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Sustainable Buildings – Energy Efficiency
Nature is their Model
State-of-the-art technology is making it possible to reduce energy consumption in buildings by up to 30 %. Four buildings—in New York, Malmö, Madrid, and Sydney—demonstrate what can be achieved for people and the environment when sensors, special materials, energy supply systems, and information technology interact in an optimal manner.
Back in June, 2008 Alain Robert climbed the facade of the new headquarters of the New York Times Company to call attention to the problem of global warming. Ironically, the building on which he chose to unfurl a banner with a message about climate protection was designed precisely to address that issue.
In fact, the 52-story building in Manhattan scaled by Robert, who is also known as "Spiderman," offers an impressive example of how modern technology can be employed to conserve energy and cut CO2 emissions without sacrificing comfort. The New York Times Building (NYTB), which opened in November 2007, uses up to 30 % less energy than conventional office high-rises. Designed by star architect Renzo Piano, the building has an unusual ultra-clear glass facade that allows neighbors to not only look into the interior, but also all the way through to the other side. The design allows passersby to look right through the lobby and into a garden featuring birch trees and moss. It’s like an oasis in the middle of Manhattan, one that symbolizes a key principle behind the building—to conserve energy with the help of, and in harmony with, nature.
Glass skyscrapers normally waste a lot of energy because they collect heat like a greenhouse and then use air conditioning to keep themselves cool. But the NYTB is different. It has a second facade made of ceramic rods that extends from the ground floor to the roof and keeps out direct light. A shading system is programmed to use the position of the sun and inputs from an extensive sensor network to raise and lower shades, either blocking extreme light to reduce glare or allowing light to enter at times of less direct sunlight. The shading system works in tandem with a first-of-its-kind lighting system that maximizes use of natural light so that electric lighting is used only as a supplement. Each of the more than 18,000 electrical ballasts in the lighting system contains a computer chip that allows it to be controlled individually.
The Times Company is also able to use free-air cooling, meaning that on a cool morning, air from the outside can be brought into the building. Everyone knows it makes sense to air out your home in the morning on hot summer days—but it takes high-tech systems to achieve the same practical results in a building as big as the NYTB. The task is enormously complex. Interior temperature, outside temperature, the building’s configuration, the angle of the sun, and the electrical and heat output of the in-house gas-fired combined-heat-and power generation systems are just a small sample of the many variables that have to be monitored to ensure efficient use of energy in such a skyscraper. No building superintendent could ever make decisions on the basis of so much information. But in The New York Times Building these decisions are made by a building management system from Siemens that automatically monitors and controls the air conditioning, water cooling, heating, fire alarm, and generation systems.
The building management system seamlessly integrates equipment from other manufacturers, which can then be operated by means of a centralized control interface. Building technicians are provided with real time information via an extensive network of hundreds of sensors, including those for monitoring temperature, which are distributed throughout the building. While all functions can be regulated from a central control room, this usually isn’t necessary because all it takes is a few commands to get the systems to automatically adjust themselves to conditions on any day. Whether it’s a hot, humid work day, or a cold and dry holiday when only a few offices are being used—the goal is always to save energy by ensuring that as few systems as possible are in operation, without diminishing comfort in any way.
"Nobody benefits from cooling an empty office in the evening," says Gary Marciniak, Account Executive at Siemens Building Technologies. "That’s obvious," he adds. "But other factors are less apparent. For example, sometimes it’s more efficient to have one of two water pumps operating at full capacity, while at other times the greatest efficiency is achieved by letting them both run." The system itself recognizes and automatically exploits such situations in order to maximize resource conservation.
Crystal Tower. Similar technologies are being used in the Torre de Cristal skyscraper, which is still under construction in Madrid’s Fuencarral-El Pardo district, one of Spain’s prime locations. When completed in November 2008, the "Crystal Tower" will be the second tallest building in the country. "Desigo"—an integrated building management system from Siemens—will help ensure that the most demanding tenant requirements will be met while using as little energy as possible. Siemens has also installed access control, video surveillance, and a complete fire protection systems in the Torre de Cristal.
All relevant information—from lighting and air conditioning to heating systems, for example—will be available on control panels located throughout the building, thus helping to ensure smooth operations. Stability will also be maintained in the event of a failure of individual systems or in case the central control room itself is damaged. If a fire breaks out, for example, ventilation dampers would still automatically close throughout the building to prevent smoke from spreading. The control panels will also use information from sensors to regulate air flows and thus the temperature of individual sectors of the building. If part of the building is not in use, its light and ventilation systems will be shut down.
Individual control units will be networked and will constantly exchange information on conditions in their sectors, thus providing a real time overview of all building conditions and processes. Automated control procedures can then be used to make continual adjustments to enable optimal energy utilization. If, for example, the system finds that the upper floors are warmer than the lower ones, it will cool things off by automatically sending cold water to the upper floors through high-pressure pipes. Warmer water from the top floors can transport heat down to the lower floors. Instead of heating the ground floor at the same time that the air conditioning is running in the top floor, the building automatically regulates itself to ensure energy efficiency.
The intelligent control panels are also very efficient, consuming around 15 % less energy than conventional units, says Margarita Izquierdo of Siemens Building Technologies, who is responsible for Energy & Environmental Solutions. Izquierdo helped her Siemens colleagues on the Torre de Cristal project to optimize energy efficiency in all areas. "The Torre de Cristal is truly avant-garde for Spain," says Izquierdo. "Solutions for energy efficiency in buildings are in many respects still in their infancy here, which is why I’m convinced this project will serve as a model in many ways."
LED Lighthouse. Another energy-saving building is the 190-m Turning Torso in Malmö, Sweden, which was completed in 2005. The building’s ambitious architectural style led the New York Museum of Modern Art to induct it into its Hall of Fame of the world’s 25 most fascinating skyscrapers. Light is one of its design key elements, with LEDs used to flood the corridors in symmetrical white light.
"Other solutions like fluorescent lights would have created unattractive shadows," says Jørn Brinkmann, who coordinated the installation of some 16,000 LEDs for Siemens’ Osram subsidiary in what was the first mass architectural application of such technology. When the Turning Torso was built, LEDs consumed about as much energy as fluorescent tubes—but today they use around a third less energy for the same output. But it was their long service life that made them appealing in 2005. Back then, the owners of the Turning Torso may not have realized they would become pioneers in lighting systems for buildings.
Minimizing Resource Consumption. The fact that impressive aesthetics and energy efficiency needn’t be mutually exclusive is also demonstrated by the 30 The Bond office complex in Sydney—the first building in Australia to receive five stars from the Australian Building Greenhouse Rating Scheme (ABGR). This stringent certification system was introduced by the government of New South Wales to encourage building owners to use state-of-the-art technology to minimize resource consumption. The highest rating is issued to buildings that operate with a carbon footprint that falls below a set benchmark. Greenhouse gas emissions at 30 The Bond, which was completed in 2004, are around 30 % lower than in similar buildings. Those who visit it generally don’t realize at first that they’re in an office building, as there is a café located in an eight-story atrium whose huge size helps to cool the structure. The back wall is made entirely of sandstone, and the roof features a small garden right in the middle of the Australian metropolis.
Depending on the weather, the garden is watered by a timed, drip irrigation system at night, so the upper floors take longer to heat up in the morning. Sixty percent of all workstations have a clear view outside, making the building a part of its natural surroundings.
As with similar buildings in New York and Madrid, intelligent building management technologies from Siemens integrate various systems at 30 The Bond, including those for heating, air conditioning, energy and water supply, fire protection, and lighting. Several of the energy conservation strategies are also similar. Sydney’s 30 The Bond is divided into 80 zones that can be controlled individually, with only those parts of the building that are actually in use being illuminated, cooled, and ventilated. There are also CO2 sensors for measuring air quality in the conference rooms. The system channels fresh air into a room only if people are present.
Completely new for Australia at the time the 30 The Bond building opened was the method used for cooling it. Instead of passing cold air directly into the office space, the system pumps chilled water through passive chilled beams (or radiators) mounted in ceilings. Chilled beams cool the space below by acting as a heat sink for naturally-rising warm air. Once cooled, the air drops back to the floor where the cycle begins again.
Says Lynden Clark, who was responsible for engineering the Siemens solution at 30 The Bond: "When it comes to such ambitious projects Siemens is an enabler helping customers to achieve their individual goals, whereby we decide on a case-by-case basis which technologies are most suitable for a given situation."
It’s no coincidence that in many cases the solutions are based on the same principle as that applied in New York, Madrid, and Sydney, which calls for more extensively exploiting the surroundings of the buildings, the natural heat or cold, and the light of the sun. After all, nature opens up all kinds of opportunities for living and working in harmony with it in modern high-tech buildings—and intelligent building technology makes it possible to seize these opportunities.