17. Plant Selection and Placement Criteria for Landscape Design

This study explores how landscape design can be optimized by considering specific plant traits and their corresponding temperature reduction potential. An initial study was conducted with the aim of quantifying the impact of rooftop greenery on mean radiant temperature (T _mrt ). Results show that under clear sky conditions, plots with vegetation can reduce surrounding T _mrt by up to 6.0 °C. The effect in temperature reduction is evident for a distance up to 3.0 m away from the center of the green plots. Thereafter, a second set of measurements was made to identify specific plant traits that contribute to temperature reduction. Results indicate that the temperature reduction potential of different types of vegetation varies according to their physical characteristics as well as physiological attributes such as plant evapotranspiration rate and shrub albedo. An empirical model was developed to establish the relationship between T _mrt reduction, plant evapotranspiration and shrub albedo. Findings from these studies are used as a basis to formulate a framework for landscape planning and design. In the proposed framework, vegetation as well as building information are superimposed using a Geographical Information Systems (GIS) platform. A hypothetical scenario is used to illustrate the efficacy of the proposed landscape planning framework.