Ashrae Journal - December 2008 - (Page 33) Building Model & Simulation Results Hood Exhaust The NJEDA building model includes 4,000 cfm about 11,000 ft2 (3353 m2) of interior Exhaust “Neutral” TE 400 cfm laboratory space. Offices and conference 7,800 cfm Air Supply With 6 rooms along the perimeter of the building Air Changes Minimum 94 DB 75 DB 50 DB are not included in this analysis. The design criteria used for HVAC capacity and Heating Cooling Pre-Heat energy use are a maximum of 8.5 W/ft2 To Other Coil Coil Coil 2) of equipment load and 2.0 W/ Spaces (91.5 W/m 97 DB 50 DB 97 DB 70 DB 68 49.5 WB 65 WB 79 WB 79 WB ft2 (21.5 W/m2) of lighting. The building is 68 DB DB normally occupied from 7 a.m. to 7 p.m. To Air simplify the model, this is assumed to be Terminal Chilled Outside seven days a week. During occupied hours, Units Water Air summer indoor design conditions are 75°F 12,200 cfm Ceiling Typical Exhaust Diffusers 93 DB/78 WB (24°C) and 50% RH. Winter indoor design Space Grills 6,200 cfm Combined Lab/Office conditions are 70°F (21°C) without huActive Chilled Beam midity control. During unoccupied hours, (10 W/ft2) (24% Cooling Air-to-Air Heat Coverage) 6,000 cfm Recovery Devices the temperatures are allowed to setback to 78°F (26°C) during the summer and 65°F (18°C) during the winter. To effect more Hood Exhaust realistic energy simulations, the following 4,000 cfm diversity factors are included: Exhaust “Neutral” TE 400 cfm • 60% of design peak lighting and 7,800 cfm Air Supply With 6 equipment loads (L&E) during Air Changes Minimum 72 DB 72 DB 22 DB occupied hours; • 10% of design peak L&E during Heating Cooling Pre-Heat unoccupied hours; and To Other Coil Coil Coil Spaces • 60% of fume hoods used during 68 DB 47 DB 47 DB 47 DB 15 DB 11 DB occupied hours (40% of them with sashes down). Air Table 2 shows the results of the energy Terminal Chilled Units simulations, as well as the size of the Outside Water Air boilers and chillers required for three Ceiling Typical 12,200 cfm Exhaust Diffusers Space systems. The first system serves as the 11 DB Grills 6,200 cfm Combined Lab/Office base case, which satisfies the minimum Active Chilled Beam requirements of ANSI/ASHRAE/IESNA Air-to-Air Heat (10 W/ft2) (24% Cooling Recovery Devices Coverage) 6,000 cfm Standard 90.1-2004 as applied to the NJEDA Tech IV Building. Energy recovFigure 5 (top): Dual air-to-air energy recovery (peak summer). Series arrangement with ery is not included in the base case since chilled beams. Figure 6 (bottom): Dual air-to-air energy recovery (peak winter). Series arthis system includes a VAV design. The rangement with chilled beams. second system includes energy recovery in the design of the air-handling system, using a single total enAs illustrated in the table, a large reduction in the annual spaceergy wheel, in addition to VAV operation. In Systems 1 and 2, the cooling energy is required under System 3. This is partially due to VAV system maintains 6 ACH as the minimum ventilation rate the reduced airflow of outside air in the air-handling unit, and also due to the much higher cooling efficiency attained from using dual in laboratory spaces during occupied and unoccupied hours. System 3 comprises a combination of dual energy recovery energy recovery. The required preheat energy at the air-handling in the design of the air-handling system, using energy wheels, unit is greatly reduced in the chilled beam design (System 3), as and active chilled beams in the laboratory spaces. As stated well as in System 2, as compared to the base case (System 1). Also previously, the maximum total airflow requirement for the air- evident in the table, the heating (reheat) energy is the same for handling unit for this system is roughly 50% of that required for Systems 1 and 2 but virtually eliminated with System 3. Fan static is slightly higher with System 2 as compared to System Systems 1 and 2, since the air-handling unit is delivering air for ventilation and exhaust makeup purposes only. In this model, the 1, and increased slightly with System 3 as compared to System 2. air-handling unit used in System 3 operates at constant volume This is due to the added pressure drops associated with the energy to maintain the minimum 6 ACH of ventilation required in the recovery device (the dual energy recovery devices in System 3). However, due to the reduced airflow with System 3, there is still laboratory spaces during occupied and unoccupied hours. Off Off Off On On December 2008 ASHRAE Journal On Off On On On 33
For optimal viewing of this digital publication, please enable JavaScript and then refresh the page. If you would like to try to load the digital publication without using Flash Player detection, please click here.