Vertical axis wind turbines for energy efficiency of buildings

Darrieus Wind Turbine
Darrieus type wind turbines are commonly called "Eggbeater" turbine[4]. The construction of Darrieus wind turbines is simple and consists mainly of 2 or 3 blades. Darrieus type wind turbines have a higher efficiency than Savonius type wind turbines. However, the large mechanical pressure on the support and the large torque required by this type of wind turbines are their disadvantages. Below are the types of Darrieus wind turbines (Figure 2)[ 5 Amlan Das, Pradip Kumar , Modelling and Analysis of a Mini Vertical Axis Wind Turbine , International Journal of Emerging Technology and Advanced EngineeringWebsite: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 6, Issue 6, June 2016]

Figure 2. Different types of Darrieus Wind Turbines.

Building Augmented Wind Turbines(BAWT)
The height of high-rise buildings can be several tens or even several hundred meters. Considering this, the wind speed on the roof of these buildings is several times greater than the wind speed on the bottom of the building. This makes it possible to install wind turbines on the roof. Wind turbines can be installed in different parts of the building. Based on this, BAWT can be divided into the following three categories[6 Marco Casini, SMALL VERTICAL AXIS WIND TURBINES FOR ENERGY EFFICIENCY OF BUILDINGS, Journal of Clean Energy Technologies, Vol.4, No. 1, January 2016] :

• 
  Mounted on the roof;
  
• 
  Installed between buildings;
  
• 
  Installed in the ventilation system of the building.
  

Mounted on the roof
In this category, wind turbines are installed only on the roof of buildings, and mainly vertical type wind turbines are used. Because the air flow turbulence is high on the roof of tall buildings, vertical type wind generators are effective in this air flow (Figure 3).
Figure 3. Wind turbines mounted on the roof

Installed between buildings
Installation of wind turbines between interconnected buildings requires a special technical and architectural solution. Because the geometric structure of the existing buildings and the air flow crossing the buildings, the distance between the buildings plays an important role for the installation of the wind generator. Usually, wind generators are installed between two buildings or in structures connecting buildings. Horizontal wind turbines are mainly used in this category. The magnitude of wind speed and pressure between two buildings allows the use of horizontal type wind generators(Figure 4).

Figure 4. HAWT installed between buildings.

Installed in the ventilation system of the building
Another category of implementing the integration of wind turbines and high-rise buildings is the use of building ventilation systems. In high-rise buildings, artificial air flow is created inside the building to ensure continuous air flow movement. This air flow moves through the tubes. Electricity can be generated by installing a small wind turbine at the inlet or outlet of these pipes. In this system, HAWT is used because of the perpendicular direction of the wind (Figure 5).

Figure 5. Installed in the ventilation system of the building

As can be seen from the above analysis, it is possible to integrate vertical type wind turbines with modern buildings. This shows that it is possible to achieve energy savings by partially covering the energy needs of buildings. Also, the transition of buildings and structures to green energy will reduce human impact on the environment.