Energy Efficiency Measures
Energy efficiency measures do not operate in isolation from one another.
Solar gain through windows that warms in the winter also heats in the summer and
can be a source of glare unless controlled. Similarly, lighting efficiency
measures affect the operation of heating and air conditioning systems in a
building. Accordingly, planning for and executing retrofits should be done with
a whole-building performance perspective to ensure cost-effective and efficient
performance over the year - and for the long term.
The following sections discuss the key energy efficiency measures outlined in
the Recommendations by Sector section of the Guide, organized by area. The
measure descriptions are relatively brief, but often include links to more
detailed information and/or lists of qualifying high-efficiency products.
Motors, Pumps and Fans
Motor-driven equipment, including pumps and fans, accounts
for about 64% of electricity and about 30% of total energy
consumed in the industrial sector.
There are two general tactics for saving electricity in motor
systems: 1) developing a plan for upgrading your motors to
premium efficiency motors when they require replacement; and 2)
matching instantaneous motor power most efficiently to the needs
of the task. Implementing an effective motor strategy involves
carefully considering both approaches, and taking practical
action. The results are likely to save energy, reduce
maintenance costs, and may also improve productivity.
Plan for motor replacement decisions. Before your existing
motors fail, it is helpful to have a plan in place for whether
to replace or repair the motors, and which replacement motors to
choose in the former case. How do you decide whether to have the
motor repaired (such as through rewinding) or to replace the
motor with a new premium efficiency motor? In many cases the
latter is actually the smartest choice. This is because
rewinding can degrade the efficiency of a motor by 1 or 2
percentage points, while premium efficiency motors can be 3 or 4
percentage points more efficient than the original standard
efficiency motor. For an average motor, the purchase cost is
often less than 2 percent of a motor's total lifetime cost, and
the motor will consume 50-60 times its initial purchase price in
electricity within 10 years of service.
Performing this cost-effectiveness analysis is easy with the
use of the Motor Master software available from the U.S.
Department of Energy Industrial Technologies Program (ITP). (See
This free software tool includes a catalogue of motors of
various sizes, along with their costs and rated efficiencies. By
inputting data such as your price of electricity, load factor,
and hours of operation, the software provides the energy and
cost savings, and the payback period and return on investment
for the particular replacement choice.
Institute a motor maintenance program. This includes routine
inspections of all motors (with emphasis on those critical to
production), including the drive train, which should be
realigned and lubricated as needed; measuring energy use; and
identifying any overheating of mechanical and electrical
components. Prepare a list of premium efficiency motors for
replacing existing motors when replacement is necessary.
Match motors with loads. Motors are often oversized for their
loads, mainly due to conservative design practices, or
subsequent modifications to processes and equipment. In addition
many motors are sized to provide the maximum output required
under the worst operating conditions, but during typical
operation the motor system seldom requires this much output. The
excess energy during other times is usually dissipated through
some type of throttling device such as dampers or valves. There
are two general strategies to save energy in these situations:
1) Install a smaller motor to replace the oversized one, or 2)
Install an adjustable speed drive.
As a general rule of thumb, if the maximum loading on the
motor is less than 50% of its rated capacity, it may be
cost-effective to replace the motor motor with a smaller and
more efficient one. The Motormaster+ software tool mentioned
above (available at
is also very useful for evaluating these opportunities.
For applications in which the loads vary considerably,
installing an adjustable-speed-drive (ASD) can be a good
investment. In general, installing an ASD is considerably more
expensive than buying a new smaller and more efficient
replacement motor, so if the load is consistently low (such as
below 50% of the rated output), the motor replacement option is
the smarter choice. Another option, rather than installing a
variable speed drive on a single motor, is to use several
smaller motors, bringing them on incrementally to meet load
Determining if a motor system is a good candidate for
variable speed operation requires knowledge of the loads and
hours of operation per year. Good potential ASD applications
have significant hours of operation at less than the rated
(maximum) output. Motors driving pumps and fans should always be
evaluated, and potential energy savings from these systems can
exceed 50%. Motor and load systems that deliver rated output
less than 40 percent of the time, or for which the average
output is less than 60% of the rated output are good
variable-speed prospects. To be economical, the motor system
should also be in operation for many hours per year. Generally,
the payback period for an ASD installed on a pump or fan
application operating more than 6000 hours per year will be less
than two years when the average output is less than 70% of the
rated load. DOE's Industrial Technologies Program has software
tools to assist in evaluating the cost-effectiveness of ASDs for
pump or fan systems. (See "fan system assessment tool" and "pump
system assessment tool" at
In addition, installing multiple pumps, fans, or motors for
other applications, and staging their operations to match loads
is another practical energy and cost savings strategy.
Compressed Air Systems
Compressed air accounts for about 5% of total electricity
consumption in industry. Most plants use compressed air for at
least some functions; for many, compressor energy is a
substantial portion of the electric bill. Many compressor
systems are poorly laid out, have leaking fixtures, and
motor/compressor systems are frequently mismatched to loads.
Suggestions for curbing energy waste in air compressor systems
include the following:
- Use properly-sized, energy-efficient compressors driven
by energy-efficient motors and associated storage tanks that
are matched to loads.
- Ensure that systems can operate efficiently at part
- Use electronic controls on individual compressors to
optimize pressure and output.
- Consider installing a smaller, high pressure compressor
to meet a specific need in order to allow the main
compressor to operate at a lower pressure.
- Meter energy, flow, and other parameters to assess
- Maintain the system to minimize air leakage.
Technical resources and a compressed air assessment tool (Airmaster+)
are available through the DOE's Industrial Technologies Program,
About 20% of all energy consumption by industry is used to
generate steam, which is used for a variety process heating
applications as well as facility space heating. There are many
opportunities to improve the efficiency of steam systems, which
can be summarized into four main areas:
- Steam generation -- boiler controls, water treatment,
maintenance/cleaning of heat transfer surfaces, matching
pressure to end-use needs, etc.;
- Steam distribution -- better insulation, steam trap
maintenance, and finding leaks;
- Steam end-use -- heat exchanger maintenance and other
measures to optimize end-use;
- Condensate return -- optimize the amount of condensate
return and use of low-pressure steam.
DOE also has several steam systems tools and other technical
resources to help optimize the efficiency of steam systems.
Many industrial facilities use process heating, for a variety
of operations. Direct process heating (not including steam
systems) accounts for about one-fourth of total industrial
energy use. Opportunities to improve efficiency in this area
- Optimize burner air to fuel ratios;
- Maintain clean heat transfer surfaces;
- Install furnace pressure controllers;
- Install waste heat recovery systems;
- Preheat combustion air;
- Reduce air infiltration in furnaces;
- Reduce radiation losses from heating equipment.
DOE's Industrial Technical Program offers a free process heat
assessment tool (PHAST), tip sheets, and technical resources.
Combined Heat and Power (CHP) Systems
Combined heat and power (CHP) refers to generating electricity at or near the
building where it is used, and then "recycling" the waste heat and using it for
space heating, water heating, process steam for industrial steam loads, humidity
control, air conditioning, water cooling, product drying, or for nearly any
other thermal energy need. The end result is significantly more efficient than
generating cooling, heating, and power separately.
The heat from most conventional large-scale power plants is
wasted. This is because electricity can be sent over long
distances but the heat cannot. And since power plants are
typically located far from population centers and far from
buildings that could beneficially use the heat, that thermal
energy is instead just vented to the surrounding environment.
On the other hand, small-size power plants can be located
close to or even within facilities which can make good use of
the heat resulting from electricity generation, thereby raising
the net efficiency of generating electricity by a factor of two
or more and saving substantial energy and money. Hospitals,
commercial buildings, apartment complexes, and industrial
facilities can often take advantage of combined heat and power
To make them most economical and practical, CHP systems need
to have a relatively high and constant thermal load so it can
match the heat output of the generation process. Keep in mind
that in addition to supplying heat for hot water, low pressure
steam for heating, sterilizing, and sundry industrial needs, CHP
systems can also supply cooling energy via absorption chilling
equipment. Generally, it is most cost-effective to size CHP
systems to supply the facility’s “base” heating load rather than
to size the system based on the electrical load.
Most sites stay connected to the utility grid for back-up
power during periods of maintenance or malfunction, although the
utility charges standby fees for this. A number of sites also
sell their electricity back to the grid when generating more
than is needed.
Financial assistance can often be found for installing CHP
systems, since they have substantial energy efficiency benefits.
The DSIRE Database is one good place to search for funding
opportunities for CHP and other energy efficiency measures:
In Colorado and four other western states, the Intermountain
CHP Center provides free feasibility analysis, technical
assistance, and expert advice; as well as information on
available grants and incentives. For more information see the
Intermountain CHP Center website at
www.intermountainCHP.org. The EPA CHP Partnership is another
Lighting is responsible for approximately 4% of total
electricity use in the industrial sector. There are many
opportunities for cost-effective lighting energy savings in many
industrial facilities. Measures frequently found to be practical
- Paint ceilings and sidewalls with a white semi-gloss
paint. This will enhance the lighting quality at most work
stations by raising brightness levels and softening shadows
and glare whether light is from electric fixtures or from
- Consider replacing conventional high intensity discharge
lighting in medium and high bays with fixtures that use more
efficient T-5 fluorescent lamps that may be dimmed step-wise
when daylighting is available.
- Replace T-12 fluorescent fixtures with T- 8 or T-5
fixtures with electronic ballasts.
- To prevent glare from direct beam sunlight, install
reflectors ("light shelves” either inside or outside high
bay windows on the east, south, and west to redirect light
onto the white ceiling. High bays with windows toward the
top are ideal for providing natural lighting, but they can
also be a source of glare from direct beam sunlight. Light
shelves allow the ceiling itself to function as a source of
diffuse natural light, creating an attractive, virtually
shadow-free lighting environment at the work stations below.
- Install systems that redirect direct beam sunlight from
rooftop windows onto light-colored ceilings, thereby
controlling for glare and converting sunlight into a diffuse
- Install and adjust automatic dimming controls to take
advantage of daylighting. The "Cool Daylighting" approach
keeps most outside light out of the field of view, thereby
controlling for glare, producing better distribution, and
lowering cooling costs. See www.daylighting.org/what_is_cool_daylighting.htm.
- Install LED exit signs.
- Upgrade parking lot lighting to save energy and reduce
the environmental impacts associated with lighting the sky
instead of the parking lot.