Wind Speed Measurements

We have access to many meteorological sites around the country that give detailed data on wind measurement including access to NIWA wind maps. This information gives a good indication of the general wind conditions in your area. However, localised conditions can be very different.

Gaining a better idea of your wind conditions can be done in various ways to differing levels of accuracy:

Looking at relevant wind data and using local knowledge to assess if you are in a windy or sheltered spot compared to the local area. This is highly subjective and will only give a rough indication.

Using the Griggs Putnam Index of Deformity as shown below. This uses local conifer tree growth and gives a good indication of long term wind-speeds gathered over the lifetime of the trees. It is surprisingly accurate but is still somewhat subjective.

The most accurate method is to undertake a wind survey by installing an anemometer and taking readings. Ideally you would have a minimum of 1 year of data although longer would be more accurate. These would be compared to national figures to assess if the year was a standard one.

To reduce time (with a subsequent loss of accuracy) three months readings could be taken and then compared with a local site. This comparison can then be extrapolated to give an annual variation from the local site.

Griggs-Putnam Index of Deformity

Wind Speed	I	II	III	IV	V	VI	VII
km/hr	11-14	14-18	18-22	22-25	25-29	29-32	36
Knots	6-8	8-10	10-12	12-14	14-16	16-18	20
m/s	3-4	4-5	5-6	6-7	7-8	8-9	10

Tecnico can help with all of these methods and are happy to advise you further.