From audit to implementation: Saving energy in a manufacturing environment
Manufacturers these days are being asked to produce products that are “green” to satisfy corporate sustainability goals.
Manufacturers these days are being asked to produce products that are “green” to satisfy corporate sustainability goals. These goals are often set by top management to position the company’s products in the eyes of consumers as the most friendly to the environment. Many companies have discovered the benefit of thinking beyond the product and the package and have extended the search for efficiency to the manufacturing facility itself.
With today’s technologies for lighting, heat recovery, HVAC, compressed air and improving the building envelope, it is very likely that the actions that save the most energy and provide the best financial return are related to the manufacturing building and infrastructure. The project described here demonstrates the importance of including the facility itself when making decisions around sustainability and continuous improvement.
A diverse portfolio of buildings, plants
During the past year, a global food products company began a new series of broad goals around sustainability and awareness about the energy future for its plants in the U.S. The task then fell to a group of engineering and production professionals in the organization to implement the energy efficiency portions that support their sustainability goals. The first eight plants selected for lighting retrofit were designed and installed by our offices in Glendora, CA; Salt Lake City, UT; and Austin, TX.
Over the years, major US corporations have expanded their market offerings through acquisitions and by expansion of their traditional brands. This growth has created groups of facilities of various ages that represent several decades of energy-using systems. At the same time, accelerating energy costs that outpace inflation are putting obvious focus on energy use.
Looking at all options for energy projects, this food products company selected a program of lighting retrofits in several of its U.S. plants to capture the energy savings that are easiest to implement and have the highest financial return. The new lighting designs in the first group of eight plants are projected to save nearly 4 million kWh annually, which reduces carbon dioxide (CO 2 ) emissions by more than 5.4 million pounds each year %%MDASSML%% the equivalent of permanently taking 611 cars off the road.
Audit, design, installation
When approaching a project of this magnitude, the first step is to conduct a comprehensive lighting audit of each building, because the audit then acts as the blueprint in the redesign process. Audit data include the existing lighting fixture type, lamp and ballast from every room in each building. The audit also identifies opportunities for lights to be turned off when not needed such as unoccupied warehouse aisles. Lighting in a manufacturing plant generally operates far more hours per year than in an office or retail environment, so efficient lighting equipment is crucial.
The audit is then turned into a formal proposal where alternate fixtures are identified and installation costs are prepared. The proposal also makes a detailed calculation of energy savings projected from the new fixtures because of reduced energy use, fewer operating hours or both. Although new lighting had been installed over the years, the proposal identified several typical examples where the existing lighting fixtures could be changed; saving significant energy and CO 2 emissions, with an average 50% first-year return on investment (Fig. 1).
By far, the most common lighting fixtures replaced to date are the metal halide high bay lights found in production areas and warehouses. When new, metal halide lamps have tremendous light output at very high efficiency. But manufacturer’s ratings show a degradation of light output over time, losing more than 40% of the initial output after only 60% of the useful life %%MDASSML%% even though the energy use stays the same as new lamps (Fig. 2).
Because of the degradation, metal halide lighting systems are designed to provide excess light when the lamps are new, so that they can still be counted on to supply the necessary light levels after the light output has dropped. Also, because of the high temperatures generated by this type of light source, these lamps cannot be turned off and on again by a sensor in response to building occupancy patterns.
The metal halide replacement selected most of the time is a multi-lamp fluorescent fixture with a high-output lamps and often with high-power ballasts. These lamps degrade by no more than 10% over their entire useful life, so they are producing the needed light output with less energy. Fluorescent lamps use about one-half the energy of the metal halide, and depending on the price of energy and the number of operating hours each year, the fluorescent retrofit can pay for itself between one and four years.
Next in order of common retrofits is replacement of older-style fluorescent T-12 lamps and magnetic ballasts with current generation T-8 lamps and more efficient electronic ballasts. In this project (food products company), the age and location of the various buildings dictated where T-12 lamps were still in use. As expected, the older T-12 lamps were found most often in older buildings in cities with low energy rates.
Lighting control with fluorescent lamps can be accomplished with motion sensors and photocells. This strategy simply keeps lights off when they are not needed. The use of sensors can significantly add to the energy savings and results in even more reduction in CO 2 emissions. When they are installed with “program start” ballasts, they can be turned on and off repeatedly each day without harming lamp life. Use of motion sensors in a warehouse is particularly ideal for the aisles that are visited less frequently.
The new lighting design had to account for several other factors in order to be compatible with operations in food products manufacturing. First, the manufacturing areas require that lamps cannot shed glass from the fixture in case of breakage. In these areas, the specified lamps have a coating that holds the broken glass pieces in place if they were to break inside the fixture. Second, our designers had to be aware of the ambient temperatures in the facility and take care to specify fixtures that can handle the temperature extremes of hot and cold specific to each plant.
Third, the height of the fixtures must be considered for optimal energy use. Light output decreases dramatically the farther you are from the light source, so the light fixtures should be repositioned to be as close as practical to the task at hand in order to deliver the most effective light with the least energy use (Fig. 3). Finally, the color temperature of the light sources is important to the operation of any industrial or manufacturing plant. This is because color temperatures that are closer to the blue spectrum allow humans to see better at the same light levels when compared with lamps that have a predominantly yellow color temperature.
The process from audit to installation for eight plants has taken about one year for a total cost of nearly $900,000. The time frame could have been much shorter, but projects were staged according to a capital budget schedule developed by the client. At the time of the audits and proposal, savings were estimated to be nearly $400,000 per year %%MDASSML%% this benefit is sure to increase with rising energy costs.
David R. Laybourn is director of marketing and sales at LIME Energy in Glendora, CA. Laybourn has more than 25 years experience in new technology for resource conservation as product manager, sales manager and marketing director. He holds a bachelor’s degree in Management Engineering from Claremont McKenna College and Mechanical Engineering from Stanford University.
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