Description

The use of high efficiency HVAC filters is often an effective strategy to control exposure to particulate matter of both indoor and outdoororigin. In high-performance green buildings, filtration can be an attractive alternative to supplying additional ventilation because it can lowerparticle matter (PM) concentrations in a less energy intensive fashion, and it is effective even when outdoor concentrations of PM are high.However, little is known about the potential energy impacts and overall air quality consequences of filters installed in commercial buildings. Toexplore these effects for filters in the built environment, system airflow, filter and coil pressure drop, fan pressure rise, and power draw weremeasured for at least four different filter pressure drops in 14 rooftop units equipped with no fan speed control. The rated cooling capacity of theseunits ranged between 8.5 and 20 tons. The dataset was further analyzed to estimate the power draw during cooling and fan-only modes and cleanair delivery rate for three different filter efficiencies (MERV8, MERV11, MERV14). Increased filter pressure drop caused decreases in flow,fan power, cooling capacity, and compressor power; and increase in duty cycle time to meet the same cooling load requirements. Consequently, theenergy efficiency ratio (EER) dropped by 1.4% (median decrease) when flow was decreased between 0 and 15% and by 7.3% when flow wasdecreased within the range of 35 and 50%. To be economically attractive, the energy cost of using high efficiency filters must be justified by higherclean air delivery rate. The median clean air delivery rate increased 2.4 times for PM2.5 and 1.2 times for PM10 when replacing MERV8 withMERV14. However, replacing MERV8 with MERV11 did not improve the indoor air quality because the diminished flow was notcompensated for by the increased filtration efficiency. The potential cost of improving air quality when using high efficiency filters (i.e., decreasingparticle concentrations) translated in a median 3.5% increase in total power draw and potential savings resulted in a median of 12.4% decrease infan power. The actual energy impact of high filter efficiency depends on the operation of the rooftop unit (compressor versus fan-only mode, and dutycycle). A comprehensive understanding of the impact of filtration is essential to selecting the appropriate efficiency of filters that ensures low-energyuse and healthy buildings.

Citation: IAQ Conference: IAQ 2013: Environmental Health in Low Energy Buildings

Product Details

Published:

2013

Number of Pages:

9

File Size:

1 file , 1.4 MB

Product Code(s):

D-2013IAQConf-08