Recent visitors to the airport may have noticed a long, low building sporting a fuzzy green growth.

Soon to be part of the Auckland International Airport offices, the green roof is the work of innovative Auckland company Stormwater 360.

The company were also behind the small green roof at Wynyard Quarter, and a more substantial project - the 900 square metre green roof on the Mt Difficulty winery in Central Otago.

The benefits of green roofs are numerous - they catch and hold about 70 per cent of the rain that falls on them, so significantly reduce run-off (the reason our beaches often end up with sewerage on them).

They also prolong the life of the roof, by protecting it from the sun, and reducing the contraction and expansion wear and tear of an exposed roof.

The evaporation from the plants also cool the building in summer, and the thick substrate serves as as insulation in winter.

The combined effect of many green roofs in an urban environment have the effect of cooling the district.

As the plants grow, they also provide an urban haven for birds and bees.