Dedicated Outdoor Air System
The system is currently designed to supply 100% outdoor air to handle the heating and cooling loads of the medical center. The air handlers are designed to supply more than the minimum ventilation air requirements. The first depth will be to change the air handlers to dedicated outdoor air systems to supply the minimum ventilation air needed.
Comparison of a Variable Refrigerant Flow System and a Water Source Heat Pump System
Two systems will be considered to run parallel with the dedicated outdoor air system. Both systems use heat recovery to move heat from one space to another, assuming the system is balanced correctly. Through this analysis, indoor air quality will be monitored to ensure the decreased ventilation does not poorly affect the quality of air.
By switching to a DOAS unit supplying minimum ventilation air, the amount of air supplied to the zones will decrease by half. The IBS floors which are only used for maintenance, currently consume up to 9 feet per floor of the entire building. However, with the proposed system, the IBS floors can be converted into large plenums for the building’s systems. The large plenums will reduce the overall height of the building, thus saving structural and façade materials. The cost benefit of reducing the overall height of the building will be analyzed to determine if the loss in maintenance accessibility is worth the savings. A cost estimate will be created in order to compare the cost savings between the original design and the new system. The effect of these design changes on the schedule will be reviewed as well.
The structural loads on the roof will change by converting the air handler into a smaller dedicated outdoor air unit. The structural loads for each system will vary as well. With the implement of a variable refrigerant flow system, condensing units will be placed on the roof, thus adding to the dedicated outdoor air unit. The water source heat pump will need a cooling tower which will most likely be located on the central utility plant, however, it may be placed on the roof of the medical center in order to reduce the amount of piping.
Content from Centralized Cooling Production and Distribution Systems, AE 557, will be used in the analysis of the three systems being considered. Since the supply air will be reduced to the minimum ventilation air, an indoor air quality analysis will use the course content of AE 552: Air Quality in Buildings.