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3.4.2 Particle Measurement

Airborne particle concentrations were measured using three types of instruments: two
models of the Climet™ laser particle counter (Climet Instruments Co., Redlands, California),
the Aerodynamic Particle Sizer , Model 3321 (TSI Inc., St. Paul, Minnesota), and the
DustTrak (TSI Inc., St. Paul, Minnesota).
The Climet models CI-550 and Spectro.3 count particles from 0.3 μm to greater than 10 μm in aerodynamic diameter. The CI-550 particle counter measures six particle size ranges (six channels) including 0.3 – 0.5 μm, 0.5 – 1.0 μm, 1.0 – 3.0 μm,
3.0 – 5.0 μm, 5.0 – 10.0 μm, and greater than 10 μm. The Spectro.3 particle counter measures sixteen particle size ranges (16 channels) including 0.3 – 0.4 μm,
0.4 – 0.5 μm, 0.5 – 0.55 μm, 0.55 – 0.7 μm, 0.7 – 1.0 μm, 1.0 – 1.3 μm, 1.3 – 1.6 μm,
1.6 – 2.0 μm, 2.0 – 2.2 μm, 2.2 – 3.0 μm, 3.0 – 4.0 μm, 4.0 – 5.0 μm, 5 – 5.5 μm,

5.5 – 7.0 μm, 7.0 – 10.0 μm, and greater than 10.0 μm.
Each Climet instrument was connected to a valve that enabled sequential automated sampling from two separate locations. The Climet Spectro was set up to sample air from outdoors and in the bathroom, while the Climet CI-550 sampled air from the supply duct immediately downstream of the AHU and in the dining room near the AHU return grille. For the in-duct measurement, an isokinetic sample probe was used to ensure a representative air sample from the moving aerosol stream.
The Aerodynamic Particle Sizer  (APS) measures a range of particle sizes from 0.5 μm to 20 μm with a maximum particle concentration of 1,000 particles per cubic centimeter at 0.5 μm. The APS instruments were used to measure particle levels at the return air grille intake for the AHU and in bedroom 2.
3.4.3 Other Parameters
Ambient indoor temperature and relative humidity were measured in each room of the test home with a HOBO™ model H8 portable temperature/relative humidity data logger manufactured by Onset Computer Corp. (Bourne, Massachusetts). Test house air handler fan amperage draw was measured with a HOBO™ equipped with an external
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AC current sensor input. Temperature and relative humidity sensors were compared to primary standards. As discussed above, air exchange rate was measured during each test according to ASTM E779-98. Outdoor temperature, relative humidity, wind speed, and direction were measured with a Davis weather station during each test as well.
3.4.4 Portable Air Cleaners
In addition to Trane CleanEffects™/American Standard AccuClean™ and other in-duct air cleaners, EH&E included two types of portable air cleaners in the testing program: the Hunter Quiet Flo™ HEPA Air Purifier Model 30216 and the Ionic Breeze Quadra™ Silent Air Purifier. The Hunter model is manufactured by Hunter Fan Company (Memphis, Tennessee) and equipped with 3 user selectable fan speeds. The Hunter units were run at the highest fan speed, approximately 220 cfm of air, during the testing. The Ionic Breeze model tested is manufactured by Sharper Image (San Francisco, California) and has electronically charged rods that capture particles. The Ionic Breeze does not have any fans or filters.
To ensure that the test home environment was consistent among trials, EH&E carried out a cleaning protocol between tests. Prior to cleaning, EH&E set the AHU fan to run continuously and verified that the heat pump was not being used to condition the space. The AHU cooling coil was disengaged to prevent condensation from forming on the coil and possibly enhancing particle removal.
To remove particles from the air between tests, EH&E installed a five-inch pleated induct filter in the AHU and allowed the system to run for 30 minutes. While the AHU was operating, the carpet in the test home was vacuumed with a Dirt Devil Vision™ vacuum equipped with high efficiency particle air (HEPA) filtration. After vacuuming, the AHU was run an additional 10 minutes to filter out any particles suspended by the vacuuming operation. The air cleaner being tested was then placed in the AHU.
Monitoring data were collected for at least 10 minutes of data prior to the beginning of each test. After the proper air cleaner was installed in the AHU and the fan was operating again, the aerosol generator was run for one minute. During the introduction of fine test dust, a vacuum cleaner with the filter and bag removed was operated in the area of the AHU return grille to suspend carpet dust and thereby increase the number of coarse (>2.5 μm particles) particles in the air. After the aerosolization period, the AHU (and portable air cleaners when tested) was run for approximately 80 minutes. At the end of each test, data collected by the monitoring equipment was downloaded to a network drive and underwent preliminary data reduction. The test protocol was repeated generally 6 times for each combination of air cleaner and challenge aerosol (fine test dust or ambient fungal spores). Protocols for the fine dust standard and fungal spore tests are presented in Appendix A and B, respectively.
Raw data generated from the multi-channel sampling equipment was sorted and organized
into the following discrete size bins:

  1. 0.3 – 0.5 microns (Climet only)
  2. 0.5 – 1.0 microns
  3. 1.0 – 3.0 microns
  4. 3.0 – 5.0 microns
  5. 5.0 – 10.0 microns
  6. 10.0 – 20.0 microns

Fungal spore samples were identified to the level of genus or spore type.
The size-specific particle data and total fungal spore concentrations collected during the respective tests were analyzed to ascertain nominal removal efficiency, whole aerosol removal rate, and whole house clean air delivery rate,
Details of the data analysis methods are described below.
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Removal Efficiency
Particle concentration measurements were made upstream and downstream of the induct air cleaners to ascertain nominal size-specific removal efficiencies and thereby support interpretation of the whole house air cleaning data. The protocols employed in the test home were designed to allow determination of whole house particle removal rates rather than removal efficiency for in-duct air cleaners. For example, determination of removal rate requires that concentrations change over the course of a test. In contrast, protocols for determination of removal efficiency require that concentrations remain constant over a test (ASHRAE 1999). In addition, the determination of removal efficiency for an air cleaner requires zero by-pass. However, the whole house testing regimen employed by EH&E used a standard air handler cabinet with no special modifications to eliminate by-pass. For these reasons, the removal efficiencies observed during the test home work are considered nominal and qualitative rather than a quantitative measure of air cleaner efficiency.
Nominal removal efficiency for each filter was determined from particle counts collected by a Climet instrument that sampled from return air (CR) and supply air (CS) for alternating one-minute periods during each test.
Removal efficiency for each test was calculated as the average of the one-minute efficiencies.

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