source strength source strength removal rate removal rate ventilation and iaq
TRANSCRIPT
SourceStrengthSource
Strength RemovalRate
RemovalRate
Ventilation and IAQ
Random air leaks do not provide effective fresh air through a home
Depends on temperature difference, wind, exhaust
Random air leaks do not provide effective fresh air through a home
Where are the holes?
Random air leaks do not provide effective fresh air through a home
Where are the holes?
Random air leaks do not provide effective fresh air through home
Where are the holes?
Random air leaks do not provide effective fresh air through home
Where are the holes?
Ventilation Basics
How does ventilation work ?
How much ventilation do I need in my climate ?
Ventilation is not a cure-allLimit and control pollutants at the source
carbon monoxide asthma triggers moisture allergens particles radon VOCs chemicals
etc. etc. etc.
Limit moisture sources
Cook with lids
Keep bathroom doors closed until moisture is removed
No indoor clothes lines
Limit indoor plants
Capture & Remove moisture at source:ShowersCookingLaundry
Ventilation Examples1,500 Sq Ft House70 degrees indoor air temperature85% outdoor relative humidity
Let’s look at what happens at …1. 30 degrees outdoor temp ?2. 50 degrees outdoor temp ?3. What happens if we double the indoor moisture load?
Ventilation (Air Changes Per Hour) VS
Indoor Relative Humidity (%)
0
20
40
60
80
100
0.1 0.3 0.5 0.7 0.9 1.1 1.3 1.6 1.7 1.9
I
nd
oor
Rel a
tive H
um
i dit
y
( %)
1,500 ft sq house700 F indoor temp85 % outdoor RH
300 F outside temp typical moisture load
.35 AC/h
based on G. Tsongas
l l .35 l l l l l l l l l l l l l
Ventilation: Air Changes per Hour (AC/h)
Extreme Ventilation Makes Little Difference
Ventilation (Air Changes per hour) VS
Indoor Relative Humidity (%)
0
20
40
60
80
100
I
nd
oor
Rel a
tive H
um
i dit
y
(%)
1,500 ft sq house700 F indoor temp85 % outdoor RH
500 F outside temp typical moisture load
.35 AC/h
based on G. Tsongas
l l .35 l l l l l l l l l l l l Ventilation: Air Changes per Hour (AC/h)
Ventilation (Air Changes Per Hour) VS
Indoor Relative Humidity (%)
0
20
40
60
80
100
I
nd
oor
Rel a
tive H
um
i dit
y
( %)
1,500 ft sq house700 F indoor temp85 % outdoor RH
300 F outside temp typical moisture load 2 X moisture load
500 F outside temp typical moisture load 2 X moisture load
.35 AC/h
based on G. Tsongas
l l .35 l l l l l l l l l l l l l Ventilation: Air Changes per Hour (AC/h)
Drying Potential of Outside Air:
The colder the outside air, the more drying effect when this air
is warmed inside
Warm, humid air has much less drying potential
(can cause problems)
Good News for Energy & Comfort
When it’s cold outside: need less air exchange
When it’s mild outside: need more exchange
Exhaust Moisture at the Source
Fan & Light Switch
Fan delay time1 to 60 minutes
If double pane windows are getting foggy on the room side, condensation
& mold growth are on the way…
Comfort, Moisture, Noise, Pollen, Dust, Odors, Security
Open Windows for Ventilation?
Ventilation Systems
1. Central Exhaust2. Multi-port Exhaust3. Heat Recovery Ventilator
(balanced)
Dry air in
Exhaust Fan
Dry air in
Wet air out
Central Exhaust
Manual and Automatic Controls
Should operate 24 hours per day
2 Speed Whole House Fresh Air Fan Low speed 24/7 continuous fresh air
High speed for odors moisture VOCs particles etc.
Fan off delay timer
Super Quiet
Motion Sensor turns fan to high speed
24/7 Low Speed CFM Setting
Fan off delay timer
24/7 Low Speed CFM Setting
Fan off delay timer
Air Inlets Built Into Window Frame
Through-the-Wall Fresh Air Vent
Ventilation Systems
• Central Exhaust• Multi-port Exhaust• Heat Recovery Ventilator (balanced)
Air out thru roof
Air out from rooms in home
Exhaust fan in Box
Unit suspendedin attic
Bedro
om
Cen
tral
Zo
ne
Bathroom
Bedro
om
Bathroom exhaust grill
about 20 CFMContinuous
65 -80 CFMHigh Speed
Bedroom exhaust grill
about 10 CFMeach room continuous
Ventilation Systems
• Central Exhaust• Multi-port Exhaust• Heat Recovery Ventilator (balanced)
Heat Recovery Ventilation
Stale Moist Exhaust From
House
TemperedFresh Air
Into House
OutsideFresh Airto House
Stale HouseAir Exhaust
Outside Air
Supply Air
Return Air
Exhaust Air
Defrost Damper
Airborne Mold Sampling
EPA, ACGIH* and other peer reviewed guidelines do not recommend airborne mold sampling as part of an investigation or remediation…
*American Congress of Governmental Industrial Hygienists
It is very unlikely that airborne mold samples will provide evidence
that cannot be more easily and reliably obtained by
a thorough inspection
Airborne Mold Sampling
Airborne Sampling can produce False Negatives . . but not False Positives
“Absence of Evidence is NOT Evidence of Absence”
Consensus is that traditional methods used to identify increased mold
exposure do not reliably predict increased health risks.
California Department of Public Health Statement on Building Dampness, Mold, and Health, September 2011
Current practices for collection, analysis, and interpretation of environmental samples for mold…
cannot be used to quantify health risks posed by dampness and mold in buildings or to guide health-based actions.
California Department of Public Health Statement on Building Dampness, Mold, and Health, September 2011
California Department of Public Health Statement on Building Dampness, Mold, and Health, September 2011
Current consensus does not justify the differentiation of some molds (such as Stachybotrys species) as “toxic molds”
California Department of Public Health Statement on Building Dampness, Mold, and Health, September 2011
The only types of evidence that have been related consistently to adverse health effects are:
current or past water damage, damp materials, visible mold, mold odor.
But not the number or type of mold spores nor the presence of other markers of mold in indoor air or dust.
The most effective tool for locating mold growth and building dampness: a detailed site inspection,
understanding moisture dynamics,
building science fundamentals.
(Light, 2009)
One set of investigations based on detailed building inspection, Parallel investigations based on mold testing.
Results indicated that extensive collection of air and surface samples failed to identify mold growth in addition to that observed using visual indicators.
Moreover, the inspector using visual cues located hidden mold growth undetected by sampling in half of the cases (6 of 12).
(Light, 2009)
12 cases where opposing experts evaluated the same water damaged site: