Egypt Today.com posted an article dated August 7, 2019, that brings to light an unusual construction project concept. It combines building towers with an agricultural development project. The project concept if multiplied in numbers will certainly be increasing Egypt’s limited area of farm land that is confined to the Nile Valley and Delta, with a few oases and some arable land in the Sinai peninsula.
CAIRO – 7 August 2019: Italian Architect Stefano Boeri spoke to CNN about Africa’s first vertical forests that will be built in Egypt’s New Administrative Capital (NAC), which is still under construction and is 30 miles east of Cairo.
Each of the three cube-shaped blocks will be 30 meters high and will house seven floors, 350 trees, and 14,000 shrubs of over 100 species. “Each tower of trees aims to provide its human residents with an average of two trees, eight shrubs and 40 bushes each,” as reported by CNN.
Boeri has been designing the blocks in collaboration with Egyptian designer Shimaa Shalash and Italian landscape architect Laura Gatti. Shalash told CNN that execution of the project is set to start in 2020 and finish in 2 years. One of the three buildings will be an energy self-sufficient hotel, while the other two will contain residential apartments.
“Each apartment will have its own balcony with a range of plant species suited to the local climate, planted at various heights and to bloom at different times to provide a lush appearance year round. Plants at every level will provide natural shading and improve the surrounding air quality by absorbing an estimated 7 tons of carbon dioxide and producing 8 tons of oxygen per year,” CNN reported.
Shalash and colleagues explained to CNN that the project – owned by a private real estate developer – is part of a bigger plan to introduce “thousands of green flat roofs and a system of “green corridors” in the city.”
According to an expert in sustainable design, how to keep buildings cool without air conditioning, is by no mean as impossible as it may sound.
The warmer it gets, the more people crank up the air conditioning (AC). In fact, AC is booming in nations across the world: it’s predicted that around two-thirds of the world’s households could have an air conditioner by 2050, and the demand for energy to cool buildings will triple.
But unless the energy comes from renewable sources, all that added demand will generate more greenhouse gas emissions, which contribute to global warming – and of course, to hotter summers. It’s a vicious cycle – but buildings can be designed to keep the heat out, without contributing to climate change.
1. Windows and shading
Opening windows is a common way people try to cool buildings – but air inside will be just as hot as outside. In fact, the simplest way to keep the heat out is with good insulation and well-positioned windows. Since the sun is high in summer, external horizontal shading such as overhangs and louvres are really effective.
East and west-facing windows are more difficult to shade. Blinds and curtains are not great as they block the view and daylight, and if they are positioned inside the window, the heat actually enters the building. For this reason, external shutters – like those often seen on old buildings in France and Italy – are preferable.
2. Paints and glazes
It’s now common for roofs to be painted with special pigments that are designed to reflect solar radiation – not just in the visible range of light, but also the infrared spectrum. These can reduce surface temperatures by more than 10°C, compared to conventional paint. High-performance solar glazing on windows also help, with coatings that are “spectrally selective”, which means they keep the sun’s heat outside but let daylight in.
There’s also photochromic glazing, that changes transparency depending on the intensity of the light (like some sunglasses) and thermochromic glazing, that becomes darker when it is hot, which can also help. Even thermochromic paints, which absorb light and heat when it’s cold, and reflect it when it’s hot, are being developed.
3. Building materials
Buildings which are made of stone, bricks or concrete, or embedded into the ground, can feel cooler thanks to the high “thermal mass” of these materials – that is, their ability to absorb and release heat slowly, thereby smoothing temperatures over time, making daytime cooler and night time warmer. If you have ever visited a stone church in the middle of the Italian summer, you will probably have felt this cooling effect in action.
Unfortunately, modern buildings often have little thermal mass, or materials with high thermal mass are covered with plasterboard and carpets. Timber is also increasingly used in construction, and while making buildings out of timber generally has lower environmental impacts, its thermal mass is horrendous.
4. Hybrid and phase change materials
While concrete has a high thermal mass, it’s extremely energy intensive to produce: 8% to 10% of the world’s carbon dioxide (CO₂) emissions come from cement. Alternatives such as hybrid systems, composed of timber together with concrete, are increasingly being used in construction, and can help reduce environmental impacts, while also providing the desired thermal mass.
Another, more exciting solution is phase change materials (PCMs). These remarkable materials are able to store or release energy in the form of latent heat, as the material changes phase. So when it’s cold, the substance changes to solid phase (it freezes) and releases heat. When it becomes liquid again, the material absorbs heat, providing a cooling effect.
PCMs can have even greater thermal mass than stones or concrete – research has found that these materials can reduce the internal temperatures by up to 5°C. If added to a building with AC, they can reduce electricity consumption from cooling by 30%.
PCMs have been hailed as a very promising technology by researchers, and are available commercially – often in ceiling tiles and wall panels. Alas, the manufacture of PCMs is still energy intensive. But some PCMs can cause a quarter of the CO₂ emissions that others do, so choosing the correct product is key. And manufacturing processes should become more efficient over time, making PCMs increasingly worthwhile.
5. Water evaporation
Water absorbs heat and evaporates, and as it rises, it pushes cooler air downwards. This simple phenomenon has led to the development of cooling systems, which make use of water and natural ventilation to reduce the temperature indoors. Techniques used to evaporate water include using sprayers, atomizing nozzles (to create a mist), wet pads or porous materials, such as ceramic evaporators filled with water.
The water can be evaporated in towers, wind catchers or double skin walls – any feature which creates a channel where hot air and water vapour can rise, while cool air sinks. Such systems can be really effective, as long as the weather is relatively dry and the system is controlled carefully – temperatures as low as 14°C to 16°C have been reported in several buildings.
But before we get too enthusiastic about all these new technologies, let’s go back to basics. A simple way to ensure AC doesn’t contribute to global warming is to power it with renewables – in the hot weather, solar energy seems the obvious choice, but it takes money and space. The fact remains, buildings can no longer be designed without considering how they respond to heat – glass skyscrapers, for example, should become obsolete. Instead, well insulated roofs and walls are crucial in very hot weather.
Everything that uses electricity in buildings should be as energy efficient as possible. Lighting, computers, dishwashers and televisions all use electricity, and inevitably produce some heat – these should be switched off when not in use. That way, we can all keep as cool as possible, all summer long.
Actions by individuals and businesses, such as improving energy efficiency in the home or office, make a difference.
The role of technology in keeping climate catastrophe at bay is becoming ever more critical. The resurgence of protests around the world such as the civil havoc wreaked by Extinction Rebellion or the school strikes begun by Swedish schoolgirl Greta Thunberg has renewed pressure on governments to “do something”, no matter how unrealistic or economically ruinous.
The individual and political solutions usually meant by “doing something” are not as straightforward as they sound and may actually create more difficulties than they solve. Actions by individuals and businesses, such as improving energy efficiency in the home or office, make a difference, but this is still a drop in the ocean when put up against the output of the world’s biggest emitters of greenhouse gases. They are also a bit hit-and-miss. Many of us are happy to do our bit of recycling or to stop the tap running while we brush our teeth, but how many of us are prepared never to fly again or to take up a vegan diet?
Similarly, swingeing political solutions such as carbon and fuel taxes can jolly things along, but such taxes inevitably hit the poor hardest and contribute to their own political unrest, as seen with the Yellow Vest movement in France, which could backfire by encouraging the election of more climate-sceptic leaders such as Donald Trump.
Technology presents only opportunities Yet where individual and political solutions pose their own problems, the technological approach presents only opportunities. The growing recognition of the essential role played by green technology is highlighted by the fact that the World Green Economy Summit held in Dubai last year included a discussion on the role of technology in the green economy, this year it will be the summit’s overarching theme.
One example of the win-win nature of technological solutions to green issues is renewable energy. In its early days, renewables were seen by many as nothing more than a way for governments to spend taxpayers’ money on switching to more expensive energy. But we hung in there and the fruits are beginning to show. Prices of renewables, particularly solar, are through better technology being brought to a point where not only do they no longer require public subsidy, but turn a profit enough that they become an attractive business proposition.
Much still to be done Still, despite renewable power having accounted for 70 percent of net additions to global power generating capacity in 2017, greenhouse gas emissions edged higher that year nonetheless, showing there is still much work to be done. The main laggards were the heating, cooling and transport sectors, which account for about 80 percent of global energy demand.
This shows that although technological breakthroughs in areas such as renewable energy can have a win-win impact – reduced emissions and cheaper energy – the road ahead isn’t easy. For example, if there is a greater take-up of electric cars this might cause oil prices to fall, which in turn could increase demand from the aviation sector that would push up emissions.
Despite advances in green technology such as the smart grid, electric vehicles, bioplastics, carbon capture and storage, green computers and green packaging, some critics insist that these advances are not nearly enough. They say that although we have been led by some of the modern world’s amazing inventions into believing that technology can achieve anything that simply isn’t true. They contend that future advances in green technology cannot be blindly relied upon to save the planet, and that essential breakthroughs such as improved battery efficiency in electric vehicles may still be a long way off.
Technology predicted to potentially cut emissions by 64 percent by 2050 But if there are problems with green technology, they are considerably less than those created by a purely political approach, which will inevitably lead to punitive, and polarising, taxes. Governments would do better to ease the path for innovative firms and startups through funding and supportive legislation so they can find the myriad solutions that will be needed to meet or go beyond the carbon targets of the Paris Agreement. ING in a report issued last year predicted that such an approach could result in a 64 percent decrease in greenhouse gas emissions by 2050.
To conclude, while the political pressure intensifies to enact all sorts of rash and damaging ecological measures, it is best to keep our heads and do all we can to back and push forward the technological innovations that may not just combat climate change, but do so while strengthening the global economy.
It could one day reduce the need for air conditioning.
Wednesday, June 12, 2019
Researchers at Columbia University are working on a new way to keep buildings cool. They drew inspiration from an unlikely source: a heat-tolerant species of ant called the Saharan Silver Ant. It lives in the scorching desert.
Yu: “They are only active in the middle of the day when the surface of the desert is the hottest.”
In 2015, physics professor Nanfang Yu discovered that this ant’s silvery coating of hair reflects sunlight and radiates heat back to the sky.
Now, he and his colleagues have developed a paint-like material that mimics these functions.
Yu: “So this coating doesn’t heat up under the Sun.”
When applied to a rooftop, it reflects up to ninety-nine per cent of sunlight and emits heat back to the atmosphere.
Yu says that helps cool the building underneath. And it does so far more effectively than white paint, which only reflects certain wavelengths of solar radiation.
New York Mayor Bill de Blasio has declared that skyscrapers made of glass and steel “have no place in our city or our Earth anymore”. He argued that their energy inefficient design contributes to global warming and insisted that his administration would restrict glassy high-rise developments in the city.
Glass has always been an unlikely material for large buildings, because of how difficult it becomes to control temperature and glare indoors. In fact, the use of fully glazed exteriors only became possible with advances in air conditioning technology and access to cheap and abundant energy, which came about in the mid-20th century. And studies suggest that on average, carbon emissions from air-conditioned offices are 60% higher than those from offices with natural or mechanical ventilation.
As part of my research into sustainable architecture, I have examined the use of glass in buildings throughout history. Above all, one thing is clear: if architects had paid more attention to the difficulties of building with glass, the great environmental damage wrought by modern glass skyscrapers could have been avoided.
Heat and glare
The United Nations Secretariat in New York, constructed between 1947 and 1952, was the earliest example of a fully air-conditioned tower with a glass curtain wall – followed shortly afterwards by Lever House on Park Avenue. Air conditioning enabled the classic glass skyscraper to become a model for high rise office developments in cities across the world – even hot places such as Dubai and Sydney.
Yet as far back as the 19th century, horticulturists in Europe intimately understood how difficult it is to keep the temperature stable inside glass structures – the massive hothouses they built to host their collections. They wanted to maintain the hot environment needed to sustain exotic plants and devised a large repertoire of technical solutions to do so.
Early central heating systems, which made use of steam or hot water, helped to keep the indoor atmosphere hot and humid. Glass was covered with insulation overnight to keep the warmth in, or used only on the south side together with better insulated walls, to take in and hold heat from the midday sun.
The Crystal Palace
When glass structures were transformed into spaces for human habitation, the new challenge was to keep the interior sufficiently cool. Preventing overheating in glass buildings has proven enormously difficult – even in Britain’s temperate climate. The Crystal Palace in Hyde Park – a temporary pavilion built to house the Great Exhibition of the Works of Industry of All Nations in 1851 – was a case in point.
The Crystal Palace was the first large-scale example of a glass structure designed specifically for use by people. It was designed by Joseph Paxton, chief gardener at the Duke of Devonshire’s Chatsworth Estate, drawing on his experience constructing timber-framed glasshouses.
Though recognised as a risky idea at the time, organisers decided to host the exhibition inside a giant glasshouse in the absence of a more practical alternative. Because of its modular construction and prefabricated parts, the Crystal Palace could be put together in under ten months – perfect for the organisers’ tight deadline.
To address concerns about overheating and exposing the exhibits to too much sunlight, Paxton adopted some of the few cooling methods available at the time: shading, natural ventilation and eventually removing some sections of glass altogether. Several hundred large louvres were positioned inside the wall of the building, which had to be adjusted manually by attendants several times a day.
Despite these precautions, overheating became a major issue over the summer of 1851, and was the subject of frequent commentaries in the daily newspapers. An analysis of data recorded inside the Crystal Palace between May and October 1851 shows that the indoor temperature was extremely unstable. The building accentuated – rather than reduced – peak summer temperatures.
These challenges forced the organisers to temporarily remove large sections of glazing. This procedure was repeated several times before parts of the glazing were permanently replaced with canvas curtains, which could be opened and closed depending on how hot the sun was. When the Crystal Palace was re-erected as a popular leisure park on the outskirts of London, these issues persisted – despite changes to the design which were intended to improve ventilation.
These difficulties did not perturb developers in Chicago from building the first generation of highly glazed office buildings during the 1880s and 1890s. Famous developments by influential architect Ludwig Mies van der Rohe, such as the Crown Hall (1950-56) or the Lakeshore Drive Apartments (1949), were also designed without air conditioning. Instead, these structures relied mainly on natural ventilation and shading to moderate indoor temperatures in summer.
In the Crown Hall, each bay of the glass wall is equipped with iron flaps, which students and staff of the IIT School of Architecture had to manually adjust to create cross-ventilation. Blinds could also be drawn to prevent glare and reduce heat gains. Yet these methods could not achieve modern standards of comfort. This building, and many others with similar features were eventually retrofitted with air conditioning.
Yet it’s worth noting that early examples of glass architecture were not intended to provide airtight, climate controlled spaces. Architects had to accept that the indoor temperature would change according to the weather outside, and the people who used the buildings were careful to dress appropriately for the season. In some ways, these environments had more in common with the covered arcades and markets of the Victorian era, than the glass skyscrapers of the 21st century.
Becoming climate conscious
The reality is that the obvious shortcomings of glass buildings rarely received the attention they warranted. Some early critics raised objections. Perhaps the most outspoken was Swiss architect Le Corbusier, who in the late 1940s launched an attack on the design of the UN Secretariat, arguing that its large and unprotected glass surfaces were unsuitable for the climate of New York.
But all too often, historians and architects have focused on the aesthetic qualities of glass architecture. The Crystal Palace, in particular, was portrayed as a pristine icon of an emerging architecture of glass and iron. Yet in reality, much of the glass was covered with canvas to block out intense sunlight and heat. Similarly, the smooth glass facades of Chicago’s early glass towers were broken by opened windows and blinds.
There’s an urgent need to take a fresh look at urban architecture, with a sense of environmental realism. If de Blasio’s plea for a more climate conscious architecture is to materialise, future architects and engineers must be equipped with an intimate knowledge of materials – especially glass – no less developed than that held by 19th century gardeners.
The world’s fourth largest cement company pledged on Monday to bring its emission reduction targets in line with the goals of the Paris Agreement, in a first for the industry.
HeidelbergCement, which employs some 58,000 people in 60 countries, committed to slash direct emissions by 15% per tonne of its products by 2030 from 2016 levels.
The construction behemoth also committed to cut indirect emissions, for example from its electricity supply, by 65% a tonne within the same time-frame.
“The commitment, which is part of the company’s wider vision to realise CO2-neutral concrete by 2050 at the latest, is a powerful signal that the built environment is transitioning towards a zero-carbon future,” said Jennifer Gerholdt, corporate engagement director at We Mean Business, a coalition of companies promoting climate action.
“It’s also vital for the decarbonization of entire economies, given concrete is the most widely used man-made substance on earth, one of the hardest to decarbonize and in growing demand due to rising population and urbanization.”
The move comes as the number of new buildings is tipped to grow in the coming years, in particular in Africa and Asia. This rapid expansion will test a 30% energy intensity improvement in buildings by 2030, required to put the industry on track to meet the goals of the Paris Climate Change Agreement, according to the IEA and UN Environment.