Chemicals giant BASF estimates that 75% of the world population will be urban dwellers by 2050. This finding comes with a unique set of challenges – not least in terms of housing, sanitation and energy. The added threats associated with climate change have focused attention on the need for new innovations to address these challenges.
Research by the United Nations Environment Programme (UNEP) suggests that smarter building construction offers the greatest opportunity for cost-effective cuts in harmful greenhouse gas emissions. According to the UNEP, buildings globally consume 40% of our energy resources and emit a third of global greenhouse gas emissions. And this figure is set to rise as more people move into cities.
There is no shortage of ideas about how to improve the environmental profile of buildings, including smart materials for temperature control (see Box 1), better systems for monitoring efficiency and managing systems in buildings (see Box 2), and even designing buildings that also act as power stations (see Box 3).
And there are some 178 environmentally-sustainable ‘eco-city’ initiatives at various stages of development around the world. Of these cities, 78 were classed as ‘retrofits’ and 76 as ‘infill developments’. The remaining 24 were classed as eco-cities built from scratch. The four most prominent new build eco-cities are Masdar in Abu Dhabi; Dong Tang and Tianjin in China; and Songdo in South Korea.
Set in the desert of Abu Dhabi, Masdar was hyped as the world’s first carbon-neutral and zero-waste city. Designed by British architect, Norman Foster, in 2006, and funded by the Abu Dhabi development company, Mubadala, the city was touted as a ‘living laboratory’ for green technology. The aim was to create a city with a population of 40,000 by 2016, but so far only around 300 people live there.
The first of 40 eco-cities planned for China, Dong Tang, was to be located on Chong Ming Island, close to Shanghai. In 2005, the developer Shanghai Industrial Investment Company commissioned the British firm Arup to design the city, but, largely due to political problems, it has never been built, and Arup has dropped the project. Despite the failure of Dong Tang, 200 new eco-cities are planned in China.
A flagship cooperation project between the governments of Singapore and China, Tianjin is located around 150km from Beijing in the Tianjin Binhai New Area – one of the fastest growing regions in China. Planning for the city to house 350,000 people began in 2007, but by 2014 only about 3km2 had been developed and just 6000 permanent residents have moved in.
One of the more successful eco-city projects is the Songdo International Business District (IBD), 48km west of Seoul in South Korea. Designed by international architects Kohn Pedersen Fox Associates, the city is expected to cost over US$30bn, house 75,000 residents and handle 300,000 commuters. Songdo is advertised as ‘the world’s first fully IT-networked city, built on eco-friendly principles, where everything from grocery orders to medical check-ups can be done remotely, computer to computer’. Although building the city is ongoing, it is already home to nearly 40,000 people and another 55,000 commute to Songdo every day for work.
However, despite the potential success of the South Korean eco-city, a common observation made about current ‘clean slate’ eco-city initiatives – eco-cities built from scratch, as opposed to ‘retrofitting’ existing cities – is that few people want to live in them.
‘One problem,’ says Simon Joss, professor of science and technology studies at the University of Westminster, UK, who studies urban technology and eco-cities, ‘is that eco-cities are perceived by many people as technological fixes designed by architects and engineers, with not enough focus on the social and economic aspects of living. A major question remains as to whether the eco-city initiatives can produce liveable places with favourable environmental performance where people want to live.’
One way to overcome some of the reluctance to embrace life in eco-cities may lie in providing better information about what new environmental technologies have to offer. This is a major goal at The Crystal in Newham, east London, UK. Advertised as a ‘living example of green design’, The Crystal, which opened in 2012, was developed by engineering firm Siemens in collaboration with the London Borough of Newham. The centre includes a range of interactive exhibits designed to demonstrate the importance and role that eco-cities and their infrastructure have in creating a sustainable future.
The all-electric building relies on ground-source heat pumps, a natural ventilation system and triple-glazed and coated windows to provide a high performance ‘building envelope’, ie a three-way barrier to weather, air and heat that helps to maintain a comfortable environment. These technologies are sourced from a range of companies, but all are controlled by Siemens’ proprietary building management system, Desigo. This system relies on a range of field devices, including temperature, humidity and air quality sensors, and meters for electricity, heat and water, all designed and made by Siemens.
‘As well as hosting the world’s largest exhibition on urban sustainability and providing a dialogue platform for sustainable business, the building itself was designed to serve as a show case for the application of environmentally-friendly technologies that are currently available,’ explains Siemen’s Joachim Kiauk. ‘It’s one thing to come up with a seemingly perfect vision or plan, but another to actually translate it into practice on the ground. Buildings such as The Crystal are designed to show how it can be done.’
Building management systems can play a key role in controlling the operation of heating, lighting, ventilation and air conditioning systems in a building to minimise energy consumption and greenhouse gas emissions. Furthermore, they optimise the performance of all integrated technologies and ensure a comfortable internal environment. They work by exchanging information gathered using sophisticated monitoring systems, automatically making adjustments to keep all components running at peak efficiency, while also allowing individuals to set controls to adapt spaces to suit their preferences.
The building automation system used in Siemens’ The Crystal sustanable building in London, for example, takes advantage of Desigo, which can collect five times the information than is typically used in a standard building management system. It also incorporates additional advanced instrumentation, including sensors for detecting air quality and lighting level measurement.
Much of the development in the eco-city sector concentrates on developing effective ways to reduce energy use in buildings. But at the Sustainable Product Engineering Centre for Innovative Functional Coatings (SPECIFC), based at the University of Wales in Swansea, UK, the focus is on developing buildings that are producers – rather than consumers – of power.
The SPECIFIC consortium, which includes Tata Steel, BASF, NSG Pilkington and a number of other business and academic partners, was set up in 2011. The project is funded to the tune of £20m over five years by grants from the Engineering and Physical Sciences Research Council (EPSRC), Innovate UK and the Welsh Government together with investment from Swansea University and its strategic industrial partners.
SPECIFIC’s aims to develop functional coatings for roofs and walls that can be manufactured in large volumes and used to generate, store and release renewable energy. As part of the SPECIFIC project, for example, BASF and Tata Steel are working together on energy-generating systems that can be installed as an additional micro-perforated steel skin, or smart coating, onto an existing or new wall or roof. These solar collectors work by creating a cavity of heated air between the surface of the building and the metal skin. The heat can be drawn from the cavity and fed into the building to provide heat and power. SPECIFC estimates that if just 10% of the steel produced each year by Tata had the smart coating, ‘10 GW of power could be generated, equivalent to the annual output from one nuclear power station’.
The potential spin-offs from the expertise gained during the development of the coatings are encouraging BASF to explore other ranges of heat- and light- emitting coatings, and to work to develop better batteries for energy storage.
The thermal behaviour of a building is influenced by the materials used in its construction. Although the use of heavy materials, which have a greater thermal mass, helps to maintain more constant internal temperatures, modern construction methods are generally based on the use of lightweight materials, such as wood and steel. As a result, they can be subject to greater fluctuations in temperature, for example, from solar radiation. This can make buildings uncomfortable to work in and increases the need for energy-consuming systems such as air conditioning.
To reduce energy use while maintaining comfortable internal environments, the walls of modern eco-buildings are highly insulated and at least some of the materials used in their construction incorporate phase change materials to help stabilise internal temperatures. Phase change materials exist either as a liquid or a solid, depending on the temperature. They take advantage of the principle of latent heat storage – the same principle behind the use of a melting ice cube to keep a drink cool – to maintain more constant temperatures inside buildings.
Micronal, for example, is a latent heat storage material developed by BASF, and is made from a wax mixture designed to complete a phase change from solid to liquid within the indoor temperature range of between 21–26°C. When the temperature rises above a defined limit, the excess heat energy is absorbed automatically, the material ‘melts’ and the excess energy is stored in the phase change. When the temperature falls below the defined threshold, the material solidifies and the stored heat is released. The discharged heat can then be released via natural or mechanical ventilation systems or via sustainable or conventional cooling systems.
Held in formaldehyde-free microcapsules, Micronal is available in liquid and power form, and has been incorporated into a number of different building products, including gypsum wall boards, plaster and aerated concrete blocks, to enhance their thermal characteristics.
1 S Joss, R. Cowley and D. Tomozeiu, 2013, Urban Research & Practice, doi: 10.1080/17535069.2012.76; http://dx.doi.org/10.1080/17535069.2012.762216
2 The Crystal: a landmark building for technology and innovation. Published by Seimens, ISBN 978-1-90686608.
Nina Morgan is a freelance science writer based near Oxford, UK