The UK wind tunnel facility at the UKAS laboratory of Young Calibration has its’ ISO 17025 accreditation schedule upgraded for the calibration of Ultrasonic and Rotating Cup Anemometers.These anemometers are often utilised in windfarm feasibility studies to determine the wind power density estimates and to improve the energy production predictions of future wind farms. Critical to improving the energy predictions and modelling data are the baseline calibration and measurement uncertainty of the in service anemometers. Accredited calibrations for Ultrasonic anemometers to ISO 17025 across wind speeds of 0.05 to 80 m/s are now feasible with a measurement uncertainty from 0.16% + 0.0003 m/s using laser doppler anemometry reference standards.