Airtightness of Large Buildings - Where We're At and Where We're Going

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Airtightness of Large Buildings:
Where We’re At and Where We’re Going
HPO & BCBEC - BUILDING SMART WITH AIR AND VAPOUR BARRIERS
FEBRUARY 18, 2016
PRESENTED BY LORNE RICKETTS, MASC

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 Airflow in and out of buildings affects:
 Building Energy Consumption
 Indoor Air Quality
 Building Durability
 Occupant Comfort (Thermal & Acoustics)
 30% of secondary energy is used by buildings¹
 >10% of that energy is attributable to air leakage² ³
1. Natural Resources Canada, 2014
2. VanBronkhorst, Persily, & Emmerich, 1995
3. Canadian Mortgage and Housing Corporation, 2007

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Despite the significant impact of
air leakage on building energy
consumption:
 Building energy codes provide
little to no guidance
 No verification of air barrier
performance is required
 Many jurisdictions are
considering implementing whole
building airtightness testing
 Is common for Part 9 already

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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

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AccessoriesMaterials Components
BRAND
BRAND
House Wrap
Whole
Building
Airtightness

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 Testing: House versus High-rise
 Where We’re At
 Impact of Testing
 What it Is and What it Isn’t
 Coming to a City Near You…
Outline

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House versus High-rise

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Test Methods and Procedures
 Most common airtightness
test methods are based on
similar fundamental
principles
 Fans are used to create a
pressure difference across
the building enclosure
 Airflow rate through the fan
at specific pressure
difference(s) recorded

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 Fan induced pressures must
exceed building pressures to
mitigate noise in data and
potential for error
 More difficult for large buildings
than for houses

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 More than just a
bigger house test
How do you get here
to seal these?
Fans

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 Lots of Gear…

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Standards and Qualifications
Many Standards Exist
 CGSB 149.10 & 149.15
 ASTM E 779 & ASTM E 1827 (blower door)
 US Army Corps of Engineers
 Air Barrier Association of America (ABAA)
 National Environmental Balancing Bureau (NEBB)
 Airtightness Testing and Measurements
Association (ATTMA) in the UK
Not Many Qualification Programs Exist
 NEBB Building Enclosure Testing Certified Professional

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 Testing may be difficult for
buildings which are:
 Large
 Tall
 Air-leaky and/or
 Compartmentalized
 It may be more feasible to
test smaller sections
 Floor-by-Floor
 Suite-by-Suite

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+50 Pa
0 Pa 0 Pa
0 Pa
0 Pa 0 Pa
Exterior=0Pa
0 Pa
0 Pa
0 Pa
Exterior=0Pa
+50 Pa
Section View – Floor Above and Below Plan View – Test Floor
Test # 1 – Pressurize Suite (Adjacent Suites Open to Exterior)
+50 Pa
+50 Pa +50 Pa
0 Pa
0 Pa 0 Pa
Exterior=0Pa
0 Pa
0 Pa
0 Pa
Exterior=0Pa
+50 Pa
Test # 2 – Pressurize Suite and Floor Above
+50 Pa
+50 Pa +50 Pa
0 Pa
+50 Pa +50 Pa
Exterior=0Pa
0 Pa
0 Pa
0 Pa
Exterior=0Pa
+50 Pa
Test # 3 – Pressurize Suite, Floors Above and Below
+50 Pa
+50 Pa +50 Pa
+50 Pa
+50 Pa +50 Pa
Exterior=0Pa
0 Pa
+50Pa
0 Pa
Exterior=0Pa
+50 Pa
Test # 4 – Pressurize Suite, Floors Above and Below, and Hallway
+50 Pa
+50 Pa +50 Pa
+50 Pa
+50 Pa +50 Pa
Exterior=0Pa
+50 Pa
+50Pa
0 Pa
Exterior=0Pa
+50 Pa
Test # 5 – Pressurize Suite, Floor Above and Below, Hallway and Left Suite
+50 Pa
+50 Pa +50 Pa
+50 Pa
+50 Pa +50 Pa
Exterior=0Pa
+50 Pa
+50Pa
+50 Pa
Exterior=0Pa
+50 Pa
Test # 6 – Pressurize Suite and All Adjacent Interior Surfaces

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Performance & Testing Requirements
 Washington State & Seattle, ABAA
Target, GSA, IBC Option
< 2.0 L/(s·m²) @ 75 Pa
 US Army Corps of Engineers
< 1.26 L/(s·m²) at 75 Pa
 Passive House
0.6 ACH50 (~0.12 cfm/ft² at 75 Pa)
 LEED, 6-sided apartment test
(~1.25 L/(s·m²) at 50 Pa)
 UK (AATMA) Large Buildings
~0.70 to 1.75 L/(s·m²) at 75 Pa
 Canada – currently no requirement

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 Database of Test Results
 Survey of Industry Preparedness
Where We’re At

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Where We’re At – The Data
 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
Building Types
25%
20%
9%
46%
Types of Buildings in Database
Commercial
MURB
Institutional
Military
Sample of 566 buildings
16%
66%
18%
Location of Buildings in Database
Canada
USA
UK
Sample of 566 buildings
Building Locations

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Whole Building Airtightness Data
0.0
1.0
2.0
3.0
4.0
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
1945 1955 1965 1975 1985 1995 2005 2015
Airtightness[cfm/ft²@75Pa]
Airtightness[L/(s.m²)@75Pa]
Construction of Building [year]
Airtightness Vs Year of Construction of All Buildings
Sample of 179 Buildings
Airtightness versus Year of Construction

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0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0
1
2
3
4
5
6
7
8
9
10
Research USACE Washington
Airtightness[L/s·m2@75Pa]
Summary of Airtightness of Buildings, Research vs Required
Performance
Requirement
Performance
Requirement
(214 Buildings) (260 Buildings) (44 Buildings)
Maximum off scale at 25
Minimum
Median
Third Quartile
First Quartile
Airtightness of Buildings – Impact of Requirements
Mandated performance and testing
makes a big difference!

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2.12
1.12
0.94
0
0.1
0.2
0.3
0.4
0.5
0.0
0.5
1.0
1.5
2.0
2.5
No Requirement, Post 2000
Construction
Washington USACE
Airtightness(cfm/ft²@75Pa)
Airtightness(L/s·m²@75Pa)
Jurisdiction Testing Requirements
Average Airtightness Test Results by Jurisdiction
Performance
Requirement
(2.0 L/ s·m2 @ 75 Pa)
Performance
Requirement
(1.25 L/ s·m2 @ 75 Pa)
(Count 31)
(Count 38) (Count 245)
Airtightness of Buildings – Impact of Requirements
Reporting Only

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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)
Curtain
Wall/Window
Wall/Storefront
(15 Buildings)
Airtightness[L/(s·m²)@75Pa]Where We’re At – Washington State
Leakiest Tested
Tightest Tested
Median
WA State Requirement
54 Buildings, Oct 2015 RDH Seattle Data
Passive House Range
equivalent ~ 0.6 ACH50

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Impact of Requirements – Mandatory
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 rep
opinion of current whole building air leakage targe
jurisdiction:
Okay A
Too Str
Too Len
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
f, do you feel that whole building
the total cost of construction?
No, or not significantly
Yes, significant
Yes, moderate
56%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

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84%
11%
5%
Impact of Requirements – Mandatory
Beneficial and
Worthwhile
Not Beneficial and Not
WorthwhileBeneficial, but
Not Worthwhile

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Passive House Airtightness
<0.6 ACH @ 50 Pa
~0.029 cfm/ft2 @ 75 Pa
Self-adhered sheet membrane
primary AB, transition to poly at
ceiling

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Passive House Airtightness
0.13 ACH @50 Pa
~0.014 cfm/ft2 @75 Pa
Sealed sheathing primary AB transition to SA membrane at roof

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Industry Testing Capacity
Locations of Companies Contacted to Complete Survey

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Availability of Testing Services

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 Ratings of qualifications, cost and availability of whole
building airtightness testing services in Canada
Sample of 105 responses
Shift

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Impact of Testing
The Life of a Building

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Impact of Testing
Other In-Situ M&V Measures
Commissioning of Fire
Safety Systems
Balancing of
HVAC Systems
Water Penetration
Testing of Windows

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Impact of Testing
Upstream Effects
Material Selection
Assembly Design
Quality Control

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 Seeing Shifts from Mechanically Attached to
Self-Adhered Membranes & Liquid Applied Membranes
Trends in Air Barrier System Selection

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Trends in Air Barrier System Selection
 Seeing shifts from common sheet applied bituminous
peel and stick membranes to non-bituminous
adhesives, and to liquids

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New AB/WRB Materials in a Growing Market
 Many new self-adhered
and liquid applied vapour
permeable sheathing
membranes available on
the market
 Fills a niche of combined
vapour permeable
air-barrier/WRB on
exterior of sheathing

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Lessons Learned with New Materials So Far…
Compatibility?
Wet Weather?
Long-term Durability?
Self-Sealing?
Cold Weather?
Crack Bridging?

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Changes in Design Process
 Clear identification of air
barrier on all drawings
both at detail level and
at whole building level

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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

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Impact of Testing
Upstream Effects
Material Selection
Assembly Design
Quality Control

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Impact of Testing
Downstream Effects
Energy Consumption
Indoor Air Quality
Acoustics
Durability

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 Why Airtightness isn’t Air Leakage
What it Is and What it Isn’t

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Airtightness vs Air Leakage
 Airtightness is only tells us about the size of the hole,
says nothing about the pressure difference
No pressure
difference, no flow
No hole,
no flow
It takes BOTH pressure
difference and a hole for flow.

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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

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Driving Forces
 Climate
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
PercentageofDrivingForcePressure
Daily Average Distribution of Pressure Difference due to Driving
Forces for a 40 m Tall Building in Miami40m Tall Building in Miami
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Forces for a 40 m Tall Building in Vancouver40m Tall Building in Vancouver40m Tall Building in Toronto
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Forces for a 40 m Tall Building in Toronto
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Forces for a 40 m Tall Building in Fairbanks40m Tall Building in Yellowknife
Wind Stack Effect Mechanical
(10 Pa)

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 Building Height
Driving Forces
Wind Stack Effect Mechanical
(10 Pa)
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Forces for a 20 m Tall Building in New York
20m Tall Building in Vancouver
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%

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Determining Air Leakage from Airtightness
 Difficult to extrapolate airtightness test results to air
leakage rates because in-service pressure differences
are unknown

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Airtightness & Windows
Average
Operable
Window

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Only One Piece Of the Puzzle
Building
Airflows
Occupants
Whole Building
Airtightness
Controls
Ventilation
Equipment
Climate
Operable Windows
Airtightness testing helps with
modelling inputs, but doesn’t
give us the whole answer.

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Coming to a City Near You

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Where We’re At - Summary
 Airtightness performance and testing requirements
have been implemented in other jurisdictions such as
Washington State, USACE, and GSA.
 Target of 2.0 L/(s·m²) (0.40 cfm/ft²) at 75 Pa is
common
 Numerous whole building airtightness testing
procedures and methodologies exist
 Overall perceptions of whole building airtightness
testing seems positive
 There is currently some capacity for whole building
airtightness testing in Canada/BC, but further capacity
needs to be developed
 Technical training of testers likely needed

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Airtightness is Coming…
 What’s in the code?
 BCBC 2012, NECB 2011 and ASHRAE
90.1-2010
› Something like: The building envelope shall
be designed and constructed with a
continuous air barrier system.
› Some material requirements
› No testing requirements
 What’s coming?
 Next code cycles expect to adopted in
BC late 2017 to 2018 and likely to
include a testing requirement, and
potentially a performance requirement

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 rdh.com | buildingsciencelabs.com
RDH Building Engineering Ltd. and Building Science Consulting Inc. have merged. Effective November 1, 2015, we now operate as
one integrated firm. The merger brings two of the leading building science firms in North America together to provide a
combination of cutting-edge research with leading design and implementation capabilities. The result is a unique offering for our
clients–an ability to explore new and innovative ideas based on science and our practical knowledge of what can be built. We are
excited about the possibilities as we launch the new firm.
Discussion + Questions
LORNE RICKETTS – LRICKETTS@RDH.COM
FOR FURTHER INFORMATION PLEASE VISIT

Airtightness of Large Buildings - Where We're At and Where We're Going

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