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Time to take action on green roof policy in Sydney

Sydney urban area

One thing is certain as we look to the year ahead – it’s going to be HOT. In the first week of 2018, Sydney scorched with 40 degree temperatures and nearby Penrith was the hottest place on earth, hitting a searing 47.3 degrees.

As Sydney’s building boom rages on, never before has the need for green infrastructure with an emphasis on sustainable cooling been so important. With more apartment buildings and concrete streetscapes likely to increase the urban heat island effect, these same apartment buildings hold the key to a much-needed cooling innovation.

Architecture and sustainability experts say there is an unprecedented opportunity to harness the ever-expanding rooftop coverage by making green roofs and walls a standard feature on new residential and commercial buildings. Scientific research has repeatedly recognised the insulation benefits of living infrastructure in reducing energy consumption in summer and winter.

However, the lack of proactive policies mean this opportunity is quickly slipping through the fingers of government, councils, and residents alike. In the City of Sydney, the only NSW council that has a specific policy on green roofs and walls, there are just 53 green roofs, which equates to less than 1% of the total available roof space. A waste indeed.

At a policy-level, Sydney lags well behind other, denser cities such as Singapore, London, Stockholm, and Toronto when it comes to promoting the installation of green roofs and walls. Sara Wilkinson, from the UTS school of Built Environment, said about 32% of horizontal surfaces in Sydney are rooftops, but the potential has remained largely untapped. “Greening them really does make a change to heat stress and your urban environment. We are missing an opportunity to create a beautiful garden city.”

Let’s hope we can emulate places like Singapore where the uptake of green roofs has boomed by more than 800% in the past decade, with 80.5 hectares of skyrise greenery across 182 projects. Our environment, wellbeing, and wallets depend on it.


New study: plant 20% more urban trees and double the benefits

urban forest

A study in Ecological Modelling, conducted by Parthenope University of Naples in Italy, has found that planting just 20% more trees in our megacities would double the benefits of urban forests, including pollution reduction, carbon sequestration, and energy reduction. Authors of the study say city planners, residents, and other stakeholders should increasing the nature in our urban areas by planting more trees.

Nearly 10% of the world’s population live in megacities – that is, cities of at least 10 million people. For these people, urban forests are paramount to physical and mental wellbeing and economic prosperity. Examples of urban forests in megacities include Central Park in New York, St James’ Park in London, and Bosque de Chapultepec in Mexico City.

In the study, the team used a tool called i-Tree Canopy to estimate the current tree coverage in cities and the potential for more urban forest cover, and worked out the benefits that would bring. They estimated the current tree cover in ten megacities in five continents, looked at the benefits of urban forests – including removing pollution from the air, saving energy, and providing food – and approximated the current value of those benefits at over $500 million per year.

Theodore Endreny, Ph.D., PH, PE, lead author of the paper and now professor of the Department of Environmental Resources Engineering at the State University of New York ESF campus, said, “By cultivating the trees within the city, residents and visitors get direct benefits. They’re getting an immediate cleansing of the air that’s around them. They’re getting that direct cooling from the tree, and even food and other products. There’s potential to increase the coverage of urban forests in our megacities, and that would make them more sustainable, better places to live.”


Introducing Stephen Lovering, Technical Product Consultant, Victoria, Vancouver Island BC, Canada

Steve Lovering Photo - Citygreen

Kicking off 2018, we’re thrilled to welcome Stephen Lovering to the Citygreen team, based in Canada. With a Bachelor’s Degree in Landscape Architecture from Leeds Metropolitan University in the UK, Stephen has spent the last five years assisting municipalities, design professionals, and contractors with innovative solutions and products relating to the building industry. Previous to that, he worked as a Landscape Architect designing new communities in and around Calgary, Alberta.

The common thread connecting all his previous roles is an in-depth understanding of how landscapes effect the way people live and move within their community, and the impact this has on their happiness and health. Well-designed green spaces and well-located tree canopies enable people to move around streets, parks, and playgrounds easily – providing a raft of physical, mental, and economic benefits in the process.

As Technical Product Consultant at Citygreen, Stephen will collaborate closely with councils, municipalities, and design professionals in Canada to incorporate cutting-edge urban landscape solutions into their projects, while supporting contractors with best practice techniques and technical knowledge around the installation of Citygreen products. Together, they’ll be addressing issues around public health, lack of tree canopy coverage, and stormwater development – contributing to our overriding vision of a world where sustainable green space is within reach of every person, every day, and natural resources are utilized (not wasted) for the benefit of mankind.

To get in touch with Stephen, call 778-533-7764, email, connect with him on LinkedIn, or book a meeting time a meeting



Removal of Hoddle Street trees follows disturbing trend

Hoodle street trees

Roadworks on Melbourne’s notoriously congested Hoddle Street aren’t just proving a nightmare for commuters, but also for some of Melbourne’s mature street trees. Local residents and a tree expert have condemned the felling of 16 mature plane trees, with more to go to make way for the roadworks.

VicRoads Acting Project Director, Catherine Gunn, said, “The decision to remove trees from Hoddle Street was made following detailed investigation and careful consideration and we continue to work hard to minimise our impact on the local environment.”

But, others are not convinced with Paul Collins, a local publisher, saying, “It’s quite saddening to see trees going, to be replaced with a lane that is going to get everybody down to the next traffic jam, two minutes faster.” Many agree, saying in such a concentrated urban area every tree is precious.

Many trees have been lost in Melbourne in recent times, including 400 for water pipe works along St Georges Road, Northcote. The West Gate Tunnel project could see the loss of almost 750 trees and more than 100 will be removed for the Metro Tunnel project.

Dr Greg Moore, the chair of the National Trust of Victoria’s Register of Significant Trees, said, “That section of Hoddle street is pretty wide, has lots of bitumen, but those trees did provide a bit of relief, particularly on a hot day. The problem of all these tree removals is that inch by inch we’re losing more and more of the tree cover that Melburnians have taken for granted. You start nibbling away at your urban tree population, and it’s possible that you lose a whole forest, simply by removing one tree at a time.”


Urban trees are growing faster than rural ones – but is that a good thing?

urban trees are growing faster

A newly published study, completed by researchers at Germany’s Technical University of Munich (TUM), concluded that urban trees can grow up to 25% faster than their rural counterparts. You’d think that’s a good thing, right?

Unfortunately, wrong. Per the study, the fast growth rate of urban trees is believed to be a direct result of climate change – specifically the heat island effect (HIE). HIE is an urban or metropolitan area that is significantly warmer than its surrounding rural areas due to human activities and causes a range of problems, including: increased heating and cooling costs, limited outdoor recreation, poor quality of life, and heat-related mortality.

In urban heat islands, higher-than-normal temperatures boost photosynthesis which cause trees and other forms of vegetation to grow faster. Sounds great, but the very temperatures that are causing urban trees to grow fast are also causing their early demise.

While findings vary within different climate zones, the research concludes that urban trees must be treated with extra care and consideration in light of this accelerated aging process, ensuring they can last the distance and continue to provide the many benefits that they deliver.


Urban trees don’t just keep us cool – they also keep us warm

urban trees

The cooling power of trees in urban areas has long been known. Now, scientists have learned that urban trees can also provide warmth by shielding homes and offices from the chill of cool winds.

A new study, published in the journal Advances in Water Resources, could help urban planners to design urban landscapes to enhance peoples’ comfort and prevent energy loss, while also improving weather forecasts by helping meteorologists predict the impact of storms on structures and pedestrians.

Marco Giometto, who wrote the paper as a civil engineering postdoctoral fellow at the University of British Columbia (UBC), said, “Wind pressure is responsible for as much as a third of a building’s energy consumption. We were surprised to find such a dramatic decrease in wind speed. Trees act as a filter, protecting us from what’s above, that is, high wind speeds, turbulence and particulate matter.”

The scientists used remote-sensing laser technology to design a highly-detailed computer model of a Vancouver neighbourhood down to every tree, plant, and building. A computer simulation then played out how different scenarios — no trees, trees in full leaf, and bare trees — affected air flow and heat patterns on the streets and homes, and compared them against ten years of measured wind data from a nearly 100-foot tall research tower operated by the university in the same Vancouver neighbourhood.

The researchers found that removing all the trees could increase wind speed by a factor of two, “which would make a noticeable difference to someone walking down the street,” Giometto said. Secondly, the scientists found that removing all the trees around buildings increased the buildings’ energy consumption by as much as 10% in the winter and 15% in the summer.

“The beneficial effects of trees in reducing wind speed was actually well known by farmers before this study,” he said. “Now we have a tool to quantify it and help the design of future windbreaks to maximize their effects.”


Asset Handover – Who is Assessing the Trees

assessing trees

The Urban Forest and Urban Greening are increasingly being recognised as hugely beneficial to society. These benefits are so well understood that tree planting is a commonplace requirement of many building permits and development approvals.

Traditionally though, this has often been a half-hearted affair – with budgets dwindling at the end of the construction, subpar trees are chosen, and lowest cost planting methods are utilised. Let’s be clear, low cost is not the issue. Its low ROI and low lifetime value of the green asset that we are looking to improve.

Huge amounts of all tree maintenance issues are a result of a poor decision at design, poor planting methodologies or issues during early tree establishment.

tree maintenance issues

That is the end of the rant… NOW…

Complaining about a problem without proposing a solution is called whining. Theodore Roosevelt

Some Ideas on the Solution

Handover inspections – Assess your trees before the contractor handover period ends

Inspection of trees should be conducted at least twice prior to handover of landscaping to any asset holder one of these should be in the growing season and well after planting to allow the trees to respond to planting treatments. These inspections should be completed by an urban forester, arborist, or soil scientist. If any concerns are raised nutrient testing of soil or leaf nutrient tissue should be done or a full arborist report should be completed if the trees are significant. This enables any issues to be identified and also allows time for the contractor to rectify these issues prior to handover. This is all about making sure the tree achieves its intended social or economic ROI for the community. This inspection also reduces risk of later issues with the tree and reduces cost of lifetime tree maintenance.

Review tree planting codes

If you are in the role of developing a planting guideline for urban trees then consider these things;

  • Tree species – Assess what value trees are currently providing in your area. Remember that human habitat value is just as important as wildlife habitat value, because if residents value trees then the process is much smoother. Local trees can provide shade in summer, sunlight in winter (deciduous trees), visual amenity colours or flowers (tourist attraction), wind protection, high canopies that are natural or lifted to allow lines of sight to be maintained. These are just a few. Talk to your local Landscape Architecture Association, these designers carry a wealth of knowledge. #American Society of Landscape Architects #Australian Institute of Landscape Architects #International Federation of Landscape Architects
  • Planting Details / Planting Requirement – Trees need their roots and their roots need soil to grow into. Just thought I’d let you in on that little secret. If you only give your trees a very small amount of root volume / Small tree pit you will have one of these.

Bonsai – tree or shrub that has been dwarfed, as by pruning the roots and pinching, and is grown in a pot or other container and trained to produce a desired shape or effect.

Urban Bonsai – A tree or shrub planted into compacted subgrade. Root growth is limited due to compaction and tree growth is stunted. Occasionally tree root balls are pruned to ensure it fits into is new home. Urban bonsai often results in conflicts between tree roots and pavement causing maintenance headaches.

tree maintenance

Enforce the Codes

  • Handover inspections – Inspect the green assets just as would be done for hard assets
  • Use suitability qualified professionals to review tree planting compliance and tree health prior to handover
  • Extend handover and maintenance periods for price significant or amenity significant tree plantings to ensure that trees are
  • Hold bonds – Tree valuation is a science and accurate financial values can be placed on trees. This method can be used for both new plantings as well as protecting current tree installations.

Urban Greening – Cooling the city one tree at a time

urban greening

City of Adelaide leads Urban Greening Program to mitigate heat island effect.

By Nathaniel Hardy | Citygreen USA – Soil and Horticultural Consultant

With a population of 1.3 million people over a 3,258 km² area, Adelaide is one of Australia’s rapidly-growing capital cities. Like many cities around the world, the City of Adelaide recognised urban heat island effect was becoming a major problem with an increasing impact on the health and wellbeing of its people. An urban or metropolitan area that is significantly warmer than its surrounding rural areas due to human activities, urban heat island effect causes a range of problems, including: increased heating and cooling costs, limited outdoor recreation, poor quality of life, and heat-related mortality.

The City of Adelaide piloted an innovative Urban Greening Program, whereby they used thermal imaging and aerial heat mapping to identify areas with the hottest temperatures. This heat map was then overlayed onto a geographical map, enabling hot spots to be identified and transformed into opportunities for city greening. A plan was then created to mitigate heat island effect in these areas with an innovative curbside plantout program.

street garden

With a number of roads and city blocks identified, holes were cut in the pavement between carparks, Citygreen’s innovative Stratacell system was installed, and trees were planted – ensuring adequate space and uncompacted soil for the trees to thrive without impeding the surrounding pavement and / or infrastructure. Crucially, because curbside plantouts were implemented between car parking spots, no carparking space was lost.

urban greening

So far, numerous trees have been planted via this program, which continues to roll out across the city. Whilst it is too early to know the impact in terms of urban heat island specifically, community feedback has been overwhelmingly positive with trees beautifying previously-drab urban streets and providing the promise of future shade.

New York’s College of Environmental Studies and Forestry. Showing in 10 megacities an increase in urban greening would achieve an annual half-million saving in heating and cooling costs. [1]


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