Can I put a small turbine on my roof or on a pole fixed to the building?

Current planning regulations state that roof or building mounted turbines are not exempt from the planning requirements. Therefore an application to your local authority through the normal planning mechanisms is required. Only mast mounted turbines of a certain size may be exempt from planning requirements under certain conditions.

Building mounted turbines have a history of poor performance. The building itself affects the flow of air around it. Even if the turbine is fitted in a position well above the uppermost part of the pitch or flat of the roof the airflow is still negatively impacted. Thus the output from the turbine is often very low and the return on the investment non-existent.

The ideal air flow over the blades of a turbine is smooth, constant and unidirectional over a period. In aerodynamics this kind of air flow is known as laminar flow. When air flow meets an obstruction currents, or 'eddies', are induced, creating turbulent flow. Visualise the wake caused by a rock in a fast flowing river or rapids.

Turbulent flow is not only undesirable for efficient electricity generation it is also undesirable from a mechanical point of view. The turbulent flow causes the turbine to yaw excessively in an attempt to always face into the wind. This excessive yawing causes cycling forces and premature wear on the unit and may significantly reduce its life span and increase maintenance costs.

If you choose to go ahead and apply for planning permission to mount a turbine on an inhabited building it should be remembered that there will be some vibration and noise transmitted into and through the fabric of the building. The transmitted vibrations and noise may not be fully counteracted by damping or sound proofing of the mounting. For that reason if you are choosing to mount a turbine on a structure it is advisable to seek planning to mount it on an adjacent non-inhabited building or solid separate structure.