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Methods, Technology and Best Practices for Saving Energy with Pumps
Greg Towsley, LEED AP BD+CInnovation Director
Grundfos
Objectives• Identify where pumps are used in systems of
commercial buildings• Identify system design methods that can reduce energy
consumption in the pumping systems of commercial buildings
• Identify technologies that can reduce energy consumption in the pumping systems of commercial buildings
• Identify best practices that can reduce energy consumption in the pumping systems of commercial buildings
2006 Commercial Energy End-Use (Quadrillion Btu)
Lighting25%
Space Heating12%
Water Heating6%
Refrigeration4%
Electronics7%
Ventilation7%
Computers4%
Cooking2%
Other20%
Space Cooling13%
Source: U.S. Energy Information Administration (EIA)
The Pumping System• Space heating• Air conditioning• Water heating• Domestic pressure boosting• Waste water removal
Chiller
Cooling towerCooling ceiling
Cooling surface
Secondarypumps
Heat recovery Fan coils M
MM M
Buffer tank
M
MPrimarypump
Pressureholding
Chiller
Cooling towerCooling ceiling
Cooling surface
Secondarypumps
Heat recovery Fan coils MM
MMMMMM MMM
Buffer tank
MM
MMPrimarypump
Pressureholding
System knowledgemeans getting the right
system design
System knowledgemeans getting the right
system design
System characteristics
(Flow)
(Pressure)
System Performance CurveH
ead
Net Elevation Change
Pressure Required
Pump Flow Rate
Friction Loss
System Performance
Curve
Load profile for a secondary chilled water system
5 510 10 10
20
30
10
05
10152025303540
% O
pera
ting
hour
s
30 40 50 60 70 80 90 100% Max. volume flow rate
Load profile for a water pressure booster system
42
33
138
4
05
1015202530354045
% O
pera
ting
Hou
rs
15 25 50 75 100% Max. Volume Flow Rate
Know Your System Select The Right Pumps
The Right Pump
Initial Costs
Installation andCommissioning Costs
EnergyCosts
DowntimeCosts
OperatingCosts
EnvironmentalCosts
Decommissioning /Disposal Costs
MaintenanceCosts
Proper operationConstant / constant
System flow/pump speed
Variable / constant
Variable / variable
Variable / variable
Maintaining the pump (or 10 ways to kill your pump)
• Over work it
• Starve it
• Choke it
• Fry it
• Poison it
• Stab it
• Break its limbs
• Shake it to pieces
• Drown it
• Neglect regular check-ups
Continuous monitoring
Summary• Knowledge of the pump system
– Building load requirements change over time– Gain knowledge and continue to optimize systems
• Right-size the pump– Installed pump typically selected based on peak load condition– Choose the best pump for the operating load profile
• Pump control– Control the pump and components based on the need– On-off or variable speed to optimize pump performance
• Maintenance and Repair– Continuous monitoring of key characteristics – Q, TDH, kW– Repair to manufacturer’s standards
Case StoryCase Story
Toronto East General Hospital• Responsible environmental management
program– Improve energy efficiency– Improve water efficiency
• Pressure boosting for domestic water main part of hospital
• Domestic water booster pump system– Three pumps: one (1) 20 hp, two (2) 40 hp– All constant speed– 20 hp continuous operation – “brake” to control– “High” maintenance costs– No flow – by-pass to drain– Unknown flow profile and water waste– Exact energy consumption unknown
Consumption Profile
• Assume 84,500,000 gallons per year• Assume maximum flow in any day – 515
gpm• Pump TDH – 135 ft. (58 psi)• Following have been estimated for
simplicity……
Consumpton Profile
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
1:00 A
M2:0
0 AM
3:00 A
M4:0
0 AM
5:00 A
M6:0
0 AM
7:00 A
M8:0
0 AM
9:00 A
M10
:00 AM
11:00
AM12
:00 Noo
n1:0
0 PM
2:00 P
M3:0
0 PM
4:00 P
M5:0
0 PM
6:00 P
M7:0
0 PM
8:00 P
M9:0
0 PM
10:00
PM11
:00 PM
12:00
AM
Consumption Profile
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Load Profile
Hours per day
Per
cent
of m
axim
um fl
ow
% of Max GPM
# of hrs/day
100% 515 175% 386 250% 258 325% 129 815% 77 10
Existing Pumps• Design point:
– 515 gpm at 135 feet TDH
– 58 psi pump pressure boost
• Pump follows performance curve
• Anything above 135 ft. is wasted energy
135 ft.
515 gpm
Existing Pumps
% of Max GPM
# of hrs/day
Total Hours
# of Pumps
Hp @ Point
kW @ Point
kWh @ Point
Cost @ Point
($0.10/kWh)
100% 515 1 365 1 23.60 17.60 6,423 $ 642.35 75% 386 2 730 1 21.20 15.81 11,540 $ 1,154.05 50% 258 3 1,095 1 16.73 12.48 13,661 $ 1,366.07 25% 129 8 2,920 1 13.48 10.05 29,352 $ 2,935.19 15% 77 10 3,650 1 11.60 8.65 31,573 $ 3,157.29
8,760 92,550 $ 9,254.95
New Packaged Pump System• Sized for the needs of the
hospital – not oversized
• Three (3) 15 hp pumps
• All pumps controlled with pressure sensors and variable speed drives– Slow the pump down to
meet the flow and head requirements
– Not braking
– No waste of energy
New Packaged Pump System @ 135 ft. TDH• Three (3) equally sized
pumps
• Speed controlled by variable frequency drives
• Able to meet system head conditions at reduced speed, thus reduce hp/kWh
515
New Packaged Pump System% of Max GPM
# of hrs/day
Total Hours
# of Pumps
Hp @ Point
kW @ Point
kWh @ Point
Cost @ Point($0.10/kWh)
100% 515 1 365 3 23.40 17.45 6,369 $ 636.90
75% 386 2 730 3 17.55 13.09 9,554 $ 955.35
50% 258 3 1,095 2 11.58 8.64 9,456 $ 945.55
25% 129 8 2,920 1 5.79 4.32 12,607 $ 1,260.74
15% 77 10 3,650 1 4.10 3.06 11,159 $ 1,115.94
8,760 49,145 $ 4,914.49
kWh Consumption
Energy Cost of Operation
Old System 92,550 $ 9,254.95New System 49,145 $ 4,914.49SAVINGS 43,405 $ 4,340.46
515
New Packaged Pump System ADDITIONAL BENEFIT
• After installation of new system:
– Booster system ran at less than 50% speed for >1.5 hours
– Flow was approximately 80 gpm at 40 feet TDH
– Less water demand, lower pressure loss
• Pressure monitoring in the control system turned pumps off when there was no water demand
New Packaged Pump System ACTUAL SYSTEM CURVE
% of Max GPM
# of hrs/day
Total Hours
# of Pumps
Hp @ Point
kW @ Point
kWh @ Point
Cost @ Point($0.10/kWh)
100% 515 1 365 3 23.40 17.45 6,369 $ 636.90
75% 386 2 730 3 12.36 9.22 6,728 $ 672.83
50% 258 3 1,095 2 5.64 4.21 4,605 $ 460.53
25% 129 8 2,920 1 1.95 1.45 4,246 $ 424.60
15% 77 10 3,650 1 1.26 0.94 3,429 $ 342.95
8,760 25,378 $ 2,537.81
kWh Consumption
Energy Cost of Operation
Old System 92,550 $ 9,254.95New System Curve 25,378 $ 2,537.81
SAVINGS 67,172 $ 6,717.14
