Climate explained: how white roofs help to reflect the sun’s heat



http://www.shutterstock.com

Nilesh Bakshi, Te Herenga Waka — Victoria University of Wellington and Maibritt Pedersen Zari, Te Herenga Waka — Victoria University of Wellington

Climate Explained is a collaboration between The Conversation, Stuff and the New Zealand Science Media Centre to answer your questions about climate change.

If you have a question you’d like an expert to answer, please send it to climate.change@stuff.co.nz

Does the white roof concept really work? If so, is it suitable for New Zealand conditions?

Generally, white materials reflect more light than dark ones, and this is also true for buildings and infrastructure. The outside and roof of a building soak up the heat from the sun, but if they are made of materials and finishes in lighter or white colours, this can minimise this solar absorption.

During the warmer part of the year, this can keep the temperature inside the building cooler. This is especially important for building and construction materials such as concrete, stone and asphalt, which store and re-radiate heat.




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On a hot day, a white roof can keep the temperature cooler inside the building.
from http://www.shutterstock.com

A New Zealand study tested near-identical buildings in Auckland with either a red or white roof. It found that even in Auckland’s temperate climate, white roofs reduced the need for air conditioning during hotter periods, without reducing comfort during cooler seasons.

The study also identified several large-scale white-roof installations, including at Auckland International Airport, shopping centres and commercial buildings, but the effect was less clear.

This research suggests that there is potential for white-roof installations to significantly reduce the amount of energy needed to cool buildings. This would in turn reduce greenhouse gas emissions and also help us to adapt to rising temperatures.

It is difficult to quantify the impact for New Zealand’s housing stock because existing studies are mostly limited to larger commercial buildings. But research carried out so far suggests white roofs could be a viable approach to minimising the heat taken up by buildings during hotter parts of the year.

Cooling cities

White roofs can also help reduce the temperature of whole cities. Many city centres include large buildings made of concrete or other materials that collect and store solar heat during the day. In a phenomenon known as the “urban heat island” effect, city centres can often be several degrees warmer than the surrounding countryside.

When cities are hotter, they use more energy for cooling. This usually results in more greenhouse gas emissions, due in part to the energy consumed, and contributes further to climate change.

New Zealand is different because our land mass has a maximum width of 400 kilometres. This means that unlike many urban islands on the African, Asian or American continents, New Zealand’s city centres benefit from the cooling effects of being near the ocean.




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There are many international studies showing white roofs are effective in mitigating the urban heat island effect in densely populated cities. But there is little evidence that using white roofs in New Zealand cities could result in significant energy reductions.

A growing number of studies suggest making the surfaces of buildings and infrastructure more light reflecting could significantly lower extreme temperatures, particularly during heat waves, not just in cities but in rural areas as well. A recent study shows strategic replacement of dark surfaces with white could lower heatwave maximum temperatures by 2℃ or more, in a range of locations.

But studies have also identified some practical limitations and potential side effects, including the possibility of reduced evaporation and rainfall in urban areas in drier climates.

In conclusion, white roofs could be a good idea for New Zealand to keep homes and cities slightly cooler. As temperatures continue to rise, this could reduce the energy needed for cooling. We should consider this option more often, particularly for commercial-scale buildings made of heat-retaining materials in larger cities.The Conversation

Nilesh Bakshi, Lecturer, Te Herenga Waka — Victoria University of Wellington and Maibritt Pedersen Zari, Senior Lecturer in Sustainable Architecture, Te Herenga Waka — Victoria University of Wellington

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Buildings kill millions of birds. Here’s how to reduce the toll



These birds were killed by flying into a set of surveyed buildings in Washington DC in 2013.
USGS Bee Inventory and Monitoring Lab/Flickr

Norman Day, Swinburne University of Technology

As high-rise cities grow upwards and outwards, increasing numbers of birds die by crashing into glass buildings each year. And of course many others break beaks, wings and legs or suffer other physical harm. But we can help eradicate the danger by good design.

Most research into building-related bird deaths has been done in the United States and Canada, where cities such as Toronto and New York City are located on bird migration paths. In New York City alone, the death toll from flying into buildings is about 200,000 birds a year.

Across the US and Canada, bird populations have shrunk by about 3 billion since 1970. The causes include loss of habitat and urbanisation, pesticides and the effects of global warming, which reduces food sources.

An estimated 365 million to 1 billion birds die each year from “unnatural” causes like building collisions in the US. The greatest bird killer in the US remains the estimated 60-100 million free-range cats that kill up to 4 billion birds a year. Australia is thought to have up to 6 million feral cats.




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But rampant global urbanisation is putting the reliance on glass buildings front-of-stage as an “unnatural” cause of bird deaths, and the problem is growing exponentially.

In the line of flight

Most birds fly at around 30-50km/h, with falcons capable of up to 200km/h. When migrating, birds generally spend five to six hours flying at a height of 150 metres, sometimes much higher.

And that’s where the problems start with high-rise buildings. Most of them are much taller than the height at which birds fly. In Melbourne, for example, Australia 108 is 316 metres, Eureka 300 metres, Aurora 270 metres and Rialto 251 metres. The list is growing as the city expands vertically.

The paradigm of high-rise gothams, New York City, has hundreds of skyscrapers, most with fully glass, reflective walls. One World Trade is 541 metres high, the 1931 Empire State is 381 metres (although not all glass) and even the city’s 100th-highest building, 712 Fifth Avenue, is 198 metres.

To add to the problems of this forest of glass the city requires buildings to provide rooftop green places. These attract roosting birds, which then launch off inside the canyons of reflective glass walls – often mistaking these for open sky or trees reflected from behind.

Reflections of trees and sky lure birds into flying straight into buildings.
Frank L Junior/Shutterstock

A problem of lighting and reflections

Most cities today contain predominantly glass buildings – about 60% of the external wall surface. These buildings do not rely on visible frames, as in the past, and have very limited or no openable windows (for human safety reasons). They are fully air-conditioned, of course.




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Birds cannot recognise daylight reflections and glass does not appear to them to be solid. If it is clear they see it as the image beyond the glass. They can also be caught in building cul-de-sac courtyards – open spaces with closed ends are traps.

At night, the problem is light from buildings, which may disorientate birds. Birds are drawn to lights at night. Glass walls then simply act as targets.

Some species send out flight calls that may lure other birds to their death.

White-throated Sparrows collected in a University of Michigan-led study of birds killed by flying into buildings lit up at night in Chicago and Cleveland.
Roger Hart, University of Michigan/Futurity, CC BY



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We can make buildings safer for birds

Architectural elements like awnings, screens, grilles, shutters and verandas deter birds from hitting buildings. Opaque glass also provides a warning.

Birds see ultraviolet light, which humans cannot. Some manufacturers are now developing glass with patterns using a mixed UV wavelength range that alerts birds but has no effect on human sight.

New York City recently passed a bird-friendly law requiring all new buildings and building alterations (at least under 23 metres tall, where most fly) be designed so birds can recognise glass. Windows must be “fritted” using applied labels, dots, stripes and so on.

The search is on for various other ways of warning birds of the dangers of glass walls and windows.

Combinations of methods are being used to scare or warn away birds from flying into glass walls. These range from dummy hawks (a natural enemy) and actual falcons and hawks, which scare birds, to balloons (like those used during the London Blitz in the second world war), scary noises and gas cannons … even other dead birds.

Researchers are using lasers to produce light ray disturbance in cities especially at night and on dark days.

Noise can be effective, although birds do acclimatise if the noises are produced full-time. However, noise used as a “sonic net” can effectively drown out bird chatter and that interference forces them to move on looking for quietness. The technology has been used at airports, for example.

A zen curtain developed in Brisbane has worked at the University of Queensland. This approach uses an open curtain of ropes strung on the side of buildings. These flutter in the breeze, making patterns and shadows on glass, which birds don’t like.

These zen curtains can also be used to make windows on a house safer for birds. However, such a device would take some doing for the huge structures of a metropolis.

More common, and best adopted at the design phase of a building, is to mark window glass so birds can see it. Just as we etch images on glass doors to alert people, we can apply a label or decal to a window as a warning to birds. Even using interior blinds semi-open will deter birds.

Birds make cities friendlier as part of the shared environment. We have a responsibility to provide safe flying and security from the effects of human habitation and construction, and we know how to achieve that.


This article has been updated to correct the figure for the estimated number of birds killed by the cats in the US to “up to 4 billion”, not 4 million.The Conversation

Norman Day, Lecturer in Architecture, Practice and Design, Swinburne University of Technology

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Making every building count in meeting Australia’s emission targets



While many Australian households have solar power, our very large houses and wasteful use of building space are factors in our very high emissions.
Jen Watson/Shutterstock

Timothy O’Leary, University of Melbourne

Buildings in Australia account for over 50% of electricity use and almost a quarter of our carbon emissions but the failures, frailties and fragmentation of the construction sector have created a major obstacle to long-term reductions. Reducing our carbon footprint plays second fiddle to the multibillion-dollar work of replacing flammable cladding, asbestos and other non-compliant materials and ensuring buildings are structurally sound and can be safely occupied.

Buildings – whether residential, commercial or institutional – do not score well under the nation’s main emissions reduction program, the A$3.5 billion Climate Solutions Package. This is intended to help meet Australia’s 2030 Paris Agreement commitment to cut emissions by 26–28% from 2005 levels.

This climate fund has very successfully generated offsets under the vegetation and waste methods – these projects account for 97% of Australian carbon credit units issued. But built environment abatements have been very disappointing.




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Australians have very high emissions per person. That’s partly due to how we use our buildings.

Our states and territories control building regulations. This year the Council of Australian Governments (COAG) set ambitious energy-reduction trajectories for buildings out to 2022 and beyond. This was to be achieved through amendments to national codes and implementing energy-efficiency programs.

Making the best use of our buildings

Last month, the Green Building Council and Property Council launched a policy toolkit, called Making Every Building Count. The councils urged governments to adopt practical plans to reduce emissions in the building sector.

The toolkit contains no fewer than 75 recommendations for all tiers of government. These are the result of work done through industry and university research partnerships in places like the Low Carbon Living Collaborative Research Centre – now disbanded after its seven-year funding ended.




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Most energy-efficiency studies and programs focus solely on the operational aspect of buildings, such as the energy used to heat and cool them. However, various studies have proved that the energy and emissions required to manufacture building products, even energy-saving products such as insulation, can be just as significant.

A more holistic approach is to look at the embodied energy already in our building stock, which then poses a serious question about our consumption. So, besides aspirational codes for net zero-energy buildings, we should be asking: can we meet our needs with fewer new buildings?




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In Melbourne, for example, an estimated 60,000 homes are sitting unused. Commercial property has very high vacancy rates – up to one in six premises are unoccupied in parts of the city. This points to a less-than-effective market in valuing our embodied carbon emissions in property.

If we are to get serious about reducing emissions, we need to tackle inefficient space use.

Empowering people to cut emissions

In occupied commercial buildings, some evidence suggests most building managers are grappling with complexity and challenging tenant behaviours. They also don’t get the clear information they need to continually improve their building’s performance beyond a selected benchmark.

In residential property, home energy performance is very much in our own hands. So we need to consider the means, motivations and opportunities of households, which I did in my doctoral study. A major barrier is that most of us don’t even know what we are getting when we buy or rent an ageing stock of more than 9 million homes.

Europe and the United States moved to mandatory residential energy disclosure at point of sale and lease well over a decade ago. If you rent or buy a home in these countries you get an energy performance certificate. It identifies emissions intensity and gives advice on how to operate the home more efficiently and hence with lower emissions.

In Australia, we have just sat on a commitment made by COAG back in 2009 to introduce a nationwide scheme.

Size matters, too. Residential space per person is high by international standards. Although McMansions are on the wane, our apartments are getting a bit bigger. The average size of freestanding houses built in 2018-19 shrank by 1.3% from 2017-18 to a 17-year low of 228.8 square metres.

And we are putting more solar on our roofs as a carbon offset. As of September 30 2019, Australia had more than 2.2 million solar photovoltaic (PV) installations. Their combined capacity was over 13.9 gigawatts.

However, the trend towards high-rise living is not helpful for emissions. Solar for strata apartments is tricky.

I recently worked with colleagues in Australia and overseas in a study of the user experience of PV. We found residents face a range of issues that limit emission reductions. These issues include:

  • initial sizing and commissioning with component failures such as faulty inverters
  • lack of knowledge about solar and expected generation performance
  • regulatory barriers that limit the opportunity to upgrade system size.

Looking to improve regulations and codes and billion-dollar funds may be sensible ways to meet emission targets, but human empowerment is the secret weapon in improving energy performance and lowering emissions. Good low-carbon citizens will help create good low-carbon cities.




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A set of clear guides on how to use a building is a good starting point. The low-carbon living knowledge hub provides these.

What will make every building count in lowering emissions is the behaviour of occupants, the commitment of owners to make their buildings low-carbon and building managers’ ability to become more adept at reducing building-related emissions.The Conversation

Timothy O’Leary, Lecturer in Construction and Property, University of Melbourne

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Green cement a step closer to being a game-changer for construction emissions



If the cement industry were a country, it would be the third-largest emitter of CO₂ in the world.
Joe Mabel/Wikimedia, CC BY-SA

Yixia (Sarah) Zhang, Western Sydney University; Khin Soe, Western Sydney University, and Yingying Guo, UNSW

Concrete is the most widely used man-made material, commonly used in buildings, roads, bridges and industrial plants. But producing the Portland cement needed to make concrete accounts for 5-8% of all global greenhouse emissions. There is a more environmentally friendly cement known as MOC (magnesium oxychloride cement), but its poor water resistance has limited its use – until now. We have developed a water-resistant MOC, a “green” cement that could go a long way to cutting the construction industry’s emissions and making it more sustainable.

Producing a tonne of conventional cement in Australia emits about 0.82 tonnes of carbon dioxide (CO₂). Because most of the CO₂ is released as a result of the chemical reaction that produces cement, emissions aren’t easily reduced. In contrast, MOC is a different form of cement that is carbon-neutral.

Global CO₂ emissions from rising cement production over the past century (with 95% confidence interval).
Source: Global CO2 emissions from cement production, Andrew R. (2018), CC BY



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What exactly is MOC?

MOC is produced by mixing two main ingredients, magnesium oxide (MgO) powder and a concentrated solution of magnesium chloride (MgCl₂). These are byproducts from magnesium mining.

Magnesium oxide (MgO) powder (left) and a solution of magnesium chloride (MgCl₂) are mixed to produce magnesium oxychloride cement (MOC).
Author provided

Many countries, including China and Australia, have plenty of magnesite resources, as well as seawater, from which both MgO and MgCl₂ could be obtained.

Furthermore, MgO can absorb CO₂ from the atmosphere. This makes MOC a truly green, carbon-neutral cement.




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MOC also has many superior material properties compared to conventional cement.

Compressive strength (capacity to resist compression) is the most important material property for cementitious construction materials such as cement. MOC has a much higher compressive strength than conventional cement and this impressive strength can be achieved very fast. The fast setting of MOC and early strength gain are very advantageous for construction.

Although MOC has plenty of merits, it has until now had poor water resistance. Prolonged contact with water or moisture severely degrades its strength. This critical weakness has restricted its use to indoor applications such as floor tiles, decoration panels, sound and thermal insulation boards.

How was water-resistance developed?

A team of researchers, led by Yixia (Sarah) Zhang, has been working to develop a water-resistant MOC since 2017 (when she was at UNSW Canberra).

Adding industrial byproducts fly ash (above) and silica fume (below) improves the water resistance of MOC.
Author provided

To improve water resistance, the team added industrial byproducts such as fly ash and silica fume to the MOC, as well as chemical additives.

Fly ash is a byproduct from the coal industry – there’s plenty of it in Australia. Adding fly ash significantly improved the water resistance of MOC. Flexural strength (capacity to resist bending) was fully retained after soaking in water for 28 days.

To further retain the compressive strength under water attack, the team added silica fume. Silica fume is a byproduct from producing silicon metal or ferrosilicon alloys. When fly ash and silica fume were combined with MOC paste (15% of each additive), full compressive strength was retained in water for 28 days.

Both the fly ash and silica fume have a similar effect of filling the pore structure in MOC, making the cement denser. The reactions with the MOC matrix form a gel-like phase, which contributes to water repellence. The extremely fine particles, large surface area and high reactive silica (SiO₂) content of silica fume make it an effective binding substance known as a pozzolan. This helps give the concrete high strength and durability.

Scanning electron microscope images of MOC showing the needle-like phases of the binding mechanism.
Author provided



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Although the MOC developed so far had excellent resistance to water at room temperature, it weakened fast when soaked in warm water. The team worked to overcome this by using inorganic and organic chemical additives. Adding phosphoric acid and soluble phosphates greatly improved warm water resistance.

Examples of building products made using MOC.
Author provided

Over three years, the team has made a breakthrough in developing MOC as a green cement. The strength of concrete is rated using megapascals (MPa). The MOC achieved a compressive strength of 110 MPa and flexural strength of 17 MPa. These values are a few times greater than those of conventional cement.

The MOC can fully retain these strengths after being soaked in water for 28 days at room temperatures. Even in hot water (60˚C), the MOC can retain up to 90% of its compressive and flexural strength after 28 days. The values remain as high as 100 MPa and 15 MPa respectively – still much greater than for conventional cement.

Will MOC replace conventional cement?

So could MOC replace conventional cement some day? It seems very promising. More research is needed to demonstrate the practicability of uses of this green and high-performance cement in, for example, concrete.

When concrete is the main structural component, steel reinforcement has to be used. Corrosion of steel in MOC is a critical issue and a big hurdle to jump. The research team has already started to work on this issue.

If this problem can be solved, MOC can be a game-changer for the construction industry.




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The Conversation


Yixia (Sarah) Zhang, Associate Professor of Engineering, Western Sydney University; Khin Soe, Research Associate, School of Computing, Engineering and Mathematics, Western Sydney University, and Yingying Guo, PhD Candidate, School of Engineering and Information Technology, UNSW

This article is republished from The Conversation under a Creative Commons license. Read the original article.

We have the blueprint for liveable, low-carbon cities. We just need to use it



Increasing heat in Sydney and other Australian cities highlights the urgent need to apply our knowledge of how to create liveable low-carbon cities.
Taras Vyshnya/Shutterstock

Deo Prasad, UNSW

Over the past seven years more than 100 research projects at the Co-operative Research Centre for Low Carbon Living, in collaboration with industry across Australia, have pondered a very big question: How do we build future cities that are sustainable, liveable and affordable?

This is exactly what Australians want, as the recent Greater Sydney Commission report, The Pulse of Greater Sydney, revealed. People want cities in which they live close to jobs and have reasonable commuting times. They want access to parks and green space, and relief from ever-increasing urban heat.




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The good news is we already know what it will take to deliver on much of this wish list. Since 2012, I have headed the A$100 million Low Carbon Living CRC, which has brought together Australian businesses, industries, communities and many of our brightest researchers to work out how to steer change.

Our Cooling Sydney Strategy, for instance, is the result of years of research into how to combat urban heatwaves. The burden of this heat is unevenly spread across our cities.

For example, residents of Sydney’s western suburbs are exposed to many more days hotter than 35 degrees than Sydneysiders living in the CBD and the city’s north. Last summer that meant over a month’s worth of intense heat in the suburb of Penrith, including nine days in a row above 35°C.




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Building cool cities for a hot future


While the recent winter sun might feel welcome, the negative impacts of increasingly hot cities on our health, lifestyle and energy use greatly outweigh any winter comfort.

So what are the solutions?

Our researchers have already found how we can offset increasing heat. The strategies includes cool and permeable pavements, water features and evaporative cooling, shade structures, vertical gardens, street trees and other plants – even special heat refuge stations.

Keeping cool inside, without huge power bills, is possible too. During last summer’s heatwave, our pilot 10-star energy-efficient house in Perth remained a comfortable 24°C inside, without air conditioning, when it was over 40°C outside. The exceptional thermal performance of the house was down to its evidence-based design.

Josh Byrne explains how his house keeps temperatures comfortable year-round with low energy use and no net emissions.



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This work is just one part of our wider remit. Our UNSW-based centre is on track to deliver independently verified cuts of 10 megatonnes of carbon emissions generated by Australia’s built environment by 2020. By integrating renewable energy systems, smart technologies, low-carbon materials and people-centred design into buildings and urban precincts, we have developed a sustainable, liveable and affordable urban blueprint for Australia. A PwC study (yet to be released) estimated cumulative economic benefits totalling A$684 million by 2027.

To put this another way, we have identified and verified evidence-based pathways to cut emissions equivalent to taking some 2.1 million cars off the road.




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Some of the progress to date is not immediately obvious to the casual observer. Take an otherwise unremarkable stretch of road along the back way to Sydney Airport. Recently, a 30-metre section of concrete was installed, which looks more like an ad hoc road repair than an important scientific pilot study.

Bu 15 metres is paved with a new geopolymer concrete that slashes greenhouse gas emissions by 50%. The other 15 metres is conventional concrete, the most widely used man-made material on the planet. Concrete production, using cement as its binder, accounts for about 8% of all global emissions.

The geopolymer concrete developed through our research centre is a similarly high-performance product but its binder safely incorporates otherwise noxious industrial waste streams, such as fly ash from coal-fired power stations and slag from blast furnaces. Australia has stockpiled about 400 million tonnes of waste from coal-fired power generation and steelmaking.

In Alexandria, in collaboration with the City of Sydney, we are testing this low-carbon concrete as a road surface that could help clean up industrial waste while slashing emissions. Working with NSW Ports, we’ve also shaped it into low-carbon bollards to form a breakwater to protect the coastline at Port Kembla from extreme weather.

Waste from coal-fired power stations has been used to make low-carbon bollards to protect the coastline at Port Kembla.

We now have the know-how to do better

There are many such success stories, but with 150 CRC Low Carbon Living projects the list is too long to detail. What’s more important, as our funding period comes to an end and Australia loses its only innovation hub committed to lowering carbon in the built environment, is to note how we got to where we are today.

The federal government’s Co-operative Research Centre program fosters co-operation and collaboration on a grand scale. Industries, businesses, government organisations and communities with a stake in solving big, complex challenges partner with researchers from a wide range of academic fields. This structure brings together sectors and people whose paths might otherwise rarely cross.

The cross-fertilisation of ideas, expertise and skills delivers innovative solutions. Research worldwide has consistently shown that collaboration drives innovation, and that innovation drives economic growth. Our experience confirms that as we partnered with organisations such as Multiplex, AECOM, BlueScope Steel, Sydney Water, ISCA, CSIRO and the United Nations Environment Program.

Cities are complex, exciting beasts, but we have the knowledge and expertise to live better, more comfortable urban lives in Australia while reducing demand for energy, water and materials. That is, we have the blueprint for low-carbon urban living. We must now choose to use it.


This article has been updated to correct the number of CRC Low Carbon Living projects to 150 and the amount of stockpiled waste from coal-fired power generation and steelmaking to 400 million tonnes.The Conversation

Deo Prasad, Scientia Professor and CEO, Co-operative Research Centre for Low Carbon Living, UNSW

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Daylight robbery: how human-built structures leave coastal ecosystems in the shadows



Human-built structures are home to a wide variety of creatures.

Martino Malerba, Monash University; Craig White, Monash University; Dustin Marshall, Monash University, and Liz Morris, Monash University

About half of the coastline of Europe, the United States and Australasia is modified by artificial structures. In newly published research, we identified a new effect of marine urbanisation that has so far gone unrecognised.

When we build marinas, ports, jetties and coastal defences, we introduce hard structures that weren’t there before and which reduce the amount of sunlight hitting the water. This means energy producers such as seaweed and algae, which use light energy to transform carbon dioxide into sugars, are replaced by energy consumers such as filter-feeding invertebrates. These latter species are often not native to the area, and can profoundly alter marine habitats by displacing local species, reducing biodiversity, and decreasing the overall productivity of ecosystems.

Incorporating simple designs in our marine infrastructure to allow more light penetration, improve water flow, and maintain water quality, will go a long way towards curbing these negative consequences.

Pier life

We are used to thinking about the effects of urbanisation in our cities – but it is time to pay more attention to urban sprawl in the sea. We need to better understand the effects on the food web in a local context.




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Most animals that establish themselves on these shaded hard structures are “sessile” invertebrates, which can’t move around. They come in a variety of forms, from encrusting species such as barnacles, to tree-shaped or vase-like forms such as bryozoans or sponges. But what they all have in common is that they can filter out algae from the water.

In Australian waters, we commonly see animals from a range of different groups including sea squirts, sponges, bryozoans, mussels and worms. They can grow in dense communities and often reproduce and grow quickly in new environments.

The sheltered and shaded nature of marine urbanisation disproportionately favours the development of dense invertebrate communities, as shown here in Port Phillip Bay.

How much energy do they use?

In our new research, published in the journal Frontiers in Ecology and the Environment, we analysed the total energy usage of invertebrate communities on artificial structures in two Australian bays: Moreton Bay, Queensland, and Port Phillip Bay, Victoria. We did so by combining data from field surveys, laboratory studies, and satellite data.

We also compiled data from other studies and assessed how much algae is required to support the energy demands of the filter-feeding species in commercial ports worldwide.

In Port Phillip Bay, 0.003% of the total area is taken up by artificial structures. While this doesn’t sound like much, it is equivalent to almost 50 soccer fields of human-built structures.

We found that the invertebrate community living on a single square metre of artificial structure consumes the algal biomass produced by 16 square metres of ocean. Hence, the total invertebrate community living on these structures in the bay consumes the algal biomass produced by 800 football pitches of ocean!

Similarly, Moreton Bay has 0.005% of its total area occupied by artificial structures, but each square metre of artificial structure requires around 5 square metres of algal production – a total of 115 football pitches. Our models account for various biological and physical variables such as temperature, light, and species composition, all of which contribute to generate differences among regions.

Overall, the invertebrates growing on artificial structures in these two Australian bays weigh as much as 3,200 three-tonne African elephants. This biomass would not exist were it not for marine urbanisation.

Colonies of mussels and polychaetes near Melbourne.

How does Australia compare to the rest of the world?

We found stark differences among ports in different parts of the world. For example, one square metre of artificial structure in cold, highly productive regions (such as St Petersburg, Russia) can require as little as 0.9 square metres of sea surface area to provide enough algal food to sustain the invertebrate populations. Cold regions can require less area because they are often richer in nutrients and better mixed than warmer waters.

In contrast, a square metre of structure in the nutrient-poor tropical waters of Hawaii can deplete all the algae produced in the surrounding 120 square metres.

All major commercial ports worldwide with associated area of the underwater artificial structures (size of grey dots) and trophic footprint (size of red borders). Trophic footprints indicate how much ocean surface is required to supply the energy demand of the sessile invertebrate community growing on all artificial structures of the port, averaged over the year. This depends on local conditions of ocean primary productivity and temperature. Ports located in cold, nutrient-rich waters (dark blue) have a lower footprint than ports in warmer waters (light blue).

Does it matter?

Should we be worried about all of this? To some extent, it depends on context.

These dense filter-feeding communities are removing algae that normally enters food webs and supports coastal fisheries. As human populations in coastal areas continue to increase, so will demand on these fisheries, which are already under pressure from climate change. These effects will be greatest in warmer, nutrient-poor waters.

But there is a flip side. Ports and urban coastlines are often polluted with increased nutrient inputs, such as sewage effluents or agricultural fertilisers. The dense populations of filter-feeders on the structures near these areas may help prevent this nutrient runoff from triggering problematic algal blooms, which can cause fish kills and impact human health. But we still need to know what types of algae these filter-feeding communities are predominantly consuming.




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Explainer: what causes algal blooms, and how we can stop them


Our analysis provides an important first step in understanding how these communities might affect coastal production and food webs.

In places like Southeast Asia, marine managers should consider how artificial structures might affect essential coastal fisheries. Meanwhile, in places like Port Phillip Bay, we need to know whether and how these communities might affect the chances of harmful algal blooms.The Conversation

Mussels in the port of Hobart.

Martino Malerba, Postdoctoral Fellow, Monash University; Craig White, Head, Evolutionary Physiology Research Group, Monash University; Dustin Marshall, Professor, Marine Evolutionary Ecology, Monash University, and Liz Morris, Administration Manager, Monash University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Don’t forget our future climate when tightening up building codes



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Australia’s new National Construction Code doesn’t go far enough in preparing our built environment for climate change.
Sergey Molchenko/Shutterstock

Deo Prasad, UNSW

Too often it takes a crisis to trigger changes in legislation and behaviour, when forward thinking, cooperation and future planning could have negated the risk in the first place. Australia’s building and construction industry is under the microscope and changes in the law are in the wind, due to situations that could have been avoided. These include the evacuation of Sydney’s Opal building and the fires in Melbourne’s Lacrosse tower in 2014 and the Neo200 apartment building in February, both of which were fuelled by combustable cladding, as was the 2017 fire in London’s Grenfell Tower that killed 72 people.

The Shergold Weir report made 24 recommendations to improve the National Construction Code to ensure compliance, integrity and more. Commissioned by federal and state building ministers, the report was made public at the Australian Building Ministers Forum in April 2018. But implementation has been too slow to prevent the problems in the Opal and Neo200 apartment buildings. And it included no changes to climate-proof buildings.




Read more:
Australia has a new National Construction Code, but it’s still not good enough


A new National Construction Code comes into effect on May 1. Recent events have, however, exposed inadequate construction standards and increased public pressure for further change. This presents an opportunity to future-proof our cities as well as restore public confidence in our construction industry.

Construction codes were created to eliminate “worse practice”, but we are now in a position to make them “best practice”. Importantly, we must prepare for climate change. Australia is increasingly experiencing more extreme weather patterns, but are we ready?

The legislative overhaul must also include building sustainability and higher performance requirements. A low-to-zero-carbon future must be part of the picture.

Construction code changes are needed urgently, not just for increased safety, but to ensure future urban developments:

  • are ready for higher energy demands to cool and heat buildings
  • are designed to maximise sun and shade at the appropriate times to cool and warm both building and street
  • use materials that reflect heat for hot climates and absorb it for cooler ones
  • maximise insulation to reduce energy use
  • provide enough green space to give shade, produce oxygen and sustain a healthy environment
  • use water features to cool common and public areas
  • install smart technology to monitor and manage buildings and precincts.



Read more:
As climate changes, the way we build homes must change too


Many leading developers are taking the initiative to ensure projects include high-performance, zero-carbon, highly energy-efficient buildings, with top star ratings, but action needs to be across the board. This can only be done via tough legislation and enforced compliance.

The University of NSW’s Tyree Building is an excellent example of a high-performance building, as is One Central Park, Sydney, which features hanging gardens and an internal water recycling plant. But its most striking feature is its “heliostat”, a large array of mirrors that reflect sunlight to areas that would otherwise be in shadow.

One Central Park.
SAKARET/Shutterstock

Around the world, high-performance buildings are on the increase, such as 313@Somerset in the heart of Singapore, and the Sohrabji Godrej Green Business Centre in Hyderabad – India’s first Leadership in Energy and Environmental Design (LEED) platinum-rated building. There are many more.

Changing the law

New building standards and compliance are required to ensure high-performance buildings are the norm, not the exception. The construction industry should fulfil a “cradle to cradle” objective for materials. This means accounting for:

  • where materials come from
  • how materials are made
  • safety levels
  • carbon component
  • recyclability at demolition.

Laws covering low-carbon building design are imperative, setting standards for geography, maximising natural light, air flow, insulation and smart technology. Technology can monitor and run a building’s utilities to ensure it’s not only energy-efficient but also delivers a health standard that’s adaptable to the future pressures of climate change.




Read more:
Green buildings must do more to fix our climate emergency


Sustainable buildings are achievable now

Current know-how makes all this achievable. Over the past seven years the Cooperative Research Centre for Low Carbon Living and its industry partners have funded research into most low-to-zero-carbon aspects of the built environment. This has led to many recommendations in reports like Built to Perform, produced by the Australian Sustainable Built Environment Council.

The many research projects include:

  • 17 living laboratories providing cutting-edge data
  • creating low-carbon communities
  • developing tools to measure carbon outputs, from materials to services
  • studying the effects of heatwaves in Western Sydney and ways to cool cities
  • research into low-carbon concrete made of fly ash.

This plethora of data reveals that sustainable cities and precincts are achievable, while providing for a growing communities. Blockchain and solar technology, for example, is now proven for managing a precinct’s energy needs and can help turn energy users into providers.




Read more:
Beyond Bitcoin: how blockchains can empower communities to control their own energy supply


Although we are more global than ever, online and social media have in turn made us locally focused. We can know what’s going on in our street at a click and this technology is applicable to the operation of our future, sustainable cities.

We have the data, expertise, tools and knowledge to make safe, low-to-zero-carbon cities part of our future. But there’s much work to do. We still need to implement this knowledge, use the tools, change behaviour and instil 100% trust in the design and construction process. There’s no time to waste.The Conversation

Deo Prasad, Scientia Professor and CEO, Co-operative Research Centre for Low Carbon Living, UNSW

This article is republished from The Conversation under a Creative Commons license. Read the original article.