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GREEN WALL IS A SUSTAINABLE APPROACH TO A BUILDING FACADE DESIGN

GREEN WALL IS A SUSTAINABLE APPROACH TO A BUILDING FACADE DESIGN

Green wall - living wall facade

GREEN WALL - INTRODUCTION

A wall which is partially or completely covered with vegetation which will include growing medium such as soil and water that is known as a green wall. The green wall is also known as a vertical garden. The green wall provides temperature insulation to the building indoor. Most of the green walls also include an integrated water delivery system. Basically, there are two types of green walls one is known as the living wall and another one is known as the green façade. The living wall includes green panels and module plants (short plant) and green wall includes climbing plants or plants which hang down. Twining, tendrils, and planters are used to support the plants for green walls.

The green wall concept was basically come up from the hanging garden of the Babylonian city. It was first implemented by an architect in 1938 by Stanley hart white at in his backyard in Urbana, Illinois.

AIM

   To prove the green wall is a sustainable approach to a building façade design.

HYPOTHESIS

   A green wall is a sustainable approach to a building facade design.

OBJECTIVE

1)   To study the concept of Green wall and understand its history.

2)   To study the types, characteristics, and benefits of the green walls.

3)   To study the types of vegetation that can be grown vertically.

4)   To analyze and conclude that green wall as a sustainable approach to a building façade.

RESEARCH METHODOLOGY

Green wall- research methodology of Dissertation

SCOPE AND LIMITATION

·       Understanding the importance of vegetation and green walls.

·       This study does not include climatic studies.

·       This study does not include indoor green walls.


NEED OF THE STUDY

     The city is turning into a concrete jungle the scope for maintaining a garden in today’s world is extremely limited. In this kind of situation, green walls are ensuring the building to cover maximum coverage.


GREEN WALL - DEFINITION

Green walls are also known as ‘living walls’, ‘bio-walls’ and ‘vertical gardening’.

It is a descriptive term that refers to the form of vegetate wall surfaces.

Green walls are installed because they provide an attractive look to a building wall and they also used to block out a view or to provide shade or insulation to a building. A green wall can create a cooler microclimate immediately adjacent to a building, primarily through direct shading of the building facade, but also from cooling from plant foliage (transpiration of water through the leaves) and evaporative loss of water from the growing medium. All plants provide some retention of stormwater, protection of its surface, shading of the building, and capture of airborne particulate matter and volatile gaseous pollutants. All the green walls are simply based on physical and biological processes that contribute to better comfort inside and outside of the building.

Green walls are very flexible so that they can be suitable for any climate. The green wall completely depends on the type of installation and type of plants which actually depends on the micro and macro climate of that area. Green walls are making our lives closer to nature. Green walls can be installed indoors or outdoor in the building.

Patrick Blanc was the architect who created the landmark vegetal exterior wall he created the first successful indoor green wall in 1986.

    There are many iconic green walls which are being constructed at institutions or public buildings now days these green walls are becoming common. As of 2015, the largest green wall in the world covers 2700 square meter which is located at Los Cabos international Convention Centre which is designed by Fernando Romero a Mexican architect. 


GREEN WALL - HISTORY

·       Green walls are an ancient feature of architecture. This concept was developed from Babylonians (the famous hanging garden of Babylon ) one of the famous ancient wonders of the world. even Romans used grapevine on the villa walls and garden trellises.

·       Back 2000(two thousand years) years ago in the region of Mediterranean the places with the narrow back yard were covered with the vines this was basically the earliest concept of green walls or can be said vertical gardens. It basically provided profit from itself like, providing shade to the façade design, transportive cooling and it also had some economic values as the fruits on that vertical garden can be sold out or can be used by the owner.

·       Back 500 (five hundred) years ago in central Europe, the most used or popular climber plants were woody vines it was basically used on the castles or villages. Fruit espalier and the climbing roses became the most famous and most favorite climbing or ornamented plant.

·       In rural areas vertical gardening was used as a vertical decorative material the mainly featured pattern was to use summer flower as a fashionable idea. This concept was basically used in the traditional balconies of Bavaria. It was even used in many growing cities at the time of industrialization.

·       The concept of climber plant in vertical gardening was especially used on the terraces and the balconies. So the so-called ‘traditional’ system of the green façade as a vertical garden was the most economical and oldest green façade these facades consist of planting elements like soil.

The basic chain of development of the green wall is given bellow.

3rd c. BCE to 17th c. AD: Romans train grapevines on villa walls and garden trellises. They also used climbing roses as a symbol of secret gardens.

1920: British and north American garden city movement promotes garden features like pergolas, trellis, and self-climbing plants.

1988: Stainless steel the cable system was introduced.

1990: North American market developed cable and wire-rope net and modular panel system.

1993: The first trellis panel system was applied at universal city walk in California.

1994: Bio-filtration in the indoor living wall in Canada life building in Toronto, Canada.

          This same year first wall plant was designed by Patrick blank which is based on hydroponic which means that the system is independent of soil as a plant growing medium.

2002: 1,300 climbing plants were used at MFO Park a multi-tiered 300’ long and 50’ high park structure opened at Zurich, Switzerland.

2005: 30 different modular green wall systems comprised at a single wall as a centerpiece of expo 2005 in Aichi, Japan. Which consumes 300 green wall panels of 3.500 sq. m?

2007: GRHC (Green roof for healthy cities) launched a full-day green wall design in North America.

2008: GRHC launches a green wall award of excellence.

GREEN WALL - TYPES


Types of green wall

Green wall is divided on the basis of the growing medium. Itis basically divided into two categories which are the following:-

1.    1. Living wall

       2. Green facade

GREEN WALL TYPE 1 - LIVING WALL

The living wall is a type of green wall composed of pre-vegetated panels of plants grown vertically using hydroponics on a structure which can be fixed free-standing structure or attached to walls. These walls support plant species like a lush mixture of ground covers, ferns, low shrubs, perennial flowers, and edible plants. The living wall typically requires higher maintenance than a green façade. Living walls are subdivided into many parts like the free-standing wall, panel system, versa wall which is basically a tray system. Living walls are subdivided into many parts on the basis of growing medium.

Green wall - living vs facade

GREEN WALL TYPE 2 - GREEN FACADE

Green façade in a type of green wall in which plants are rooted at the base of the structure, in the ground, in intermediate planters or at the rooftop, and then climbed up or hanged down the plant over the structure. Green façade takes almost 3 to 5 years to achieve full coverage. Green façade can be grown to an existing wall or built as free-standing. Green façades are further divided into many types like the direct system and indirect system.

 

GREEN WALL - TREND

 

Green living wall trend

The green wall is a growing design trend in today’s green construction. Nowadays green walls are spreading across the world. Green wall system was first developed by a professor of landscape architecture “Stanley hart white” in 1938.  A lot of public building around the world features green wall system which is mainly a living wall and green facades are mainly used in the residential buildings. It provides good aesthetics to the building and even reduces energy costs. The concept of green walls is mainly used in public areas. There are many apartments and airports around the world features green wall-like,

Example:

      I.            Chhatrapati Shivaji international airport, India

   II.            Singapore Changi Airport, Singapore

III.            Edmonton International airport, Canada

 

Currently largest green wall in the world is located at Los Cabos international convention center which is designed by a Mexican architect “Fernando Romero” in 2015 with a size of 2,700 square meters (29,063 square feet).

Green walls are still considered newcomers in today’s landscape architecture. Green wall innovation going fast. Green walls can help to cover the decaying or unpleasant concrete structure on bridges or roads. E.g. Mexico City.

There are some green walls around the world that are specifically designed for herbs and vegetables due to lack of space.

Green walls can be installed indoors or outdoor in a building.

GREEN FACADE - DEFINITION

According to "URBAN GREEN BLUE GRID"

Green facade gardens, whereby plants grow upwards from pots fastened to the facade or from a substrate attached to it.

According to "APPLIED MECHANICS AND MATERIAL"

Green façades are defined according to the application of climbers (deciduous or evergreen), as attaching themselves  directly to  the building  elevation  (in traditional  architecture), or  indirectly supported  by  steel  cables,  mesh  or trellis.

Green facades are often installed because they provide an attractive look to a building fence or they may be used to block out sight or to offer shadow for a building. Green facades can create a cooler microclimate immediately together to a building, mostly through straight shading of the building facade, but also from cooling from plant greenery (transpiration of water through the vegetations), and evaporative loss of water from the growing medium. All climbing vegetation will provide roughly retention of stormwater, shielding of the building facade, protection of its external surface, and apprehension of airborne particulate substance and volatile gaseous impurities. Green façade is a tradition feature for a building façade design which was basically developed from the Babylonian city.

List of Green facade building:-

Green wall's building list

TYPES OF GREEN FACADE

There are 2 types of green façade.

     1)   Direct system

     2)   Indirect system

Direct system of green facade

Green facade direct system

In this case, climbers planted in the ground at the base of the building as in traditional architecture, allow obtaining a cheap façade greening work. Self-clinging plants, which have been used frequently, have sucker root structure allowing them to attach directly to a wall and covers the entire elevation. But they cannot be applied for all building facades. These aggressive climbers can decay inappropriate walls and cause some problems for maintenance or when the time comes for plant removal.

Indirect system of green facade

Green facade indirect system

In this case, vegetation is supported by cables or meshes while keeping them away from the walls and other surfaces of the building. Different materials such as aluminum, plastic, wood, steel (stainless steel, coated steel, galvanized steel) can be used as a supporter for climbing plants. Each of the materials causes changes in the functional and aesthetical properties due to cost, profile thickness, different weight, and durability.

The indirect greening the system can be integrated with planter boxes at different levels of the façade. In this case, the system requires nutrients and a watering system if the rooting space is not adequate and can be defined as a kind of living wall the system, but two indirect green facade systems which are commonly applied are “modular trellis panel” and “cable and wire-rope net” systems.

(i) Modular Trellis Panel System  

This modular system consists of a three-dimensional, rigid, lightweight, panel, and designed to hold a green facade of the building membrane because plant materials do not attach directly to the buildings’ façade. Panels are normally made from a powder-coated, galvanized and welded steel wire and prepare a captive rising environment for the climbing plants with numerous supports for the climbers. Panels are usually made from steel and rigid enough to both span between structures and be applied as freestanding green facades. They can be fixed and combined to cover large parts and designed to form different shapes.

(ii) B: Cable or Wire-Rope Net System

wire rope system of living wall

Cable or Wire-Rope Net The system applies high-tensile steel cables, anchors, and also complimentary equipment. Numerous patterns and sizes can be accommodated as flexible vertical and horizontal wire-ropes are joined through cross clamps. Wire-nets which are more flexible than cables and provide a greater degree of design utilization are often used for slower growing plants, but for green facades that are designed to support the faster-growing climber with denser foliage, cables are employed.



Indirect greening the system combined with planter boxes

If planter boxes at different heights are combined with indirect greening systems, greenery can cover a vaster area of the façade. In this case, if the rooting space is not satisfactory, the system requires a watering and nutrients system therefore can be defined as a living wall system.

SUPPORTING ELEMENTS OF GREEN FACADE

Modular Panels

Usage for covering walls, as freestanding fences, screens, or attachments.

Columns

Usage as a vertical freestanding element or as a shelter for existing poles. Coiled or flat for easy field connection in average or custom diameters.

Curved Panels

Usage for describing curved surfaces, for covering walls, as freestanding fences, screens, or enclosures.

Planters

It is used to mounting panel screens in the shape of planters, or we can say that it acts as adjacent to structure’s wall mounting.

Custom

Usage for basic board panel as the building blocks and create the solutions from flat, curved, or formed arrangements.


LIVING WALL - DEFINITION

Living walls are plants grown in vertical systems that can be freestanding but are generally attached to internal or external walls. Green walls are totally different from these green facades applications as well as functions in which the entire vertical the structure is planted, as opposed to planting at the bottom of a structure and encouraging vertical growth. In green walls, the plants, growing substrate, irrigation, and drainage are incorporated into the one system.

Living wall

Living wall system (LWS) is built of modular panels. Each part holds its own soil or artificial growing medium, for example, perlite, felt foam, and mineral wool. If the wall is to be a primarily self-sustaining ecosystem, it should be much easier to use soil as a planting medium. It is based on hydroponic culture, using balanced nutrient solutions to provide the plant’s food and water requirements, although hydroponic chemical plant nutrients may destroy or disrupt the non-hydroponic component of the vertical green areas. From a functional viewpoint in comparison to the green facade, most of these systems need more complex design, as a greater number of variables must be considered, there are more supporting materials, several layers are involved, and the mechanism of water and nutrient should be conducted. From an economic point of view, they are more energy-consuming and difficult to maintain (e.g. supply nutrients to fertilize the plants) and therefore very expensive. These systems increase the variety of plants engaged mostly evergreen plants like ferns, low shrub, perennial flowers, and even edible plants. They do not make use exclusively of climbing plants; therefore they offer much more aesthetic and creativity. Selecting  the  plant  species  for the operative  green  wall  is  a  complicated procedure. It is vital to select the plants that are modified conveniently to the environment where they will be living in. The durability of living wall systems is important to take into account and varies according to the type of system. Living wall systems with panels based on felt layers have an average life expectancy of 10 years, and living wall systems based on planter boxes last more than 50 years.


TYPES OF LIVING WALL

DIFFERENT KIND OF GREEN WALLS

    (A)    Passive living wall

    (B)    Active living wall

    (C)   Mur-Vegetal and Landscape wall

PASSIVE LIVING WALL

Passive living walls are basically used in the Green roof, which we also called as innovation by technology. It is mostly applied in modular systems that are made up of rectangular or square panels which contain a growing media and keep plant material. The necessity nutrient requirements are prepared in the growing media. Irrigation which applies gravity to transfer water through the growing media is supplied with this equipment along the wall at different heights. A waterproof substance insulates the system from the building wall in order to prevent wetting problems, furthermore emitters, fertilizers, irrigation, and lighting systems may be required.

(1) Panel 

(2) Non-soil structural growth medium

(3) Plants

(4) Fertilization system

(5) Stainless steel

 

Active Living Walls

Green wall active living wall

Active living walls apply a forced airflow through the subs-tract which considerably improves designed to act as bio-filters indoor air and ecological air conditioning systems. 

This hydroponic system is fed by rich nutrient water that is re-circulated from a manifold. When these systems are integrated with the building's air conditioning, installations, reductions in energy consumption can be obtained up to 30% and there is potential to apply these systems on a large scale

Mur-Vegetal and Landscape wall

The Mur-Vegetal is an exclusive type pioneered by Patrick Blanc who is a French botanist specialized in plants from tropical forests and well known as the contemporary innovator of the green wall. In this, 2 types of layers are there which is of synthetic fabric that physically keeps on growing so that they support plants because of the fabric wall’s high moisture content.

The landscape wall is an evolution of landscape berms. They are normally sloped against the vertical barrier and have the major functions of slope stabilization and noise reduction. Actually, they are playing a very strategic and vital role to approach to green architecture.  They are constructed from some stacking material made of concrete or plastic with spaces for plants and growing media.

 

Hydroponic green wall systems

The hydroponic green wall systems are of two types in which some are modular containers and some comes in large panels. The systems are installed via brackets that sit out from the load-bearing wall (or a stand-alone structure) to create an air gap between the wall (and other structure) and the backing sheet of the green wall system. In a hydroponic system, an inert growing medium is provided to which the plants physically anchor, such as horticultural foam, a mineral fiber or a felt mat.  These materials can act as a water-retentive sponge, although the more they soak up the heavier the system becomes. The advantage of the hydroponic system is that there is no structural decay of the growing medium, no salt build-up from fertilizers and nutrients are supplied in a precise and controlled manner. Plant roots grow and also ramify through all the entire system so that they can create robust network.

Living Walls are basically based on-

·       Based on planter box

·       Foam substrate

·       Felt layers

 

VEGETATION

Choosing appropriate plant material for green wall requires careful consideration of climate zone, sun exposure, soil type, soil volume, area of coverage, irrigation needs, fertilization, adjacency to other plants and desired visual effects.

While it might be easiest just to pick plant material from the appropriate hardiness zone. Experience and observation has shown that making successful plant material choices are based upon these additional considerations:

        ·   Matching a plant’s growth habit to the type of installation

         ·   Choosing plants based upon seasonal cycles

          ·   Selection of plant materials based on the client’s requirement and maintenance cost.

          ·  Choosing mixed plantings to ensure the long term success of the project

           ·         Using native plants

Hardiness Zone Selection

For projects in North America the U.S. Department of Agriculture maintains a map that designates zones for plant growing adaptability. This map shows areas as the average for lowest temperature and represents the extreme temperatures to which a plant would generally be exposed. The zone designation can be matched with the range that is listed for each named plant. The plant list is categorized for the lowest zone tolerance for each plant, and also shows a range of zones in which each plant may thrive.


Plant Growth Habits

T – Twining - Twining vines use their leaf structure or main stem to twist or circle around any type of support. Plants with this growth habit are strongly recommended for wall-mounted installations in proximity to the building envelope.

Green Wall twinning

Example:

• Honeysuckle varieties (Lonicera)

• Jasmine varieties ( Trachelospermum )

• Black-Eyed Susan Vine ( Thunbergia )

 

LS - Leaf Stem – are called as tendrils.

The vines of leaf stem use very thin, wire structures along the plant’s stem that coil so that they can find a way to take necessary support to grow vertically. In Leaf Stem vines, it includes both the stem and leaf tendrils, which are recommended for both the wall mounted as well as the free standing installations. Example:

• Clematis varieties (Clematis x)

• Passion Flower (Passiflora)

 

S – Scramblers - Scrambling or rambling vines and shrubs have long, flexible stems that may look like vines, but they are unable to climb on their own. For vertical growth sometimes plants use thorns or hook. One of the best, excellent and beautiful choices to give your wall a 3D look by green wall panels and these panels may be wall mounted or freestanding, but additional maintenance may be required to keep them on the panels. Example:

• Bougainvillea varieties (Bougainvillea)

• Climbing Rose (Rosa varieties)

 

AS - Adhesive Sucker - Adhesive sucker vines support themselves with short lateral shoots tipped with discs that stick to any surface. This type of plants and their growth habits are not usually made for wall-mounted installations. Example:

• Boston Ivy (Parthenocissus tricuspidata)

• Virginia Creeper (Parthenocissus quinquefoliate)


RC - Root Climbers – The vines of root climbers produces stout roots as well as cluster of short. This type of plants and their growth habits are not usually made for wall mounted installations. These plants are recommended for freestanding installations that have moderate to high maintenance resources. Example:

• English Ivy (Hedera helix)

• Climbing Hydrangea (Hydrangea petiolaris)

Types of vegetation in green wall

Maintenance

• Pruning

• Fertilization

• Mulch

• Irrigation Check


Planting Guidelines

For determining the number of plants per panel, the typical plant spacing is from 1 - 4’ and is dependent upon vine species, container size and desired effect. General plant spacing recommendations are:

• 1 containers 12”-24” o.c.

• 3 containers 24”-36” o.c.

• 5 containers 36”-48” o.c.

Closer spacing with larger plant material may provide quicker results, but may also require additional maintenance in the short term. Additional information regarding plant installation can be found in the document green wall Planting Guidelines. Plants placed in a raised planter or container condition may have different requirements than those placed in an at-grade planting bed. Particular attention should be paid to extreme hot or cold temperature exposures, consistent irrigation, and adequate soil volume and soil nutrient delivery.


 EFFECT ON ENVIRONMENT 

The environment is majorly effected through Vegetation and because of this affects the changes in the pattern of climate and weather also. Vapour has released in the air by which the surface energy fluxes and this leads to the formation of clouds. Because of this the amount of sunlight intensity that reaches the Earth's surface is altered by the cloud which leads to precipitation in some areas.

Green wall benefits

Benefits of vegetation

-      Reducing carbon dioxide levels.

-      Increasing humidity.

-      Reducing levels of certain pollutants, such as benzene and nitrogen dioxide.

-      Reducing airborne dust levels.

-      Keeping air temperatures down.

-      Dampen sound.

-      Provide a neighborhood buffer and increase privacy.

-      Preventing the tissue’s burn of the lung by reducing air pollutants known as the Ozone layer or gas.

-      Reduce stormwater runoff and flood damage downstream.

-      reduce water temperature downstream (needed for trout)


MAINTAINANCE

 At a minimum, all plant the material should receive the following annual applications:

• Pruning

• Fertilization

• Mulch

• Irrigation Check

• Any dead, damaged or diseased plants should be replaced.

• All staking of A temporary plant must be removed during installation. Somehow, if staking of plant remains then remove the plant materials as well as weave the plant material into the grid or we can attach the remaining branches of the plant to that installed panel with the help of ties which should be biodegradable.

• This information is provided for general information. Please refer to landscape drawings, details, maintenance manuals.

 

The Guidelines for maintenance of green façade plant installation so that they can survive for a long period of time successfully.

·       Pruning Application – Always pruned the plants to maintain the plants so that it can easily grow on panels. Remove all the damaged or diseased tendrils. The frame of the panel can be used as a pruning template in any dimension. Every plant has its own growth timing schedules, so always adjust the pruning timing also according to the growth of plants. If plant material is aggressive, additional pruning schedules may be required. To maintain the visual and aesthetic appearance of the blooming plant should be pruned after the flowering season. Shearing on the front of the panels can be beneficial in tight right-of-way’s to maintain circulation and heavy pruning at the top and sides of the panel will encourage uniform coverage. When shearing with gas-powered trimmers, care must be taken to prevent damage to the panels, attachments, and posts. Remove all the branches which are growing horizontally around the panels. And also remove any pruning clippings and compost.

·       Fertilization Application – Following the manufacturer’s recommendations, apply a slow-release, water-soluble 12- 12-12 fertilizer around the base of all plants. Sprayed on, water-soluble, foliar applications can also be scheduled to encourage healthy, vigorous plants. Recommended fertilization rates should be determined by plant material, soil conditions, and planting bed location. Raised planters may require supplemental fertilizer during the growing season.

·       Mulch Application – After planting the area has been properly cleaned and weeded, apply a pre-emergent herbicide according to the manufacturer’s recommendations. Apply a 2-4” layer of mulch material to the planting bed and around the crown of new plant material. Natural, biodegradable mulch, such as shredded hardwood or pine straw, will help to retain moisture, add additional organic material to the soil and cut down on weeding maintenance. After the mulch application, water in new plant material as necessary.

·       Irrigation Check – The irrigation system should be inspected for broken or clogged lines, damaged spray heads, and line leaks. All drip irrigation should be checked to ensure adequate water delivery. Visually check that zones are operating efficiently and adjust controller time settings based upon installation timing, growing season, and watering requirements. Water requirements may be different during the 1-2 year plant establishment period.

 

BENEFITS OF GREEN WALL

Green wall benefits with living wall

Environmental Advances:

A Vertical garden offers immediate environmental advances by reducing organic compounds from our polluted cities. Plants act as bio-filters and purifiers having a dramatic influence in the improvement of air quality in cities by removing or reducing airborne pollutants from both the inside or outside of a building’s air. Studies have shown that they are considerably less concentrations of toxins in the air surrounding a Vertical garden. Theoretically speaking, if one Living wall is situated in every house in a row of 50 houses, then this is equivalent to having 50 trees planted on the street. By acting as purifiers, plants replace CO2 with oxygen, this means that the air breathed is fresher and healthier.

Improved Air Quality:

It is scientifically proven that leaves improve air quality; why else would the Amazon forest be referred to as ‘the lungs of the world’. A Vertical wall will help improve the air around it acting as an air filter by purifying the polluted air and releasing oxygen. When implemented in an office space, the existence of a Green wall can result in greater employee productivity and general health; as clean air leads to greater concentration, much healthier employees, and eventually less sick days announced. Improvement in air quality from plants has been measured to reduce coughs up to 30% and dry throat up to 20%; substantial differences in the air humans breathe.

Water Conservation:

A huge benefit is how Vertical gardens manage water. First of all, watering is very efficiently handled as it is done through an irrigation system. Wastewater is collected by a basin at the bottom of the garden where it can be emptied out. This water can also be recycled and inserted back into the wall, thus all the water is used and there is little to waste.

Mitigating the UHIE (Urban heat island effect):

Cities are becoming warmer with the transformation of natural environments to engineered infrastructure, accompanied with increased heat generation from human activities and summer heat accumulation due to massive heat absorbing surfaces (Chen 2012). This results in high temperatures in urban areas in comparison with rural areas, a phenomenon known as the urban heat island (UHI) effect. In Melbourne, research has shown a UHI of a mean of around 1 to 4°C and as high as 7°C depending on the location, time of the year and day. Urban summer heat accumulation is likely to be further exacerbated with global warming. Climate change projections for Australia suggest an increase in the number of warm nights and heat waves which can pose significant threats to human health (Alexander and Arbalster, 2008). The heat wave event in Melbourne, in early 2009, may have resulted in 374 excess deaths over what would normally be expected for the period: a 62% increase in total all-cause mortality and an 8 fold increase in direct heat-related presentations in the emergency departments (DHS, 2009).

Green roofs and walls, implemented as a city-wide strategy, can mitigate the heat island effect (DDC 2007). By introducing vegetation onto roofs and walls temperatures can be reduced by means of evapotranspiration (evaporation of water from the soil and plants, and plants transpiring by taking water in through roots and releasing it through leaves) and simply through covering the roof with a less absorbing surface. Energy from incoming solar radiation that would otherwise heat the roof or wall surface and increase ambient air temperatures is instead used in the evapotranspiration process, resulting in latent heat loss that lowers surrounding air temperatures (Peck and Richie, 2009).

An ‘Inquiry into Environmental Design and Public Health in Victoria’ recommended that the Victorian Government urgently develop a response to the emerging health problems stemming from poor air quality and the urban heat island effect in Melbourne. The inquiry suggested that the design of residential communities should prioritize tree planting and green spaces to provide shade, improve respiratory health and to lower ambient temperatures in summer months (Legislative Council Environment and Planning References Committee 2012). In many built-up areas, the only options for green spaces may be rooftop and vertical greening.

Benefits of living wall

Wall Greening to Improve Aesthetical Value of Urban Living:

According to Frank Lloyd Wright “A doctor can bury his mistakes, but an architect can only advise his clients to plant vines.” (Wright, 1931). This brought a good idea for those who use their rooftops for gardening; instead they can hang them on the walls to make it more visible for people (Alter, 2008).

The master of green façade Edouard Francois was quoted saying “Man can live solely within architecture. He needs a complex building which must be decorated. Only in this way can he be happy”. Indeed, in Francois’s view, working with nature offers a welcome complexity: ‘Watch a tree. It has a thousand branches, it moves, grows, changes color’(Alter, 2008). Sir William Dobell once said, “A sincere artist is not one who makes a faithful attempt to put on to canvas what is in front of him, but one who tries to create something which is, in itself, a living thing.” (Mike, 2011)Now that it is a known problem, that green spaces in urban areas are disappearing day by day due to urbanization. Integrating greenery on building façade as part of city planning will have an impact urban areas. If carefully designed and constructed, it can also be applied to other structures like bridges and can also serve as a cover for ugly and old buildings. Green façade will definitely improve the environment aesthetically (Michelle, 2011). If properly designed and maintained, a green facade can enhance the appearance of buildings and any other structure. Another thing is the careful selection of plants to use which varies in their looks and texture; if properly done it can also enhance the building appearance. In parts of the world where graffiti is not accepted, façade greening can serve as protection which makes it almost impossible (Mir, M. A. 2011). The high degree of maintenance is the weakness of façade greening, it requires a lot of maintenance work such as trimming, replacing the death once, and watering to keep it natural and in healthy condition (Ghaffarian Hoseini, 2012) (Ghaffarian Hoseini, 2012).

Green walls to Improve Urban Climate:

Green wall have a direct positive impact on both the cities and their inhabitants. Those living in the cities can see the plants used on the green façade as hanging gardens. Walls that are directly exposed to sun and UV will conduct heat and transfer it into the building, which will lead to a significant rise of temperature in the building. This shows the Urban Heat Island effect. The plants used on the green façade lose water via their leaves in a process called evapotranspiration which helps in moderating the temperature around the buildings. Green façade in urban areas helps in moderating the microclimate, therefore, improving the living condition in such cities (Peter, 2013).

Now that green areas are disappearing in urban areas, the excessive heat built up due to the presence of more hard surfaces which doesn’t absorb but only reflect the heat, combined with other pollutants distorts the weather of a particular area and its surrounding environment. This is what led to urban heat island effect. The urban heat island effect is an area of the city that is extremely warmer than its neighboring rural area. The integration of plants on building façade can drastically bring down the urban heat island effect and make urban life healthier (Patrick, 2011). Green façade always promote the building’s cooling process, if design and construction are done properly.

Green Façade to Reduce Carbon Footprint and Improve Air Quality:

Biologically, plants absorb carbon dioxide in order to synthesize food from sunlight; this process is generally known as photosynthesis. Oxygen is been released as a by-product of this process. This shows that the more plants we have in urban areas the more clean air we get (Patrick, 2011).Plants growing on building façade absorb carbon dioxide and release oxygen. The plants also serve as filters to other pollutants like; cadmium and lead. They also act as carbon filters by absorbing the greenhouse gases emitted by the atmosphere and store them in their tissues. The arrangement of plants on living walls is thick which gives room for planting more on a small area. The carbon absorbed by 20m2 of a living wall is equivalent to that absorbed by a medium-sized tree(Patrick, 2011). Integration of greenery to building façade can improve the air quality in cities. Air quality can also be improved through the process called biofiltration. Biofiltration can simply be described as a technique used in controlling pollution using living materials; here the living materials serve as filters for the air and dust that passes through it. The microbes contained by the plants absorb must of the pollutants. In this process the plants absorb the carbon dioxide produced, therefore releasing oxygen to the environment (Apothecia, 2012). It is proved that; green façade has the capability of saving energy in buildings. They also help in preventing the formation of dust by absorbing dangerous atmospheric particles (Marie, 2012). According to Patrick (2011), the moisture level of the green wall needs to be monitored and controlled, due to too much amount of water retention which may contribute to high moisture index leading to mold growth effect.

Temperature Reduction:

According to research, in a humid climate, the use of greenery on building façade in an urban canyon can help in achieving the substantial benefit of maximum temperature reduction of up to 8.4°C (Alexandri et. al,. 2008). This is important because, the energy consumption of buildings is influenced by the distribution of ambient air in a canyon as higher temperatures in canyon increase heat convection to a building and similarly increases the cooling load (Santamouris, 2001). By directly shading the heat absorbing surfaces of a building with vegetation, it will help in alleviating UHI through evapotranspiration cooling (McPherson, 1994). The use of greenery on building façade can drastically reduce the temperature of a building to as much as 50% by shading walls from direct sunlight. The process of evapotranspiration helps in converting large amounts of solar radiation into latent heat which does not cause any rise in temperature. Furthermore, an efficient green façade has the ability to protect the building from intense solar radiation during the summer period and can use its leaf cover to reflect and absorb between 40% and 80% of the received radiation, which depend on the amount and the type of vegetation used (sheweka et. al., 2012).

In other studies, at the University of Toronto since 1992, the surface temperature of vertical greenery have been observed in different settings (Bass, et. al., 2003). The results consistently show that areas with vertical greenery are cooler than areas with light-colored bricks, walls, and other surfaces found in the urban areas. Another experiment in Japan shows that climbing plants can reduce the temperature of a veranda with south-western exposure (Hoyano, 1988). While in Africa, the temperature reduction of 2.6°C behind panels covered with vines (Holm, 1989). Thus, temperature fluctuations on the wall surface can be moderated from between 10°C and 60°C to between 5°C and 30°C (Peck, et. al., 1999)

Shading and Insulation:

The use of greenery on building façade as shades to solar radiation is obvious, with the advantage that the traditional concrete or brick facades which radiate the heat in and around the building, while greenery does not. This depends crucially on the density of the foliage (sheweka et. al., 2012). In a double skin façade, the temperature is generally lower if greenery is used in between the skins. In a case where plant is used instead of slat in double skin façade the temperature never exceed 35°C, while with slats, temperature can exceed 55°C. The amount of energy required for air conditioning can be reduced by up to 20% with the use of plants in an internal double skin façade (Stec, et. al., 2004). The physiology of plant implies that some portion of sunlight received by the vegetation is used for the process of photosynthesis, while the remaining is used for evapotranspiration, hence, making them mechanism for Temperature moderation. This is what makes vegetation effective in blocking solar radiation without increasing it Temperature. The transmittance factor of a leaf is 0.2, while it absorbance is 0.5 (sheweka et. al., 2012).

According to an experiment “Bioshader” conducted in University of Brighton, in this experiment an office space was used as a case study, the windows of the office were covered with vegetation. The temperature recorded was between 3.5°C to 5.6°C lower than when the windows are covered with other materials. The solar transmittance of the foliage was also measured, which ranges from 0.43, with a single layer leaves, and up to 0.14 with five layers of leaves, and also a reduction in solar radiation of up to 37% in a single layer leaf cover and 86% in five layer leaf cover as shown in figures (7, 8 and 9). (Miller, et. al., 2007). In another experiment, it suggested that more thermal energy flows into the non-shaded walls due to their direct exposure to sunlight, which results in higher wall surface temperature. The heat absorbed by the non-shaded surface will later advance to the inner wall surfaces making the temperature interior rise, which leads to more energy consumption for cooling (Neila, 2004).

Evaporative Cooling

According to a study, in a tropical climate, it was confirmed that vegetation has a cooling effect. The study was done by measuring the temperature atmosphere at different altitudes. The maximum difference in temperature recorded was 4.2°C. Based on this study, it shows that the cooling effect is limited with the height (Wong, et. al., 2003).

In the project of the institute of physics of the Humbolt University Berlin, Adolershof, combines rainwater management and energy savings with natural conditioning through vegetated walls. The shadow cast on the façade by the vegetation affects the cooling of the building, which influence the energy consumption of the building Figure.

Evapotranspiration is the most significant environmental benefit of green roofs and facades in the urban areas. This process has effect on urban hydrology, in reducing the temperature of urban surfaces and improving the management of rainwater runoff (Stec, et. al., 2004).More so, the experiment conducted at University of Brighton “Bioshader” which compared an office space with window covered with vegetation and with other covers, verifies that humidity level in the office with bio shade is higher than that without. This shows that the use of greenery on building façade provides additional moisture to the dry indoor environment (Miller, et. al., 2007).

Lastly, the cooling effect of greenery due to evapotranspiration helps in moderate the temperature around the building, and the evaporated water by the plants increase the humidity up to 2 kg of water per m3 of dry air.

 Decrease in Energy Costs:

Living walls come and act as natural air-conditions, balancing humidity levels for our comfort, though the process of evapotranspiration. Therefore, in the summer our houses and offices are cooler and, in the winter, acting as an insulator we are warm; which in turn reduces our over-the-top bills all year round. Studies have shown that interior Green walls can reduce electricity bills up to 30%.


CASE STUDY

1.    Consortia Santiago Building Santiago, Chile

Building Data’s:

Year of Completion     :    1993

Height                          :     58 meters

Stories                          :     17

Gross Floor Area         :     27,720 square meters

Building Function        :     Office

Structural Material

Concrete

 

Green Wall Overview:

·       Green Wall Type  -  Façade-supported green wall (horizontal aluminum slats)

·       Location on Building  -  On the north and west façades from 4th to 8th, 10th to 12th, and 13th to 14th floors

·       Surface Area of Green Coverage  -  2,293 square meters (approx.)

·       Design Strategies  -  Horizontal aluminum slats, offset 1.4 meters from façade, support climbing plants over 2–4 floors in height.

-      Green wall split into three separate sections vertically, each with the support of one horizontal planter at green wall base

-      Deciduous plants provide solar shade in summer, color in autumn/fall and admit solar/light during leafless months

-      Coordination between occupiers and gardener to prune plants to control solar heat gain and light emittance

-      Exterior street trees protect lower floors from solar heat gain/glare

Climatic Data:

·       Location  -  Santiago, Chile

·       Geographic Position  - Latitude 33.5° S

                                   - Longitude 70.7° W

·       Elevation  -  550 meters above sea level

·       Climate Classification  -  Warm temperate, summer dry, warm summer

·       Mean Annual Temperature  -  14.4 °C

·       Average Daytime Temperature during the Hottest Months(December, January, February)  -  20.5 °C

·       Average Daytime Temperature during the Coldest Months(June, July, August)  -  8.7 °C

·       Annual Average Relative Humidity  -  58% (hottest months) 83%(coldest months)

·       Average Monthly Precipitation  -  30 millimeters

·       Prevailing Wind Direction  -  Southwest

·       Average Wind Speed  -  2.5 meters per second

·       Solar Radiation  - Maximum: 976 Wh/m2 (December 21)

                            - Minimum: 815 Wh/m2 (June 21)

·       Annual Average Daily Sunshine  -  6.6 hours

Local Climate

The climate of Santiago is Mediterranean, with typically hot, dry summers, and mild, moist. In summer, November to February, temperature varies from 17 °C to 20 °C. The summer months can be quite windy and dry, with prevailing winds from the southwest. In winter, May to August, temperature varies from 0 °C to 13 °C. Temperatures in winter seldom drop below freezing. Rain falls mainly during winter, which is a more humid season. Snowfall is extremely rare in Santiago, although it is common in the Andes mountain range that looms above the city. Temperature inversions cause smog to be trapped in the valley for spells during the winter months. Santiago is considered one of the most polluted cities in the world, largely due to its location in a natural bowl, and the smog is at its worst in winter.

 

case study of green wall

Background

This office building is located in the Las-Condes Neighbourhood, in Santiago, Chile (see Figure 2.1.2). The floor plan of the building has the form of a “boat looking south with the alignment of the main façade generated by the main street axis that surrounds the building (El Bosque Avenue and Tobalaba Avenue). Initially, the plan was that the floor space would be divided into two sectors, with the first three floors occupied by Consorcio, while the higher floors would be rented; however, the Consorcio Company eventually occupied most of the floors in the building. The south side of the building is shaped as a high vertex, because there was an open angle of 148° between both avenues. This symbolically marks the beginning of the office area of the neighbourhood. The west façade was curved to visually receive the pedestrians coming from the nearby subway and down.

 

Case Study 2

2.    Newton Suites, Singapore

Building Data:

Year of Completion        :        2007

Height                             :        120 meters

Stories                             :        36

Gross Floor Area            :        11,835 square meters

Building Function           :        Residential

Structural Material          :        Concrete

Green Wall Overview:

·       Green Wall Type  -  Façade-supported green wall (metal mesh)

And Tree planters and gardens on communal cantilevering balconies

·       Location on Building  -  South façade: 6th to 36th floor (green wall)

                               - Balcony tree/gardens every 4th floor.

                                    - Green walls to car parking podium on south, east and west façades, 1st to 5th floor.

·       Surface Area of Green Coverage  -  1,274 square meters (approx.)

·       Design Strategies  -

-      Trellis-supported green wall runs nearly full height of building from the podium (30 floors)

-      The green wall actually 30 overlapping separate one-story green walls, supported by horizontal planters at each floor

-      Communal cantilevering “sky garden” balconies, with trees, significant planting and water features, every four floors

-      Significant planting to individual unit balconies encouraged

-      Luxuriant planting elsewhere, including car parking podium green walls and landscape podium top

-      Vertical greenery, podium top, and other sites vegetation achieving 130% of the plot as greenery

Climatic Data:

·       Location  -  Singapore

·       Geographic Position  -  Latitude 1° 22' N

                                   - Longitude 103° 58' E

·       Elevation  -  16 meters above sea level

·       Climate Classification  -  Equatorial, fully humid

·       Mean Annual Temperature  -  27.5 °C

·       Average Daytime Temperature during the Hottest Months (April, May, June)  -  28.3 °C

·       Average Daytime Temperature during the Coldest Months (November, December, January)  -  26.6 °C

·       Annual Average Relative Humidity  -  82% (hottest months)

                                                               -  86% (Coldest months)

·       Average Monthly Precipitation  -  201 millimeters

·       Prevailing Wind Direction  -  North

·       Average Wind Speed  -  4.4 meters per second

·       Solar Radiation  -  Maximum: 837 Wh/m2 (December 21)

                           -  Minimum: 737 Wh/m2 (September 21)

·       Annual Average Daily Sunshine  -  5.6 hours

Local Climate

Located in an equatorial climate zone, according to the AF Koppen system, and classified as a fully humid zone, Singapore has little temperature and humidity variation between seasons but instead experiences consistently high temperatures year-round. Relatively stable air temperatures, high average humidity and significant rainfall makes Singapore a beneficial location for growing plants. The average temperatures range from 23°C to 32°C, with May being the hottest month of the year. A high relative humidity of near 90% in the morning moves to around 60% in the mid-afternoon.

Background

Newton Suites is a 36-story high-rise residential building located in downtown Singapore, adjacent to the commercial and retail hub of Novena. The building site is located at the edge of a high-rise zone and fronts a height-controlled area, which allows unique views of the central nature reserves. The building was carefully positioned on its narrow site, flanked by tall buildings on three sides. The tower sits on top of a five-story podium that serves as enclosed car parking for 125 cars, with public amenities for the residents located on the podium roof. The building features 118 residential units, located between the sixth and 36th floor of the tower, with two and three-bedroom units arranged in a cluster of four per floor, with two top floor occupied by Penthouse units. Newton Suites is considered a high-rise building model appropriate for the tropical climate of Southeast Asia, based on passive climate-control design principles and maximizing the incorporation of nature into the building. The natural landscape features were included in the architecture from the early design stage.


CONCLUSION

The integration of vegetation on buildings and other structures wall can of great benefit to the urban environment; it can also be used as a tool for passive thermal control of buildings. If carefully design and maintained, green walls have the ability to moderate urban temperature. In conclusion, the benefits of wall greening can be categorized into two; private benefits and public benefits Private Benefits.

-      Green wall helps in improving indoor air quality. when used in the interior of the building, the plants on the wall have the ability to filter the noxious gases from the carpets and other furniture. The greenery also absorbs airborne pollutants like dust and other unwanted gases.

-      Protecting the building structure: Generally building facades are exposed sun, water and other weathering elements and with time most of the construction materials start to break down, due to heating and cooling which causes contraction and expansion of the materials. The green wall can protect the building wall from direct exposure to sunlight.

-      Energy efficiency in the building: Green wall can serve as a windbreaker during the winter; it can also reduce the ambient temperature through the evapotranspiration process. If applied internally helps in reducing the amount of energy required in cooling the outdoor air for indoor use.

Public Benefits:

-      Green the wall helps in reducing urban heat island effect this effect is caused by the replacement of green areas with hard surfaces, which lead to the conversion of sunlight to heat. It is a well-known fact that greenery cools the building by shading it from direct exposure to sunlight which leads to the reduction of reflected heat and also through evapotranspiration, therefore with this we can say the wall greening helps in natural cooling processes of buildings and environment and moderating the ambient temperature in urban areas.

-      Green wall helps in improving outdoor air quality: there is a lot of pollution in urban area due to the presence of a high number of industries, vehicles, and other things that emit a lot of unwanted gases. One of the benefits of the green wall is that the plants have the ability to absorb the airborne pollutants and other deposits on their leaf.

-      Green wall helps in improving the appearance of a building or a street, due to the nature of the plants used. They may have different appearance and texture which will give variation in the appearance.

Finally, the integration of greenery on building wall shows great potentials in attaining a sustainable built environment through the reduction of an urban heat island effect, improving both indoor and outdoor air quality, making the environment more aesthetically pleasing and also reducing the carbon footprints in urban areas.

                                   

GREEN WALL – OUR RECOMMENDATION

There are lots of suggestions which we can implement but we are listing some important recommended points to be implemented in your design for green walls to improve both the ambient as well as thermal condition.

1.    Plants and vegetation should be introduced extensively yet carefully on the building wall in the urban area. Selection of plants should consider their natural supporting mechanism and adaptability harsh environment.

2.    Plants and vegetation implemented on the urban wall should be located accordingly to receive full sunlight in the highest amount of time possible.

3.    Maintenance of plants introduced on the vertical plane in the urban area should be considered as the plants will need sufficient watering and also regular trimming to prevent hazards.

4.    High relative humidity will offset thermal comfort especially when the temperature is high and no wind to overcome heat discomfort. Therefore it is important to consider the location of the green wall in enclosed areas as it will affect the temperature as well as humidity.

 

 

Green wall Dissertation topic by Aditi Jangir

Thanks to Ar. Aditi Jangir who wrote this Dissertation topic for 

Pop Arch Design.



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