DOE-2 Energy Modeling Summary - Office Building
Page 11 of 21
Economizer (waterside):
Strainer cycle with chilled-water/tower-water heat exchanger
Economizer operates when outdoor temperature is less than 55F
Cooling Tower:
Design wetbulb temperature 74F (per ASHRAE 1%, Washington DC)
Design approach 11F
Design range 10F
Wetbulb reset
Tower outlet water temperature 85F; throttling range 2.5F
Minimum water temperature 66F
Two speed cooling tower fans (high speed, 100%; low speed, 40%)
Tower capacity control: maximum cells possible at lowest fan speeds
Primary Chilled Water Pump
20 ft pump head
77% impeller efficiency
90% motor efficiency
Constant speed
Secondary Chilled Water Pump
40 ft pump head
77% impeller efficiency
90% motor efficiency
Variable speed; 30% minimum pump speed
Condenser Water Pump
60 ft pump head
77% impeller efficiency
90% motor efficiency
Heating Plant
Two (2) 115 BHP natural gas fired, hot water boilers (80% nominal efficiency, reduced to 76%
Operating Parameters
Heating plant operates winter and summer (to provide reheat)
Water loop temperature drop 50F
Hot Water Pump
60 ft pump head
77% impeller efficiency
90% motor efficiency
Variable speed; 30% minimum pump speed
APPENDIX J - GSA LEED COST STUDY
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