Wind across an open urban plaza makes the space unattractive for people. Place planting and trees strategically to create comfortable spots for people to sit, walk and play, and to create areas of privacy.
Shade beneath a tree can make the apparent temperature at ground level 5-20˚C cooler. This perceived temperature beneath a tree is lower due to the reduction of direct sunlight that reaches the ground and evapotranspiration of water via the leaves. Deciduous trees allow sun to reach the ground and heat the surface in winter, and prevent the sun from reaching the ground and heating the surface in summer. Not only trees but also vine-covered pergolas and other planting can deliver shade solutions. Ground-cover plants can also reduce surface heat.
Protect outdoor spaces from local air pollution through the use of vegetation, Trees and greenery can act as a buffer to prevent local sources of pollution, such as from traffic, from entering the plaza. Trees and shrubs can force the polluted air upwards so it blows over the plaza and not through it. A continuous canopy of trees over a plaza can prevent background air pollution from settling in the plaza.
The temperature, season, and time of day determine where people prefer to sit in a plaza. Personal preferences also vary: some people enjoy sitting in the full sun, others prefer to sit in the shade. Use plants to provide a variety of places to sit, walk or play so everyone has a choice
Prevent local hot spots in urban plazas by planting trees to increase shade and reduce wind and make outdoor spaces more comfortable.
“People want green and trees in plazas. Trees can function as protection from the wind and sun. But they need to be planted in the right spot, otherwise they can actually create a wind tunnel effect.”
Sandra Lenzholzer, Wageningen University
In new development:
Base the design and layout of new urban spaces on the microclimate and existing conditions of the space and the way the plaza will be used. Use green to make spaces more comfortable.
In existing development:
Plant trees with wide canopies in order to increase the amount of shade on the surface in plazas, public outdoor spaces and along streets where shade is desired. Use shrubs, pergolas and green walls where wind protection is needed.