Wind monitoring is one of Dulas’s core activities. We have many decades of experience and offer a complete service, from initial planning, through installation and operation right up to decommissioning.

Project overview

A major energy supplier asked us to install a met-mast at a remote upland location in Wales. The wind data was to be collected using instruments mounted on a 90-metre met mast, comparable in height to the anticipated hub height of the wind turbines. As well as wind speeds and directions at different heights, the data would also show the impact of the site’s topography, and as a result, identify the optimal siting of each turbine. Additionally, the data would be used for overall wind farm energy generation calculations (to give an expected capacity factor) and can also be used during noise monitoring.



The process of installing a met mast starts long before the actual build. Every mast is subject to local authority approval, and before this is granted, various criteria must be surveyed and assessed. These can include impact on the local ecology and local archaeology, which has to be noted and protected from potential damage. Any constraints arising from the legal status of the land – common land, forestry, rights of way – must also be addressed.

In this case, the intended location of the site is an area of upland grazing. Our site surveyors identified a suitable location that would deliver the required wind data.

Dulas’s ability to handle every aspect of wind monitoring in-house delivers a significant advantage. We have known situations where surveyors not later involved in the installation have identified locations that create logistical problems. Moving the mast location just tens of metres could have made installation simpler, but deviation is not allowed without revised plans being submitted and approved. The choice then is to proceed with the sub-optimal site or submit new plans. Either way, there is extra expense and delay.


Raising the mast: the gin pole comes down from vertical to horizontal, so the mast goes up. (Photo from another Dulas project in the UK)

Our installation team transported the mast sections on a lorry as far as surfaced roads allowed, then to the final site on a tractor-towed trailer. The mast itself was one of our tubular ‘tilt-up’ types. With this type of mast, the mast sections are bolted together while laid out on the ground. Once the mast is assembled, a gin pole about twenty metres long is erected vertically. This is used in combination with a winch and some muscle to rotate the mast up around a pivot.

Our tubular tilt-up masts are held in place by eight galvanised steel guy wires, anchored around the mast. As the mast is raised to the vertical position, adjustments are made as necessary to equalise the tension in all eight guys. As the gin pole moves from vertical to flat on the ground, the mast is raised to the vertical.

Instruments are then mounted on the mast at various heights. We use a solar PV array to power the aviation light atop the mast.

The PV array and the datalogger. The datalogger includes a modem so that the collected wind data can be examined remotely.

In operation

The met mast is generating a vast amount of wind data. All the data can be downloaded and examined through a web portal.

We carry out two maintenance visits a year, checking the instruments and the integrity of the mast and guy lines. When the time comes, we will also handle the decommissioning of the site. This will involve not only removing the mast and associated equipment but also returning the site to its original state.

Benefits delivered:

A one-stop solution.
The initial site survey, planning application, design and build of the mast, instruments and power supply were all handled in-house.

Single point of contact.
As we handled the whole process, our client had just one point of contact throughout.

Reduced risk.
By handling everything ourselves, we avoided problems that can easily arise when multiple agencies lack a holistic overview of a project, for example ensuring a location is suitable for installation of the mast prior to planning submission.

Accurate, bankable data.
The met mast not only provides the data needed for the optimal siting of turbines but is also ‘bankable’ – acceptable to investors.

Jeremy Brett
Project Manager

For further information, feel free to get in touch.

Renewables Tel: 01654 705 000

Images shown in this article are of another Dulas project in the UK.