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BEST
PR
O
JECTS
80
CONSTRUCTION WORLD
DECEMBER
2015
Project information
• Company entering: WBHO Construction
• Project start date: 29 October 2012
• Project end date: 31 October 2014
• Client: Redefine Properties
• Project team: 90 Grayston Drive Team
• Main contractor: WBHO Construction
• Architect: GLH Architects
• Principal agent: Betts Townsend
• Quantity surveyor: MLC Quantity Surveyors
• Consulting engineer: Sutherland
• Project value: R280-million
Afrisam Innovation Award for Sustainable Construction
E
The 90 Grayston Drive building is a 21
level office block development with
11 parking levels, one atrium level
and nine offices. It is a multi-functional
building with 19 343 m
2
of office space and
946 parking bays.
The building was designed to have a
unique and aesthetically pleasing façade
which makes it stand out above the neigh-
bouring buildings in Sandton. The external
façade cubes and rectangles on the façade
are a series of cantilevers that are protruding
in and outside of the building envelope.
The building was designed to have very
little impact on the environment. This led
the designers to opt for the use of ammonia
chillers for air conditioning and rain water
harvesting for flushing toilets.
The building has been designed to
have a double façade based on the explora-
tion and testing by Le Corbusier in the 20
th
Century. The two glass skins form a 900 mm
cavity and they are positioned so that air
flows naturally between them. This contin-
uous natural flow of air in the façade cavity
improves the energy performance of the
building in all seasons. The double façade
system also provides more insulation than
conventional types.
The architects, Grosskopff Lombart
Huyberechts & Associates opted for a new
look on the façades called ‘fritting’. This
is essentially a high resolution decora-
tive glazing with continuous lines flowing
throughout all the panels of glass.
The building is fitted with ‘intelligent
blinds’ which follow the sun throughout the
day. The façade is fitted with sensors that
track the movement of the sun and guide
the blinds to provide optimum protection
from the heat and glare so the interior stays
comfortable in all weather conditions.
In a drive to minimise the energy
footprint, the elevators were fitted with
an advanced, high speed elevator manage-
ment system which swiftly delivers the
passengers to their chosen stop while
conserving energy.
90 Grayston has been designed for
optimal power efficiency. The building
draws 1 700 kVA from the council supply and
is backed-up by two synchronised diesel
generators providing 100% standby power.
The diesel generators are fed by a bulk diesel
tank that allows 24 hours standby power
without being refilled.
A cast resin transformer located on
the roof supplies the mechanical cooling
chillers, minimising maintenance and
increasing electrical efficiency. The lighting
is integrated with motion sensors fitted in
the parking areas, common areas and rest
rooms to activate lighting when these areas
are in use.
The water system has been designed to
use water wisely and reduce waste to the
barest minimum. The building will harvest
rain water into tanks that can store up to 70
cubic metres, which will be used primarily
for toilet flushing.
The project structure programme was
essentially 21 levels in 16 months. This
appeared to be a daunting task until the
entire project team started to re-engineer
the building to achieve programme.
This process yielded changes to the
slabs from conventional reinforced concrete
slabs to post tensioned slabs, to reduce the
amount of reinforcement steel to be handled.
This led to 90 Grayston Drive being amongst
the few buildings with Post Tensioned slabs
throughout all levels.