Skyscrapers as symbols of solar prowess?
Ever since skyscrapers started to capture our imagination, they have been recognized as a city’s symbol of economic power and financial might. They have not, however, ever been accused of being particularly energy efficient. Skyscrapers are notoriously huge energy consumers, which is why we were impressed by some recent efforts for building owners to try to reduce the carbon footprint of their massive buildings.
Skyscrapers consume a large amount of energy when people are working. They consume a lot more electricity because potable and non-potable water have to be pumped to the highest occupied floors, mechanically ventilated design makes elevators generally used instead of stairs, and many lights are installed in rooms far from the windows and the windowless spaces. Furthermore, the gathered skyscrapers always contribute to the urban heat effect which urban residents suffer from.
With all of these inefficiencies, can a skyscraper be “green”? You no longer just need to dream of “green” skyscrapers or see them in the science fiction movies, eco-friendly solar skyscrapers are coming!
Solar panels on skyscraper roof top
In January 2012, Deutsche Bank completed the highest solar panel system in the world. The solar panels are perched at the top of its 50-story Americas’ headquarters building in Manhattan, 60 Wall Street.
The sun rises on the tallest solar energy system ever since the array was installed. The 122.4 kilowatt (kW) solar photovoltaic (PV) system on the rooftop is 737 feet above the ground, on the inclined south and east portions of the roof at 60 Wall Street. By commercial standards, the size is relatively modest, but the size of the roof it the major constraint on the size of the system.
The roof top solar panels will produce much energy for commercial use. The solar energy system can cut the building’s electricity bills by about 2 million dollars a year and decrease carbon emissions by 100 metric tons a year, 34% off. There is nothing particularly ambitious about this project—other than the height of the building on which the solar panels were installed. The building, however, is a symbol for a new frontier for solar panels—if you can get them up on a skyscraper, solar panels with a secure mounting system must have reliable performance.
Solar glass — skyscraper’s living skin
There is one technological development that may actually make an impressive dent on the carbon footprint of one of these tall buildings. More than 60% of skyscraper’s surface area is glass, so taking advantage of the glass area is what scientists and engineers are working hard on. Some have been focusing their attention on breakthroughs in solar glass.
Solar glass is a type of glass integrated with thin-film PV panels. The glass has several layers or coatings. Thin-film materials are doped between two layers of the glass and form their own PV tilt. It makes windows, skylights, and doors use part of the glass to produce electricity and the rest let in light. The windows are transparent, so people can still see out, and diffused sunlight can still provide natural lighting inside the building. Moreover, the solar glass’s efficiency can reach a rooftop PV panel. So each solar glass with solar power is like a cell producing oxygen, together making a building’s living skin.
In March 2011, Chicago’s tallest building Willis Tower began its solar experimental program. It now features high power density solar glass units on the south side of the 56th floor, replacing the existing windows. The new windows will preserve the scenic views while reducing heat gain and producing the same energy as conventional solar panels. The project could grow to 2 MW in size — which is comparable to a 10-acre field of solar panels — turning North America’s tallest building into a huge urban vertical solar farm.
Rooftop PV panels and solar glass, together with wind turbine, LED technology, and recyclable material, can make future skyscrapers more eco-friendly and save a huge amount of energy.
Manhattan — enormous power station of the future
As the world’s financial center, Manhattan has the largest density of high-rises and skyscrapers, about 500 skyscrapers above 492 feet and 5,000 high-rises, offering a sea of rooftops and sides of building for solar power harvesting. As time passes, the cost of solar panels, solar glass and system installation and maintenance will all decrease gradually.
And the lifespan of a solar energy system, which is now about 25-30 years, should improve to as much as 50 years in the next 15 years. All of these serve as the prerequisite and positive signal for those buildings to go green. A skyscraper with high-power rooftop solar panels and several floors’ solar glass can run as a vertical solar power station. Imagine, if all skyscrapers and high-rises become solar buildings, what will Manhattan be? At that time, Manhattan will become one of the largest solar power stations in the world, redefining the city’s symbol!
Yes, solar skyscrapers are on the rise.