Wind flow over urban areas is very difficult to characterize. This is due to a number of factors, such as high turbulence and other strong effects created by complex urban geography. When placing wind turbines, it is critical that the exact flow pattern of the area is well understood.
Current urban wind assessment tools are costly in relation to the cost of a small wind turbine. It can take up to a year and cost €12,000 to carry out the necessary measurements, which can easily double the cost of placing a single turbine.