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.

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The integration of wind energy converters into buildings, and
here in particular into high-rise buildings, is a challenging problem which is still largely unsolved.

A modern adaptation of the vertical axis Sistan type windmill was investigated looking at its efficiency as an energy converter and its possibilities for architectural integration.

Theoretical development, employing geometry changes to
induce a 2D flow field as well as flow separation to induce a low-pressure zone at the leeward end, indicated that maximum
converter efficiencies of 48–61% can be expected.

Model tests were conducted to test the theory, and efficiencies of 42% for the highest measured power output were determined.

The simplicity of the proposed design will allow for cost-effective construction and the optically solid view means that the machine can be integrated architecturally.

This is felt to be a significant advantage compared to many current wind turbine designs which often appear out of place
if installed on a building.