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1
Impact of Large Building
Airtightness Requirements
Buildings XIII Conference
December 6th
, 2016
Lorne Ricketts | MASc, P.Eng.
2
Intro to Requirements
Measured Performance
Industry Impact
What it Is, and What it Isn’t
Airtightness vs Air Leakage
Outline
3
Why We Care
Infiltration and Exfiltration Affect:
Building Energy Consumption – Heat Loss and Gains ($)
Indoor Air Quality - Pollutants
Building Durability - Condensation
Occupant Comfort - Thermal & Acoustics
4
Many Air Barrier Systems Available
Loose Sheet Applied
Membrane – Taped Joints
& Strapping
Sealed Gypsum Sheathing
– Sealant Filler at Joints
Liquid Applied
Sealants/Membranes
Self-Adhered vapor
permeable membrane
Self-Adhered vapor
impermeable membrane
Curtainwall, window-wall
& glazing systems
Mass Walls
(concrete)
Sprayfoam
BUT, IT’S THE DETAILS THAT MATTER
5
AccessoriesMaterials Components
BRAND
BRAND
House Wrap
Whole
Building
Airtightness
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Standards & Qualifications
Washington State & Seattle, ABAA
Target, GSA, IBC/IECC Option
< 2.0 L/(s·m²) [0.40 cfm/ft²] @ 75 Pa
US Army Corps of Engineers & IGCC
< 1.26 L/(s·m²) [0.25 cfm/ft²] at 75 Pa
Passive House
0.6 ACH50
(~0.60 L/(s·m²) [0.12 cfm/ft²] at 75 Pa)
LEED, 6-sided apartment test
(~1.25 L/(s·m²) [0.25 cfm/ft²] at 50 Pa)
UK (AATMA) Large Buildings
~0.70 to 1.75 L/(s·m²) at 75 Pa
[~0.14 to 0.34 cfm/ft² at 75 Pa]
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Measured Performance
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Where We’re At – The Numbers
Airtightness testing data was compiled in a database from the
following sources:
Published literature
Industry members
Unpublished data provided by the project team
721 Airtightness Tests
584 Unique Buildings
566 Acceptable Tests
for Comparison
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Where We’re At – The Numbers
25%
20%
9%
46%
Types of Buildings in Database
Commercial
MURB
Institutional
Military
Sample of 566 buildings
Building Types
Multi-Family
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Where We’re At – The Numbers
Building Locations
16%
66%
18%
Location of Buildings in Database
Canada
USA
UK
Sample of 566 buildings
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Where We’re At – The Numbers
Airtightness vs Year of Construction
0.0
1.0
2.0
3.0
4.0
0123456789
1011121314151617181920
1945 1955 1965 1975 1985 1995 2005 2015
Air
tigh
tne
ss [
cfm
/ft²
@ 7
5 P
a]
Air
tigh
tne
ss [
L/(s
.m²)
@ 7
5 P
a]
Construction of Building [year]
Airtightness Vs Year of Construction of All Buildings
Sample of 179 Buildings
Air
tigh
tne
ss [
L/(s
·m²)
@ 7
5 P
a]
Air
tigh
tne
ss [
cfm
/ft²
@ 7
5 P
a]
1945 1955 1965 1975 1985 1995 2005 2015
Construction of Building [year]
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Where We’re At – The Numbers
Airtightness vs Height of Building
0.0
1.0
2.0
3.0
4.0
0
5
10
15
20
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26
Air
tigh
tne
ss [
cfm
/ft²
@ 7
5 P
a]
Air
tigh
tne
ss [
L/(s
.m²)
@ 7
5P
a]
Height of Buildings (Stories)
Airtightness Vs Height of All Buildings
Individual Buildings
Average
Sample of 420 Buildings
Height of Building (Storeys)
Air
tigh
tne
ss [
L/(s
·m²)
@ 7
5 P
a]
Air
tigh
tne
ss [
cfm
/ft²
@ 7
5 P
a]
13
Impact of Requirements
14
Impact of Requirements
15
Performance of Air Barrier Systems
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
4.00
4.50
5.00
Liquid Applied(10 Buildings)
Sealed Sheathing(11 Buildings)
Sheet Applied(28 Buildings)
CurtainWall/Window
Wall/Storefront(15 Buildings)
Air
tigh
tnes
s [c
fm/f
t² @
75
Pa]
Air
tigh
tnes
s [L
/(s·
m²)
@ 7
5 P
a]
Leakiest Tested
Tightest Tested
Median
WA State Requirement
54 Buildings, Oct 2015 RDH Seattle Data
Air
tigh
tne
ss [
L/(s
·m²)
@ 7
5 P
a]
Air
tigh
tne
ss [
cfm
/ft²
@ 7
5 P
a]
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Impact of Testing
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The Life of a Building
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The Life of a Building
Upstream Effects
Material Selection
Assembly Design
Quality Control
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Changes in Air Barrier System Selection
Seeing shifts from Mechanically Attached to
Self-Adhesive & Liquid Applied membranes
20
New AB/WRB Materials
Many new self-adhered
and liquid applied vapour
permeable sheathing
membranes available on
the market
21
Changes in Quality Control
Noticeable improvements as soon as somebody cares –
specific people designated to look at air barrier
Coordination between all team members essential
Air Boss
22
Impact of Requirements
Does airtightness
requirement increase cost?
Opinions of the Current
Airtightness Target
(< 0.40 cfm/ft² at 75 Pa)
[< 2.0 L/s·m² at 75 Pa]
56%
0%
33%
11%
Choose one of the following statements that best represents your opinion of current whole building air leakage target in your
jurisdiction:
Okay As Is
Too Stringent
Too Lenient
Other
39%
0%
61%
Aside from the cost of the test itself, do you feel that whole building air leakage requirements increase the total cost of construction?
No, or not significantly
Yes, significant
Yes, moderate
39%
0%
61%
Aside from the cost of the test itself, do you feel that whole building air leakage requirements increase the total cost of construction?
No, or not significantly
Yes, significant
Yes, moderate56%
0%
33%
11%
Choose one of the following statements that best represents your opinion of current whole building air leakage target in your
jurisdiction:
Okay As Is
Too Stringent
Too Lenient
Other
61%
39%
56%33%
11%
23
Impact of Requirements
84%
11%
5%
Beneficial and
Worthwhile
Not Beneficial and
Not WorthwhileBeneficial, but
Not Worthwhile
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The Life of a Building
Upstream Effects
Material Selection
Assembly Design
Quality Control
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The Life of a Building
Downstream Effects
Energy Consumption
Indoor Air Quality
Acoustics
Durability
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Airtightness vs Air Leakage
What it Is, and What it Isn’t
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Airtightness vs Air Leakage
In-service air leakage is the combination of airtightness and
pressure differences created by the driving forces of airflow
Stack Effect
(-5°C)
Wind
(4 m/s)
Mechanical Systems
(5 Pa)
Cumulative
28
Determining Air Leakage from Airtightness
Difficult to extrapolate from airtightness test
results to air leakage rates
-1
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
-5
-4
-3
-2
-1
0
1
2
3
4
5
-100 -75 -50 -25 0 25 50 75 100
No
rmal
ize
d A
irfl
ow
[cf
m/f
t²]
No
rmal
ize
d A
irfl
ow
[L/
(s·m
²)]
Pressure Difference [Pa]
Airflow versus Pressure
Leaky
Average
Tight
In-ServicePressure Differences
TestPressure
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Only One Piece Of the Puzzle
Building
Airflows
Occupants
Whole Building
Airtightness
ControlsVentilation
Equipment
Climate
Airtightness testing helps with
modelling inputs, but doesn’t
give us the whole answer.
Operable
Windows
30
Summary
Airtightness performance and testing requirements have
been successfully implemented in jurisdictions such as
Washington State, the USACE, and the GSA.
Target of 2.0 L/(s·m²) (0.40 cfm/ft²) at 75 Pa is common and
demonstrated to be consistently achievable
Overall perceptions of whole building airtightness testing
seem positive
Airtightness is part of the puzzle for understanding building
airflows & energy efficiency, but further research required to
tie directly to indoor air quality and energy savings
31
Discussion + Questions
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www.rdh.com
www.buildingsciencelabs.com
OR CONTACT ME AT
