Estimating wind speed

Estimating wind speed

To find an estimated annual average mean wind speed (AMWS) for your proposed site you will need a grid reference number. Click here for our simple guide on how to obtain this.

The NOABL database provides a good idea of the wind at a site and gives us the annual mean wind speed.

This database requires the land ranger coordinates; these are the grid references that are formatted with two letters at the start followed by 6 numerical digits. Write down your grid reference and space it so that you have the two letters and then the numbers are split into 2 even groups of digits. The leave out the number on the end of each block of numbers, shown in red in the below example:

Grid Reference: NY 795 022

This gives us: NY 79 02

Enter into NOABL database: NY7902

The NOABL database gives the long term average and there a few things to think about in regards to the results for your site

  1. This average (mean) speed is based on the 1km grid square that you fall into. This means there will be a difference in average speed within the grid square, if you are on a hill your wind speed will be higher, if you are on a valley floor, it will be lower.

  2. Factors are applied because wind will slow down as it passes over obstacles, whether they are nearby and over longer distances,

  3. The wind speed is not measured at your site, it is calculated and could overestimate as easily as underestimate.

You can see a list of terrain categories and information on the nature of the surrounding site by following this link.

 

Variation from NOABL

An example of where the data may vary is in Hebenbridge, a land of steep valleys, the wind speed is given as 3.5 m/s, deemed too low for useful power. Wind measurements on the top of the hills were recorded as 5.2 m/s.

Speak to us today if you need any assistance estimating your wind speed.

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