Transcript Indoor Air Quality

WEATHERIZATION ENERGY AUDITOR SINGLE FAMILY
Indoor Air Quality
WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – December 2012
1 | WEATHERIZATION
ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – December 2012
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Learning Objectives
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By attending this session, participants will be able to:
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Recognize about the factors affecting IAQ.
Describe the role moisture plays in IAQ.
Discuss moisture movement.
Formulate pollutant remediation techniques.
Examine the impact of occupant behavior on IAQ.
Describe the evolution of ventilation standards.
Describe the requirements of ASHRAE 62.2 2010.
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IAQ and Moisture
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• Moisture and Mold
• Stored Toxic Materials
• Carbon Monoxide (CO)
• Radon
• Sewer Gas
Photo courtesy of The PA WTC
• Other
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Occupant Driven IAQ Sources
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• Common household pollution sources
o Pet dander
o Volatile Organic Compounds (VOC’s)
 Improperly stored solvent, paints, cleaners
o General unhygienic conditions
o Rodent or Insect Infestations
• Making things worse
o Tight house with a lack of ventilation
o Uninformed occupants
Photo courtesy of The US Department of Energy
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Sources of Water Vapor
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Source
Quarts per Day
Construction materials first year
40
Standing water in basement
30
Damp basement or crawlspace
25
Greenhouse connected to house
25
Humidifier - large
20
Drying 1 cord of firewood
16
Clothes dryer vented to inside
13
Respiration/perspiration – 4 people
4.7
Clothes washing
2.1
Unvented gas range
1.3
Cooking without lids
1.0
Houseplants – average number
0.5
Dish washing
0.5
Floor mopping
0.4
Showering/bathing
0.3
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Related to the
building
Related to occupant
behavior
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Moisture Movement
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Air
flow
Air molecules
are blocked.
Both water vapor
and air molecules
pass through.
Water vapor
molecules are
passed.
Diffusion Through Surface
Convection Through Holes
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Permeance of Building Materials
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Permeance of
Building Materials
Material placed on the warm
side of a building surface to
retard diffusion of water
vapor is called a vapor
barrier. Material intended to
retard convection is called
an air barrier. Material
which accomplishes both is
termed an air/vapor barrier.
A material qualifies as a
vapor barrier if its
permeance is 1.0 perm or
less.
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IAQ and Relative Humidity
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Relative Humidity and Indoor Air Quality Relationships
Decrease in bar width indicates decrease in effect
Bacteria
Viruses
Fungi
Dust Mites
Respiratory Infections
Allergic Rhinitis and Asthma
Clinical Interactions
Ozone Protection
Percent Relative Humidity
0%
10%
20%
30%
40%
50%
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60%
70%
80%
90%
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What Determines IAQ?
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Photos courtesy of The US Department of Energy
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Client Interview
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Use the interview process to learn more about how the client uses
their home as it relates to health and safety:
• How many people live in the home?
• Are there cold rooms? Hot rooms?
• Do they use the fireplace or unvented space heaters?
• Does anyone in the home have asthma or other illnesses?
• Are headaches a chronic problem in the heating season?
• Do they use their kitchen and bathroom exhaust fans?
• Do they dry clothes or wood in the house?
• Are there any unpleasant odors or burning sensations?
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Client Education
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• Properly size central AC units.
• Talk people out of using unvented heaters.
• Don’t overcool the house in summer.
• Don’t hang wet clothes in the house.
• Don’t dry wood indoors.
• Use kitchen and bath exhaust fans.
• Enhance room circulation with fans to avoid cold spots.
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What WAP Can and Cannot Do
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• Testing and abatement is not an allowable expense.
(WPN 11-6 H&S Guidance)
• Mold clean-up is not an allowable expense
• Correcting moisture problems that may cause mold is
allowable
o Controlling surface temperatures with good
insulation and air sealing practices
o Venting dryers
o Installing mechanical ventilation
o Fixing minor drainage issues
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Pollutant Action Tree
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Source
• Eliminate
• Encapsulate
• Dilute
Driving Force
• Eliminate
• Weaken
Path
• Eliminate
Photo courtesy of The US Department of Energy
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• Block
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Outside Air and IAQ
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How much outside air do we need for good IAQ?
How do we get it?
WIND
DIRECTION
Exhaust
Fan
Wind
Buoyancy
Mechanical Fans
Stack effect - warm air rising
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How has natural ventilation
been calculated?
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N-factor variables:
• Geographic location
• Building height
• Building exposure
The n-factor for the house illustrated at right would be
different if it was one story taller, or less shielded. The
map shown below is the LBL Climate Zone Map used
to determine the geographic variable.
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Why Isn’t the MVG Our Best Tool?
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A single-point blower door test will see these holes as identical!
Photos courtesy of The US Department of Energy
The matched board ceiling above has many feet of linear
cracks that expand and contract depending on relative
humidity (RH).
The missing flue plug creates a
stable-sized round hole with little air
flow drag.
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Random Size & Distribution?
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Neutral pressure plane
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An Important Corollary!
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250
Based on single-story 1,500ft2 house
200
CFM50 = 4000
150
CFM50 = 1000 + 75 CFM fan
100
CFM50 = 2000
50
Desired ventilation = 75 CFM
0
CFM50 = 1000
0
20
40
Outdoor Temperature, degrees F
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60
80
Chart courtesy of Paul Francisco
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What is the DOE Requirement Now?
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ASHRAE 62.2-2010
A Wisconsin pilot study conducted
in 2004 found that 78% of
weatherized units required
additional mechanical ventilation
under 62.2, up from 47% using the
previous ASHRAE standard,
62.1989.
Average installed cost, including
controls: $525 (2004-2005 prices).
www.ashrae.org
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ASHRAE 62.2-2010
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Photos courtesy of The US Department of Energy
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ASHRAE 62.2-2010 Table
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Table 4.1a: Minimum Ventilation Air Requirements, CFM, New
Buildings1
BEDROOMS
Floor Area (ft2)
0-1
2-3
4-5
6-7
>7
< 1500
30
45
60
75
90
1501 – 3000
45
60
75
90
105
3001 – 4500
60
75
90
105
120
4501 – 6000
75
90
105
120
135
6001 – 7500
90
105
120
135
150
> 7500
105
120
135
150
165
1
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ASHRAE 62.2-2010, p 4
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ASHRAE 62.2-2010 Formula
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New or Existing Buildings2:
CFMfan = 0.01Afloor + 7.5(Numberbedroom + 1)
+ (alternative compliance supplement)
- (Infiltration credit)
A = conditioned floor area; “the part of the building that is capable of being
thermally conditioned for the comfort of occupants.” (ASHRAE 62.2, p.3)

Assumes two occupants in master bedroom and one each in the other bedrooms. Over
this density, increase ventilation by 7.5 cfm/person.

Whole building, intermittently operating ventilation may be used under some conditions
for compliance.

Ventilation air must come directly from the outdoors.

Credit is allowed for envelope air leakage in some cases,
based on ASHRAE 62.2 and 136.
2
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Slide content from ASHRAE 62.2-2010
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Beyond Fan CFM Requirements
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ASHRAE 62.2 2010 includes:
• Spot ventilation requirements as mentioned.
• Attached garages must be adequately sealed from living
space to prevent migration of contaminants.
• Clothes dryers must be vented to exterior.
• All duct joints outside conditioned space must be sealed.
• Sone rating requirements must be met.
• Branch duct systems must have backdraft
dampers.
• Whole-home fan flow must be verified.
• Continuous vs. intermittent fan specifications.
Photo courtesy of The US Department of Energy
23 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – December 2012
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Summary
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• IAQ depends on the pollutant source strength and the air
change rate. Elimination at the source is preferable to
confinement, which is preferable to dilution.
• Many pollutants are present in the average home: The air
change rate is a function of inside to outside pressure
difference, hole size, and hole location.
• A higher air change rate equals better IAQ, and usually
higher space conditioning costs.
• ASHRAE 62.2 2010 guidelines are a required standard for
new and existing buildings.
• Occupant behavior can have a major impact on IAQ.
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