TECHNICAL 15
USAGE PHASE OF CONCRETE IS GREENER The energy requirements of a completed
the owner or user needs to understand
that draughts do not negatively affect
structure, once occupied and operational,
the sustainability features incorporated
energy usage for heating and cooling.
are still too often overlooked in assessing
in the structure.”
• Designing buildings to use solar energy
the “green” or sustainability status of
Impor tant design considerations
and tap into the benefits of thermal
to ensure sustainability in concrete
mass to save energy.
structures include:
• Designing structures to reduce the
ity in the design of concrete structures
• Ensuring that the building is orientated
requirements for maintenance or
should pay more attention to lowering
to take advantage of natural elements
to make maintenance simple and
energy usage during the full life of the new
to provide natural lighting, heating
cost-effective.
buildings they create, says Bryan Perrie,
during winter, cooling during summer
• Designing structures to promote
MD of The Concrete Institute (TCI).
and natural ventilation.
new developments. Architects who strive for sustainabil-
saving of finite resources by, for
• Ensuring correct window and door
example, designing systems to pro-
level of sustainability of a new building
type and placement to take advantage
mote rainwater harvesting, re-use
is heavily judged on its design with
of sunlight during winter, as well as
of grey water and other water-use
rating systems such as the Green Star
the flow of air from prevailing winds.
efficiencies.
system of the Green Building Council
Eave depths should be designed to
of SA and the Leadership & Energy in
shade the inside of the building during
Lifetime costs
Environmental Design (LEED) system in
summer, but allow winter sun to
“Engineers focus on structural de-
the USA, bestowing points for various
warm rooms.
sign, construction materials and the
sustainability initiatives during the design
• Using atriums, wind/stack ventilators
construction process itself, as well as
stage of a building.
or ventilation panels to assist natural
recycling, resource conservation and
ventilation, and under-floor vents or
embodied energy. These are commend-
Cost offset
permeable ceilings to unlock the
able, but far too little attention is paid by
“However, these systems often lead
thermal mass in the upper part of
this profession to the use phase and full
to chasing poin ts f or a p ar ticular
concrete slabs.
life-cycle assessment of new structures.
rating, rather than concentrating on
• Choosing roofing and external wall
real sustainability stretched over the
material and colours that will reflect
lifetime operating energy consumption
entire life-cycle of a new structure,”
heat away (lighter colours) from the
c o u l d r a n g e f r o m 8 7- 97 % o f t h e
says Perrie.
building or absorb solar energy (darker
structure’s total energy requirement,
He adds that there are substantial
colours, dark floor tiling) to reduce
while the embodied energy accounts
economic benefits to considering life-
energy demands for heating or cooling.
for only 3-13% of the total energy. This
cycle costing from the outset. “The
• Choosing the correct insulation type
makes it clear that the use phase of
potential increase in cost during the
and location. A well-insulated roof and
a building is the major contributor to
design and construction phases of a
floor may keep the interior temp-
sustainability,” says Perrie.
‘green’ structure will generally be more
erature cooler in summer and cut
than offset by the savings from reduced
air - condi tioning costs, bu t may
energy consumption during the use
pr e v en t w in ter solar hea t f r om
phase of the concrete structure. The
being absorbed into the interior of
architect or designer needs to assess
the building.
the inter-relationship of all factors, while
• Air- and weather-proofing to ensure
In many countries, including SA, the
PRECAST | ISSUE ONE | 2020
“Research has shown that a building’s
(Above, from left): Atriums could provide natural lighting in any type of new structure, particularly heavy electricity consumers such as shopping malls, and energy-saving measures during the use phase of a city’s concrete structures are often overlooked by the designing profession, says The Concrete Institute.
