Failure Mechanisms and Re-Glazing of an all Glass Tower
Lessons in Insulating Glazing Unit Failures
Graham Finch, MASc, P....
Outline
How do Building
Enclosures and Insulating
Glazing Units (IGUs) Fail?
Standard and Innovative
In-Situ IGU Testing
M...
Failed Building Enclosures – Rot and Corrosion
Failed Windows – Corrosion & Wind
Alright… So What Fails Here?
Failed Tempered Glazing – Nickel Sulphide Inclusions
Overheating in a Cold Climate
Residential condo building constructed in 2002 – entirely
structurally glazed curtainwall – R-5 proprietary triple IGUs
Fi...
Insulating Glazing Units
Patent Application Drawing 2002
Visual Review
Rating based on visual
observation and level of fogging
and low-e corrosion damage
visible from 10 feet away...
Fogged and Corroded Glazing Units (Surface #5)
Visual Review of IGU Conditions, 2006 through 2009
2006 & 2007 Visual Review Summary
Clear
43%
Minor
23%
Moderate
17%
Seve...
Mapping IGU Degradation with Time
N
2006
2006
Corrosion Legend
Clear
Minor
Moderate
Severe
2006 Frost points: -55, -10, -8...
Further testing procedures
evolved:
Desiccant saturation
measurement
Pressure testing
• Measure leakage rate of IGUs
Flow ...
Once desiccant reaches 80%, it no longer protects IGU from
fogging – dewpoint above 0°C (32°F)
Found saturated desiccant i...
In-situ IGU Pressure Testing
Purpose to determine how “sealed” the IGUs actually are
Built a specialized testing apparatus...
Pressure Testing Apparatus
Glazing
Unit
Desiccant Tube
Pump air into unit
up to 250 Pa
P
Compressor
Pressure
Gauge
Pressur...
Pressure Testing Theory
A completely sealed IGU will retain applied pressure
indefinitely (i.e. car tires, basketball etc)...
Pressure Decay Testing
Flow Monitoring
Low Flow sensors
connected to open end of
desiccant tubes
Data recorded every
second
Temperature data also...
Pressure and Flow through Desiccant Tube
In-Situ Monitoring Results
Air flows from outside into the IGU through edge seal defects
then into suite through desiccant...
Partial IGU Removal – Replace Broken IGU
Eventual (2 year later) IGU removal of Intact IGU
IGU Perimeter Seal Discontinuity Testing
Over 20 unique leakage
locations observed in
addition to the desiccant
tube hole
...
Systemic failure of IGUs due to an inadequately sealed
“thermally efficient” edge spacer
PVC, aluminum, stainless steel fo...
Criteria: Match existing residential
portion plus improve performance
Lower SHGC to reduce overheating
and issues with und...
Selecting New Glazing Units
Why Mockups are Performed
Trend towards “thermally broken” edge spacer bars with plastic
thermal breaks (polyurethanes, PVC)
Have investigated the f...
Structural Silicone Sealant Detailing in the Field
CONCEPT 1
Why More Mock-ups are Performed
Replacing Floor-Ceiling IGUs in a Fully Occupied Condo
In strive for more energy efficient products and buildings –
inevitably some do fail
Lessons learned from failures provide...
Discussion
gfinch@rdhbe.com
604-873-1181
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Insulating Glazing Unit Failures - Lessons From an All Glass Tower

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glazing problems and failures with high performance IGUs - presentation from 2012 BEST 3 conference in Atlanta, Georgia

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  • Two years later removed igus. Vinyl, aluminum, hot melt butyl, stainless steel – all have different thermal expansion. Vinyl moved, gaps opened up
  • Insulating Glazing Unit Failures - Lessons From an All Glass Tower

    1. 1. Failure Mechanisms and Re-Glazing of an all Glass Tower Lessons in Insulating Glazing Unit Failures Graham Finch, MASc, P.Eng RDH Building Engineering, Vancouver, BC BEST 3 Atlanta – April 3, 2012
    2. 2. Outline How do Building Enclosures and Insulating Glazing Units (IGUs) Fail? Standard and Innovative In-Situ IGU Testing Methods Selection of New IGUs and Replacement in an Occupied Building
    3. 3. Failed Building Enclosures – Rot and Corrosion
    4. 4. Failed Windows – Corrosion & Wind
    5. 5. Alright… So What Fails Here?
    6. 6. Failed Tempered Glazing – Nickel Sulphide Inclusions
    7. 7. Overheating in a Cold Climate
    8. 8. Residential condo building constructed in 2002 – entirely structurally glazed curtainwall – R-5 proprietary triple IGUs First fogged IGUs reportedly observed in 2003 Contractor replaced all desiccant tubes More fogging persisted Corrosion of low-e noticed More desiccant tubes replaced Retained by owners to first investigate in 2006 Continued investigations through 2007-2008 Acknowledgement of widespread and worsening problem Owners decide to proceed with re-glazing Design in 2011 - Re-glazing in 2012 Background – Case Study
    9. 9. Insulating Glazing Units Patent Application Drawing 2002
    10. 10. Visual Review Rating based on visual observation and level of fogging and low-e corrosion damage visible from 10 feet away Dew/frost-point testing (ASTM E-576) Measures how dry the IGU airspace is and estimate the saturation level of the desiccant Can estimate remaining service life of IGUs Can quantify failed units and units close to failure Quantifying IGU Failures in the Field
    11. 11. Fogged and Corroded Glazing Units (Surface #5)
    12. 12. Visual Review of IGU Conditions, 2006 through 2009 2006 & 2007 Visual Review Summary Clear 43% Minor 23% Moderate 17% Severe 17% 34% of all units are showing considerable low-e corrosion Atotal of 239 IGUs reviewed in 2006 & 2007 2008 Visual Review Summary Minor 30% Moderate 32% Severe 25% Clear 13% 57% of all units are showing considerable low-e corrosion 8 suites - Atotal of 163 IGUs reviewed in 2008 2009 Visual Review Summary Clear 0% Minor 15% Moderate 26% Severe 59% 85% of all units are showing considerable low-e corrosion 3 suites, 3204, 3304, 3803 (All new suites) - Atotal of 53 IGUs reviewed in 2009
    13. 13. Mapping IGU Degradation with Time N 2006 2006 Corrosion Legend Clear Minor Moderate Severe 2006 Frost points: -55, -10, -8 C 2008 2008 2008 Frost points: all between 2 and 6C
    14. 14. Further testing procedures evolved: Desiccant saturation measurement Pressure testing • Measure leakage rate of IGUs Flow testing • Measure flow through the desiccant tube in service Eventual removal • For visual and laboratory testing • Delayed for several years to get safety variance to remove IGUs But How and Why are They Failing So Fast?
    15. 15. Once desiccant reaches 80%, it no longer protects IGU from fogging – dewpoint above 0°C (32°F) Found saturated desiccant in all fogged units, and drier desiccant in clear IGUs Desiccant Saturation Testing
    16. 16. In-situ IGU Pressure Testing Purpose to determine how “sealed” the IGUs actually are Built a specialized testing apparatus to measure pressure decay of IGUs in-situ Correlate condensation/low-e corrosion with “leakiness” of the IGUs Pressurize IGU through hole at removable desiccant tube
    17. 17. Pressure Testing Apparatus Glazing Unit Desiccant Tube Pump air into unit up to 250 Pa P Compressor Pressure Gauge Pressure decay indicates number and size of leaks Pump-up unit through desiccant tube hole Typical Window (Elevation View) Disconnect tube
    18. 18. Pressure Testing Theory A completely sealed IGU will retain applied pressure indefinitely (i.e. car tires, basketball etc). A leaky unit will exhibit a loss of pressure with time (pressure decay). Air is leaking out through perimeter glazing seal The pressure decay can be measured and an approximate leakage area calculated Correlate with corrosion and dewpoint measurement Units that cannot be pressurized are very leaky (i.e. like a flat tire) Can also use to test new units (originally the IGU company was going to replace all fogged units)
    19. 19. Pressure Decay Testing
    20. 20. Flow Monitoring Low Flow sensors connected to open end of desiccant tubes Data recorded every second Temperature data also collected Wind speed and direction data taken from site Q flow Desiccant Tube Glazing Unit
    21. 21. Pressure and Flow through Desiccant Tube
    22. 22. In-Situ Monitoring Results Air flows from outside into the IGU through edge seal defects then into suite through desiccant tube – driven by wind pressure differences and thermal expansion/contraction Desiccant tube flow rate of <0.01 L/min resulting in exchange of 1-5 Liters of air per day just from wind Estimated service life of external desiccant tubes with these average flow rates is <5 years to saturation Not accounting for other leaks (as indicated by pressure decay testing) Could this replaceable desiccant tube design have worked in theory? 10x more desiccant by volume within IGU edge seal anyway
    23. 23. Partial IGU Removal – Replace Broken IGU
    24. 24. Eventual (2 year later) IGU removal of Intact IGU
    25. 25. IGU Perimeter Seal Discontinuity Testing Over 20 unique leakage locations observed in addition to the desiccant tube hole Stainless Steel Foil Discontinuities in edge seal Exterior lite
    26. 26. Systemic failure of IGUs due to an inadequately sealed “thermally efficient” edge spacer PVC, aluminum, stainless steel foil & hot-melt butyl differential expansion/contraction No real durable structural edge seal Removable desiccant tubes easily overwhelmed in service IGU failure led to frequent fogging and corrosion of silver low-e coating on surface #2 All IGUs need to be replaced Other units in building with stainless steel (not silver) low-e coating are also fogging but not corroding. Remaining Life? Investigation Summary
    27. 27. Criteria: Match existing residential portion plus improve performance Lower SHGC to reduce overheating and issues with undersized AC units All-glass triple vs previous PET suspended film triple Durable edge seal spacer (thin stainless, dual seal with proven track record) Original low-e coating not available (old AFG) and hard to match Narrowed down hundreds of new alternate options for Owners and City to choose from Many plant and site mock-ups for color Selecting New Glazing Units
    28. 28. Selecting New Glazing Units Why Mockups are Performed
    29. 29. Trend towards “thermally broken” edge spacer bars with plastic thermal breaks (polyurethanes, PVC) Have investigated the fogging of several brand-new IGUs where VOCs (mainly ethanol and propanol & water) were present in all fogged units but not within any good un-fogged units. Some molecular sieve desiccants are better at absorbing VOCs than others Need to be careful with edge seal spacer selection Selection of New IGU Spacers
    30. 30. Structural Silicone Sealant Detailing in the Field CONCEPT 1
    31. 31. Why More Mock-ups are Performed
    32. 32. Replacing Floor-Ceiling IGUs in a Fully Occupied Condo
    33. 33. In strive for more energy efficient products and buildings – inevitably some do fail Lessons learned from failures provide valuable lessons in durability Edge seal durability very important in thermally efficient IGUs In-situ pressure decay testing of IGUs a possible diagnostic tool to test seal integrity (in factory QC and in-situ) Mock-ups during Restoration as useful as New Construction Conclusions
    34. 34. Discussion gfinch@rdhbe.com 604-873-1181

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