CSC Victoria Air Barriers and Airtightness Testing for Large Buildings CSC VANCOUVER ISLAND CHAPTER, VICTORIA, BC

Transcription

1 Air Barriers and Airtightness Testing for Large Buildings CSC VANCOUVER ISLAND CHAPTER, VICTORIA, BC FEBRUARY 15 TH, 2018 Graham Finch, MASc, P.Eng Principal, Senior Building Science Engineer 1 Outline Why do we Care? Why is the Code Changing? What s an Airtightness Test? What s the Impact of Testing? Resources 2 G.Finch - RDH - gfinch@rdh.com 1

2 Spot the Difference 3 Spot the Difference 4 G.Finch - RDH - gfinch@rdh.com 2

3 Why We Care Infiltration and Exfiltration Directly Impact: Building Energy Consumption Heat Loss and Gains ($) Indoor Air Quality - Pollutants Building Durability - Condensation Occupant Comfort - Thermal & Acoustics 6 Why We Care 7 G.Finch - RDH - gfinch@rdh.com 3

4 What Have We Had Up Until Now? What s in other codes? BCBC, NECB, ASHRAE 90.1: Something like: The building envelope shall be designed and constructed with a continuous air barrier system. Some material & assembly requirements No testing requirements (though sometimes is an option) 8 Most Common Air Barrier in Canada as Result of Prescriptive Based Old Codes 9 G.Finch - RDH - gfinch@rdh.com 4

5 Context - Other Jurisdictions Washington State & Seattle, ABAA Target, GSA, IBC/IECC Option < 2.0 L/(s 75 Pa US Army Corps of Engineers & IGCC < 1.26 L/(s m²) at 75 Pa Passive House 0.6 ACH50 (~0.60 L/(s m²) 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 10 Local Drivers New BC Energy Step Code 11 G.Finch - RDH - gfinch@rdh.com 5

6 NEW Whole Building Airtightness Requirements in BC BC Energy Step Code Part 9: Required testing and targets of 1.0 to 3.0 ACH 50 (no performance target for Step 1) Part 3 Buildings (Part 10) Whole building airtightness testing required for all Steps Except Step 1, measured airtightness result to be reflected in the energy model No specific target, though less than 2.0 L/s 75 Pa is advisable City of Vancouver - VBBL Part 9: 1- & 2-family Dwellings Testing to achieve <3.5 ACH 50 Green Buildings Policy for Rezonings Testing & reporting required Target is 2.0 L/s m² at 75 Pa 12 What happens if we fail? 13 G.Finch - RDH - gfinch@rdh.com 6

7 Why Is the Code Changing? 14 What is an Air Barrier System Made of? 16 G.Finch - RDH - gfinch@rdh.com 7

8 Air Barrier System Criteria Air Barrier Systems must: Be Continuous Be Durable Resist Structural Loads Sufficient Stiffness & Strength for Design Wind Load Be Airtight Wind loads & air pressures on midto high-rise buildings can be significant and approaches commonly used for low-rise buildings are typically not appropriate 17 The 5 Requirements for Air Barrier Systems #1: Continuity Must be continuous between all enclosure elements, from above to below grade, walls to windows and doors, roof & everything in between Relies on more than one material Compatibility of adjoining materials critical for long term sealing All trades on project must understand criticality of air barrier system & methods for sealing penetrations 18 G.Finch - RDH - gfinch@rdh.com 8

9 Continuity Detailing Early Often 19 The 5 Requirements for Air Barrier Systems #2: Air Impermeability Materials must be resistant to flow or air at pressures experienced in the building Is a referenced building code requirement Air barrier materials of less than cfm/ft Pa (0.02 L/s m 2 ) Air barrier systems of less than 0.04 cfm/ft Pa (0.2 L/s m 2 ) Most materials & systems easily meet requirements While important to meet standard a lower number doesn t always translate to better overall building performance Most CMU is not an airtight material by code definition unless coated Open & closed cell sprayfoam can be an air barrier, but gaps, cracks will negate these numbers by an order 20 of magnitude G.Finch - RDH - gfinch@rdh.com 9

10 Material Air Permeability is Pretty Easy... Peanut Butter (Skippy Brand) 20 mils Pa More than twice as tight as Housewrap BUT, IT S THE SYTEM DETAILS THAT MATTER 21 The 5 Requirements for Air Barrier Systems #3: Durability Air Barrier System must be durable enough to last as long as the enclosure assembly that it is installed into (at least 25 to up to 100+ years) Must be able to take stresses due to assembly/material movement, not be fatigued by cyclical movement Must not degrade due to high or low temperatures, moisture, chemicals, contaminants, UV (if exposed) during construction & inservice Untried air barrier membrane product from Europe failed due to heat aging effects in roof assembly 22 G.Finch - RDH - gfinch@rdh.com 10

11 The 5 Requirements for Air Barrier Systems #4: Strength Air Barrier materials must be designed for the structural wind & resulting building pressure loads (i.e. 1 in 30 year wind gust) Joints and fasteners often critical, especially for flexible unadhered membrane systems Need for sealing/reinforcing around sharp fasteners and penetrations Adhesion of tapes/sealants critical to performance & are often the strength limiting component 23 The 5 Requirements for Air Barrier Systems #5: Stiffness Air Barrier System must be stiff enough so that deformations do not change the air-permeance and/or distribute air though unintentional openings One-side supported sheet membranes create challenges without strapping 24 G.Finch - RDH - gfinch@rdh.com 11

12 Additional Considerations for an Air Barrier Vapour permeability of air barrier should also be considered Should be designed so that it does not negatively affect durability 25 Many Air Barrier Systems & Products Available Loose Sheet Applied Membrane Taped Joints & Strapping Sealed Gypsum Sheathing Sealant Filler at Joints Liquid Applied Sealants/Membranes Mass Walls (concrete) BUT, IT S THE DETAILS THAT MATTER Self-Adhered vapor permeable membrane Self-Adhered vapor impermeable membrane Sprayfoam or Sealed Foam Sheathing Curtainwall, window-wall & glazing systems 26 G.Finch - RDH - gfinch@rdh.com 12

13 Airtightness Does Not Happen By Accident 27 The Air Barrier: As Strong as the Weakest Detail 28 G.Finch - RDH - gfinch@rdh.com 13

14 What s an Airtightness Test? 29 The Life of a Building 30 G.Finch - RDH - gfinch@rdh.com 14

15 Other On-Site M&V Measures Commissioning of Fire Safety Systems Water Penetration Testing of Windows Balancing of HVAC Systems 31 Airtightness Testing Airflow In = Airflow Out 32 G.Finch - RDH - gfinch@rdh.com 15

16 Airtightness Testing Airflow In = Airflow Out Air Leakage Rate (L/s m²) 33 Standards & Qualifications Many Standards Exist CGSB & ASTM E 779 & ASTM E 1827 US Army Corps of Engineers (UCACE v. 3) 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 35 G.Finch - RDH - gfinch@rdh.com 16

17 Airtightness Testing Standards USACE ASTM E 779 CoV Rezoning Policy 36 Test Methods and Procedures Fan induced pressures must exceed building pressures to mitigate noise in data and potential for error More difficult for large buildings than for houses 37 G.Finch - RDH - gfinch@rdh.com 17

18 Planning: How are we going to test? What about mixed/phased occupancy? 38 Planning: Where will the fans be installed? Need to get uniform pressure throughout the building Rule of thumb: never more than 6500 L/s through a typical single door opening Everything is simpler when the building is tight 39 G.Finch - RDH - gfinch@rdh.com 18

19 Test Methods and Procedures 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 40 Planning: What building preparation is needed? Typically test the air barrier system only Shut down HVAC Close dampers Mask openings with gravity dampers or no dampers (i.e. continuous exhaust) This can cost thousands of dollars in MURBs 41 G.Finch - RDH - gfinch@rdh.com 19

20 Large Building Test Considerations Fans More than just a bigger house test How do you get here to seal these? 42 Lots of Gear 43 G.Finch - RDH - gfinch@rdh.com 20

21 Very Large Building Test Equipment 44 Troubleshooting... Where s the open window? 45 G.Finch - RDH - gfinch@rdh.com 21

22 Troubleshooting All the small details Tubing & connectors Data cables & switches Power supply Gauge batteries Need mechanical/electrical for operating the HVAC Need somebody there with the keys! Retrotec Support Monday Friday, 8am - 4pm 47 G.Finch - RDH - gfinch@rdh.com 22

23 Finding the Leaks Infrared Thermography 48 Finding the Leaks Infrared Thermography Pressurized Depressurized 49 G.Finch - RDH - gfinch@rdh.com 23

24 Finding the Leaks Smoke Tracer 50 What s the impact? 52 G.Finch - RDH - gfinch@rdh.com 24

25 The Life of a Building Material Selection Assembly Design Quality Control Upstream Effects 53 Changes in Air Barrier System Selection Seeing shifts in large buildings from Mechanically Attached to Self-Adhesive & Liquid Applied membranes 54 G.Finch - RDH - gfinch@rdh.com 25

26 Changes in Air Barrier System Selection Seeing the introduction of many new to market proprietary air barrier sheathing products 55 Changes in Air Barrier System Selection Seeing the construction industry finding refinements & cost savings to achieve exceptional levels of airtightness with very simple materials and methods 56 G.Finch - RDH - gfinch@rdh.com 26

27 New Air Barrier/Water Resistive Barrier Materials Many new self-adhered and liquid applied vapour permeable sheathing membranes available on the market 57 Lessons Learned So Far... Compatibility? Wet Weather? Long-term Durability? Cold Weather? Crack Bridging? Self-Sealing? 58 G.Finch - RDH - gfinch@rdh.com 27

28 Changes in Design Clear identification of air barrier on all drawings both at whole building and detail level 59 It s all in the details 60 G.Finch - RDH - gfinch@rdh.com 28

29 Changes in Design It s not the details you have, it s the details you don t have Fluted decks are often a challenge Don t forget interior smoke seals that are part of air barrier 61 Changes in Construction Practice Sequencing when different trades comes together is a significant consideration for achieving airtightness 62 G.Finch - RDH - gfinch@rdh.com 29

30 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 63 The Life of a Building Material Selection Assembly Design Quality Control Upstream Effects 64 G.Finch - RDH - gfinch@rdh.com 30

31 The Life of a Building Downstream Effects Energy Consumption Indoor Air Quality Acoustics Durability 65 Where We re At The Numbers Airtightness Airtightness [L/(s.m²) Pa] Pa] Airtightness vs Year of Construction Sample of 179 Buildings Construction of of Building [year] [year] Airtightness Pa] Pa] 66 G.Finch - RDH - gfinch@rdh.com 31

32 Impact of Requirements 68 Performance of Wall Air Barrier Systems Airtightness Airtightness [L/(s m²) [L/(s Pa] 75 Pa] WA State Requirement Liquid Applied (10 Buildings) Leakiest Tested Median Tightest Tested Sealed Sheathing (11 Buildings) Sheet Applied (28 Buildings) Curtain Wall/Window Wall/Storefront (15 Buildings) Airtightness [cfm/ft² Pa] 75 Pa] 69 G.Finch - RDH - gfinch@rdh.com 32

33 Common Challenges with Exterior Air Barrier Systems 70 Usual Location of Air Leaks Modern Mid to High-rise Buildings 50% 45% Percent of Respondents 40% 35% 30% 25% 20% 15% 10% 5% 0% Roof to wall transitions Base of wall or floor line transitions Mechanical penetrations Dampers Soffits Vented roof assemblies 71 G.Finch - RDH - gfinch@rdh.com 33

34 Roof Wall Transitions for Exterior Air Barrier Systems 72 Impact on Energy Consumption Case Study 6-storey 4,700 m² wood-frame multi-unit residential building Energy Efficient R-25 walls and U-0.27 windows 60% efficient HRV Victoria, BC Climate Zone 73 G.Finch - RDH - gfinch@rdh.com 34

35 Impact on Energy Consumption Case Study 74 Impact on Durability - Air Leakage Condensation Interior Exterior 75 G.Finch - RDH - gfinch@rdh.com 35

36 Impact on Durability 76 Industry Survey 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] 11% 11% 39% 61% 61% 0% 33% 33% 56% 56% No, or not significantly Yes, significant Yes, moderate 0% Okay As Is Too Stringent Too Lenient Other 77 G.Finch - RDH - gfinch@rdh.com 36

37 Impact of Requirements Beneficial, but Not Worthwhile 11% 5% Not Beneficial and Not Worthwhile 84% Beneficial and Worthwhile 78 Guide to Achieving Airtight Buildings 79 G.Finch - RDH - gfinch@rdh.com 37

38 Illustrated Guide 80 Guide to Achieving Airtight Buildings 81 G.Finch - RDH - gfinch@rdh.com 38

39 Guide to Achieving Airtight Buildings 82 Video: Engineers & Geoscientist of BC Building Coming soon! 83 G.Finch - RDH - gfinch@rdh.com 39

40 Discussion + Questions FOR FURTHER INFORMATION PLEASE VISIT Graham Finch gfinch@rdh.com G.Finch - RDH - gfinch@rdh.com 40