This 71-storey tower block is being touted as the greenest skyscraper on Earth, but what makes it so energy efficient?
While many buildings flaunt their green credentials by incorporating a single piece of in-your-face, eco-friendly technology into their design, the Pearl River Tower in Guangzhou City, China, goes much further, drawing together a bevy of cutting-edge systems to jump closer to an almost zero-energy building (ZEB) -the holy grail for today’s architects.
This is achieved first and foremost through its 309-metre (1,014-foot)-high sculpted faces, which redirect wind to four openings at its mechanical floors. Here, the wind is drawn through the building’s body and into a series of turbines, which combined generate electricity for the offices within.
In addition to driving turbines, the wind that is pulled in is also rerouted throughout the tower’s ventilation system, with the air being filtered through the building’s floor and ceiling spaces. This ambient cooling of the offices negates the need for energy-hungry air-conditioning units in hot weather, which saves a considerable amount of electricity.
The entire building is also fitted with an advanced, double-glazed skin. The outer layer of this can be penetrated by heat from sunlight, however the inner layer cannot, causing the rays’ heat to become trapped and not enter the interior. This trapped heat therefore rises through the skin’s cavity to heat exchangers where it is absorbed and stored for reuse in both energy generation and heating processes.
Lastly, large solar panels are installed on the building’s exterior roof, which directly absorb sunlight for generating energy. This energy is used to provide power for the skyscraper’s perforated metal window blinds, which automatically track the Sun and open/close to minimise heat loss or to moderate ambient office temperature. The blinds themselves are also equipped with photovoltaic cells, so even when they are closed, the Sun’s energy is still being efficiently harvested.
The turbines equipped between the mechanical floor spaces of the Pearl River Tower can generate in excess of four per cent of the building’s total power draw annually. This is due to the turbines being specifically designed to work across a variety of wind speeds, ranging from small flows moving at around eight kilometres (five miles) per hour, right up to intense 225-kilometre (140-mile)-per-hour surges. Due to the building’s orientation, the prevailing winds from the north and south of Guangzhou City are harnessed, with the tower’s curvilinear form funnelling indirect wind flows into the turbine inlets.
Anatomy of an eco-skyscraper
Solar panels – The roof of the Pearl River Tower is fitted with a large, curved array of solar panels. These panels soak up sunlight and generate electricity – the energy being used to power the building’s automatic blinds.
Turbine inlet – Prevailing northerly and southerly winds are drawn through four inlets in the building’s facade (two on either side) into a series of wind turbines. These produce electricity for use in the building’s offices.
Ventilation system – Air drawn into the building through its four main inlets is also rerouted into the structure’s ventilation system. This can then be used to cool the ambient temperature of the office space so air conditioning is not needed in the summer.
Vertical axis – The vertical axes of the tower combine to grant it a revolutionary curvilinear form that both funnels approaching wind into the facade’s turbine inlets as well as exploiting the area’s solar path to harvest more energy.
Triple glazing – On the eastern and western faces (the thin ends) a triple-glazed coating is used to prevent heat loss from within and excess heat from the Sun’s rays entering.
Double skin – On the building’s two vertical axes a two-layer facade traps hot air generated by the Sun in a thin cavity. The hot air, rather than seeping into the office space, rises to heat exchangers located on mechanical floors.
Photovoltaic cells – A photovoltaic energy capture system is integrated into the Pearl River Tower’s external shading system (blinds) and glass outer skin. As with the solar panels, this system can convert sunlight into electricity.