RACA Journal September 2021 | Page 47

Project
The Carrier heat recovery chiller . refrigerant is contained in the two chillers on the roof . With no refrigerant gas circulating through the building and intelligent leak detection on the chillers , this greatly reduces the chances of having a leak and eliminates the risk of leaks going unnoticed .
To further enhance energy efficiency of the HVAC system , air-to-air plate heat exchangers were added into the new air handling units ( AHU ). The heat exchangers were also specified with bypass-dampers to allow an economy cycle when outside conditions permit .
The same plant footprint now has sufficient capacity to supply the entire building and not only two of the six wings .
Additionally , the severe impact of Covid on the shipping industry meant each piece of imported equipment was delayed . CP flew in what they could with the assistance of the suppliers but could not arrange this for the larger pieces of equipment . With close co-ordination between Lombard Consulting Engineers
ELEMENTS OF DIFFICULTY IN THE PROJECT
Working in a partially occupied building is always difficult and
required open lines of communication with the occupants .
All parties had to ensure a seamless , covid-friendly transition
from occupied space to site and back to occupied space in a
very short period .
Limited availability of existing as-built drawings made
pre-contract planning of vital importance to ensure
everything would fit as was intended . The ceiling void was
designed for small refrigerant pipes , not larger chilled
water pipes . With some clever engineering , the team could
optimise riser locations to keep the pipes in the ceiling void to
the smaller diameters .
The type of composite pipe specified for use in the void
was crucial to this project ’ s success as it required no hot works
or welding , does not sag under warmer temperatures , and
increased the speed of installation ultimately enabling the
team to meet the very tight deadline .
The limited plant space on the roof also proved difficult
to navigate , however , with the aid of Revit and AUG
( Augmentecture ) the LCE and Coldfact Projects ( CP ) team
was able to install a 1200kW plant with two large air handling
units in the same space that was previously fully occupied by a
250kW VRV system and two heat recovery wheels .
www . hvacronline . co . za
RACA Journal
I September 2021

45