An increasing number of progressive organizations are adopting omni-directional VAWTs because of their aerodynamic performance advantages with characteristically turbulent and moderate winds in densely populated urban settings. VAWTs operate quietly, deliver clean electricity directly to the owner, and can feed excess electricity into the local power grid, which can further reduce the owner’s energy consumption costs. The use of VAWTs to produce distributed energy also reduces both the need for unpopular transmission lines and emissions from fossil-fuel-fired generators that contribute to climate change, and it provides points for LEED certification.

Wind flow within urban and suburban environments is turbulent and veering. Increased turbulence levels yield greater fluctuations in wind speed and direction. Unlike a traditional horizontal axis wind turbine (HAWT), a VAWT rotates around the shaft vertically. VAWTs provide good performance in urban and suburban environments due to their inherent design characteristics. Some key benefits of VAWTs over HAWTs are:

• Ability to effectively capture turbulent winds which are typical in urban settings, especially in built-up areas.
• No need for a yaw mechanism to face the blade rotor into veering wind directions; VAWTs therefore have higher efficiency and no orientation parts to maintain.
• Operation at lower rotational speeds, thereby reducing or eliminating turbine vibration and noise.
• Durability and reliability working in multi-directional wind.
• Easier and less expensive repair and maintenance with generator on rooftops.
• Lower noise and vibration.

	VAWTs	HAWTs
Effective in laminar winds (1)	Yes	Yes
Effective in turbid urban winds (2)	Yes	No
Effective in low mountings	Yes	Sometimes
Ground mounting	Yes	No
Rooftop mounting	Yes	Sometimes

⁽¹⁾ Laminar: fluid air flow which occurs in "sheets" parallel to each other.
⁽²⁾ Turbid: flow that changes directions quickly and often and has turbulences.

Noise & Vibration: Although urban settings are inherently noisier than rural areas, an additional noise can affect a small minority of people. A popular concern with the use of large-scale wind turbines for power generation is noise. The majority of large HAWT noise is generated from the gearbox and the aerodynamic noise of the blades. With small-scale VAWT’s, however, a gearbox is not required, and VAWT blade speeds are much lower than small HAWTs, so noise is also much lower.

In a 2007 test by McMaster University, a small VAWT was tested for noise generation, which revealed that the overall noise level of the turbine remains below 50 decibel (dB) for all normal operating conditions (the turbine rarely operated at a wind speed beyond 15 m/s). When this range is converted to the dBA scale, based upon the average human hearing capability, the level drops to 20 dBA. This is because the majority of the turbine noise is produced in the infrasound range (frequencies below human perception), which is quieter than a whisper. Ultimately, the test determined that the noise level produced by the small VAWT is insignificant and poses no threat to the comfort of nearby persons or wildlife.

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