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Project
takes place to transfer energy onto the slabs . Emissivity then occurs with the aid of air circulation . For the offices located on the perimeter of the building , windows need to be opened for the TABS system to take effect . For the offices located in the middle of the building , the fresh air supplied from the roof-top package unit aids in the transfer of temperature from the slabs into office spaces . The communication between the chiller and the TABS control unit is through sensors that are installed in the slabs throughout the building . This in turn communicates as to how much chilled water can be generated from the chiller and in turn , the chiller does not run at 100 % capacity – to save energy consumption .
ELECTRICAL ROOM AND SERVER ROOM AIR- CONDITIONING SYSTEM The electrical room and the server room require cooling at all times to prevent overheating of the equipment being stored in the rooms . The cooling is achieved by means of two midwall split units installed in each room . An outdoor VRV system was ideal in this case as it reduced the need to have two outdoor units . This reduced the footprint of the installation . Furthermore , this meant that longer pipe runs could be achieved .
All floors at the CLM building have toilets . Due to space constraints , the system was forced to use one extraction air fan for both sides of the toilets . That is , one fan extracts from the male and female sides of the building .
SUNDRY FACTORS AND RISK MITIGATION During the design phase , Maninga Engineering highlighted that the TABS system uses thermal comfort as a way of temperature control . As part of risk mitigation , the design opted for the route of increasing the fresh air system air flow in order to increase the system ’ s efficiency .
For the server room and the electrical battery room , a VRF system was ideal because it has longer pipe run allowance . This was crucial in a sense that otherwise the façade of the building would be tainted with pipes running from the roof plant .
The usage of chilled beams eliminated the noise generated by conventional HVAC systems . The chilled beams seamlessly met the requirements of the acoustic engineer for the meeting rooms and the recording room . The chilled beams , coupled with the roof-top package unit , also eliminated the formation of condensate .
The two chilled beams used on this building are hydronic module chillers and they use R32 refrigerant gas . The refrigerant gas meets the Global Warming Potential ( GWP ) requirement as it is not part of the group of hydrofluorocarbons ( HFCs ) refrigerant gases .
Occupants ’ thermal comfort is the primary objective in radiantly heated or cooled space . To provide an acceptable
Fresh air supply system .
thermal environment for the occupants , the requirements for general thermal comfort shall be taken into account by using the index of predicted mean vote ( PMV ) or operative temperature ( OT ), and local thermal comfort , for example , surface temperature , vertical air temperature differences , radiant temperature asymmetry and draft .
The operative temperature range corresponds to 20-24 ° C for cooling season and 23-26 ° C for heating season in spaces with sedentary activity .
The main advantages of using the TABS system are :
• Reduced building height ( saving 500-600mm per story of building height )
• No suspended ceiling is needed to cover air ducts which results in a significant saving of building materials
• It is also possible to operate the system at 30-50 % lower peak loads allowing reduced plant sizes and possible operation of heating / cooling systems with temperatures close to room temperature – allowing increased plant efficiency
• No noise levels . RACA
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RACA Journal I January 2024 www . refrigerationandaircon . co . za