Feasibility Assessment of the Pearl River Tower

This research report provides a feasibility assessment of the Pearl River Tower. The Pearl River Tower upon completion plans to be the most energy efficient and sustainable of all mega structures in the world till present day. Conventional building is preferred due to its economic benefits and amount of time needed for completion of a project, but it is one of the biggest contributors to global warming. Green building, which is perfectly portrayed in the Pearl River Tower, serves as a good solution for the ongoing environmental problem. This report defines the Pearl River Tower and explains the way it functions as well as its numerous benefits. The Pearl River Town is more efficient than and other super tall structures, is economically feasibly, can generate its own energy as well as an additional amount of energy that can be supplied to exterior sources. After a full analysis of each criterion, a recommendation will be reached concerning the implementation of the Pearl River Tower and similar green structures.
1.Introduction:
1.1 Background to the Problem:

One of the greatest hurdles of the 21st century is the excessive emission of CO2. The environmental conditions are regressing annually and have reached a point where it has become a strain on human and animal life. Buildings and other mega structures are primary contributors to global warming. Classical building’s main concern was purely based on economy, durability, and comfort. However nowadays people have become more aware of the environment, and are therefore taking drastic measures to improve this situation. Some of these measures include green building, which refers to building using energy efficient methods, and shifting from fossil fuels to renewable energy.
Buildings are responsible for a minimum of 40% of energy consumption and carbon emissions in most countries (4, para.1). The per capita carbon emission in china was almost five tons in 2008 (average is 4.18 tons per capita), which is about 18% of world emissions (3, para.7). The Chinese government aims to reduce 40-45% of emissions by 2020(6, para.1). International companies are taking on new sustainable and renewable projects, many of which are based in China. Energy-saving technologies in buildings can drastically reduce carbon emissions.
The main problem with traditional towers is the consumption of fossil fuels, which results in numerous types of wastes. The methods applied within the structures to generate and consume energy are polluting and hazardous to the environment. They use artificial lighting, cooling, and heating systems that demand a great deal of electricity, which in turn is a result of burning fossil fuels. The glass that these buildings are composed of is another example of the inconvenient methods applied. This glass is called architectural glass that allows the transfer of heat and energy, which leads to the squandering of heat.
All these negatives have lead to the development of various renewable energy techniques. Solar energy, wind power, hydropower, biomass, biofuel, and geothermal energy are all types of renewable energy that could be used in green buildings.
1.2. Substitute Technology:
The Pearl River Tower was recognized as a major substitute for traditional buildings. It is a structure that is non-hazardous to the environment and that can generate and supply energy.
1.2.1. Description of Pearl River Tower:
The Pearl River Tower is a 309.6-meter tower, consisting of 71 floors, and extending over 214,100 square meters of land (5, project facts). This tower, upon completion, is expected to be the most efficient of all the super tall structures in the world. It is located in Guangzhou, China. The Pearl River Tower is designed to generate its own energy using sustainable methods, which decreases its dependency on the electrical network, therefore reducing consumption of fossil fuels required to power it.
The design took many aspects into consideration, which included the integrated system’s interdependence and the building site. To achieve the optimum design many factors were studied such as the site, wind direction and speed, material, sun path, energy sources and building alignment. After these numerous studies, the team of engineers and architects where able to combine a number of different systems which include wind turbines, photo-voltaic, active facade, and double wall systems (7, para 7)
Although the structure was originally designed to be “net zero energy”, such that the building is self-sustaining, and any extra power would be sold and sent back to the grid; however, there were modifications to the plan. The tower was optimized in a way to consume 60% less energy than any other conventional building of its size (1, para 1).
1.1.2. Purpose of the report:
Constructing “carbon- neutral” structures has become of major interest to engineers recently. Therefore, the Pearl River Tower would serve as a stepping stone for future designs of green skyscrapers. This report will study the feasibility of the Pearl River Tower through evaluating certain criteria. The closing of the report will include a recommendation of whether to construct green buildings such as the Pearl River Tower.

2. Method
2.1. Criteria
We will study the feasibility of the Pearl River Tower by studying various criteria:
Sustainability and Energy Generation Techniques: We will study and discuss the methods used to produce energy within the tower, in addition to the structures sustainability.
Safety: We will study the effect the tower has on its occupants and its surroundings.
Construction process: We will explore the techniques used while constructing the tower and the time needed for completion.
Economy: We will consider the cost of the tower and whether the project is economically feasible.
Efficiency: We will discuss whether the structure is efficient on the long run.

2.2. Procedure
In order to assess the mentioned criteria we gathered information from plenty of sources including a published report released by the Pearl River Tower’s construction company called SOM, numerous online articles, and interviews conducted with university professors.
3. Results
3.1. Sustainability and Energy Generation Techniques
3.1.1. Sustainability Approach: “Zero Net Energy”
The initial approach for the Pearl River Tower was one that would provide “Zero Net Energy” generated. This approach would require the implementation of four interdependent steps:
Reduction: This first step is defined by identifying the possibilities of energy reduction, then proceeding in reducing the amount of energy consumed by the building as much as possible. The focus is on systems with high power consumption such as HVAC (Heating ,Ventilation and Air Conditioning) as well as lighting systems.
Absorption: The second step is to include absorption strategies, defined by taking advantage of natural and passive energy sources, such as the sun and the wind.
Reclamation: This step in a high performance design aims to recollect all the energy that is already stored within the building. Once energy is added to the building, it could be reused. An example used in the Pearl River Tower is the recirculation of chilled air from AC systems to precool the outside air before it enters the building so that less energy is required to cool it down to required levels.
Figure 1 Micro Turbine Installation
Generation: this final step aims at generating clean power in an efficient and environmentally friendly manner. The Pearl River Tower implements micro –turbines which are able to generate energy cleaner and more efficiently than what the grid is capable of. It is worthwhile to mention that these turbines can be operated using different typed of fuel such as kerosene, diesel, propane and methane gas. (7,p4)
Figure 2 A double walled high performance facade
3.1.2 The Active Facade
Nowadays, employment of reflective, fully glazed facades is becoming increasingly common. Their popularity started in Europe and is now spreading across the United States and China. By including a second layer of glass behind the exterior one, the room for increased venting, shading and control application would be increased. The active facade is an application for the reduction strategy mentioned earlier since a dehumidification system could be applied by harnessing the heat collected in the double wall facade.
The design of the double walled facade provides benefits such as increased thermal comfort , an improved air quality due to recirculation as well as better lighting due to a transparent nature of the walls. They also provide noise insulation from outside conditions, and that is especially needed if the tower is high enough, since wind speeds at high altitudes would create vortices that produce a lot of noise, as well as the street level floors that have the problem of noise from traffic.
Furthermore, the increased penetration of light from the exterior would require less artificial lighting and therefore would lead to saving energy. The cavity also acts as a natural chimney using the cooler air from the occupied office areas to enter the cavity via a gap at floor level to allow fresher air to enter the occupied areas. The trapped hot air in the cavity is extracted through the ceiling void and is used either as a pre-heat or pre-cool depending upon outside air temperatures. The facade then acts as an integral part in our reclamation as well as reduction strategy.
3.1.3 Radiant Ceiling and Below Floor Ventilation
As mentioned previously, HVAC operation is one of the more costly operations in a building when it comes to energy. The Pearl River Tower designers therefore implemented new techniques that help cut down on costs. The traditional approach is to dump cold or warm air into the occupational space for it to mix with the ambient air in order to balance out at a comfortable temperature. This approach requires constant energy input for the HVAC system. The designers chose to implement a radiant ceiling and below floor ventilation system in order to provide that comfort from different methods, not just dumping air into a room. The room temperature would be conditioned from above and below simultaneously through a radiative system in the ceiling and a floor air delivery system. This system is effective in cutting down maintenance and operation costs compared to traditional HVAC
3.1.4. Building Integrated Photovoltaics
Building integrated photovoltaics as opposed to normal photovoltaics would make up the building exterior instead of being added as an extra feature. In the Pearl River Tower application, the photovoltaics serve a dual purpose: they provide the buildings outer envelope as well as generating electricity gathered from solar radiation. We thus save money and energy by not paying for wall mounting panels, and adding the cost of the photovoltaics as an extension. The system not only provides electricity generation, but it also shades the parts of the tower that are most susceptible to sunlight.
3.1.5 Wind Turbines
Figure 3 Building integrated Photovoltaics
Wind energy is the fastest growing renewable energy source in the world; so naturally, the Pearl River Tower will have wind turbines installed in an effort to harness the wind’s power, especially at high altitudes, where the wind speeds are highest. Wind turbine performance is also significantly increased in the tower due to their integration with the tower’s architecture. “The Pearl River tower will implement vertical axis wind turbines, as they are capable of harnessing winds from both prevailing wind directions with minor efficiency loss.”(7 p8)
Figure 5 Wind portal opening
The tower will have 4 large openings that are designed to decrease wind drag forces and optimize wind velocity. It is in those openings that the wind turbines will be installed. A model of the building with the openings was studied in a wind turbine and results showed “If the wind strikes the building perpendicular to the opening, there is a drop in portal velocity. However, from almost all other angles, the wind velocity increase exceeds the ‘ambient’ wind speeds.” (7 p 9).
Therefore by placing vertical axis wind turbines, one in each of those 4 openings, a sustainabl e and renewable energy source would be provided year round. It is noteworthy to mention that those turbines are low maintenance, low noise and low vibration devices that will not prove to be a nuisance to people in the building.
Figure 4 Vertical axis wind turbine
3.2. Safety:
The tower is beneficial for both lives inside and outside of it. Because it emits less greenhouse gasses it is prone to be less hazardous to the surrounding environment. The systems used within the tower have proved to provide a health and safe environment for its occupants. The double wall system provides a big amount of natural light into the building therefore lessening the necessity for artificial light (7, para6). This in turn affects the comfort of the human eye. The photovoltaic panels are located on the roof level of the tower therefore protecting the roof occupants from the direct and harmful effect of UV-rays. (7, para8)The absence of electric fans and air conditioners in the building in addition to the ventilation system installed, has improved indoor air quality and reduced the humidity. All these factors improve inhabitant’s comfort and productivity, and maintain a health environment.
4. Recommendation
The sum of all the sustainable and renewable methods employed in the Pearl River Tower led to a significant reduction in energy consumption. Although initial design was for the building to rely solely on those methods, the project cannot be considered as a failure, only as an achievement and stepping stone for future green buildings. The implementation of all those systems and ideas prove that the concept of a “zero energy” superstructure is within our reach in the near future and is not as crazy an idea as initially conceived. It is important to note that the micro turbines were dropped from the project since the power company in Guangzhou would not allow resale of electricity, and therefore the use of micro turbines, although beneficial, would not justify their cost of installation and operation and in an economically wise decision, they were removed from the design. Their addition would have further increased efficiency to a great extent.
After the results achieved, it is only logical to expect a rise in green buildings around the world, especially with the rapid progress of new technology in sustainable energy, and ultimately a “zero energy” superstructure will be constructed. Till then, the investors in such buildings would need government cooperation in order to continue their pioneering efforts in creating a more sustainable and healthier mode of living.
References
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