Abstract:
Global population growth and rapid urbanisation have resulted in the rapid transformation
of natural topographies that are now dominated by engineering materials and structures.
It is widely recognised that economic development is largely attributable to infrastructure
development. However, this development has come about with adverse consequences. In
this paper, the effects of surface characteristics, climatic parameters and material properties
on the thermal environment and near-surface heat islands in urban areas were investigated.
An experiment was conducted in which simple concrete structures with varying surface
characteristics were constructed and instrumented. The effect of solar absorptivity was clearly
visible, with structures surfaced with low absorptivity materials exhibiting lower surface and
effective temperatures. Following the experimental programme, numerical simulations of
the simple concrete structures were performed using finite element modelling. The analyses
showed that the thermal environment of concrete structures is sensitive to changes in solar
absorptivity, climatic parameters, cross-sectional dimensions, and material properties. It
was found that the use of low absorptivity or highly reflective surfacing and the selection
of appropriate dimensions can be used to significantly reduce the temperatures of concrete
infrastructure, including buildings and pavements, thereby providing an evidential basis for the
use of low absorptivity surfacing materials to mitigate climate change in Southern Africa.
