The role of HVAC air filtration and LEED certification

Building project managers pursuing LEED® (Leadership in Energy and Environmental Design) certification need to evaluate many things relating to energy efficiency, water efficiency, indoor environmental quality and related materials and resource selection.

But did you know that choosing the right air filter also can be an integral part of a building’s environmental sustainability strategy? In fact, implementing the right HVAC strategy could net you up to 11 LEED credits.

aIR fIlTRaTIon foR IaQ and eneRgy effIcIency

A building’s HVAC air filtration system provides tangible ways to improve indoor air quality (IAQ) and energy efficiency – two main tenets of the LEED program. In addition to contributing to the completion of LEED credits and prerequisites, careful selection of the right HVAC filter and filter media can actually save money in the long run – answering critics’ charges that green buildings always have to cost more.

Effective air filtration provides the primary defense for building occupants and HVAC equipment against particulate and gaseous pollution generated within a building, as well as pollutants from air drawn into a building by the HVAC system. At the same time, air filters play a significant role in the energy consumed to operate the HVAC system. The higher the filter’s resistance to air passing through it, the more energy is consumed to operate the HVAC system.

But even though we speak of air filters, it’s really the filter media that has the biggest effect on providing clean air, protecting HVAC equipment and minimizing energy consumption. That’s why the right filter media strategy can help buildings become more environmentally sustainable and meet LEED and other green building rating system criteria.

selecT THe RIgHT fIlTeR

To understand how the right filter can help to achieve LEED prerequisites and credits, it’s important to understand how filters should be selected to meet IAQ and energy-efficiency requirements. One of the biggest factors is filtration efficiency, which defines how well the filter will remove contaminants from air passing through the HVAC system.

The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) has an HVAC filter test standard to quantify the efficiency of filters. The ASHRAE 52.2 test standard measures the fractional particle size efficiency (PSE) of an HVAC filter. This indicates the filter’s ability to remove airborne particles of differing sizes between 0.3 and 10 microns in diameter.

A minimum efficiency reporting value (MERV) is assigned to the filter media depending on the PSE in three different particle size ranges: E1 (very fine particles in the 0.3 to 1 micron range); E2 (fine particles in the one to three micron range); and E3 (coarse particles in the three to 10 micron range). A MERV rating of five is least efficient, while a rating of 16 is most efficient. For the best and most complete way to compare the filtration efficiencies of different air filters, review the efficiency values that are included in the ASHRAE 52.2 test report.

The E1, E2 and E3 efficiencies represent the true measure of filter performance and give users a more complete picture of what the filter will actually do.

fIlTeRs and eneRgy effIcIency

Commercial and residential buildings account for 70 per cent of all electricity consumption and 40 per cent of all greenhouse gas emissions. A third of the energy used by commercial buildings goes to ventilation and space heating/ cooling. The energy used by HVAC systems is based on the resistance of the air passing through the filter. The lower the filter’s resistance, the lower the energy consumption will be. Switching to a filter with a lower resistance to airflow is one of the easiest changes building professionals can make in an effort to reduce energy usage and cost. That’s because the HVAC system fan motor needs to overcome less resistance to deliver the required airflow, thus reducing the motor’s energy consumption.

Fortunately, modern filter media has given the industry the capability to produce filters that provide a lower resistance to airflow while maintaining highparticle capture efficiencies, thereby providing the ability to improve IAQ and reduce energy costs simultaneously.

Reduce wasTe and gReenHouse gas emIssIons

In addition to providing for superior IAQ and reducing energy consumption, HVAC filter selection has a direct effect on a number of environmental sustainability issues. greenhouse gas emissions – A 0.05inch WG reduction in a filter’s initial resistance to airflow may reduce CO2 emissions up to four per cent or 120 pounds per filter. A 0.20-inch WG reduction in a filter’s initial resistance to airflow may reduce CO2 emissions by up to nine per cent or 480 pounds per filter. raw material use – Some filters provide superior performance while using less media than other filters. In addition, filter media can be made with recycled polymer from manufacturing waste streams. waste output – Choosing high-capacity pleated filters can extend filter life and reduce change-outs and associated waste streams.

Once a robust air filtration system has been implemented, it’s important to pay attention to proper filter maintenance. Delaying filter maintenance increases energy consumption and increases CO2 emissions. Reducing HVAC energy consumption therefore helps conserve natural resources – a wise sustainability strategy. b