective in narrow streets, where planting rows of trees already provides difficulties. The situation is the same when creating a planting pit for the trees and is often impossible for many reasons; transferring the growing medium onto a wall provides huge opportunities for landscaping.

The most tangible effect of green facades is their ability to trap dust. This requirement is greatest in the winter, when air pollution is at its highest. In continental climates the roadside avenues of trees deciduous, so at the most critical period no foliage is available. On green facades, a diverse range of evergreen plants can be used, thus the dust binding effect is ensured in the winter period. It also has to borne in mind that the active foliage of a vertical landscape has an immediate beneficial effect after installation, while trees take many years or even decades to achieve the same potential.

The asphalt or other hard surfaces of cities absorb and reradiate an enormous amount of heat, which is why the average temperature in metropolitan areas is higher compared with the peripheries. This phenomenon is referred to as the urban heat island and green facades can have a serious role in moderating it. Their cooling effect takes place at multiple levels: through the evapotranspiration from the foliage, the multilayer shading effect of the leaves and delivery system, as well as natural ventilation effects. The surface temperature of a façade covered in vegetation in peak summer heat can be up to 20 C less compared to plain concrete.

The research group BOKU in Vienna following meticulous and thorough work measured the foliage of a green façade (800 m2) installed on a residential building MA48 in Vienna, and amazingly found that it was equivalent to the biologically active foliage area and subsequent benefits to the urban climate of four 100 years old beech trees.

Surfaces covered with vegetation may also play a significant role in the water cycle of a city. In London, storing rain water for later use on green surfaces such as green facades has lessened the load on drainage, thus reducing the flooding of streets. more less

Urban ecology
Urban ecology is the scientific study of the relationships between living organisms existing with each other and their developed surroundings. It examines the natural and social components, which through human processes and activities influence the natural eco system and vice versa. So what is the role for green facades? By covering walls with vegetation, the intention is to bring nature back into the artificial urban environment so that is made liveable again. The decreasing number of horizontal options has resulted in landscaping flooding onto vertical surfaces. Compared with today’s widespread use of green roofs, their urban ecological benefits are similar. However, in many respects, they go beyond the scope of green roofs with their visual impact, as well as attracting birds and insects, improving the quality of life of not only those using the building, but of a wider range of the city’s inhabitants (can be seen from the street). more less

Urban landscaping systems
Green roofs and green walls make up an increasing percentage of urban landscapes. The database of greenroofs.com keeps count of 2,995,421 m2 green roofs and walls in large cities of the world. Whilst green roof construction is now widely used, green facades are still less common, however, as technology advances and prices drop, their spread similar to green roofs can be forecasted with great security. more less

Biodiversity
In 2011 the European Union released a strategy targeting the preservation of biodiversity. Amongst the objectives of the strategy that has to be complied with by 2020 is the development of “green” infrastructure, for which the installation of green facades could be an excellent tool with a great, so far unused potential. Green facades, similarly to other elements of urban landscape systems, provide habitat for numerous animal species in addition to the plants, thus helping to maintain biodiversity. Within the greenwall.pro system for example it is possible to include an integrated bird’s nest. more less

Sustainability
With the green façade, architecture aims to reintegrate nature into the built environment. As we move from close to natural trained systems towards the modular approach, the question of maintenance rightfully arises. In addition to the previously mentioned benefits it is reasonable to expect that a green facade should be constructed from 100% recyclable material, preferable manufactured as close to the site of installation as possible, reducing waste to a minimum, and in a way that allows the utilisation of rain and overflowing irrigation water to be integrated into the mechanical system. more less

What system should I choose? Does the façade have connection with the soil? If there is a connection with the soil, simpler and less costly solutions could be used, however as referred to previously, many compromises need to be made. Connection with the soil in itself is not enough, the quality of the soil is important. In poor soil, dependant on the plant species and expected foliage mass, planting pits from 50*50*50 cm to 100*100*100 cm could be required for each plant, which then needs to be filled with good quality soil. If however immediate or quick coverage is important or a more varied and colourful surface appearance is desirable, even where there is a soil connection, it may be preferable to select one of the soil independent systems. How tall a façade can be covered by vegetation? The height restricts the application of the various systems. With trained systems, it has to be noted that dependant on the species, the plants are only able to cling to a certain height and it may take several years to reach this point. We recommend these systems for facades from a few to ten meters in height, while the pocket, container or modular solutions provide almost infinite height installations. What is the geometrical design of the façade to be implanted? If the façade is compact with a sufficiently large surface, the unsupported climbing solutions can be used. The development of the leaf coverage is spontaneous in this case, growth control is not really possible. To a certain extent, it is possible to select species with the appropriate growth habit according the dimensions of the space. When designing a green façade, in addition to its geometry we also have to take any other appearing object / openings / recess into consideration. On facades with openings or where there is a need to control the spread of the plants, supported systems provide the solution. What is the façade made of? Systems without a support system can only be used on wall surfaces that the plants are able to cling to. At the same time, the wall has to be able withstand the damaging effects of the aerial roots or attachment mechanisms used by the plant, cope with chemicals emitted by them and bear the loads imposed on it by a mature planting. All of the other systems are of a mounted nature, thus with appropriate design, in theory they can be installed on a façade of any material. With certain plants the risk of façade damage still exists, even when trained onto a support system, therefore in this case, the strength of the wall also has to be considered. How strong is the facade? The possibility of training plants onto an existing façade, or whether different systems can be fixed to it needs to be considered. When designing a new façade it is advisable to assess whether the external wall will be able to hold the green facade system. For all solutions, it is important to carry out separate calculations in order to optimise material use. As a rule of thumb, in the case of a more advanced modular system the loading would be in the range of 80 kg per square meter, at full water capacity and without meteorological loads. Is there an opening on the facade? In structures that are trained without a support system, the plants around the openings can be more or less controlled by pruning. If a supported system is used, the climbing frame confines growth, thus the openings can be easily “planted around”. Spatial adaptation to the openings is best done by pocket or modular systems, however in both cases attention should be made to ensure that any excess irrigation water cannot get into the structure at the upper section of the opening and that drainage provided. In the case of facades with openings, fire hazards should also be investigated. Do we want a monochrome or figurative wall? The trained climbing systems – with or without support – provide a typically monochrome solution, for a figurative appearance, the modular system is the best choice. With these systems, varied design, multiple colours and texture can be achieved; even a logo can be displayed. It is possible to create this with pocket systems, but only with significant maintenance and plant replacements, otherwise, the plants are spontaneously selected by the nature of the system; the tempo and intensity of their development is inhomogeneous, therefore first the borders of the figurative appearance grow together, then the pattern eventually disappears. The image incurring this way (which can of course be also created by conscious design) evokes the picture of natural mixed vegetation. What colours, patterns and, texture would I like to display on the facade? The trained climbing systems provide an even appearance and texture. Design is freer with the pocket, container and modular systems; the number of available plants is massive in the most varied colours and textures. The change in the colour of the foliage through the year or flowering can provide a venue for play. The size, arrangement and undulations of the leaves provide many opportunities for the creation of a varied façade appearance. By the use of differing statured plants, a macrostructure full of movement can be created; note that not all systems are suitable for this task. What coverage is expected following installation? In case of the trained climbing systems, the plants need time to grow. The minimum time to achieve full coverage is from 6 months to a year, dependant on the surface and the plants used. For systems without soil connection, following installation, the foliage coverage in general is 10-50%. In these scenarios achieving full coverage takes from 6 weeks to 6 months, dependent on the season. Coverage of proximate of 100 % can be obtained by container and one or two modular systems (such as greenwall.pro). Deciduous or evergreen plants? Evergreen plants provide a green surface all year around, when using deciduous plants, it is important to consider that in the foliage-free period, the decorative value is drastically reduced and the structure behind the plants become visible. This is when an aesthetic background appearance of the structure will have an increased importance. greenwall.pro provides several aesthetically pleasing solutions, unique in the market. A wide range of colours, materials and textures are available; practically any weather and waterproof board material can be incorporated into the system.

When using evergreen plants, a very important plant physiology phenomenon has to be considered; this is referred to as physiological drought. In simple terms it means that the in freezing periods the water within the rooting zone of the plants is implicitly frozen, thus it is in a condition unusable for the plant. This does not present a problem as long as the foliage is also frozen, therefore inactive from the point of transpiration. The very moment the sun is on the leaves, the foliage thaws and starts to transpire. The rooting zone however has not yet thawed – this requires considerably longer time – thus the water lost cannot be replaced. Accordingly, the leaves wilt, in unfortunate cases causing the death of the plant. There are two solutions for preventing the problem: one is using deciduous plants, where there is no foliage at critical times, the other solution is the artificial thawing of the rooting zone, when the Sun is on the foliage. The greenwall.pro system also offers solutions for this. Flowering or foliage planting? All angiosperm plants have flowers, but only some of them are decorative, therefore, here “flowering” refers to decorative flowering plants. In case of free climbing systems the single possible flowering plant is Campsis radicans. For trained climbing systems the selection includes the numerous colour variants of approximately 10 species. When using soil-connected systems, there is a very wide range of flowering plants to choose from. It is important to be aware that the flowering plants almost exclusively belong to deciduous plants and perennials whose foliage recedes in winter. This in practice means that in general the flowers as decorations are only available for a period from a few weeks to a few months. The rest of the year, the foliage (which typically is less decorative) or in winter the foliage free condition is visible. To achieve a continuous show of flowers, it is not impossible; this can be achieved by the selection of “annual” (e.g. petunia, tagetes, begonia etc.) and “biennial” (viola, bellis perennis etc.) plants. In this case, we need to choose a system such as greenwall.pro , where the bi-annual replacement of plants is feasible without any damage to the carrying system. What is the orientation, sun exposure and lighting of the planted wall? For an external façade, the orientation of the wall is a definitive factor in the choice of plants. Different plants need differing light to be able to fully show their decorative value. The most favourable orientation for plants in general is eastern, followed by southern, western and the least favourable being a northern aspect. This in practical terms, means that when the orientation is favourable we have a wider range of plants to choose from as well as the general condition of the vegetation and ultimately a successful wall.

Connected building structures
The most important connecting building structure is the wall itself, which can be made of rather variable material, therefore the joining of the structural elements of the green façade can be constructed in very many ways; this is an architectural design task. In case of systems with no soil connection, at the side, lower and upper boundaries of the containers, modules or pockets as well as at the parts around the openings, the elements of the carrying structure are mostly visible and not always aesthetic in themselves. A covering is needed in a way that is in harmony with other materials of the façade. On this cover, trim panels have to be fixed to the connected façade in a way that the green façade is accessible for maintenance. Solution sketches, amongst others, for façade walls, footings, overhanging facades, negative and positive quoins are under Nodes at greenwall.pro . more less

Building physics
Heating engineering
Green walls provide multilayer protection, in winter they slow down the heat dissipation of the walls and in the summer, the warming process. This effect is due to their multi-layered shading and airing characteristics as well as the thermal inertia of the carrying structure. The transpiration of the plants and the cooling effect of the cold irrigation water flowing through the system are significant temperature reducing factors. There is an example for an external green façade being successfully used as an active cooling element, with the help of water as the transport medium and an internal heat exchanger, for the cooling of a server room.

Vapour technology
In most cases the mountings are fixed to the wall by a framework, thus the ventilation openings ensure that the façade functions as a through-ventilated wall. The pocket system is horizontally less vapour permeable, whilst in the case of the modular solution, the gaps between the cassettes further help ventilation. The green wall can also be mounted as an insulated core cover; in this case vapour technology insulation is required.

Acoustics
Green walls are able to absorb high frequency sounds; the low ones can even be blocked, if the system has sufficient mass of the planting medium (some of the container and modular systems).

Fire protection
The modern systems operate mostly as ventilated façade cover, considering that this is the most efficient way to exert their building benefits. For facades with openings however, in the necessary air gap, in case of fire, the chimney-effect may intensify the spread of the fire on the facade, thus in such a case, it is advisable to choose a system where firebreak is used in the air gap (such as the greenwall.pro system). The fireproof quality of the structure itself is equally important and the only economic choices amongst materials available today for this purpose are the dip galvanised and stainless steel systems. Other fireproof materials are either very expensive, very heavy or not weather and waterproof enough therefore cannot be considered as a material for green facades.

Structural surveys
Apart from the free climbing solution for green walls, the background system needs to be structurally surveyed. The structure has to be resistant against meteorological loads and external and internal mechanical impacts. Furthermore, the fact that the plant may develop bulky and abundant foliage, the weight and area of which is very difficult to predict, has to be taken into consideration. It is recommended therefore to considerably oversize the system or to use plants, where the maximum foliage size is not too large and can be closely estimated (typically the perennial, annual and bi-annual herbaceous plants). Attention should be paid to the part of the structure with the largest weight, which in many cases is the irrigation water. The exact quantity of water stored in the planting medium in a water-saturated condition varies per system, the amount is greater for higher value systems than for lower cost setups. In extreme cases the water-saturated weight may be multiples of the dry mass. more less

Maintenance, operation
This is one of the most important issues. As with any living organisms, plants require regular and professional care. In the case of a well designed and constructed system, the carrying structure is maintenance free, however, the plants and irrigation for any system need continuous monitoring. Outdoors the plants are exposed to the changing meteorological conditions (temperature, sun exposure, humidity etc.), to which the plants (especially the indigenous species) are able to adapt within broader-narrower limits, nevertheless, similarly to any intensive culture, continuous monitoring and intervention, if necessary, is also needed. In case of the climbing systems, maintenance is the same as for traditional garden plants, with the difference that in many cases the work has to be carried out at great heights, implicitly increasing costs. The maintenance of systems with no soil connection differs only due to the typically restricted rooting zone, which has a fraction of the buffer effect of natural soil. (This previously mentioned buffer effect is of tremendous importance in balancing temperature, water and nutrition supply extremes.) This results in the plants being able to react to the changes in the environment faster and with less help. The task of maintenance is to ensure this help artificially, without it the life expectancy of the plants is significantly reduced.

The key maintenance tasks are: providing sufficient quantity and quality of irrigation and a nutrient-combination appropriate to the age of the plant; ensuring error-free operation of the drip system and descaling the drip holes; replacing plants and the regular removal of parts that are withered and have finished flowering; protection against diseases and pests. In all cases, maintenance costs must be calculated in advance, which for example for a pocket system, due to frequent plant replacements, may be rather high.

In winter, in temperatures below zero, the irrigation system needs to be drained; the vegetation in general in these periods does not require other maintenance. In so far as the risk for physiological drought exists, and the system is equipped with a technical solution for this, care should also be taken for its operation in winter periods. As long as the temperature remains permanently above zero, standard maintenance tasks (irrigation, plant protection, pest control) become relevant. more less

Dimensions (size, weight)
The system is made up of modules, the dimensions of an average size module: 20cm*100cm*10cm (width*height*depth). These dimensions can be adopted to the characteristics of the façade and to the needs of the plants used. Each module can take 5-7 plants, vertically positioned above one another. The dimensions of the modules were established with considerations to the growth tendency of the roots. In this way, in this system, the rooting zone available for the most widely used perennials is optimally 2.5-3.5 litres. The installation stem distance is in the range of 17-21 cm.

The dry weight per square meters is between 35-40 kg, it may vary dependent on the weight of the chosen face, while the fully saturated weight is 70-90 kg. These do not include any meteorological burden such as snow. more less

Materials
The modules and the elements of the horizontal frame delivered with the system as well as the structural parts for water drainage and collection are made of 1.4301 quality stainless steel. The planting medium is dust free horticultural perlite. The default material of the front panel (a removable board that sits beneath the foliage) is a textured black plastic ABS board, however, several front panel designs are available, tailored to architectural needs. It can be made from ceramic material, resin bonded stone or brick grit panel or metal in any colours. more less

Visible surface / immediate coverage
In contrast with the other pocket or advanced modular systems – where mostly rooted cuttings are used – greenwall.pro is suitable to take mature plants with large foliage (rooted cutting do not represent a problem either). This enables immediate up to 100% coverage, furthermore in case of plant replacement the maturity of the new plant can be identical to the others, thus the surface remains perfectly constant. The use of deciduous plants does not represent a problem either, as the material and colour of the surface (front panel), visible from the end of autumn, can be aesthetically adjusted to the architectural concept within broad limits. more less

Connected building structures
Connected building structures: the design of the footing, facade and the back wall as well as drainage require custom design in all cases. Gradient water drainage (approximately every metre) is part of the system, only the lowest collecting profile needs to be integrated into the whole drainage system of the building. If the planted section of the façade has soil connection, a buried and appropriately sized pipe is suitable for drainage. In case of facades lifted from the soil, a drainage channel needs to be constructed under the lowest module. The most typical node designs can be downloaded from the node menu Nodes. more less