Figure 48: Vegetation can be used for shading, altering the microclimate and modifying the wind direction. Selecting the appropriate variety of plantation and its placement are key factors that determine how well the vegetation will serve its intended purpose

• Shading of vertical and horizontal surfaces (green walls) • Buffer against cold and hot winds • Changing direction of wind

Vegetation is a flexible controller of solar and wind penetration in buildings. It reduces direct sun from striking and heating up building surfaces and lowers the outside air temperature which in turn effects the heat transfer from outside to building envelope and interior. It can also be used as internal shading element. Used as such, plants increase the shading coefficient, a measure of the efficiency of shading devices, without compromising on external views. Plants moreover grow in the direction of sunlight and the growth varies with seasons and when used keeping in mind seasonal variations at the building location, can be cost effective, flexible shading elements.

Green roofs or roof gardens can also be used as they help to reduce heat loads in a building. The additional thickness of the growing medium provides extra thermal insulation. These also retain moisture from rainwater further cooling the roof surface. The green cover lowers ambient temperatures through evapotranspiration. Green roofs can be categorised as intensive, extensive and modular bocks. The biggest difference is with respect to the depth of soil and resultantly, the type of vegetation that can be supported in each of the types. Soil depth in intensive green roofs is at least 300mm, in extensive roofs about 25 to 125 mm, and in modular blocks about 100mm. Roof structures have to be sturdy for supporting green roofs as these impose greater dead weights than normal roofs.

Proper landscape design and vegetation can be used effectively by architects from an early design phase to lower the ambient temperature and thus reducing the resulting demand for air conditioning loads in a building.

It is preferable that architects should work with existing terrain of the site, natural topography and local species for appropriate landscaping.

FIGURE 48: VEGETATION CAN BE USED FOR SHADING, ALTERING THE MICROCLIMATE AND MODIFYING THE WIND DIRECTION. SELECTING THE APPROPRIATE VARIETY OF PLANTATION AND ITS PLACEMENT ARE KEY FACTORS THAT DETERMINE HOW WELL THE VEGETATION WILL SERVE ITS INTENDED PURPOSE

Use of local species for vegetation is highly recommended as they are accustomed to the variations in temperature, rainfall patterns and soil conditions for that region. They are relatively low maintenance in terms of water usage, and are resistant against local pests. In addition, that also support birds and insects that thrive naturally in the region and help maintain the balance of natural flora and fauna.

It is recommended that exotic species should cover no more than 25% of the landscaped area of a building.

Reduce lawn area in the garden to a minimum to reduce the amount of water that is needed for irrigation.

Reduce the area of hard paved surfaces through the use of polypropylene grass pavers. Absence of hard surfaces also ensures lower ambient temperature. It is also more pleasant for pedestrians to walk on a green, soft surface that does not radiate heat.