BestPractices Case Study

BENEFITS

• Saves $55,000 in annual energy costs

• Saves 1.3 million kWh per year 

• Increased throughput 1.5% and reduced 

downtime

• Achieved a 1-year simple payback

APPLICATION

Compressed air systems are found throughout 

industry and account for a significant amount 

of the electricity consumed by manufacturing 

plants. Applying a system-level strategy to 

optimize a compressed air system can improve 

system performance, save energy, and improve 

production. 

Weyerhaeuser: Compressed Air System Improvement 

Saves Energy and Improves Production at a Sawmill

Summary

In 2000, Weyerhaeuser Company, a U.S. Department of Energy Allied Partner, 

implemented a project that increased the efficiency of the compressed air 

system at its facility in Coburg, Oregon. The project was originally conceived 

by a Qualified AIRMaster+ Specialist. In addition to improving the system’s 

performance, this project yielded important energy savings and enabled the mill 

to increase production without reconfiguring or adding production equipment. 

The project saved 1.3 million kWh. Total production costs, after capital funds 

were obtained outside Weyerhaeuser, were $55,000. Because the project yielded 

annual compressed air energy cost savings of $55,000, it had a simple payback of 1 

year. Using the Coburg facility’s project as a model, Weyerhaeuser commissioned 

evaluations and improvements of compressed air systems at six other company 

plants and mills. The aggregate energy savings and energy cost savings resulting 

from these six facilities’ projects are 6.8 million kWh and $250,000.

Plant/System Overview

Founded in 1900, Weyerhaeuser has developed into one of the largest integrated 

forest products companies in the world, with annual sales of $18.5 billion. 

Weyerhaeuser is primarily engaged in the growth and harvesting of timber; 

production, distribution, and sale of wood and paper products; and real estate 

development. The company currently employs about 55,000 people in 18 countries. 

The company’s products are sold primarily through its customer service centers 

or to wholesalers, home improvement centers, manufactured housing companies, 

industrial manufacturers, and users. 

The Coburg facility, which opened in 1962, contains several independent 

operations, including log sorting, veneer drying, and a sawmill. The sawmill 

produces dimensional lumber for commercial sale — typically about 235 million 

feet of wood per year. Compressed air is important for air-operated cylinders and 

various pneumatic tools, and it is particularly critical for proper operation of the 

quad that saws the logs. The quad uses compressed air to precisely place the logs, 

and if a sawline is off by just one-tenth of an inch, 25% or more of a log’s potential 

yield can be lost.

Originally, the sawmill and veneer plant were each served by separate compressed 

air systems. Later, the systems were connected with crossover piping to avoid 

purchasing more compressors. The facility’s compressed air system is served by 

three rotary screw compressors with a total horsepower of 650 hp. A 300-hp unit 

resides in the sawmill, while 200-hp and 150-hp units are located in the veneer 

plant. Prior to the project, the system generated an average of 2,000 scfm for 

normal plant demand and slightly over 2,300 scfm for peak needs. 

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Project Overview

Weyerhaeuser personnel worked with a 

DOE/CAC Qualified AIRMaster+ Specialist 

from SAV-AIR, LLC. They formed a 

project team to evaluate the system for 

efficiency gains and possible energy savings. 

Part of the evaluation included preparing 

a block diagram to profile the system 

and performing baseline measurements 

of flow rate, power usage, and pressure 

levels to obtain an accurate picture of the 

system’s performance. Then, the system’s 

components were examined. 

The team discovered several problems 

that were causing unstable pressure and 

excess compressed air generation. Although 

all three compressors were operated 

simultaneously, the system’s pressure 

fluctuated by as much as 30 psi, from 65 

to 95 psig. 

One reason for the inconsistent pressure 

was the fact that the compressors were 

individually controlled, and no flow 

instrumentation was available to gauge 

the supply throughout the system. Another 

reason was that the compressors were 

located far apart from each other. This 

distance caused them to react to different 

control pressures, and consequently, 

they worked against each other. So, plant 

personnel operated all three compressors at 

full load to satisfy peak air demand. This 

arrangement generated more air than needed 

during off-peak air demand periods.

Next, the team found that a faulty timing 

board on the regenerative dryer caused both the inlet valves to close momentarily when the towers 

switched. This prevented airflow through the dryer and created a pressure spike at the compressor, 

causing it to operate erratically. Also, the inlet modulating valve on the 200-hp unit was not operating 

effectively, which caused the compressor to load up at a higher pressure. In addition, the oil cooler 

serving the 200-hp unit was smaller than the frame on which it was mounted. This problem allowed air

to pass around the oil-cooler core and prevented it from cooling the oil sufficiently. 

The review found that the condensate traps in the system were not operating well and allowed condensate 

to become entrained into the system. Also, the leak load was found to represent slightly more than 25% of 

the system’s airflow. 

To stabilize system pressure, compressed air is stored 

in containers such as this 800-gallon horizontal unit.
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Project Implementation

The Coburg facility’s project was 

performed incrementally in two 

phases. Baseline measurements were 

taken after each phase to gauge its 

effectiveness. In the first phase, the 

mill installed a multiple compressor 

network control system to modulate 

the compressors more efficiently. 

The new controls package was linked 

to a remote-monitoring device that 

allowed the system’s performance to 

be supervised by SAV-AIR. Several 

simulations were then performed 

to determine the most appropriate 

control strategies to maximize the 

system’s efficiency. 

To stabilize and lower the system 

pressure, the team installed a 

pressure/flow controller with 2,500 

gallons of additional storage capacity. 

Once these devices were in place, the 

baseline measurements were retaken 

and the system pressure was lowered 

from 97 to 85 psig. 

In the second phase, the mill’s personnel addressed many of the other issues that were discovered in 

the evaluation. Of the mill’s leak load, 25% was repaired. Several items were replaced, including the 

following:

• Ineffective condensate traps with electronic, no-loss models

• The defective timing board in the dryer 

• The oil cooler serving the 200-hp compressor

• The inlet-modulating valve on the 200-hp unit. 

When all of these measures were completed, the baseline measurements were retaken and the system 

pressure was further reduced to 76 psig.

Project Results

The Coburg mill’s project greatly improved the performance of the compressed air system, resulting in 

energy savings and better productivity. With the new control system, the mill can more accurately match 

its air supply with its air demand. This saves energy because the system no longer generates excess 

compressed air. With the lower and more stable system pressure and a reduction of the flow rate from 

2,000-2,300 scfm to 1,750 scfm, the mill can now satisfy its compressed air demand by just baseloading 

the 300-hp compressor and operating the 200-hp unit in load/unload mode. The 150-hp unit is now kept 

as a backup compressor. In addition, the repairs to the air treatment equipment have improved the mill’s 

air quality and further reduced compressed air waste.

The largest of three rotary screw compressors at the 

mill is this 300-hp unit.
Industrial Technologies Program

Printed with a renewable-source ink on paper containing at least 50% wastepaper, including 20% postconsumer waste

BestPractices is part of the Industrial Technologies 

Program, and it supports the Industries of the 

Future strategy. This strategy helps the country’s 

most energy-intensive industries improve their 

competitiveness. BestPractices brings together 

emerging technologies and energy-management 

best practices to help companies begin improving 

energy efficiency, environmental performance, 

and productivity right now.

BestPractices emphasizes plant systems, where 

significant efficiency improvements and savings 

can be achieved. Industry gains easy access 

to near-term and long-term solutions for improving 

the performance of motor, steam, compressed 

air, and process heating systems. In addition, 

the Industrial Assessment Centers provide 

comprehensive industrial energy evaluations 

to small- and medium-size manufacturers.

A Strong Energy Portfolio 

for a Strong America

Energy efficiency and clean, renewable 

energy will mean a stronger economy, a 

cleaner environment, and greater energy

independence for America. Working with 

a wide array of state, community, industry, 

and university partners, the U.S. Department 

of Energy’s Office of Energy Efficiency 

and Renewable Energy invests in a diverse 

portfolio of energy technologies.

DOE/GO-102004-1959

Revised December 2004

PROJECT PARTNERS

Weyerhaeuser Company

Coburg, OR

SAV-AIR, LLC 

Portland, OR

Emerald Peoples’ Utility District 

Eugene, OR

Northwest Energy Efficiency Alliance

Portland, OR

FOR ADDITIONAL INFORMATION, PLEASE CONTACT:

EERE Information Center

1-877-EERE-INF

(1-877-337-3463)

www.eere.energy.gov

Visit our home page at

www.eere.energy.gov/industry

Industrial Technologies Program

Energy Efficiency and Renewable Energy

U.S. Department of Energy

Washington, DC 20585-0121

The annual energy savings for 

compressed air from the Coburg 

mill’s project are $55,000 and 

1.3 million kWh. The project’s 

total costs were $110,000, but 

with an incentive payment 

of $30,000 from Emerald 

People’s Utility District (EPUD) 

and a $25,000 cost-sharing 

contribution from the Northwest 

Energy Efficiency Alliance, the 

project costs were effectively 

$55,000. This yielded a 1-year 

simple payback. In addition, the 

mill’s throughput increased by 

1.5% because of the consistent 

air pressure. With the success 

of the Coburg mill’s project, the 

compressed air systems at six 

other company wood mills were 

similarly optimized, yielding 

total annual energy savings of 

6.8 million kWh and $250,000.

As a final addendum, the project results were validated using AIRMaster+. 

Although the project was implemented before AIRMaster+ was launched, the 

baseline measurements and project measures were entered in it later. The actual 

project results were just 3.5% under the predicted values generated by the 

program.

Lesson Learned

Optimizing a compressed air system’s efficiency not only can yield important 

energy savings, it also can improve productivity. In the case of the Coburg mill, 

the location of the compressors coupled with the manual control scheme and 

convoluted piping led to severe pressure fluctuations that hindered production. 

The inconsistent pressure often caused logs to get stuck in the quad. To clear the 

jam, mill personnel had to shut off the quad and cut the logs with chainsaws to 

remove them. This resulted in production downtime and higher labor costs. It also 

caused product waste because the jammed logs were unusable.

To maintain the needed pressure, the mill had tried operating all compressors 

simultaneously, but that only generated excess air and wasted energy. The 

performance of the compressed air system improved substantially after the 

mill implemented a system-level project. The project upgraded the compressor 

controls, stabilized the pressure level, repaired leaks and fixed other problems 

with the air treatment equipment. In addition, the project served as a blueprint for 

successful projects at six other company facilities. 

An air flow meter at the Coburg mill.