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IAQ IMPROVEMENT
Ventilation, Filtration and Source Control
• The top three methods for controlling
indoor air contaminants• Control air contaminants
>>> improve IAQ
IAQ AND VENTILATION
Ventilation
• ASHRAE Standard 62• Basically contaminant dilution• Even diluted, some contaminants are
still problems• Has an energy penalty• Air usually must be cleaned
IAQ AND SOURCES
Source Control
• Source elimination, attenuation or
substitution• Requires knowledge of source• Usually complicated/impossible• Usually involves change for occupants >
> >difficult
IAQ AND FILTRATION
Filtration
Will Always Be
• Needed For Contaminants– Originating in the Building– Originating Outside of and
entering the building
IAQ AND FILTRATION
Filtration
Will Always Be • One of the most energy efficient options
for improving IAQ• One of the most doable options for
improving IAQ• One of the lowest capital cost options
for improving IAQ
IAQ AND FILTRATION
Filtration
• Also has an energy penalty• But, provides energy return by
preventing decline in other HVAC component performance
• And, provides other cost benefits, e.g. less maintenance
The Paradox
Since Filtration Is So Important& Advantageous to IAQ
Why Are There So Many Bad and Problematic Filtration
Systems?
A POSSIBLE REASON?
• At the consumer level, filtration systems are still considered dust control systems
• Filtration systems are not considered contaminant control systems
• Essentially: the arrestance vs. efficiency by size range mindset
DUST VS. CONTAMINANT
DUST• Focus is on
objects: – Coils– Fans– Building
surfaces
CONTAMINANT• Focus is on
occupants:– Health– Well-being– Productivity
DUST VS. CONTAMINANT
DUST• Goals:
dust buildup soiling maintenance equipment
protection
CONTAMINANT• Goals:
illness irritation absenteeism productivity
DUST VS. CONTAMINANT
DUST• Properties of
concern:– physical
composition– larger (visible)
particles– amount to load
filter
CONTAMINANT• Properties of
concern:– physiological
effectors– 0.3 to 10.0 m
particles– airborne
concentration
DUST VS. CONTAMINANT
DUST• Filter selection:
– what is cheapest
– arrestance– bypass and
leakage less important
CONTAMINANT• Filter selection:
– what is to be controlled
– MERV– bypass and
leakage more important
BUT
Nowadays
BOTHare important considerations, depending
on the conditionsAND
they are not mutually exclusive—control for contaminants, control for dust
IAQ and Effective Filtration Systems
Filtration system selection—the contaminant control model
1. Determine what is to be controlled
2. Determine the level of control
3. Select the best filtration system
IAQ and Effective Filtration SystemsFiltration system installation—the contaminant control model
1. Correctly install the filtration system
2. Commission the filtration system
3. Educate and train the customer on operation and maintenance
FILTRATION SYSTEM SELECTION
Determine what is to be controlled• Determine what the customer’s control
needs are—allergies, asthma, dust, etc.
• Don’t assume you know—ask
• Determine the important contaminants in the building based on the customer’s concerns
FILTRATION SYSTEM SELECTION
Determine what is to be controlled• Determine the physical properties of the
important contaminants
• Consult knowledgeable IAQ professionals (and maybe docs) when needed
• Sample when necessary
FILTRATION SYSTEM SELECTION
Determine the level of control• People factor:
– varying reactions to contaminants (medical and personal)
– varying degrees of potential exposure in the same building
– psychosocial influences
FILTRATION SYSTEM SELECTION
Determine the level of control• Contaminant factor:
– many different types (e.g. biological vs. inert)
– many different variations (e.g. 100,000 mold species)
– many different forms (e.g. particle vs. fiber)
– environmental influence– synergism
FILTRATION SYSTEM SELECTION
Determine the level of control• No exact criteria are available for most
contaminants—huge gap in research
• Building properties and air handling system design will impact contaminant concentrations—try to account for variables
FILTRATION SYSTEM SELECTION
Determine the level of control needed• Sampling might help determine
approximate contaminant concentrations
• Most times, experienced WAG is going to be good enough, but seek help when needed
• Customer’s needs should have major impact on level of control needed
FILTRATION SYSTEM SELECTION
Select the best filtration system• Best system provides control of
important contaminants to the desired concentrations
• Focus on the customer’s needs—not the products available for sale
FILTRATION SYSTEM SELECTION
Select the best filtration system • MERV 10 minimum—based on mold
(about 3.0-10.0 m particle size range)—but, system should have most efficient filtration in particle size ranges of contaminant of interest
• Filters should not exceed allowable fan pressure drop when loaded to factory specification
FILTRATION SYSTEM SELECTION
Select the best filtration system • Filters should not load up too rapidly
• System should have minimal bypass and leakage
• Gaskets should be reliable, effective, durable and easy to replace
FILTRATION SYSTEM SELECTION
Select the best filtration system • Filters should be easy to changeout and
have minimal gizmo hardware (KISS)
• System should be adaptable for future modifications
• Etc.
FILTRATION SYSTEM INSTALLATION
Correctly install the filtration system• Make sure system is installed so filters
can be easily changed and hardware can be easily maintained
• Seal all seams between filter and fan—Caulk non-removable panel seams; gaskets on removable panels or doors; tape if not gasketed
FILTRATION SYSTEM INSTALLATION
Correctly install the filtration system
FOLLOWNAFA
RECOMMENDATIONS
Training, continuing education, professional input, trade shows
FILTRATION SYSTEM INSTALLATION
Commission the filtration system• Thoroughly inspect each filtration
system to make sure it was installed according to spec and works as planned
• Dry-run filter changeout to anticipate problems
FILTRATION SYSTEM INSTALLATION
Commission the filtration system
FOLLOWNAFA, ASHRAE, SMACNA, Etc.
RECOMMENDATIONS AND GUIDELINES
Document, document, document
FILTRATION SYSTEM INSTALLATION
Educate and train the customer on operation and maintenance
• Make sure the customer understands how filtration works in general
• Make sure the customer knows how the filtration system works in particular—don’t trust the customer to read the manual