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Project
Main ductwork feeding chilled beams .
• Quiet operation : Chilled beams generate minimal noise as they do not have large fans or blowers . This low noise level is advantageous in environments like exam venues where a quiet atmosphere is essential for concentration . Laboratory environments require silence as well , so the students can listen to instructions clearly as well as concentrate .
• Improved air quality : Chilled beams can be designed to work in conjunction with dedicated fresh air systems or other ventilation systems . This allows for the supply of fresh , filtered outdoor air , promoting better indoor air quality . ASHRAE standards recommend the use of ventilation systems capable of delivering an appropriate amount of fresh air per occupant and per space .
In addition to thermal comfort , indoor air quality is another crucial aspect to consider in laboratories and exam venues . Chilled beams contribute to maintaining good indoor air quality in the following ways :
Indirect air distribution : Chilled beams operate without actively recirculating room air , thereby reducing the spread of airborne contaminants . This indirect air distribution helps minimise the potential for cross contamination between spaces .
Air filtration : By integrating chilled beams with a dedicated outdoor air system or central air handling units , air can be filtered to remove particulate matter and contaminants before being supplied to the space . This filtration process helps maintain a healthier indoor environment .
Moisture control : Chilled beams can help control humidity levels in the space . When properly designed and integrated with
the building ' s HVAC system , they can effectively remove excess moisture from the air , reducing the risk of condensation and mould growth .
SITE CONDITIONS AND INSIDE CONDITIONS REQUIRED Johannesburg has a hot summer ( November – March ) and a mild , drier winter ( May – September ). The peak travel times are March – May and October – December .
Site conditions : Johannesburg Wits Flower Hall Building :
• Altitude 1 753m
• Outside Design Conditions Summer 32 ° C db and 21 ° C wb
• Inside Conditions Required
Exam venue :
• Temperatures Summer 22.5 ° C +/ -1.5 ° C db
• Relative Humidity 50 % RH
Laboratory :
• Temperatures Summer 19.5 ° C +/ -1.5 ° C db
• Relative Humidity 50 % RH The plant is designed to control or maintain temperature in the individual spaces within a temperature variation +/ - 1.5 ° C of the design . Humidity – which is not controlled beyond the prevention of condensate and mould – will vary depending upon the outside conditions , the time of day and the occupancy .
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RACA Journal I February 2024 www . refrigerationandaircon . co . za