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Low-Cost, High-Yield Energy Saving Tips for Organizations

By David R. Simon, Rotary Club of Incline Village, Nevada

With electric costs projected to rise as much as 12% in 2008, and “carbon footprint” an issue of increasing importance, organizations are taking a hard look at their energy consumption.  Facilities can save tens of thousands of dollars in yearly electric costs, and cut harmful emissions by thousands of tons, by implementing a handful of simple, cost-effective efficiency measures. 

“Low-Hanging Fruit”

While efficiency investments of every size and cost are possible, this article addresses those measures which reduce electrical consumption and have a payback period of three years or less.  There are three areas of “low-hanging fruit” for a facility seeking to lower electric costs: lighting, cooling systems and electrical motors. 

Lighting

Lighting is often the largest piece of a facility’s electric cost and the area where the most immediate savings are available.  The first step is to replace incandescent with fluorescent lighting, and while many facilities have already taken this step, it’s just the first step.  The next steps include replacing high-intensity discharge (HID) lights with fluorescents, treating fluorescents to reduce harmonics and regulate voltage, and adding lighting controls to reduce or eliminate light in rooms with adequate ambient light or no occupants.  “Daylighting” – the practice of altering the building envelope to introduce more natural light – may also be an option, although a building’s particular features can raise the cost of daylighting so that the payback period exceeds three years.

HID lighting is found in places with high ceilings or no ceilings, like gyms, cafeterias, stadiums and parking garages.  (See photo below.)  While fluorescents historically could not match their output and thus were a poor substitute for HIDs, lighting advances have led to the development of high-intensity fluorescents (HIFs) which are now superior in most respects to their HID counterparts.  HIFs can have as many as seven advantages over HIDs: lower energy consumption, less loss of light output over product life (“lumen depreciation”), better dimming abilities, faster start-up and restart times, better color rendition, more light output in the spectrum visible to humans (“pupil lumens”), and reduced glare.  Thus, in most applications, fluorescents are both more cost-effective than HIDs and able to provide light of better quality. 

Where a facility has already replaced incandescents and HIDs with fluorescents, significant further savings can be achieved by fine-tuning the fluorescents in one of several ways.  One way to treat fluorescents is by correcting harmonic distortion, a kind of electrical “feedback” or white noise which increases heat in the light fixture and reduces its electrical efficiency.  Harmonic distortion arises in electrical systems with many “non-linear” loads – those drawing current that does not travel in a sine wave.   Fluorescent lights are a predominant non-linear load in most buildings, but other examples of this kind of load are computers, monitors, printers and photocopiers.

 Harmonics can be corrected by the use of harmonic filters or cancellers placed either at a lighting fixture or at the lighting panel to reduce harmonics in the lighting system and increase its efficiency.  (See photo above.) 

 Reducing or eliminating harmonics in an electrical system will cause all non-linear loads in the system – not just lighting – to consume less electricity and operate more efficiently.

 Another way to reduce fluorescents’ electrical consumption is by means of a voltage regulator.  A voltage regulator can reduce current to a light fixture by 15% - 30%, with a corresponding drop in electrical consumption.  The voltage regulator causes a small, often undetectable, drop in light levels.

Automated lighting controls can also help reduce a light’s electrical consumption.  The three main types of lighting controls turn lights on or off depending on ambient light, time of day, or room occupancy.

Cooling Systems

Cooling systems – refrigeration and air conditioning – use compressors and refrigerant to cool water and air.  These systems typically represent a large component of a facility’s electric bill and are another good place to find fast-payback savings through retro-fitting.  There are three cost-effective ways to improve the efficiency of cooling systems: (1) implement controls to optimize the operation of mechanical components; (2) add oil lubricants to refrigerant; and (3) treat fans and compressors to improve operating efficiency.

Various controls can be used to improve the efficiency of cooling systems’ components.  Such controls include:

·         Fan speed control – uses pressure or temperature signals to control fan speed, reducing electrical consumption when operating at lower speeds.

·         Lube oil control – monitors and controls compressor lube-oil circuits to ensure proper lubrication and efficient operation.

·         Defrost control – improves the efficiency of the defrost cycle by defrosting on demand rather than on a simple timer.

Implementing a set of controls can lower a cooling system’s electricity consumption by 10% or more.  With payback periods as short as one year in some cases, these controls are a great place to start for a facility seeking to lower its electric bills immediately.

Another way to improve a cooling system’s efficiency is to add oil lubricants to the refrigerant.  Oil lubricants serve to reduce friction in the compressor’s moving parts, improving mechanical efficiency and lowering power consumption.  Such additives may also provide other benefits, such as reducing wear on bearings and improving seal life.

Finally, cooling systems’ electrical consumption can be lowered by improving the efficiency of rotating motors that drive compressors and fans.  (See photo above.)

This brings us to the third major area of electrical consumption in a typical facility: motors.

Motors

The third major opportunity for fast-payback electrical savings is by addressing rotating electrical motors, including drives, pumps and compressors.  These are found in many kinds of equipment, such as elevators, fans, air handlers, boilers, industrial equipment, air compressors, refrigerators, air conditioning units, spas and swimming pools.  Motors are inherently inefficient in two ways.  First, because they typically lack the ability to vary their speed, they may run at full speed even when the device they are driving (such as a fan, pump or blower) does not require it. 

Second, motors rely on both “active” power and “reactive” power to operate.  Imagine pushing a ball across a field which slopes to the side – active power is the force that drives the ball across the field, and reactive power is the force that keeps the ball from rolling down the slope.  “Power factor” measures the relationship between active power and reactive power.  If the field in this analogy were level, requiring no reactive power, power factor would be 100.  Motors typically run at a power factor of 80 or 90 out of 100, representing a potential efficiency loss of 10% - 20%.  An idling motor, or one not under load, runs at an even lower power factor – sometimes as low as 50.  A motor running at a power factor less than 100 is

inefficient in two ways – first, the motor demands extra current to compensate for the power factor deficiency, which increases the electric bill, and second, the extra current causes the motor to run hotter, which reduces its lifespan.  Correcting a motor to reduce its electrical consumption by 10% can increase the motor’s life by 50%.

One way to improve a motor’s efficiency is to regulate it with a variable frequency drive (VFD).  A VFD allows the motor’s speed to change with the changing demands of the device it is driving, such as a fan, pump or blower.    A VFD can reduce a motor’s electrical consumption by 10% or more. 

Another way to help a motor run more efficiently is to increase its power factor by attaching a capacitor to the motor.  (See photo above.) 

A capacitor acts like a short-term battery, regularly storing and discharging current as necessary to provide power to the motor in a more efficient manner.  In fact, a capacitor can be attached to a motor fitted with a VFD, and it will help both the motor and the VFD operate more efficiently.  When addressing low power factor, it may be prudent to install capacitors in banks at electric panels, individually at particular loads, or both.

Low power factor is generally a problem when a facility has many motors.  Electric utilities impose a surcharge when power factor falls below a designated threshold, such as 90.  To determine whether a building has a power factor problem, check the building’s electric bill for any extraordinary charges related to power factor (e.g., “Power Factor Adjustment”). 

The Bottom Line

What can these efficiency measures achieve in financial and ecological benefits?  By correcting electrical inefficiencies using the fast-payback methods described above, an organization can lower its electric consumption by 15% or more.  At a facility using 500,000 kilowatt hours monthly, a 15% reduction could lower annual electric bills by US$100,000 or more and annual carbon emissions by more than 800,000 pounds. 

David Simon, an energy consultant with Evergreen Energy Solutions, can be reached at david.simon@evergreensolves.com