The Affinity Law is a mathematical relationship that states power consumption varies in proportion to

the cube of shaft speed. Therefore, if the speed decreases by x, power consumption decreases by the

cube of x. For example, a slight 20 percent reduction in speed results in a significant 50 percent

power savings. This mathmatical property can be put to your advantage when it comes to HVAC system

optimization.

Applying Affinity Law

To take advantage of the Affinity Law, systems require the capability to achieve varying motor speeds.

Variable-speed drives (VSDs) make it possible to vary the speed of the motors within the system. The

energy efficiency of a system can be improved most effectively by using all variable-speed equipment

and optimizing the efficiency of the entire system in response to the varying load requirements.

Optimum Energy uses patented, comprehensive mathematical models to process thousands of opera-

tional variables. Optimum Energy leverages the Affinity Law by tracking real-time system demand and

automatically calculating the most efficient sequencing of variable-speed equipment based on building

loads without compromising on occupant comfort or process cooling requirements.

The constant communication between equipment also allows for soft starts that create less wear on

the equipment as opposed to line starts, which shock the equipment into operation. The result is an

HVAC system that truly operates with variable-speed and variable-flow, eliminating excessive

resources and the associated power costs.

stay on and save

Installation of the Optimum Energy solution, in combination with VSDs, enable the entire system to

stay on to deliver the precise amount of power to meet demand while lowering energy usage, reducing

carbon emissions and significantly lowering operating expenses. Give Optimum Energy a call today and

find out how to stay on and save.

optimum energy

411 F irst Avenue South

Suite 620

Seattle WA 98104

T 888.211.0918

optimumenergyco.com

myth: to save energy, switch off poweraffinity law proves that energy use is proportional to motor speed

optimization 101

© 2011 Optimum Energy LLC V09-11

Paper contains post-consumer recycled fibers certified by the Forest Stewardship Council.

architecting intelligent energy solutionsoptimization 101: affinity law

about oeSimply put, Optimum Energy is the energy optimization

expert. We use integrated software and cloud computing to

optimize HVAC systems to deliver sustained energy reductions.

Organizations like Mineta San Jose International Airport, the

University of Texas at Austin and a variety of Fortune 100

corporations rely on the Optimum Energy OptimumHVAC

solution for the continuous commissioning that maintains

energy optimization year after year. Contact your local OE

sales representative for more information about HVAC system

optimization from Optimum Energy.

Affinity Law Table

SPEED FLOW REQUIRED POWER

100% 100% 100%

90% 90% 73%

80% 80% 50%

70% 70% 34%

60% 60% 22%

50% 50% 13%

40% 40% 6%

30% 30% 3%

Affinity Law chart

The Affinity Law chart and table show the relationship between speed, flow and the required power (energy to maintain operation.