Transcript Zone Pressure Diagnostics

WEATHERIZATION ENERGY AUDITOR SINGLE FAMILY
Zone Pressure Diagnostics
WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – December 2012
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ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – December 2012
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Learning Objectives
ZONE PRESSURE DIAGNOSTICS
By attending this session, participants will be able to:
• Demonstrate the strengths and limitations of zone
pressure diagnostics (ZPD).
• Assess when to use zone pressure diagnostics.
• Demonstrate the use of ZPD charts.
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Zone Pressure Diagnostics #1
ZONE PRESSURE DIAGNOSTICS
Conduct zone pressure
diagnostics and interpret
results to determine:
• Location and effectiveness
of the air barrier.
• Alignment of air barrier and
thermal boundary.
• Leakage between zones.
Photos courtesy of PA WTC
Photo courtesy of PA Weatherization Training Center
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Necessary Equipment
ZONE PRESSURE DIAGNOSTICS
Photos courtesy of the U.S. Department of Energy
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Practical Applications
ZONE PRESSURE DIAGNOSTICS
• Determine relative leakiness.
• Prioritize air sealing activities.
• Evaluate completed air sealing measures.
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Relative Leakiness
ZONE PRESSURE DIAGNOSTICS
1850 CFM50
Pressure house
to attic = 37Pa
37Pa
50Pa
Pressure attic to
exterior must be 13Pa
(50Pa – 37Pa = 13Pa)
Q: What does
this tell us?
? Pa
Graphic developed for the U.S. DOE WAP Standardized Curricula
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Ratio of Pressure to Leakage
ZONE PRESSURE DIAGNOSTICS
Zone Pressures
Relative Size of Leaks
Zone-House
Zone-Out
Zone-House
Zone-Out
12
38
2
1
25
25
1
1
37
13
1/2
41
9
1/3
45
5
1/4
48
2
1/8
1
49
1
1/13
1
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TO
1
1
TO
1
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Probing Cavities
ZONE PRESSURE DIAGNOSTICS
41Pa
37Pa
Let’s put a probe into
the cellar.
What does
25Pa mean?
50Pa
25Pa
What if we stick a
probe into the first floor
ceiling cavity and read
41Pa?
Graphic developed for the U.S. DOE WAP Standardized Curricula
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Changing Pressures
ZONE PRESSURE DIAGNOSTICS
25Pa
50Pa
If we open the cellar
door to the house and
put a probe into the
attic we might find the
attic 37Pa has
dropped to 25Pa.
0Pa
The pressure between
the house and
basement will now be
zero.
Why?
Graphic developed for the U.S. DOE WAP Standardized Curricula
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Simple Zone Pressure
Diagnostics #1
ZONE PRESSURE DIAGNOSTICS
Pressure difference
of attic with
reference to the
house should be
close to -50 Pa.
ΔP = -50 Pa
Blower Door
Graphic developed for the U.S. DOE WAP Standardized Curricula
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Simple Zone Pressure
Diagnostics #2
ZONE PRESSURE DIAGNOSTICS
Pressure difference
of interior wall with
reference to the
house should be
close to 0 Pa.
ΔP = 0 Pa
Blower Door
Graphic developed for the U.S. DOE WAP Standardized Curricula
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Where Is the Air Barrier? #1
ZONE PRESSURE DIAGNOSTICS
Cape Cod
1½ Story House
Graphic developed for the U.S. DOE WAP Standardized Curricula
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Where Is the Air Barrier? #2
ZONE PRESSURE DIAGNOSTICS
Pressure difference of
the floor cavity with
reference to the
house should be
0 Pa.
But, is it?
48
Graphic developed for the U.S. DOE WAP Standardized Curricula
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Where Is the Air Barrier? #3
ZONE PRESSURE DIAGNOSTICS
Unsealed/Uninsulated
Two-story balloon-framed
house with one-story
addition and unheated
porch over unconditioned
basement
Graphic developed for the U.S. DOE WAP Standardized Curricula
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Where Is the Air Barrier? #4
ZONE PRESSURE DIAGNOSTICS
Sealed/Insulated
Air-sealed/Insulated with
air barrier and insulation
in alignment
Graphic developed for the U.S. DOE WAP Standardized Curricula
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Can We Size The Holes?
ZONE PRESSURE DIAGNOSTICS
25Pa
50Pa
0Pa
Pressure is gradually
reduced by each layer
of wall or ceiling
between inside and
outside.
Collecting CFM50 and
pressure across each
configuration lets us
calculate hole size in
each surface.
Graphic developed for the U.S. DOE WAP Standardized Curricula
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Here is what we know
ZONE PRESSURE DIAGNOSTICS
1850 CFM50
2200 CFM50
50Pa
50Pa
25Pa
25Pa
Basement
door closed
0Pa
50Pa
Basement
door open
Graphics developed for the U.S. DOE WAP Standardized Curricula
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Open A Door –
Zone To Main Body
ZONE PRESSURE DIAGNOSTICS
25Pa
1850
2200
350
350
2.76
966
97 sq”
350
2.76
966
97 sq”
350
1.76
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616 CFM50
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What Do The Results Mean?
ZONE PRESSURE DIAGNOSTICS
H/Z 350 x 2.76 = 966
CFM50 = 96.6 sq”
of hole in the floor
Z/O 350 x 2.76 = 966
CFM50 = 96.6 sq”
hole in basement walls
50Pa
50Pa
T/P 350 x 1.76 = 616
CFM50 is attributable
to the path
Graphic developed for the U.S. DOE WAP Standardized Curricula
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Open A Door – Zone To Outside
ZONE PRESSURE DIAGNOSTICS
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No Door on the Zone?
ZONE PRESSURE DIAGNOSTICS
At 1850 CFM50, house to
attic pressure = 37Pa.
20Pa
50Pa
Open attic hatch enough
to create at least 6Pa
change.
Bring the blower door
back to 50Pa.
CFM50 is now 2500
House to attic pressure
is now 20Pa.
Graphic developed for the U.S. DOE WAP Standardized Curricula
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Flow Method:
Hole – Zone To House #1
ZONE PRESSURE DIAGNOSTICS
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Flow Method:
Hole – Zone To House #2
ZONE PRESSURE DIAGNOSTICS
1850
37Pa
2500
20Pa
650
1.38
884
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Flow Method:
Hole – Zone To Outside
ZONE PRESSURE DIAGNOSTICS
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What Did We Learn Overall?
ZONE PRESSURE DIAGNOSTICS
Of 1850 CFM50:
Through attic ≈ 900
50Pa
Through basement ≈ 600
Walls (remainder) ≈ 350
Graphic developed for the U.S. DOE WAP Standardized Curricula
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Checking Air Sealing
ZONE PRESSURE DIAGNOSTICS
How about a garage?
50Pa
48Pa
2Pa
Any space that will
accept a probe can be
checked for pressure.
ZPD requires being able
to change the pressure
over the surface to
determine hole size.
Graphic developed for the U.S. DOE WAP Standardized Curricula
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Limitations
ZONE PRESSURE DIAGNOSTICS
• Not great for excessively leaky buildings
• Requires being able to change the pressure over the
tested surface to determine hole size
• Not great in windy conditions
• Time consuming
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Practice!
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Open A Door – Zone To Main Body
ZONE PRESSURE DIAGNOSTICS
40Pa
2050
2550
500
500
500
500
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Open A Door – Zone To Main Body
ZONE PRESSURE DIAGNOSTICS
40Pa
2050
2550
500
0.63
315
31.5 sq”
500
1.54
770
77 sq”
500
0.54
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500
270 CFM50
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Flow Method:
Hole – Zone To House
ZONE PRESSURE DIAGNOSTICS
1200
45Pa
1850
18Pa
650
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Flow Method:
Hole – Zone To House
ZONE PRESSURE DIAGNOSTICS
1200
45Pa
1850
18Pa
650
0.43
280
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Summary
ZONE PRESSURE DIAGNOSTICS
• ZPD can help you determine the relative leakiness of a
home, prioritize air sealing activities, and evaluate
completed air sealing measures.
• ZPD requires a computer or charts to do the calculations.
• The calculations can be time consuming, so use ZPD
only when needed to prioritize or verify critical air sealing
activities.
• ZPD does not work well in extremely leaky homes or
when it’s very windy.
• ZPD requires being able to change the pressure over the
tested surface to determine hole size.
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