HVAC - Resource Guide For Green Building Design - Trane

EARTHWISE SYSTEMS
CHILLED-WATER SYSTEMS (CWS)
green options green criteria reference
1
2
Reduce waterflow
rate in
chilled-water
loop (12-20˚F, or
6.7-11.1˚CΔT)
condenser
water loop
(12-18˚F or 6.7-
10˚CΔT)
Variable flow
chilled-water
systems
Vary the
water flow rate
through the
chiller evaporators
during system
operation
• Increase efficiency of chilled-water
plant so that pumps and cooling towers
consume less energy
• Reduce building materials (smaller
pump, cooling tower, fan)
• Reduce water pipe sizes, save cost and
material
Reduce system materials required, using
fewer pumps than the common primarysecondary
system; for example, reduced
• piping connections
• strainers
• electrical connections
• valves and specialties
• pump starters
• space required
Improve system efficiency modestly by
reducing pumping energy.
(1)
(2)
(3)
(4)
(5)
(6)
(7)
3
System optimization
controls
Condenser
water temperature
reset and
optimization
• Improve system efficiency
• Optimize the condenser water system
by balancing the chiller and tower power
• Iterate for the best condenser water
temperature to minimize the combined
chiller-tower energy use at all time
(8)
(9)
4
Pumping pressure-speed
reset
• Reset the pump operating pressure to
ensure that the control valve needing the
highest pressure is about 90% open
• Save pump energy
(10)
5
Refrigerant
charge per ton
Select systems that require less refrigerant
charge to operate
• Less refrigerant means less impact on
the environment in case refrigerant leaks
from the system
• Use ASHRAE Standard 147 to further
minimize leakage or overall refrigerant
emissions
(11)
2