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In addition to removing the contaminants from the air that passes through the system to the building occupants and equipment, filters play a significant role in the amount of energy consumed in operating the system. The energy use is based on the resistance of the air passing through the filter, therefore the lower the filter’s resistance, the lower the energy consumption.
Unfortunately, many businesses look at the media used in their filters as a commodity that provides little differentiating performance value. Recent advances in filtration media technology show that this is not the case. However, because of the perceived commodity status, price has become the determining factor for building owners and managers when deciding what type of filter and media to use.
It is important to understand that the cost of energy used by filters far outweighs the initial cost of the filter itself. In fact, energy costs can be 10 times the initial filter cost for standard pleated filters and four to five times the initial filter cost for higher-efficiency final filters. Therefore, with filters controlling a majority of a HVAC system’s energy consumption companies should look to the filter itself as a method of conserving energy.
Fortunately, there is a way to use filters as an energy conservation tool. That is to consider the total life-cycle cost of the filter and the long-term impact on energy costs that a particular filter will have. More energy-efficient filters do not necessarily cost more, so energy savings can often be achieved without any investment at all. Life-cycle costs, energy costs and filter pressure drop should all come into play during the filter selection process.
The three major components of life-cycle cost for HVAC filters are initial investment and maintenance, energy consumption and disposal. On average, energy cost accounts for an astounding 81 percent of the total life cycle of a filter system. The initial investment and maintenance accounts for 18 percent and disposal accounts for one percent.
How can life-cycle costs of filters be applied to energy efficiency?
Development of new materials has given the filter industry a chance to produce lower pressure-drop media while maintaining high particle capture efficiencies. Switching to a lower pressure-drop filter is one of the easiest changes for building owners and facility managers to make in an effort to reduce energy costs. That is because, with a lower pressure drop, the HVAC system motor needs to overcome less resistance to deliver the required airflow, therefore reducing the motor’s energy consumption.
Most building owners and facility managers would agree that filtration efficiency comes first. Beyond the efficiency rating, buyers and specifiers often use filter price as the next decision-making criteria. However, after examining life cycle cost data and energy savings data; it is evident that the key criterion should be energy consumption. When considering the energy costs of various filter technologies they should ask the following questions:
• At what pressure drop reduction would a filter upgrade pay for itself?
• At a given performance level, how much money could be saved by using a lower pressure drop filter?
• How much of my filter costs does that cost-saving offset?
The lowest-cost air filtration system is dependent on many factors, including investment and maintenance costs as well as hidden costs such as energy, disposal and shrinkage due to damage. Contrary to industry beliefs, high filtration efficiency no longer means high-pressure drop. There are commercially available 95 percent efficiency synthetic media filters that have the same pressure drop as 65 percent efficiency glass media filters. They provide the ability to increase filtration efficiency by 30 percent without increasing energy cost at all.
