Repeated measurements were taken in a printers' office where one case of humidifier lung disease had occurred. In water supplies of the office's air conditioning systems, the number of moulds was mainly below 50 colony-forming units (CFU)/mL, the quantity of anaerobic bacteria mostly below 10,000 CFU/mL. Twenty-nine out of the 120 participating employees complained of symptoms such as dyspnea, cough, malaise whose majority was not associated with the workplace. Twenty-eight had IgG antibodies to humidifier antigens prepared from water supplies of the air conditioning systems.
This case study conducted in a new air-conditioned building in Singapore was aimed at identifying, and assessing indoor levels of VOCs using a GC-MS method. The study identified 80 different compounds with Toluene appearing in all locations. Most VOCs detected were from building materials, adhesives, varnishes, sealing compounds, polyester carpets reflecting the age of the building and vehicular emissions reflecting the poor positioning of the air intake.
The traditional way to dehumidify the outdoor air in an A/C-system is by cooling the air downbelow the dew point temperature. For this process a refrigeration system is necessary torealise these low temperatures. Nowadays the disadvantages of refrigeration systems fordehumidification are widely known. An alternative method to dehumidify the air is byseparating the process of dehumidification and cooling.The paper will present a testing plant of 1200 m air/h which is installed in the University ofEssen. This A/C-systems works with liquid desiccants.
Kakegawa City Hall, completed in March 1996, contains a sixstorey high glass-walled atrium integrated into the open-plan main office areas via stepped terraces. To save energy while still providing a comfortable indoor environment, the type of HVAC system adopted required careful consideration. Frost prevention fans normally used for tea plantations were installed on the terraces to blow warm air downwards during the heating season. Transferring air from the ventilation windows in the office spaces to those in the upper parts of the atrium also achieved effective natural ventilation.
Different types of air-conditioning systems, including constant-air-volume air systems, variable-air-volume air systems, fan coil systems, other terminal unit systems, induction units, etc., are described in this paper. Different types of rooms are described. The advantages, disadvantages, and different maintenance needs of a variety of air-conditioning systems, including constant-air-volume air systems, variable air- volume air systems, fan coil systems, terminal unit systems, dual-duct systems, and induction unit systems are reviewed.
A genetic algorithm technique is used to design an HVAC air duct system with minimum life-cycle cost. The approach has the capability to incorporate standard (discrete) duct sizes, variable time-of-day operating conditions and variable time-of-day utility rates. An example is used to illustrate these capabilities and results are compared to those obtained using weighted average flow rates and utility rates to show the life-cycle cost savings possible using this genetic algorithm methodology.
This paper describes a procedure for deriving a dynamic model of an air-conditioned room (space) by applying physical laws to it. The room under control is divided into five zones. The dynamics of each zone can be described by a lumped-capacity model, and a total of I 5 linear differential equations can be obtained. The model parameters derived from this procedure can be numerically related to the overall heat transfer coefficients for the room, and the various significant time constants associated with the room envelope.
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