Home' Trinidad and Tobago Guardian : June 5th 2014 Contents BG16 | COMMENTARY
BUSINESS GUARDIAN www.guardian.co.tt JUNE 2014 • WEEK ONE
Walk along the streets of
any urban centre in
T&T and it is impos-
sible to ignore the
sweltering heat beneath
your feet, radiating from beneath the surface
of the road itself. This is as a result of the
phenomenon known as the urban heat island
According to the US Environmental Pro-
tection Agency, an urban heat island is created
in developed areas as built surfaces absorb
and retain incoming solar radiation. Built
surfaces are impervious and resist infiltration
by air or water.
These materials are usually dense and
compact and so prevent the movement of
air and water (cooling agents) through these
impervious surfaces thereby creating hot
The retention of heat by these built sur-
faces---particularly roofs and pavements--- increases land surface temperature significantly.
The heat is trapped within the "island" of the urban
area as the vegetation of the neighbouring suburban
and rural areas cool the surrounding air through evap-
oration and transpiration. Built surfaces are impervious,
and so cannot be infiltrated by air or water. The
tightly packed composition of these materials prevents
the movement of air and water which are key in the
process of evaporation and transpiration. These imper-
vious surfaces therefore become proverbial hot beds.
Urban Heat Island Impacts
The impacts of urban heat islands include increased
energy consumption, higher concentrations of air
pollutants and poorer water quality. As temperatures
rise and people seek to cool themselves, energy con-
sumption surges. The resulting strain on the electric
grid causes an overall reduction in the strength of
electrical output and an increase in the frequency of
There are also more direct implications for public
health and social well-being. Heated air fosters a
higher concentration of air pollutants and promotes
the creation of ground level ozone which triggers a
number of health problems and exacerbates the effects
of respiratory diseases like emphysema, asthma, and
bronchitis. Extremely hot days have a particularly
severe impact on vulnerable groups like children and
the elderly with the added risk of heat exhaustion.
Heated urban surfaces also increase the temperature
of storm water run-off flowing into surface water-
courses and surrounding seas.
Warmer temperatures alter habitats and life cycles
of aquatic life and encourage the migration of species
to cooler marine environments. These changes in the
behaviour of marine species have already begun to
affect the availability of some commercially-important
species. Also of great concern, especially as it relates
to tourism, is the impact of higher sea temperatures
on coral health since previous warming events have
led to coral bleaching.
Cooling it down
The uses of building materials that mimic natural
systems are one of our greatest tools in reducing urban
heat island impacts. Natural systems have greater
albedos and thus are better at reflecting solar radiation.
As such, they do not heat up as much as the built
environment. Globally, many cities have created cool
roof and cool pavement initiatives to increase the
reflective properties of urban surfaces. These initiatives
include a variety of solutions such as repainting
surfaces in lighter colours and use of materials with
high solar reflectance.
Our twin isles are less than 12 degrees north of the
equator and we cannot afford to degrade our natural
cooling system through the widespread use of untreat-
ed, impervious surfaces.
Disturbingly the development trend in T&T involves
the clearing of forested areas and an overuse of imper-
vious paving materials. Planned developments may
retain trees and grow manicured lawns for aesthetic
purposes but the trees are usually isolated and the
lawns bordered by impervious surfaces. Research sug-
gests that larger, well-connected vegetated areas do
more to reduce the impacts of urban heat islands.
If this current development trend continues, we
can count on more heat in the place.
Submitted by a member of the
T&T Society of Planners
Heat in the place
T&T Society of Planners
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