Transcript ASHRAE 62.2 for WEATHERIZATION

ASHRAE 62.2 FOR WAP
WEATHERIZATION HEALTH AND SAFETY
ASHRAE 62.2
for WAP
1 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – October 2011
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Learning Objectives
ASHRAE 62.2 FOR WAP
By attending this session participants will:
• Understand how ASHRAE 62.2 will change the role of
BTL/MVG.
• Learn the elements of ASHRAE 62.2-2010.
• Understand how to calculate ASHRAE 62.2 compliant fan CFM.
• Be exposed to different IAQ ventilation strategies.
• Learn an inexpensive method to measure exhaust fan CFM.
• Be exposed to a practical weatherization work flow sequence.
2 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – October 2011
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Beyond Fan CFM Requirements
ASHRAE 62.2 FOR WAP
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 driers 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
3 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – October 2011
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How Much Air? – Delivered How?
ASHRAE 62.2 FOR WAP
What moves air through buildings?
WIND
DIRECTION
Exhaust
Fan
Wind
Buoyancy
Mechanical Fans
Stack effect - warm air rising
4 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – October 2011
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How has natural ventilation
been calculated?
ASHRAE 62.2 FOR WAP
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.
5 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – October 2011
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BTL/MVG/MVR Theory
ASHRAE 62.2 FOR WAP
The amount of air leakage across any barrier is dependent
on:
• Hole size
• Hole type
• The pressure
differential
Long/narrow vs.
big/round
Thick vs.
thin surface
“Hairy” vs.
smooth bore
Turbulent flow vs. linear flow vs. “drag”/friction
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Why isn’t the MVG
our best tool?
ASHRAE 62.2 FOR WAP
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).
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The missing flue plug creates a
stable-sized round hole with little air
flow drag.
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Wx removes the randomness.
ASHRAE 62.2 FOR WAP
Wind
Effect
Stack
Effect
Neutral pressure plane
8 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – October 2011
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A very important corollary!
ASHRAE 62.2 FOR WAP
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?
ASHRAE 62.2 FOR WAP
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
10 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – October 2011
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ASHRAE 62.2-2010
ASHRAE 62.2 FOR WAP
Photos courtesy of The US Department of Energy
11 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – October 2011
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ASHRAE 62.2-2010 Table
ASHRAE 62.2 FOR WAP
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
ASHRAE 62.2 FOR WAP
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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ASHRAE 62.2-2010 Formula
Breakdown
ASHRAE 62.2 FOR WAP
CFMfan = 0.01Afloor + 7.5(Numberbedroom + 1)
+ (alternative compliance supplement)
- (Infiltration credit)
Break this down into 3 smaller steps:
• Use the base formula to determine the whole house
continuous requirements = 0.01A + 7.5 * # occupants
• Calculate the local ventilation deficit (alternative
compliance supplement)
• Calculate the infiltration credit
14 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – October 2011
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Calculating Required
Fan CFM #1
ASHRAE 62.2 FOR WAP
Base formula:
Whole Building Fan CFM = (7.5 * # bedrooms plus 1) + Area/100
Characteristics:
• 1,500 square feet
• 1 story
• 3 bedrooms (4
occupants)
• Norfolk, VA
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Calculating Required
Fan CFM #2
ASHRAE 62.2 FOR WAP
Base formula, step by step:
Multiply the number of bedrooms + 1 or the number of
people by 7.5 CFM per person:
4 people * 7.5 CFM/person = 30 CFM
Calculate 1 CFM per 100 square feet of floor area:
1500 ft2/100 ft2 per required CFM = 15 CFM
Add them together:
30 CFM + 15 CFM = 45 CFM continuous
16 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – October 2011
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But what if they don’t have
adequate local ventilation?
ASHRAE 62.2 FOR WAP
The alternative compliance supplement calculation lets you
take the inadequate CFM delivery or total lack of required
local ventilation fans into account.
• Kitchen requires 100 CFM on demand or 5 ACH
continuous, based on kitchen volume.
• Bathroom requires 50 CFM on demand or 20 CFM
continuous. Not required in ½ baths.
• Operable windows in those rooms reduce deficit by 20
CFM. Only one deficit reduction per room.
• Deficit cannot drop below zero.
Sum all deficits and divide by 4. Add the result to the
continuous whole building ventilation CFM requirement.
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Alternative Compliance
Supplement Calculation #1
ASHRAE 62.2 FOR WAP
Bathroom: 50 CFM required
•
Existing fan = 20 CFM
•
Operable window
(reduce deficit by 20 CFM)
50 – 20 – 20 = 10
50 CFM req. – 20 CFM
existing - 20 CFM (window) =
10 CFM deficit
Kitchen: 100 CFM required
100 – 70 – 20 = 10
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•
Existing fan = 70 CFM
•
Operable window
100 CFM req. – 70 CFM
existing - 20 CFM (window) =
10 CFM deficit
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Alternative Compliance
Supplement Calculation #2
ASHRAE 62.2 FOR WAP
Net deficit in home:
•
10 CFM + 10 CFM = 20
CFM
•
This is based on ondemand requirements.
•
We will add capacity to
the whole home
continuous fan, so can
reduce deficit.
Divide deficit by 4 for
additional continuous CFM
requirement:
Continuous CFM Req. from Base Formula = 45 CFM
•
20 CFM/4 = 5 CFM
45 CFM + 5 CFM = 50 CFM
19 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – October 2011
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Calculating the
Infiltration Credit - Steps
ASHRAE 62.2 FOR WAP
1. Estimate infiltration rate at post-weatherization
conditions (ICFM).
2. Calculate default infiltration rate (Id).
3. If ICFM is greater than the default rate, calculate
infiltration credit (Icred).
Inputs needed:
• Weather factor from ASHRAE 136
• S factor accounting for building height (table included)
• CFM50 of the home, post-weatherization.
• Area of home, square feet of conditioned space.
20 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – October 2011
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Calculating the
Infiltration Credit – Step 1
ASHRAE 62.2 FOR WAP
1. Estimate infiltration rate at operating conditions (ICFM).
(ICFM) can be estimated as:
ICFM = 0.0508 * w * S * Q50
In this equation:
• S is a factor accounting for the height of the building,
determined from Table X-1 (included).
• Q50 is the blower door test result in CFM50 (cubic feet
per minute at 50 Pa). Since we are trying to determine
the needs of the weatherized home, users must estimate
what the CFM50 will be post-weatherization.
• w is the weather factor from ASHRAE Standard 136.
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S & W Charts
ASHRAE 62.2 FOR WAP
# Stories
1
1.5
2
2.5
3
Multiply the S factor *
0.0508 * w to get a number
you can input into the
2
If we get aNorfolk
post-Wx
BD of 1250
CFM50 in our sample
1,500
City
Richmon
Roanoke
formula.
Thenftall, 1-story
you need
Norfolk
d home, the estimated infiltration
is the Q=50 for each home.
* 1s * 1250 CFM50, or
W factor 0.84 0.0508
0.75 * 0.84w
0.74
S factor
1
1.13 1.23 1.32 1.39
0.043(from the table) * 1250 = 54 CFM
Combine the two tables to simplify the calculation for your region.
0.0508 * w * S * Q50
Select city (left) and # stories (below)
City
w
1
Norfolk
0.84
Richmond
Roanoke
1.5
2
2.5
3
0.043 0.048
0.052
0.056
0.059
0.75
0.038 0.043
0.047
0.050
0.053
0.74
0.038 0.042
0.046
0.050
0.052
22 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – October 2011
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Calculating the
Infiltration Credit – Step 2
ASHRAE 62.2 FOR WAP
2. Calculate default infiltration rate (Id)
• The default infiltration rate is the assumed leakiness, and
takes the size of the home into account.
Id = 0.02 * Afloor
• A is the conditioned area of the home in square feet. For
our sample home Id = 0.02 * 1500 = 30
• This is lower than our estimated infiltration of 54 CFM, so
we will continue to step 3…
23 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – October 2011
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Calculating the
Infiltration Credit – Step 3
ASHRAE 62.2 FOR WAP
3. If ICFM is greater than the default rate (Id), calculate
infiltration credit (Icred).
•
This is where we account for the infiltration of the home
that is above and beyond the default value.
Icred = ½ (ICFM – Id)
Icred = ½ (54 – 30)
Icred = ½ (24)
Icred = 12
24 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – October 2011
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Bringing it All Together
ASHRAE 62.2 FOR WAP
CFMfan = (Base formula) + (alternative compliance supplement) (Infiltration credit)
We broke this down into 3 smaller steps and now have all the pieces to calculate our
whole home continuous fan CFM requirement for our sample home in Norfolk:
•
Use the base formula to determine the whole house continuous requirements = 0.01A
+ 7.5 * # occupants
•
•
Calculate the spot ventilation deficit = Net deficit/4
•
•
1500ft2 /100 + (7.5CFM * # occupants) = 45
20 CFM/4 = 5 CFM deficit
Calculate the infiltration credit = ½ (ICFM – Id)
•
½ (54 CFM – 30 CFM) = 12 CFM credit
CFMfan = (45 CFM) + (5 CFM) - (12 CFM)
CFMfan = 38 CFM
25 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – October 2011
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Effect of Size
ASHRAE 62.2 FOR WAP
What would change if we had the same home, but 2000 ft2 instead
of 1500?
•
Characteristics:
• 2000 square feet
• 1 story
• 3 bedrooms
• 1250 CFM50
The base formula changes = 0.01A + 7.5 * #
occupants
•
•
2000ft2 /100 + (7.5CFM * # occupants) = 50
The spot ventilation deficit is the same = Net deficit/4
•
20 CFM/4 = 5 CFM deficit
•
The infiltration credit will change = ½ (ICFM – Id)
•
Remember, ICFM = 0.0508 * w * S * Q50, and Id = 0.02 *
AFLOOR
ICFM = 0.0508 * 0.84 * 1 * 1250 CFM50 = 54 CFM
Id = 0.02 * 2000 ft2 = 40
ICredit = ½(54 – 40) = 7 CFM
CFMfan = (50 CFM) + (5 CFM) – (7 CFM)
CFMfan = 48 CFM
26 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – October 2011
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Effect of Climate
ASHRAE 62.2 FOR WAP
What would change if we had the same home, but in Portland,
ME?
•
Characteristics:
• 1,500 square feet
• 1 story
• 3 bedrooms
• Portland, ME (w
= 0.91)
• 1250 CFM50
The base formula is the same= 0.01A + 7.5 * #
occupants
•
•
1500ft2 /100 + (7.5CFM * # occupants) = 45
The spot ventilation deficit is the same = Net deficit/4
•
20 CFM/4 = 5 CFM deficit
•
The infiltration credit will change = ½ (ICFM – Id)
•
Remember, ICFM = 0.0508 * w * S * Q50, and Id = 0.02 *
AFLOOR
ICFM = 0.0508 * 0.91 * 1 * 1250 CFM50 = 58 CFM
Id = 0.02 * 1500 ft2 = 30
ICredit = ½(58 – 30) = 14 CFM
CFMfan = (45 CFM) + (5 CFM) – (14 CFM)
CFMfan = 38 CFM
27 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – October 2011
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Effect of Deficit
ASHRAE 62.2 FOR WAP
What would change if we had the original Norfolk home, but the kitchen
fan delivered only 50 CFM, and the bathroom window didn’t open?
Bathroom: 50 CFM required
•
Existing fan = 20 CFM
•
No window credit
•
•
Operable window
•
100 - 50 – 20 = 30 CFM
•
1500ft2 /100 + (7.5CFM * # occupants) = 45
The local ventilation deficit increases = Net deficit/4
•
Existing fan = 50 CFM
•
The base formula remains unchanged = 0.01A + 7.5
* # occupants
•
50 – 20 = 30 CFM
Kitchen: 100 CFM required
•
•
60 CFM/4 = 15 CFM deficit
The infiltration credit doesn’t change = ½ (ICFM – Id)
•
½ (54 CFM – 30 CFM) = 12 CFM credit
Net deficit = 30 + 30 = 60 CFM
CFMfan = (45 CFM) + (15 CFM) - (12 CFM)
CFMfan = 48 CFM
28 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – October 2011
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Effect of Leakiness
ASHRAE 62.2 FOR WAP
What would change if we got 2,000 CFM50 instead of 1250 CFM50
on the original Norfolk house?
•
Characteristics:
• 1,500 square feet
• 1 story
• 3 bedrooms
• Norfolk, VA
• 2,000 CFM50
The base formula remains unchanged = 0.01A + 7.5 *
# occupants
•
•
1500ft2 /100 + (7.5CFM * # occupants) = 45
The local ventilation deficit is the same = Net deficit/4
•
20 CFM/4 = 5 CFM deficit
•
The infiltration credit will increase = ½ (ICFM – Id)
•
Remember, ICFM = 0.0508 * w * S * Q50
ICFM = 0.0508 * 0.84 * 1 * 2000 CFM50
ICFM = 0.0508 * 0.84 * 1 * 2000 CFM50
ICFM = 85
•
½ (85 CFM – 30 CFM) = 27.5 CFM infiltration credit
CFMfan = (45 CFM) + (5 CFM) – (27.5 CFM)
CFMfan = 22.5 CFM
29 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – October 2011
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That’s complicated!
ASHRAE 62.2 FOR WAP
Three – soon to be four? – CFM calculation options:
– Appendix B of Ventilation Chapter in Workforce Guidelines for
Home Energy Upgrades, DOE/NREL, 2011(details of the
required math).
– ZipTest Pro3 for the Texas Instruments TI-89 calculator (R.J.
Karg Associates).
– ResVent 62.2 for the iPhone, iPad, and iPod touch (R.J. Karg
Associates).
– TECTITE from the Energy Conservatory, updated end of 2011.
30 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – October 2011
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Beyond Fan CFM Requirements
Review
ASHRAE 62.2 FOR WAP
Remember, ASHRAE 62.2 2010 also includes:
• Spot ventilation requirements as mentioned
• Attached garages must be adequately sealed from living
space to prevent migration of contaminants
• Clothes driers 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
31 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – October 2011
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Ventilation Options
ASHRAE 62.2 FOR WAP
Once we’ve determined required CFM, how do we get it?
• Exhaust only
– Multiple spot ventilation fans
– Balanced multiple intake - single fan, single exhaust system
• Supply only
– Into return side of HVAC system
– Direct through the wall fan
• Balanced
– Fan driven air in / air out
– Heat Recovery (HRV)
– Energy Recovery (ERV)
32 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – October 2011
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Exhaust Only – Multiple Spot
Ventilation Fans
ASHRAE 62.2 FOR WAP
Source: 62.2 User’s Manual ©2006 ASHRAE
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Exhaust Only – Single System,
Multiple Intakes
ASHRAE 62.2 FOR WAP
Source: 62.2 User’s Manual ©2006 ASHRAE
34 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – October 2011
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Supply Only
ASHRAE 62.2 FOR WAP
Supply only
could also
be a direct
through the
wall fan.
Illustration of a supply only
system with intake into the
HVAC return ducting.
Source: 62.2 User’s Manual ©2006 ASHRAE
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Balanced Ventilation System
ASHRAE 62.2 FOR WAP
Source: 62.2 User’s Manual ©2006 ASHRAE
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HRV/ERV
ASHRAE 62.2 FOR WAP
HRV
ERV
Graphic
courtesy
Popular
Mechanics
Photo
courtesy
of TheofUS
Department
of Energy
37 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – October 2011
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Other Possibilities
ASHRAE 62.2 FOR WAP
• Exhaust or supply systems with passive make-up air
inlets or outlets.
• Exhaust or supply systems with active (fan powered,
hopefully balanced) make-up air inlets or outlets.
• Supply or exhaust fans tied to HVAC systems
Passive air inlets come in many
shapes and sizes. The one
shown here is from Panasonic.
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Which system is right?
ASHRAE 62.2 FOR WAP
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Cost-effectiveness
ASHRAE 62.2 FOR WAP
Compare cost-effectiveness of exhaust only vs. HRV in a cold climate.
Annualized cost = Installed cost/lifetime + annual operational costs +
annual heating (or cooling) penalty.
Fan Type
Installed Lifetime Operational Heating
Total
Cost
(yrs)
cost/yr
penalty/yr annualized
1
cost
Exhaust
only,
20 CFM
$400
10
$30
$110
$ 180
(Client pays
$140)
HRV,
20 CFM
$1,500
10
$60
$55
$ 265
(Client pays
$115)
1Based
on electric heat at $0.11/kWh in a 6,500 HDD climate.
HRV assumed to reduce heat loss through fan by 50%.
40 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – October 2011
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Fan Flow Meter
ASHRAE 62.2 FOR WAP
A fan flow meter connected to a
manometer measures fan flow. This is
necessary for deficit calculations, and
to verify delivered CFM of newly
installed fans.
41 | WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – October 2011
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Fan Controls
ASHRAE 62.2 FOR WAP
Shown here: Tamarack Technologies, Inc and Airetrac™ fan control
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Work Flow - Auditor
ASHRAE 62.2 FOR WAP
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Audit Decisions
ASHRAE 62.2 FOR WAP
CFM
= (7.5 x BR+1) + 0.01A + (5 CFM deficit) CFMfan
fan = (7.5 x BR+1) + 0.01A + (2.5 CFM deficit)
(12
fanfan by replacing bath fan
- (12CFM
CFMInfil
InfilCredit
Credit) )==3836CFM
CFM
Characteristics:
• 1,500 square feet
• 1 story
• 3 bedrooms (4
occupants)
• Norfolk, VA
• 1,250 CFM50
• 20 CFM bath fan
• 70 CFM kitchen
fan
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Now lets replace the kitchen fan.
ASHRAE 62.2 FOR WAP
CFMfan = (7.5 x BR+1) + 0.01A (9.5 CFM Infil Credit ) = 36 CFMfan
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Characteristics:
• 1,500 square feet
• 1 story
• 3 bedrooms (4
occupants)
• Norfolk, VA
• 1,250 CFM50
• 20 CFM bath fan
• 70 CFM kitchen
fan
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Work Flow - Installer
ASHRAE 62.2 FOR WAP
Necessary ducting for existing fans must be properly installed to bring air
into or out of the dwelling.
Fan controls, like the one shown at right, must be installed to insure proper
run times.
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Work Flow - Inspector
ASHRAE 62.2 FOR WAP
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Setting the control
ASHRAE 62.2 FOR WAP
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Summary
ASHRAE 62.2 FOR WAP
• The natural ventilation calculation we’ve used for years
is flawed when dealing with weatherized homes
• ASHRAE 62.2 is a performance standard – fan flow must
be measured.
• The math to compute the required fan flow can seem
complicated, but is really a series of simple steps.
• Computer programs are available.
• The chosen ventilation method has to match local
environmental conditions.
• A properly designed workflow process will not cause
additional visits to the client home.
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