1. Building Enclosure Airtightness Testing In Washington State
Lessons learned about air barrier systems
and large building testing procedures
July 1, 2014
Presented by denali jones, RDH Building Sciences, Seattle
Welcome
My name is Denali Jones, I’m with RDH Building Sciences here in Seattle
I’m going to be talking to you guys about air leakage testing, or airtightness testing (I’m a glass half full guy), on large buildings here in Washington
ASHRAE 2014 Annual Conference
Seattle WA

2. Overview Airtightness Testing Testing Procedures
What is it?
Why test?
2009 vs energy codes
Testing Procedures
ASTM E779 and USACE
Single-family vs. large building
Challenges with large tests
Test Results & Discussion
Different air barrier types
Common leakage areas
Summary & Conclusion
So first I’ll go over a bit of background information about what airtightness testing is and why we’re doing it, and talk about the recent code requirements here in Seattle and in WA state
I’ll give you guys a brief overview of the test procedures that are used commonly here, and some of the differences between testing single family homes and large buildings, and some of the challenges with that.
Next I’ll go over our test results on new construction projects over the last few years, talk about the results of different air barrier types, and some common problem areas.
Then I’ll wrap up with a conclusion and take any questions you might have.

3. What is an Air Barrier?
A system of materials and components that resist the flow of air under a given air pressure difference
Code requirements:
Continuous
Components are joined and sealed in a flexible manner, allowing for relative movement
Withstands combined forces (negative and positive) without displacing adjacent materials
Materials: Pa
Assemblies: Pa
Whole building: Pa
So first of all what is an air barrier? Well the code defines it as a system of materials and components that resist the flow of air under a pressure. There are also weather resistive barriers, thermal barriers, and vapor barriers, and sometimes a material can serve several functions, but I’ll just focus on air barriers today.
According to the energy codes here in WA, the air barrier must be continuous, joined and sealed in a flexible manner, withstand the positive and negative forces on it, and it needs to be pretty airtight.
The requirement for air barrier materials is cfm/ft2, which actually came from the permeability of drywall (1/2” I believe) [ASTM E2178]
Assemblies need to be 0.04 cfm/ft2, 10 times leakier than materials, so this would be a wall or roof assembly [ASTM E2357]
And the whole building needs to be at 0.4 cfm/ft2, again 10 times leakier [ASTM E779]

4. Primary Air Barrier Systems
Sealed Sheathing
Sheet-Applied
Liquid-Applied
Self-Adhered
Curtain Wall/Window Wall/Storefront
Some typical air barriers we see around here are sealed sheathing; sheet applied, which is probably the most common in this market; liquid applied in some higher end buildings; there is also self adhered with exterior insulation commonly seen up north in colder climates; and also window wall or curtain wall or storefront systems, where the glazing system also functions as the primary air barrier.

5. Forces On Air Barriers Stack Effect Wind Mechanical Systems
There are really only 3 forces act on air barriers – stack effect, which is just warm air rising up through the building and creating a pressure difference;
wind, which is typically stronger further above ground (taller buildings are affected more);
and the mechanical system also pushes on the air barrier since most buildings are designed to be under a slight positive pressure.
All 3 of these forces are typically within 5-25Pa, and when they add together they can exert some powerful forces on the air barrier.

6. Whole-Building Airtightness Testing – What is it?
Quantitative testing of air barrier system performance
Calibrated fans pressurize the building and measure flow
Flow in = flow out
Results in cfm/ft2 of surface area
So what is airtightness testing? Has anybody here ever been involved in a whole building air leakage test before?
It is a way to quantitatively assess the performance of the air barrier
It involves putting calibrated fans into doors and pressurizing the building. The fans also measure flow, and if we have a constant volume and constant pressure, flow in = flow out. This means that flow in through the fans = flow out through the leaks.
We measure this in cfm, then divide by the total surface area of the building envelope to get out results.

7. Whole-Building Airtightness Testing – Why Test?
Simple answer: because the code says you have to.
To confirm air barrier performance
To identify air leakage pathways
To establish a number for future comparison
So why are we doing this? Well the simple answer is that the code says you have to; but really what we’re doing is confirming the air barrier performance. I’m a firm believer that you don’t know how well something is performing until you measure it.
Another reason is to identify air leakage pathways, which is typically done with infrared thermography. When the building is positively pressurized you can easily see where warm air is escaping. This can help remediate problems and help the design team to figure out common problem areas such as this parapet detail and vented roof assembly.
An also we want to establish a number for future comparisons. People have been doing blower door tests on single family houses for the better part of 30 years now, and the results are well documented and understood, but there is very little published data about large buildings, which can in some cases lead to bad assumptions, which I’ll talk about later.

8. 2009 Energy Codes Nonresidential air leakage testing requirements:
2009 Seattle Energy Code (SEC)
All nonresidential and multifamily family residential buildings must be tested.
Required* to achieve 0.4 cfm/ft2
2009 Washington State Energy Code (WSEC)
All nonresidential buildings > 5 stories must be tested.
*Requirement waived if air barrier has been inspected by a third party.
Main takeaway here – most buildings need to be tested. Also WSEC allows for depressurization only testing, which means possibly less prep work and easier testing.

9. 2012 Energy Codes
WSEC and SEC nonresidential air leakage testing requirements:
All nonresidential buildings must be tested.
All buildings > 3 stories must be tested.
Required* to achieve 0.4 cfm/ft2 or better.
*If 0.4 is not achieved, then reasonable efforts must be made to seal all leaks and an additional report must be submitted to the code official.
Regardless of 3rd party review – 0.4 actually means something

10. Testing Procedures – ASTM E 779 & USACE
Measure flow at multiple pressures (multipoint testing).
Highlight 75Pa
Add units

11. Test Procedures – Large Building Challenges
The concept is simple… but the execution…
Who is going to

12. Test Results - How airtight are these buildings?
Tested 31 buildings
All under 2009 code cycle
Air barrier type refers to walls
Talk about building size – most between 50,000 sq ft and 100,000 sq ft

13. Test Results – How airtight are these buildings?
Don’t talk too much about SF/CW
Show # of tests per type
Liquid Applied: 6
Curtain wall/Window wall: 3
Sealed Sheathing: 7
Sheet Applied: 12
Storefront: 3

14. Takeaways - What it takes to get an airtight building
The Good
Repetitive, simple details
Few trade interfaces
Experienced design team, general contractor, and trades
Coordination of design team, contractor, and trades

15. Takeaways – What it takes to get an airtight building
The Bad
Owner/Contractor doesn’t perceive value in airtightness
Poor/incomplete detailing
Inexperienced trades
Difficult review conditions
Sometimes field review can be difficult – 6 floor pump jacks
Add IR image of parapet – time animation with bullet point

16. What’s Next? Code target of 0.4 cfm/ft2 is attainable.
Better coordination between HVAC and envelope designers = better performance.
We know how airtight buildings are; size mechanical ventilation accordingly.
Add IR image of HVAC leakage
Careful about negative language – “narrow in on tighter design” “lower safety factors”
Look at code requirements for damper leakage

17. Discussion + Questions
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rdh.com