When you think of trees, images of the picturesque autumnal colours of an oak tree, or the breathtaking size of mature redwoods, come to mind. Trees give us as individuals a lot of joy and beauty, but in cityscapes, trees, if not managed currently, can be dangerous. Tree-related pedestrian injuries are much more common than you think and can result in costly settlements.

Tree roots like meandering outside their designated rooting zone looking for water or nutrients, causing all sorts of damage ranging from pavement cracking to underground water pipe breakages.

Tree grates are one method to manage trees in cityscapes safely. If properly installed, tree grates essentially protect trees from pedestrians and pedestrians from trees. Tree grates are often categorized as a root management product, as they help to ensure tree roots stay in their intended rooting areas. Placed over the tree roots and around the tree trunk, grates have two primary purposes.

Number one, to avoid soil compaction to allow for healthy tree growth, and number two, to ensure that the tree’s roots do not impact the surrounding pavements. With tree root protection underneath the grate, pedestrians are less likely to be tripped up by protruding roots. The tree grates also provide a more levelled surface, preventing pedestrian injury.

At Citygreen, we have developed a wide range of grates that will make cities greener and safer.

The Invisigrate™ is a pave-over grille, allowing the surrounding pavement to continue up to the tree trunk. This method eliminates any trip or slip hazards pedestrians often encounter and gives a clean style to the pavement.

This sub-surface grille can still incorporate all the essential irrigation inlets and checkpoints into the pavement. The benefit of this grate is that it allows designers to continue their choice of paving over the tree pit area for a more stylish and effortless finish.

The grate also has built-in tree irrigation/ventilation inlets and a removable inner section that allows tree growth.

We can all agree that the protection of trees is vital for retaining a city’s character and environmental feel, but within cityscapes, trees need to be managed for pedestrian safety. Installing tree grates is one easy and effective way of achieving safer, greener, healthier cities.

To learn more about our tree grates products, contact our friendly Citygreen Team.

In Australia, the Bureau of Meteorology has officially declared that a third La Niña is underway. With this announcement, it is safe that most Australians are looking forward to the eventual return of sunny skies; however, this cannot be said for other citizens around the globe.

The La Niña causing relentless rain for eastern Australia is also driving serve drought conditions in East Africa.

This is because there are ‘cool seas off Africa and warm seas off Australia, leading to rain falling over Australia instead of Africa’ (Deacon, 2022).

As the rains began to fall in Australia shortly after the Black Summer Fires in early 2020, rainfall sadly failed to eventuate in East Africa. This year, the Horn of Africa faces a record fifth failed wet season, which is impacting some of the poorest countries on earth.

The million-dollar question is what can be done about La Niña?

With climate change, these unusual, erratic weather events will be more frequent, and our cities need to be able to adapt.

At Citygreen, we believe that trees can help to alleviate the impacts of climate change, but first, we need to get them in the ground, so they thrive in our communities.

Planting trees in our bustling cities is no easy feat. The idea that you can plant a tree into a sidewalk or verge and hope that it will survive on its own during these erratic weather seasons we now face is an idea that has now been conclusively abandoned.

At Citygreen, we have been developing highly-engineering and researched products for over three decades, enabling trees to thrive and benefit our urban communities as soon as possible.

One of these products goes by the name of the RootDirector – a modular root management device designed to prevent root swirl and divert root growth downward and outward. This encourages profound root growth, which enhances the tree’s growth and overall stability.

Deeper and healthier root growth means the trees can access more subsoil moisture during dry periods. During wet periods, the roots have a greater and deeper span to find available oxygen in waterlogged soils.

Also, if tree roots are not directed downwards, they will grow horizontally and cause issues to other infrastructures like pipes and sidewalks.

At Citygreen, we believe that planting trees using an adequately designed root management system is a small cost compared to the time and labour needed to replant trees after premature death or removal due to infrastructure damage.

For more information download the free digital brochure below.
RootDirector Brochure. 

Earlier this year, an article published online by editor and writer Melissa Denchak highlighted some shocking statistics coming out of America. Denchak stated that ‘an estimated 10 trillion gallons of untreated stormwater runoff, containing everything from raw sewage to trash to toxins, enters U.S waterways from city sewer systems every year, polluting the environment and drinking supplies… [with] runoff causes significant flooding as well.’ (Denchak 2022). 

Denchak described the ‘U.S Environmental Protection Agency (EPA) estimates that upgrading the stormwater and other public water systems will require at least $150 billion in investment over the next two decades. 

This problem is not unique to the U.S, it is a problem all over the globe. The question is, how do we address the issues caused by stormwater runoff?

In this article, Citygreen will argue that green infrastructure offers a cost-effective solution to handling flooding and stormwater pollution. 

To start, let’s break down the basics. 

What is Green Infrastructure? 

Green infrastructure encompasses a variety of water management practices, such as planted verges, bioretention pits, swales and other measures that capture, filter, and reduce stormwater. Essentially, green infrastructure replicates natural hydrological processes using soil and plants to slow down, recycle and clean stormwater runoff.

What is stormwater runoff?

Runoff is the product of a rain event causing water to flow into sewers and waterways. With the expansion of our bustling cities and the widening sprawl of our urban areas, there are more impermeable surfaces than ever, changing the intensity of stormwater runoff. According to Denchak, ‘the average city block can generate more than five times as much runoff as a forested area of equal size’ (Denchak 2022). 

What is an example of a successful green infrastructure project? 

Denchak proposed that New York’s Staten Island Bluebelt was the ‘first and largest green infrastructure project in the U.S.’ A rapid increase in population size saw the Island struggling to deal with sanitary waste and stormwater runoff. The Bluebelt project ‘helped solve these issues by preserving streams, wetland areas, and other drainage corridors (Bluebelts) that use natural mechanisms to capture, store, and filter stormwater’ (Denchak 2022). Nowadays, the Bluebelt comprises more than 14,000 acres and can temporarily hold and filter as much as 350,000 gallons of rainfall. 

How does Citygreen implement green infrastructure projects?

Over the past three decades, Citygreen has made significant investments in green infrastructure projects.  We learnt early on that mimicking natural systems to manage rainfall, is the most cost-effectively way to deal with stormwater runoff.

An example of a green infrastructure designed that Citygreen has developed is the Strataflow™ system.  Instead of a traditional bioretention basin, Citygreen’s Strataflow™ uses an underground structural soil cell system, which delivers a high standard of stormwater treatment with a completely natural look. To any passer-by, what you see is a healthy, flourishing tree surrounded by a grassy verge, but beneath the ground is an advanced WSUD. 

This design starts with the Strataflow Kerb Inlet; this device sits in the road kerb alignment, retaining the inherent structure of the concrete kerb. The inlet has a grate (acting as a screen) to stop larger-sized pollutants from entering the system, which inhibits healthy tree growth. 

The inlet lets water from the road carriageway flow through the front grate of the drain at a capacity of up to 18 litres/ 5 gallons per second. This allows the inlet to minimise pollutants entering waterways and reduce flood risks by controlling the stormwater flow entering our city’s underground drains. 

When the water flows through the street, it enters through the inlet and flows underground. From there, the stormwater reaches the advanced structural soil cell system, where the stormwater is stored, filtered and distributed effectively for the benefit of urban trees and proper stormwater management.

The inlet ensures the water drains down at the correct optimal depth beneath the pavement height. From there, the stormwater reaches the structural soil cell system and the tree’s root system, where the stormwater is stored, filtered and distributed effectively to benefit urban trees and proper stormwater management.

Essentially, Strataflow™ utilises readily available stormwater rather than potable water to irrigate street trees, which improves the vitality of trees and reduces the impact of stormwater on the local environment, all while maintaining a high natural presentation. 

Call us Today 

Looking for a cost-effective and sustainable stormwater solution? Contact our friendly Citygreen Team today.

A common concern with living green walls is maintenance, which may put people off investing in this high-value asset – but don’t be afraid!

At Citygreen, we can provide continual support from installation to maintenance requirements for our Citygreen™ Living Wall system so consumers know they are getting the best return on their investment.

Below we have answered the most common concerns people have when they think about living green walls.

Do living walls create water damage to my building?

The Citygreen™ Living Wall systems have a waterproof membrane that prevents water from penetrating substructures.

Do living walls use too much water?

Compared to other greenspaces, the water usage for living walls like Citygreen’s™ Living Wall system is low, as it typically requires two litres per square metre per day to irrigate the wall.

Irrigation is the most critical part of a successful living wall system. In our Citygreen™ Living Wall system, we have designed the vertical irrigation lines to be embedded in a moisture retention layer for optimal water efficiency.

An optional recirculated irrigation system can be installed to achieve further water-saving outcomes.

Will a living green wall work in my ‘space’?

Citygreen’s™ Living Wall system is available in nine standard panel sizes; however, it can also be engineered to retrofit walls on unique buildings. The system is also the lightest on the market, weighing only 35kg per square meter, fully planted and saturated. This means that no additional support structures will be required on small-scale projects.

Also, as discussed above, wherever on the wall the system will be mounted does not require additional waterproofing, as a waterproof membrane is included in the design.

Do living walls require too much ongoing work?

The Citygreen™ Living Wall system comes with remote control monitoring. An advanced automated system ensures the consumer can control the system’s moisture, temperature, ph levels and general conductivity on their computer or phone. This remote capability extends to the automated refilling of the water tanks connected to the wall.

Liquid fertilizer concentrates can also be used in the automated irrigation system to feed the plants. This means that the consumer can easily maintain plant health, but they can also control the pace and vigour of new growth.

Are living walls too expensive?

Citygreen can provide a detailed cost estimate, ensuring that the most suitable living wall solution aligns with your budget.

Are living green walls too hard to set up?

At Citygreen, we will perform a site analysis to determine if any technical installation requirements will be required. For example, if we believe that the indoor installation site is too dark, we recommend using artificial lighting, which we can also deliver and install.

Depending on the site’s location: indoors, outdoors, small-scale, or commercial scale, Citygreen will also assist with plant selection to help find the best species that will thrive into the future.

Assistance will also continue past the set-up stage to the maintenance process, as Citygreen can help will pruning and any ongoing concerns and issues that the living wall may have post-construction.

 Call us Today 

As shown above, Citygreen is an expert in every phase of the design and implementation of living green walls– reach out to Citygreen for a Design Workshop today.

In built-up urban areas, trees can help restore pre-development water flows and remove pollutants and filter water. Trees act as natural filtration machines, which can hold and clean water through soil and evaporation.

A question often asked regarding urban trees and water capture is, can stormwater runoff from roads be too polluted for the trees to use?

Yes, stormwater can be very polluted, as large amounts of debris and rubbish can suffocate a tree and prevent water from reaching the tree’s root system for absorption.

Gross pollutants, such as plastic rubbish or vehicle parts, can largely be filtered out often by screens, like stormwater grates.

Smaller than gross pollutants are total suspended solids (TSS). TSS refers to solids suspended in water or wastewater that can be trapped by a filter. TSS can include various materials, such as silt, decaying plant and animal matter, industrial wastes, and sewage. High suspended solids concentrations can cause many problems for stream health and aquatic life.

Then there are soluble or water-borne pollutants, which are difficult to filter out economically. These pollutants can cause serve damage to ecosystems.

Storm water systems can be installed, which prevent these pollutants from accumulating in our water streams. Citygreen offers a revolutionary range of stormwater management solutions that prevent water pollution and make it easier –and more affordable–to manage and re-use stormwater.

Case Study: Pelican Waters

Pelican Waters, a residential estate located on the Sunshine Coast of Queensland, Australia, has been trialling Citygreen’s Strataflow™ system with so far great success.

This new development aimed to use the advanced water-sensitive urban design (WSUD) and improve sales of lots near bioretention basin. Research has shown that preserving natural features in residential developments can increase the value and sale price of lots.

Instead of a traditional bioretention basin, Citygreen’s Strataflow™ uses an underground structural soil cell system, which delivers a high standard of stormwater treatment with a completely natural look.

To any passer-by, what you see is a healthy, flourishing tree, surrounded by a grassy verge, but beneath the ground is an advanced WSUD.

The Strataflow™ is a specialised design ‘hybrid’ tree pit, combining the best urban forestry for sustained and healthy tree growth with fully functional stormwater management – including filtration and flow management.

These designs may start with the Strataflow Kerb Inlet. This device sits in the road kerb alignment, retaining the inherent structure of the concrete kerb. The inlet has a grate (acting as a screen), to stop larger-sized pollutants from entering the system, which inhibits healthy tree growth.

The inlet lets water from the road carriageway flow through the front grate of the drain at a capacity of up to 18 litres/ 5 gallons per second. This allows the inlet to minimise pollutants entering waterways and reduce flood risks by controlling the stormwater flow entering our city’s underground drains.

When the water flows through the street, it enters through the inlet and flows underground. From there, the stormwater reaches the advanced structural soil cell system, where the stormwater is stored, filtered and distributed effectively for the benefit of urban trees and for proper stormwater management.

The inlet ensures the water drains down at the correct optimal depth beneath the pavement height. From there, the stormwater reaches the structural soil cell system and the trees’ root system, where the stormwater is stored, filtered and distributed effectively for the benefit of urban trees and for proper stormwater management.

Essentially, Strataflow™ utilises readily available stormwater rather than potable water to irrigate street trees, which improves the vitality of trees and reduces the impact of stormwater on the local environment, all while maintaining a high natural presentation.

Growth comparison of trees planted in Strataflow (left) and trees planted in grass verge (right)

Call us today

Looking for a cost-effective and sustainable stormwater solution? Contact our friendly Citygreen Team now by clicking here.

When planting trees in urban areas, there are a few specific elements to consider. The first and most important thing to consider is that healthy trees require an adequate supply of loose, well-aerated, and uncompacted soil to thrive. This enables tree roots to obtain enough nutrients, oxygen and water so that they can reach their full potential in cityscapes.

In urban areas, where soil compaction is necessary to safely support sidewalks and pavements, conflicts arise when it comes to planting and supporting healthy trees. Over the years, many approaches have been used to help create useable, uncompacted soil for urban trees. Gradually two primary practices have emerged: supported pavement systems and structural growing media.

Structural growing media

Structural growing media are soil mixes designed to be fully compacted to support vehicles whilst allowing tree root growth. An example of a structural growing media is the Cornell Mix, which combines rock and soil.

In developing and researching this specific mix, Grabosky and Bassuk (1996) found that there was about 30% void space in a mixture of 1.9 cm diameter crushed gravel, which could be filled with clay loam soil. Creating a stone matrix and suspending soil within the matrix pores meant that the larger diameter rocks would lock together and allow for full compaction, while soil would remain loose for root growth.

Supported Pavement

On the other hand, supported pavement systems involve engineering a pavement so that lightly compacted soil can be installed in a space underneath. Implementing a load-bearing bridge with low-density soil beneath ensures that the trees rooting space cannot become heavily compacted.

Studies have found that any system that allows trees to grow in non-compacted, low-density soil media will have the most excellent chance of achieving healthy tree growth (Rahman, 2013, Fite et al., 2014, Urban and Smiley, 2016).

Comparison of Soil Treatments Under Concrete Pavement

One such study that Citygreen took part in was titled ‘Comparison of Soil Treatments Under Concrete Pavement’, conducted by the Tree Research Laboratory in Charlotte, North Carolina. The research compared tree root growth using supported pavement systems and structural growing media.

In the study, Citygreen’s Stratacell systems were tested. These structural soil vaults are modular units assembled below pavement level, which meet load-bearing requirements and provide a large volume of uncompacted soil for root growth.

The studies showed that the trees growing in these supported pavement treatments with low-density soil media had significantly more significant growth and generally appeared healthier.

Conclusion

While the study did not point to a ‘best product’, it proved that structural load-bearing modules like Citygreen’s Stratacell and Stratavault systems provide the best results in urban areas, where compaction is a real issue. What this means for urban planners, landscape gardeners, architects, and developers are that by simply choosing a structural load-bearing soil system, they can achieve the canopy cover they require years sooner than they might with other systems. Essentially, cities, communities and individuals can enjoy the environmental, economic and health benefits of healthy canopies’ growth faster and for longer.

Have one of the Citygreen contact you

For more information about our products and how we can help you create greener, more liveable cities, contact our friendly Citygreen Team now by clicking here.

Download the full report

To read more about how our system performed the best in terms of maximum root depth, moisture content and foliar colour, you can download the complete ‘Comparisons of Soil Treatments Under Concrete Pavement’ here.

Download free study report

References

Fite, K., E. Kramer, B. Scharenbroch, R. Uhlig, 2014. Beyond the Great Debate: Assessing Post Installation Manufactured Soils Performance. Presentation ASLA Annual Meeting, Denver, CO, USA. Grabosky, J. and N. Bassuk. 1996. Testing of Structural Urban Tree Soil Materials for Use, Under Pavement to Increase Street Tree Rooting Volumes. Journal of Arboriculture 22:255-263. Rahman, M. A. 2013. Effect of pit design and soil composition on the performance of Pyruscalleryana Street Trees in the Establishment Period. Arboriculture & Urban Forestry 39:256-266. Smiley, TE., Urban, J., and Kelby Fite, K. Comparison of Tree Responses to Different Soil Treatments Under Concrete Pavement. Arboriculture & Urban Forestry. Nov2019, Vol. 45 Issue 6, p303-314. 12p. Urban, J. and E.T. Smiley. 2014. Evaluation of Established Trees – Structural Soils and suspended pavement – Presentation at the International Society of Arboriculture Conference Milwaukee, WI, USA.

Over twenty years ago, landscape architect, Robert Thayer (1989) examined the importance of sustainable infrastructure. Thayer believed that successful, sustainable design projects ‘symbolize[d] resource preservation through visual, spatial and sensory means.’

Within the context of resource preservation, most people think of preserving natural resources in ecological settings, for instance, creating national parks to protect forests or fencing off wetlands for migratory sea birds.

But what about resource preservation in the built environment?

Rooftops, alleyways, medium stripes, boardwalks, etc. are all resources that can be sustainably preserved and looked after, we just need to change our thinking in this space.

Safeguarding trees within urban spaces, and capturing water runoff from streets, are all forms of resource preservation that can and should be performed within urban settings.

However, Thayer thought that resource preservation within the built environment should go beyond pure utilitarian means and encompass, as quoted above ‘visual, spatial and sensory means’.

A perfect example of resource preservation in an urban landscape that encompasses visual, spatial and sensory experiences is living green walls.

Living green walls are able to sustainably preserve and look after infrastructure in a way that invites modern living to be responsive to ecological beauty.

Aesthetically, green walls exhibit bold, living textures that intrigue people, thus raising our level of participation and interaction with the environment and ultimately improving our sense of connectedness to nature.

In terms of resource preservation, green walls not only protect structures from rain and fluctuating temperatures, they can also reduce noise levels in buildings, and act as pollution filters to improve air quality.

Within urban settings, we, the public, should be able to interact with sustainable and ecological designs, as nowadays a lot of people do not have access to open parklands and gardens, hence why living green walls are a great sustainable design that should be installed more widely.

Living green walls create new associations between the ‘built’ and the ‘natural’, essentially displacing the old normative understanding that cities should be set apart from nature unless it is in park form, where trees, shrubs, flowers etc. can conform to order.

Green walls in one way can hardly be mistaken as natural, yet once planted, they, like any living or interconnected thing, assume a life of their own. They may not conform to an initial design outcome and seek their own patterns, creating more sensory experiences for the public to enjoy.

Citygreen’s™ Living Wall system

Citygreen’s™ Living Wall system is a leading example of a sustainable and aesthetically pleasing design for modern-day living. Manufactured by the pioneering brand in advanced living wall products, Terapia Urbana in Spain, this living wall system embodies nearly 15 years of research, development and product testing.

For optimal public exposure, the living wall system can be installed for both outdoor and indoor use. The system comes with artificial lighting, automatic watering and fertilisation systems.

Compared to other more traditional green spaces like outdoor gardens and reserves, the water usage for living walls like Citygreen’s™ Living Wall system is comparatively very low, as it typically requires two litres per square metre, per day to irrigate.

A design feature that allows Citygreen’s™ Living Wall system to stand out, is the fact that the system is the lightest on the market, weighing only 35kg per square meter fully planted and saturated. This design feature enables more flexibility as to where the system can be installed without damaging existing infrastructure.

The design is made up of a three-layer system that all links together, allowing plant roots to have the ability to migrate freely and really take off to create diverse leaf patterns and colours to be enjoyed by all.

The design is available in nine standard panel sizes; however, it can also be engineered to fit bespoke sizes for unique projects. The system is also designed for quick and efficient installation for large scale commercial projects or smaller residential projects, with minimum disruption.

Conclusion

For the natural world to be appreciated by the public, it must be seen and experienced, which is why the installation of living green walls is so important, as it enables our increasingly urbanised population to experience nature in a way that is most accessible to them.

Citygreen’s™ Living Wall system, enables both sustainable preservation of infrastructure within urban settings, whilst also allowing individuals the ability to immerse themselves in the beauty of the natural world.

References

Thayer, R. 1989. The experience of sustainable landscapes. Landscape Journal. 8(2) 101-110.

Earlier this year, the United Nations Intergovernmental Panel on Climate Change (IPCC) released their starkest report on the impacts of climate change, depicting the threats to both civilisations and ecosystems around the world.

The report documented that the effects of climate change have already impacted human health, livelihoods, and key infrastructure, particularly in urban settings. Hot extremes including heatwaves have intensified in cities, where they have also aggravated air pollution events and limited the functionality of urban infrastructure systems and services.

Essential infrastructure, such as transportation, water, sanitation, and energy systems have been compromised by both, extreme and slow-onset climatic events, resulting in economic losses, disruptions of services and impacts on human well-being.

Through an egalitarian lens, the report observed that these impacts are concentrated amongst the economically and socially marginalized urban residents. Climate change is effectively exacerbating existing social, economic, and environmental drivers of risk, especially for vulnerable groups who already lack access to essential services.

The authors of the report, urgently recommend an appropriate, widespread coordinated effort to adapt our urban environments to more extreme climatic conditions.

They believe that by improving existing and new infrastructure projects, our built environment can become more resilient to climate risks in the long term.

One way of achieving urban resilience is by providing greater access to ‘green infrastructure within our cityscapes. Green infrastructure refers to all types of vegetation that provides environmental, economic, and social benefits such as clean air and water, climate regulation and places for recreation.

An example of green infrastructure that can directly limit the effects of climate change within our urban environment is green walls, also termed living walls or vertical gardens. Green walls can form an important part of a wider strategy to increase the sustainability of our built environments by regulating temperatures and improving air quality.

Regulating temperatures

According to Dr Irga, from the University of Technology in Sydney, Australia

‘thermoregulation is one of the most researched benefits of green walls.’

He explained that ‘green walls can reduce high temperatures within buildings by intercepting solar radiation and through evaporative cooling.’

Conversely, temperature regulation is not just limited to heat reduction, as the insulation ability of green walls can also be of benefit in cold climates too. Through controlling temperatures, green walls enable buildings to be less reliant upon heaters and air conditioners, resulting in reductions in energy consumption.

Improving air quality

The natural, biological processes of green walls can improve air quality in the home and in urban settings by removing polluting air particulars.

The plants used within the green walls can capture airborne particles on their foliage and, with the associated microbial community, degrade a range of gaseous pollutants, including volatile organic compounds (VOCs).

VOCs are generated by motor vehicles, fires, industrial processes, and consumer products like paint. Some are highly toxic and prolonged exposure may increase the risk of health problems.

Aside from absorbing VOCs, green walls are also able to absorb carbon dioxide (CO2). All plants including those grown inside, or on the side of buildings, act as natural carbon dioxide filters. They absorb CO2 from the air to fuel the photosynthesis which allows them to grow and thrive. Presently, more research is needed to determine the most effective CO2 absorbing plants for vertical gardens.

Citygreen’s™ Living Wall system

Citygreen’s™ Living Wall system is a leading green wall product that can directly alleviate some of the risks created associated with climate change, by creating greener, cooler, and more liveable cities.

Citygreen’s™ Living Wall system embodies nearly

15 years of research, development, and product testing.

The design is available in nine standard panel sizes; however, it can also be engineered to retrofit walls on unique buildings.

The system is designed for quick and efficient installation for large scale commercial projects or smaller residential projects, with minimum disruption. The Living Wall system has irrigation lines embedded in a moisture retention layer to ensure optimal water distribution and water efficiency.

This enables both rapid and healthy plant growth post-install.

The assembly of the Citygreen’s™ Living Wall system incorporates a waterproofing layer, a moisture retention layer, and a breathable fabric layer with pockets for the soil so that a wide variety of plants can be selected and grown within the system.

Conclusion

The ability to adapt our urban centres to the unfolding risks of climate change is becoming ever more urgent.

Urban populations, particularly those in marginalised areas, are exceedingly feeling the impacts of more intense weather patterns.

Citygreen’s™ Living Wall system is a product that once installed, can rapidly start to alleviate some of the impacts of climate change, by regulating ambient temperatures, improving air quality conditions, and absorbing CO_2.

References
P.J. Irga, et al, The distribution of green walls and green roofs throughout Australia: Do policy instruments influence the frequency of projects? Urban Forestry & Urban Greening, 24, 2017, 164-174.