Important Role Filters Play

in Industrial Hygiene

National Association of Air Filtration Conference

David W. Bearg, PE, CIH

September 21, 2006

Focus:

• Understanding the role of filtration in achieving a healthy and productive indoor environment

Achieving a Healthy & Productive Indoor Environment:

• Delivery of clean supply air

• Delivery of intended quantities of outdoor air for ventilation

• Moisture Management

• Access to daylight

WARNING:

• The Delivery of clean supply air does NOT guarantee the achievement of a clean indoor environment.

• Supply air is only one potential source of particulate matter in the indoor environment.

Particle Generation per minute:

Motionless Standing - 100,000 particles 0.3 micron or larger

Walking at 2 mph –

5,000,000 particles

Montana State University

Commissioning, Asking the Right Question:

• Not just, “Is the HVAC system working as intended?”, but

• “How is the HVAC system performing to provide a healthy and productive indoor environment for the smallest energy cost?”

Universal Truth:

• As it is with energy, if the performance of the HVAC system is not being monitored and reviewed, it cannot be managed well !!!

Monitoring Goals for HVAC System:

• Particulate levels,

• Moisture levels, and

• Carbon Dioxide concentrations

Monitoring Approaches for Assessing Effectiveness of Particulate Control:

• Visual assessment,

• Particle counting, and

• Gravimetric measurements

• Pressure drops across filters

Monitoring Approach for Assessing Effectiveness of Particulate Control:

• Measure the Pressure Drop across filter bank, either at the AHU or remotely (data-log).

Energy saving while achieving Effective Particulate Control:

• Reduce unnecessary resistance to air flow (i.e., pressure drop) by increasing surface area of filters to reduce media velocities: lower media velocities, lower pressure drop for the fan energy to overcome, and lower labor costs achieved by longer intervals between filter changes.

Interdependence of outdoor, indoor and HVAC conditions:

Whether by design or not, the components of a building and its HVAC interact -> Use Integrated Design to achieve the highest Effective Operation of a building’s systems

Interdependence of outdoor, indoor and HVAC conditions:

Since the occupant is exposed to how all of the components of a building and its HVAC interact -> The assessment of building and HVAC performance should consider how all these components are potentially interacting:

Solution:

IPA

Integrated

Performance

Assessment

Integrated Performance Assessment:

Just as with Integrated Design, IPA focuses on the end result by considering how all the various components of the HVAC system work together to achieve their intended results.

Integrated Performance Assessment:

FILTRATION

Measurements to assess the particle loading of the air delivered to the occupants, and not just after it leaves the filter bank.

IPA – Filtration: Comparison between OA and SA for fine particulate

0

2,000

4,000

6,000

8,000

10,000

12,000

14,000

16,000

10.5 11 11.5 12 12.5 13

Outdoor Air - FineSupply Air - Fine

Particulate counts / minute: 0.5 micron and larger diameter

Time, Hours

Capture Effectiveness = 90%

E-1: 0.3 to 1.0 microns

IPA – Filtration: Comparison between OA and SA for coarse particulate

0

50

100

150

10.5 11 11.5 12 12.5 13

Outdoor Air CoarseSupply Air - Coarse

Time, Hours

Particle Counts per Minute: 5 micron and larger diameter

18 particles/min

66 particles/min

Capture Effectiveness = 73%

E-3: 3.0 to 10 microns

0

10000

20000

30000

40000

50000

60000

70000

80000

90000

100000

6-Jan0

1000

2000

3000

4000

5000

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7000

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9000

10000

High traffic - fineExterior wall - fineHigh Traffic - CoarseExterior wall - coarse

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7-Jan 12-Jan9-Jan8-Jan 10-Jan 11-Jan||

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CoarseParticles perCubic

Fine Particles per Cubic Foot

Figure 3. Comparison of fine andCoarse Particles per Cubic Foot between High and Low traffic areas

IPA Filtration: Particle Generation Activities Within the Space

Effectiveness of Particulate Control:

• Intimately tied to the effectiveness of ventilation effectiveness, or how the geometry of how the air moves through the occupied spaces

RECOMMENDATIONS: 1. Harvest wasted energy in HVAC system by

increasing area of filtration.

2. Periodically compare particulate counts for the outdoor air, the supply air, and the room air to assess and document performance.

3. Also monitor HVAC performance with respect to moisture management and ventilation performance.

Integrated Performance Assessment:

MOISTURE MANAGEMENT

Measurements to assess the indoor humidity levels associated with: humidification, dehumidification, interior moisture leaks, and moisture intrusions through the building envelope.

Stratus Computer, June 19, 1995

48

53

58

63

68

0 2 4 6 8 10 12 14 16 18 20 22 0TIME OF DAY

DEWPOINT TEMPERATURE

DEG. F

O/A - Roof

O/A - Ground

RTU-1 Supply

RTU-1 Return

RTU-2 Supply

RTU-2 Return

R-2003

MS Lab

R-2498

R-2568

R-2600

R-2359

R-2122

R-2223

R-2077

R-2238

R-2639

R-1006

LAB # 5

Lab #3

Lab #8

DOCK

Lab #7

Supply Air

Dock

Outdoors

Lab #5

BIDMC Shapiro Center

20

25

30

35

40

45

50

0 2 4 6 8 10 12 14 16 18 20 22 0Time of Day

Dew Point Temperature Degrees

F

Outside Air1001 Board1002 Conf.701 B703 D7F3 Waiting747705 A707760 Conf.736 Conf.713 D721 D720724731 B7357F1 B7F2 Waiting601 B601 F603 D649605 A607610 A Conf.6F3 B613 D621 C620 Conf.6406F1 B639629 A631 G501 D5035605F3505

Sunday, December 18, 2005

1001 BoardRoom

Room 649 ( AHU 4 )

Outdoor Air

731B ( AHU 1 )

BIDMC Shapiro Center

20

25

30

35

40

45

50

0 2 4 6 8 10 12 14 16 18 20 22 0Time of Day

Dew Point Temperature Degrees

F

Outside Air AHU A SA

AHU B SA AHU C SA

AHU D SA

December 18, 2005

AHU D SA

AHU A SA

Outdoor Air

BIDMC Shapiro Center

45

50

55

60

0 2 4 6 8 10 12 14 16 18 20 22 0Time of Day

Dew Point Temperature Degrees

F

Outside AirAHU A SAAHU B SAAHU C SAAHU D SAAHU A RAAHU B RAAHU C RAAHU D RA1001 Board1002 Conf.507 D568 A513747705 A515 C521 B522713 D539531 C724731 B5F1 Waiting550 A Teach.550 B Conf.601 B601 F603 D649605 A607610 A Conf.6F3 B613 D621 C620 Conf.6406F1 B639629 A631 G501 D5035605F3505

September 23, 2005

AHU A SA

Outside Air

HVAC Monitoring, Accuracy & Confidence: Shared-Sensor Approach

DEHUMIDIFICATION

Integrated Performance Assessment:

MOISTURE MANAGEMENT

Measurements to assess the indoor humidity levels associated with: humidification, dehumidification, indoor sources of moisture, and moisture intrusions through the building envelope.

THE NEW ENGLANDApril 4, 1996

0

5

10

15

20

25

30

0 2 4 6 8 10 12 14 16 18 20 22 0

TIME OF DAY

DEWPOINT TEMPERATURE DEG. F

Outside Air

7 West (S-15)

6 South (S-16)

6 East (S-19)

9 East (S-21)

2 North (S-23)

Cafeteria

4 South (S-16)

10 West (S-15)

9 West (S-15)

8 West (S-15)

6 West (S-15)

5 West (S-15)

4 West (S-15)

Return (R-15)

3 East (S-19)

Return (R-19)

7 Core (S-21)

4 East (S-21)

3 West (S-3)

13-V (R-3-S)

SB-Loading Dock

SB-W Garage

IPA – Moisture: Identification of interior source

Newly Constructed Middle School

20

25

30

35

40

45

0 2 4 6 8 10 12 14 16 18 20 22 0Time of Day

Dew Point Temperature Degrees

F

Outdoor

Auditorium

Roof Special 1

Roof Special 2

Roof Special 3

Roof Special 4

April 5, 2005

Elevated humidity where the auditorium roof meets the vertical wall of the main school building

Outdoor humidity

Moisture Management & IAQ: Water Intrusion Evaluation

BENEFITS from MOISTURE MONITORING:

• Commissioning: Verification of Integrity of Building Envelope with respect to water entry,

• Early detection of water intrusion, as this provides an

Early Warning of potential MOLD growth !

• Improved management of indoor water features by knowing their impact on indoor humidities,

• Balancing energy and IAQ by optimizing the use of cold dry winter air for ventilation and cooling.

Integrated Performance Assessment:

VENTILATION

Measurements to assess the amount of ventilation provided, both during peak occupancies and the completeness of the overnight flushout.

300

500

700

900

1100

1300

1500

1700

1900

2100

0 2 4 6 8 10 12 14 16 18 20 22 0

Outdoor Air

Return Air

Room 112

Room 108

Room 115

Room 111

Room 107

Room 178

Room 105

CO2 ppm

TIME of DAY

IAQ DATAGRAPH MONITORED OFFICE BUILDING "CS" Locations served by AHU #2, July 2, 1997

IPA – Ventilation: Determination of Localized Ventilation Deficiencies

300

400

500

600

700

800

900

1000

1100

6-Jan 7-Jan 8-Jan 9-Jan 10-Jan 11-Jan 12-Jan 13-Jan

Pantry (3)

12 - South Area (3)

Outdoor Air

12 - NW Area (3)

Pantry (1)

Conference 11-1 (1)

12 - NW Area (1)

Pantry (2)

Conference 12-1 (2)

12 - NW Area (2)

Pantry (4)

Living Room (4)

12 - NW Area (4)

Conference 1101

Outdoor Air

Carbon dioxide, ppm

Time

780 ppm

1,010 ppm

IPA – Ventilation: Incomplete Overnight Flushout of Bio-Effluents & VOCs

BIDMCShapiro Center

300

400

500

600

700

800

900

1000

1100

1200

0 2 4 6 8 10 12 14 16 18 20 22 0

Time of Day

CO2 ppm

Outside Air

601 B

601 F

603 D

649

605 A

607

610 A Conf.

6F3 B

613 D

621 C

620 Conf.

640

6F1 B

639

629 A

631 G

September 23, 2005

Outdoor Air

610 A Conference

613 D

HVAC Monitoring should include occupied locations as well as at the AHUs to identify actual ventilation performance

BIDMC Shapiro Center

45

50

55

60

0 2 4 6 8 10 12 14 16 18 20 22 0Time of Day

Dew Point Temperature Degrees

F

Outside AirAHU A SAAHU B SAAHU C SAAHU D SAAHU A RAAHU B RAAHU C RAAHU D RA1001 Board1002 Conf.507 D568 A513747705 A515 C521 B522713 D539531 C724731 B5F1 Waiting550 A Teach.550 B Conf.601 B601 F603 D649605 A607610 A Conf.6F3 B613 D621 C620 Conf.6406F1 B639629 A631 G501 D5035605F3505

September 23, 2005

AHU A SA

Outside Air

HVAC Monitoring, Accuracy & Confidence: Shared-Sensor Approach

DEHUMIDIFICATION

Interaction of HVAC parameters?:

• Is the reduced dehumidification occurring at AHU A due to its needing to condition a larger percentage of Outdoor Air ?

BIDMC Shapiro Center

300

400

500

600

700

800

0 2 4 6 8 10 12 14 16 18 20 22 0

Time of Day

CO2 ppmOutside Air AHU A SA

AHU B SA AHU C SA

AHU D SA AHU A RA

AHU B RA AHU C RA

AHU D RASeptember 23, 2005

Outdoor Air

AHU - A SA

Comparison of Supply Air, Return Air and Outdoor Air for AHUs

Percentage of OA in SA Calculation:

% OA = Return Air – Mixed (Supply) Air

Return Air – Outdoor Air

AHU 1, between 11:17 and 11:20

%OA = (602-536)/(602-448) = (66/154)

= 43% OA

% of Outdoor Air for the AHUs can vary significantly through the day

AHU A

Percentage of Outdoor Air BIDMC Sharpiro Center

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0:00 0:00 0:00 0:00 0:00 0:00 0:00

Time, Hours

AHU-A

AHU-B

AHU-C

AHU-D

September 23, 2005

`

12:00 6:00 8:00 10:00 2:00 4:00 6:00

IPA : Combined MOISTURE and VENTILATION MANAGEMENT

Measurements to assess both absolute humidity levels and ventilation rates for

very high quality HVAC performance (Balancing IAQ and Energy Use):

• Optimizing the Delivery of wintertime dry cold outdoor air for ventilation & cooling

IPA : Integrated absolute humidity

and ventilation monitoring:

Critical Combination for IAQ

1) Diagnostic feedback on ventilation rates, critical for achieving good, or even superior, IAQ

2) Diagnostic feedback on moisture management for both comfort and preventing mold growth

Monitoring of end points: Addition of carbon dioxide to dew point monitoring to assess ventilation performance as well as moisture management performance:

Synergy yielding more robust feedback on building & HVAC performance

IPA –Integrated monitoring:

Other gaseous parameters to consider:

• Carbon monoxide

• Hydrogen sulfide

• VOCs ? ? ?

Universal Truth:

If it isn’t being effectively monitored,

how can it be effectively managed?

This applies to not only energy use, but also HVAC systems for moisture management and ventilation management

Monitoring can provide not only diagnostic feedback, but also HVAC control: DCV

1) Appropriate after it has been determined that the HVAC system is performing as intended,

2) Appropriate in areas where potential occupancies are both high and variable, and

3) Recommend logging and review of monitoring data.

BENEFITS from Verifying HVAC Performance:

Improved building operation and reduced risk in the areas of:

More optimum ventilation performance,

Moisture management.

Balancing IAQ and Energy Use

Improved management of building:

“Monitoring end points provides specific feedback that can help building owners and managers maintain the efficient performance of systems over time and remedy any problems that arise.”

Rachel Reiss

Improving the Energy Performance of Green Buildings

E Source, ER-0511, July 2005

RECOMMENDATIONS: 1. Install monitoring system that data logs both

absolute humidity (dew point) and carbon dioxide every half hour at key locations in the building.

2. Designate individual or firm to review the monitoring data in a timely fashion.

3. Periodically compare particulate counts for the outdoor air, the supply air, and the room air.

IPA –Integrated monitoring:

Achieve a healthier and more productive indoor environment for the smallest expenditure of energy

Thank you,

David Bearg, sagefarm@comcast.net