www . refrigerationandaircon . co . za RACA Journal I January 2024 33
Project
Filtered fresh air was to be introduced to all spaces according to the National Building Regulations . The fresh air systems consist of weather louvers , attenuators , filters , fire dampers , fresh air fans diffusers , ducting and volume control dampers . Various extraction systems are also included in the scope of works .
The second part of the HVAC system is the temperature control . This element is purely for comfort purposes . Hourly Analysis Program is software that is used to calculate the amount of cooling and heating energy required in a space . The system factors both sensible heat and latent heat . To achieve the cooling and heating of the CLM building , an HVAC system consisting of the following was installed :
• Chilled beams
• Mini VRV outdoor unit
• Two air-cooled chillers
• Rooftop package unit
• An extraction system
• All these systems form part of a complete HVAC system for the building .
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MEETING ROOMS ’ AND OFFICES ’ AIR- CONDITIONING SYSTEM The CLM building is a three-story building which has meetings and boardrooms placed on the west side of the building throughout the three floors . In the meeting rooms and board rooms , a chilled beam system is used to achieve the required heating and cooling through chilled water . The chilled water is generated from the chiller which is placed on the roof and is dedicated to supply all the meeting rooms and boardrooms placed on the three floors . The chiller uses an R32 refrigerant gas which is able to achieve heating in the cold months and cooling in the hot months .
The roof-top package unit supplies fresh air into the area using ducts . The fresh air is dehumidified to prevent the formation of condensate . Hence the chilled beams do not require any condensate drain pipe .
The fresh air from the roof-top package unit extends through the building to supply offices located in the centre of the building . This is because the offices in the middle of the building do not direct fresh air from the outside . It is worth noting that fresh air supply is necessary as per SANS 10400 Part O . In the atrium , there are two extraction fans that ensure there is air circulation throughout the building . Temperature control is achieved through TABS . The design for the TABS system is guided by ISO 11855-4 . The standard gives guidance as to how the TABS system should be designed for optimum performance .
TABS is a system comprising of pipes installed in the slabs of the building and a chiller to supply chilled water into the pipes . Water is circulated through the pipes , and in turn conduction
1 . Wits CLM east elevation . 2 . Atrium extraction fans . 3 . Chilled beam booster pump .
“ The chiller uses an R32 refrigerant gas which is able to achieve heating in the cold months and cooling in the hot months .”
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www . refrigerationandaircon . co . za RACA Journal I January 2024 33