To work out the grid reference of your location you will need an Ordnance Survey map of either Great Britain or Northern Ireland. Road atlases or local maps may do instead. Please go to the Ordnance Survey website and click on Get-a-map link.
Grid references are split into three parts:
- The 100km square in which they lie
- The Easting
- The Northing
The 100km square is identified by two letters for Great Britain and one letter for Northern Ireland. These are usually written on the Ordnance Survey map or in the map key. On a Landranger 1:50,000 or Outdoor Leisure map the two letters will be printed quite large and in blue. In Ordnance Survey atlases sometimes the 100km grid squares are shown on a special page at the beginning or end of the book.
The site grid reference within the 100km square uses the grid marked on the map. Use this grid to find the co-ordinates of the south-western corner of the 1km square in which your site lies. To work out the co-ordinate take the first two digits of the number on the East-West axis of the map (written usually at the bottom) and the first two digits of the North-South axis (written usually at the left-hand side of the map).
For an interactive tutorial on finding grid references try the Ordnance Survey website. From their home page click on "Get-a-map", then "understand mapping" on the left hand menu, then under the paper mapping title click on "map reading".
Great Britain example
Junction 15 on the M1 exit for Northampton is in 100km grid square SP. Within this square the junction is situated at 75km East and 54km North. We write this as SP7554. Make sure that you include any zeros in your reference for example 1km East and 5km North in grid square SP would be SP0105.
Northern Ireland example
Junction 2 on the M1 in Belfast is in 100km grid square J.
Within this square the junction is situated at 31km East and 71km North. We write this as J3171.
Make sure that you include any zeros in your reference for example 1km East and 5km North in grid square J would be J0105.
Note: These grid references are not the same as the longitude and latitude of the site.
To convert a post code to grid reference click on streetmap.co.uk
You will need to edit the eight character LR value that's returned:
Eg. DECC headquarters post code is SW1A 2AW. Typing this into the conversion tool returns: LR - TQ301802
This value is made up of three values - two letters, and then two sets of three numbers - TQ 301 802 for the above example.
The database uses a six digit grid reference, so you need to drop the third digit from each of the two numbers: this would make the above example TQ3080
Click on the Wind Speed Database
Select a region and type in the six character grid reference as described above (with no spaces) and then hit the Find Wind Data button. This should return the wind speeds for the location you specified.