Indoor Air

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Indoor Air Moisture Issues
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Indoor Pollutants

• Carbon monoxide (CO)
• Tobacco smoke
• Nitrogen oxides, hydrocarbon dust
• Volatile organic compounds (VOC)
• Radon
• Biological Particles (bacteria, , viruses, dust
  mites, cockroaches, fungi, mold, raw sewage,
  rotting wood)
• Asbestos and Fiberglass
• Lead-based paints
• Water vapor

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Indoor Pollutants How will you deal with these?

• Lifestyle (pets outside, door mats, no shoes
  indoors, regular cleaning)
• Careful product purchase decisions (low VOC)
• Hard floor surfaces in lieu of carpeting
• Sealed combustion appliances (furnace, fireplace)
• House pressure balancing (jump ducts, transfer
  grills)
• Moisture management (humidity control)
• Ventilation
• Whole house
• Spot (bathrooms, kitchen, crawl spaces for radon)
• Air filtration

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Indoor Pollutants How will you deal with these?

• Air filtration

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Indoor Pollutants How will you deal with these?

• Air filtration

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Indoor Pollutants How will you deal with these?

• Air filtration

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Indoor Pollutants
Efficiency at 0.3 Micron Particles
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Moisture

• Moisture is the number one pollutant in homes
• Need to be aware of its sources
• Basic knowledge of determining moisture levels
• Solving moisture problems

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Dealing With Moisture

• Keep water out
• Roof, plumbing, grading of groundfix problems
• Understand that moisture will get in
• Ventilation is needed
• Make sure moisture can get out
• Material selection (vinyl wallpaper is a bad
  choice)

BPI Analyst Certification Basic Principles of
Energy
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Moisture Movement Through Buildings

• Moisture in buildings can be tracked to one or
  more of the following (in order of importance)
• Liquid flow Roof leaks, plumbing leaks, ground
  water
• Capillary seepage Liquid water being pulled
  into a material or assembly
• Air movement Carrying water vapor into or out
  of a building and its cavities
• Vapor diffusion Vapor will move through solid
  objects depending on the objects permeance and
  the vapor pressure

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Controlling Moisture

• 1 inch of rain on 1,000 sq. ft. roof 623
  gallons 
• High water table
• Foundation plants
• Leaking water spigot

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Moisture Movement

• Vapor pressure Vapor pressure is created by
  different amounts of water vapor in two different
  air masses. Moves from high to low.
• Relative humidity The percentage of the maximum
  moisture that air can hold at a given temperature
• The higher the temperature of the air, the more
  moisture it can hold

BPI Analyst Certification Basic Principles of
Energy
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Relative Humidity

• Key point relative humidity (RH) changes as
  temperature changes
• When cooled enough, air at 50 RH, for example,
  will hit 100 RH and the moisture in the air will
  condense on cool surfaces
• In the winter, warm indoor air is forced out of a
  building
• In the summer, hot humid air is pulled into an
  air conditioned space. under this condition,
  there is a potential for MOLD.

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Moisture Concepts

• Vapor pressure Vapor pressure is created by
  different amounts of water vapor in two different
  air masses. Moves from high to low.

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Materials Permeance

• The ability of a material to restrict moisture
  flow is based on its perm rating
• Materials with a perm rating of 1 or less are
  considered a vapor retarder

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Structural Design

• How a building fits together can give you hints
  as to where there may be weaknesses
• Shafts and Soffits (covered already)
• Slab/Crawlspace/Basement
• Framing
• Porches/Garages
• Bonus Rooms
• Stairs
• Split Levels

Understand how design features can cause
weaknesses vapor barrier
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Slab/crawlspace/basement

• Main concern vented crawlspace. If there is a
  building component (wall, shaft) that is
  connected to a vented crawlspace and vented
  attic, high potential for problems.

Trend to build or retrofit to sealed crawlspaces.
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Framing

• Balloon framing Found in older homes, may have
  stud walls that are two stories high and usually
  do not have top or bottom plates. This may
  result in the wall being open to the
  basements/crawlspaces and the attic.

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Framing

• Platform framing, each floor serves as a platform
  for the next floor. Has top and bottom plates.

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Porches/Garage

• Issue with multi-story structures Is there
  insulation and an air barrier at the rim joist
  that is hidden by the porch or garage?

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Bonus Rooms
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Split-Levels
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Moisture Concepts

• Diffusion vs. Air Movement

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A Primer on Air Flow

• For air to flow you need a hole and a pressure.
• No hole, no flow
• No pressure, no flow

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• If air is exhausted out of a building, outside
  air must replace it
• If you pull air into a building, inside air must
  be forced out

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CFM50 Leakage Tests

• Provides information on how leaky the house is.
• Remember, how leaky, not how much leakage.
  Amount of air movement depends on pressure!
• Post air sealing test can give valuable feedback
  on the success of your work.
• Find where the holes are.
• Predictions on the impact of work.

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What does a CFM50 value tell you about the house?

• CFM50 is like a 20 mile per hour wind blowing on
  all sides of the house.
• From this value you can estimate the natural
  leakage of a home (see appendix E in the BD
  manual).
• The CFM50 value can give you a good indication of
  the total size of all the holes in a home.
• A tenth (remove the last digit) of the CFM50
  number is about equal to the square inches of
  holes in the house. 1500 CFM50 about 150 sq.
  inches of holes.

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Door Closure

• The average pressure that natural forces will put
  on a house are between 1.5 Pa (low desert) to 3
  Pa (high country).
• Pressure created by door closure can be many
  times higher than natural pressure.
• The higher the pressures, the higher the
  infiltration rate.
• Room pressure tests will show if there is a
  problem and help determine the solution.

BPI Analyst Certification Pressure Diagnostics
32
Doors Closure
140º Attic
100º outside
1000 CFM supply flow
1000 CFM return flow
Return side will go negative.
Supply side will go positive
Close a door and block the flow back to the
return.
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Room Pressure

• Room WRT outside, interior door of room you are
  testing closed, air handler on.
• Test every room with a door and supply or return
  register.

6.5
BPI Analyst Certification Pressure Diagnostics
34
The following video is a time lapse infrared of a
home under negative 3 Pa pressure for 40
minutes. Note starting temperatures.
80.7
82.7
80.8
80.0
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Temperatures after 40 minutes. 8 to 12 degree
increase in surface temperatures.
92.5
90.9
88.9
87.3
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The pressure is getting to me!
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• House pressure balancing

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• House pressure balancing

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Avoid negative pressuresin hot-humid climates

• Infiltration of warm, humid air
• Into walls
• Through chases
• Into rooms

Condensation on cool surfaces
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The Perfect House
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Indoor Pollutants

• Water vapor

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Sources of Home Moisture
An average family of four can generate over six
gallons of moisture per day.
Shower (excludes towels spillage)
1.0 pt / 10 minute shower Clothes
drying (vented indoors)
5.0 pt/ load Combustion (unvented space
heater) 7.6 pt/ gallon
of kerosene Cooking dinner (family of four)
1.2 pt(1.6 if gas
cooking) Floor mopping
1.5 pt/ 50
sq. ft. Respiration (family of four)
0.4 pt/ hour
Desorption of materials seasonal
6 to 17 pt/ day New
construction   
                         10 pt/day Ground
moisture migration
Up to 100 pt/day  1.0 pint can
increase the RH by about 8 in a 1,500 sq. ft.
single floor home.
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Optimum Indoor Relative Humidity Levels.
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Sensible and Latent Heat

• Sensible heat The basic relationship between
  energy and temperature
• Example 1 Btu 1 increase in temperature of 1
  lb of water

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Sensible and Latent Heat

• Latent heat The heat absorbed or released when
  a material changes phase between a solid and a
  liquid or between a liquid and a gas

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AIR CONDITIONING

• Utilizes the properties of latent heat to move
  heat through a forced air distribution system
• Cooling moves heat out of the house
• Removes Latent heat first
• Condenses water vapor back into liquid

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SIZING

• Over-sizing has a negative effect on energy use,
  comfort, equipment life, and system costs
• Oversized systems run for a short period and do
  not reach steady state efficiency (think of city
  vs. highway driving). Impacts both cost and
  life.
• Short run times mean that the air does not get
  mixed, causing hot spots.
• Short run times will not remove humidity,
  increasing comfort problems.
• Over sized equipment costs more to install.

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STEADY STATE EFFICIENCIES

• Mechanical devices take time to go from start up
  to their peak, steady state efficiency. Some A/C
  units will take minutes. (SEER incorporates this
  start up time)

Steady State
SEER
Over sized system replaces steady state with
start-up, lowering efficiency.
Time
Start-up
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Kitchen Bath Moisture Control

• Bathrooms, kitchens and utility areas should be
  vented to the outside never to attic or crawl
  space.
• Exhaust vents rarely discharge rated cfm

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Exhaust Vent Rules

• Size correctly
• 50 cfm bathroom venting standard (20 cfm)
• 100 cfm kitchen venting standard (25 cfm)
• 2. Exhaust to outdoor never into attic
• 3. Shortest vertical distance to outside or
  direct vent through wall
• Control bathroom exhaust with timer or humidistat
• Use aluminum piping without screws and taped
  joints

If venting is continuous
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High humidity Poor/No Ventilation
Is the exhaust fan working properly?
Is the exhaust fan vented to the outside?
Is the fan operating long enough to remove
moisture?
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Clothes Dryer

• Dryer Rules
• Always vent to outside
• With mobiles vent beyond the skirting
• Do not vent into crawl spaces
• If possible direct vent to outside using smooth
  metal piping
• If elbows are needed, limit to two

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Ventilation

• Three basic types of ventilation
• Infiltration
• Natural ventilation (opening windows)
• Mechanical ventilation
• Whole house
• Spot

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Infiltration vs. Ventilation
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Mechanical Ventilation

• A fan that moves a measured amount of air into a
  house (supply), out of a house (exhaust) or both
  (balanced)
• Ventilation systems must be selected to reduce
  the potential for causing problems (mold) in the
  building
• Do not create positive (supply) pressures in
  extremely cold climates
• Do not create negative (exhaust) pressures in
  hot/humid climates

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Do You Need Ventilation in an Existing Home?

• Depends
• First, does code apply? If so, follow code.
• If not (vast majority of weatherization work)
• What is in the home that needs to be vented
  (pollution sources)?
• How much ventilation does house already have
  (fans and leakage)?

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Minimum Building Airflow(ASHRAE 62-89)

• American Society of Heating, Refrigerating and
  Air Conditioning Engineers (ASHRAE) Standard
  62-89
• 0.35 Natural Air Changes Per Hour (NACH)
• 15 cfm per person (15 per bedroom 15 for
  Master)
• which ever is highest

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ACH vs. NACH

• Air Changes per Hour (ACH) The volume of air in
  a house that is exchanged each hour with air from
  outside the house (ACH50 measured at 50 Pa)
• ACH50 CFM50 x 60 min/hour house volume
• Example (single story, 3 bedroom home in
  Phoenix)
• 1,500 sq ft home x 8 ft ceilings 12,000 cu ft
• Measured leakage 1,500 cfm50
• 1,500 CFM50 x 60 12,000 cu ft 7.5 ACH50

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ACH vs. NACH

• Natural Air Changes per Hour (NACH) A
  calculation of the infiltration rate of a home
  under natural conditions (Home Energy,
  Infiltration Just ACH50 divide by 20)
• NACH ACH50 N
• Example
• 7.5 ACH50 (1 x 1.0 x 20) 0.375

N stories x shielding x climate factor
Stories 1 story 1.0, 1.5 story 0.89, 2
story 0.81 Shielding well shield 1.2,
normal 1.0, exposed 0.9 Climate factor for
Phoenix 20
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Minimum Building Airflow(BPI Calculation Method)

• 1,500 sf, 8 ft ceiling, single story, 3 bedroom
  home, Phoenix
• Step 1 0.35 x volume / 60
• 0.35 x 12,000 / 60 70 CFM
• Step 2 - occupants x 15 CFM/person
• occupants bedrooms 1 3 1 4
• 4 x 15CFM 60 CFM
• Step 3 choose the largest ventilation number to
  calculate minimum air flow at 50 Pa
• CFM50 ventilation target x N
• 70 CFM50 x 22 1,540 CFM50
• Phoenix N for single story 22, for two
  story 22 x 0.81 17.8

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• Ventilation (whole house)

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• Ventilation (whole house)

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Ventilation (whole house)
Motorized Damper
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Ventilation (whole house)

• 6 supply duct to return delivers about 40 - 60
  cfm of ventilation (for 3 ton 5 ton air handler)

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Health and Safety

• Health and safety should be 1 consideration when
  testing and repairing homes!
• Never do anything to save energy that has a
  negative impact on health and safety.
• All (existing and potential) health and safety
  issues should be remedied prior to, or in
  conjunction with, doing work.

Each individual organization needs to establish
its definition of remedied.
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REQUIRE IT!