Vertical axis resistance type wind turbines for use in buildings

Renewable energy generation in the urban environment has been receiving an increased attention over recent years due to the proximity with the point of use. Building integrated wind turbines are an interesting option in this respect. However, due to technical as well as architectural barriers, the uptake of wind energy converters into buildings has been rather limited. This paper analyses the oldest known form of wind energy converter, the Sistan type windmill, and discusses modern adaptations of this drag force type energy converter for building integration. It is shown that design improvements can lead to an increase of the theoretical efficiency of a drag force type rotor to about 48% (conservative) or 61% (optimistic). Initial experiments with a scale model have shown that efficiencies higher than 40% can be achieved. The integration of the proposed design into buildings is related to current building integrated wind turbine types and demonstrated architecturally.