The Science Behind Better Building Enclosures - Seattle
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Join the ROXUL EDC, Cosella-Dorken and RDH Building Science to discuss and share in resolving common problems related to building design and construction. This full-day seminar will provide 5 CONTINUING EDUCATION LEARNING UNITS and will review the following learning objectives: Understand key building science principles related to a building enclosure’s function and components. Recognize and apply critical design principles and strategies to improve building enclosure performance. Understand the in-situ performance of building enclosure materials and systems. Gain awareness of emerging issues and trends in building enclosure design that may influence design decisions and building performance. Featured Speaker: John Straube, Ph.D., P.Eng. John Straube, Ph.D., P.Eng., is a Principal at RDH Building Science Inc., where he heads forensic investigations and leads research projects in the areas of low-energy building design, building enclosure performance, hygrothermal analysis, and field monitoring of wall assemblies. In addition to his work with RDH, Dr. Straube is a faculty member at the University of Waterloo. He is also a prolific writer and a noted public speaker.
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The Science Behind Better Building Enclosures - Seattle
- 1. 17-06-13 1 Presenter: Dr John Straube P.Eng. Principal, RDH Building Science Assoc. Professor, University of Waterloo The Science Behind Be1er Building Enclosures Energy Design Centre Energy Design Centre Energy Design Centre Rough Outline • Review of Basics • Control funcAons / layers /barriers – Rain – Air – Heat • Issues & Trends… throughout – Look forward to future needs/demands • Best pracAses and case studies
- 2. 17-06-13 2 Basics of Enclosure Design Performance? • More than on-Ame, on-budget, to code – Safe – Healthy – Comfortable • A growing clamor for…. – Durable – Low-energy – Maintainable – Faster Design/ Construcion – All weather construcAon • All delivered “affordably”, reliably, predictably
- 3. 17-06-13 3 We need a “reset”! Re-assess what we are trying to do and how we are trying to do it. Much more Complexity • Many different assemblies • Many different layers • Many different materials • Many layers of consultants • Many more regulatory requirements 6
- 4. 17-06-13 4 Building Components • FuncAon of a Building: – provide the desired environment in & around • Buildings are made of several large systems • Can be grouped in four categories – Superstructure – Service Systems – Fabric – Enclosure Enclosures No. 7 / Importance of the Enclosure • Image – People see it! • Building problems – O`en heat, moisture and the enclosure • Energy consumpAon – Driven by enclosure performance • Durability o`en less than building – Roof 15-30 yrs, Windows 20-40 yrs Sealants 5-25 yrs Enclosures No. 8 /
- 5. 17-06-13 5 The Enclosure: An Environmental Separator • The part of the building that physically separates the interior and exterior environments. • Includes all of the parts that make up the wall, window, roof, floor, etc… from the innermost to the outermost layer. • SomeAmes, interior parAAon also are environmental separators (pools, rinks, etc.) Enclosures No. 9 / Building Enclosure Components Enclosures No. 10 /
- 6. 17-06-13 6 Enclosure Loadings • The separaAon funcAon generates loads • Load: any event, phenomenon or characterisAc that can affect the enclosure – Heat, Air, Moisture – Fire, Sound – UV, Ozone – Gravity, impacts, abrasion – Insects – Etc… Enclosures No. 11 / Climate / Site • Design for – Climate zone – Site – Building height, shape, complexity Marcus Vitruvius Pollio These are properly designed, when due regard is had to the country and climate in which they are erected. For the method of building which is suited to Egypt would be very improper in Spain, and that in use in Pontus would be absurd at Rome: so in other parts of the world a style suitable to one climate, would be very unsuitable to another: for one part of the world is under the sun's course, another is distant from it, and another, between the two, is temperate. Sea1le ≠ Sacramento Miami ≠ Minneapolis Edmonton ≠ Vancouver
- 8. 17-06-13 8 Climate Zones Enclosures No. 15 / Climate Load ModificaAon • Building & Site (overhangs, trees…) – Creates microclimate • Building Enclosure (walls, windows, roof…) – Separates climates – Passive modificaAon • Building Environmental Systems (HVAC…) – AcAve modificaAon – Use energy to change indoor weather Building Science Enclosures No. 16 /
- 9. 17-06-13 9 Basic FuncAons of the Enclosure • 1. Support – Resist and transfer physical forces from inside and out • 2. Control – Control mass and energy flows • 3. Finish – Interior and exterior surfaces for people • DistribuAon – a building funcAon Functional Layers Basic Enclosure FuncAons • Support – Resist & transfer physical forces from inside and out • Lateral (wind, earthquake) • Gravity (snow, dead, use) • Rheological (shrink, swell) • Impact, wear, abrasion • Control – Control mass and energy flows • Finish – Interior and exterior surfaces for people Functional Layers
- 10. 17-06-13 10 Basic Enclosure FuncAons • Support – Resist & transfer physical forces from inside and out • Control – Control mass and energy flows • Rain (and soil moisture) – Drainage plane, capillary break, etc. • Air – ConAnuous air barrier • Heat – ConAnuous layer of insulaAon • Vapor – Balance of wepng/drying • Finish – Interior and exterior surfaces for people Functional Layers Other Control FuncAons . . . • Support • Control – Fire • PenetraBon • PropagaBon – Sound • PenetraBon • ReflecBon – Light • Diffuse/glare • View • Finish Functional Layers
- 11. 17-06-13 11 History of Control FuncBons • Older Buildings – One layer does everything • Newer Building – Separate layers, . . . separate funcAons Basic Enclosure FuncAons • Support – Resist & transfer physical forces from inside and out • Control – Control mass and energy flows • Finish – Interior & exterior surfaces for people • Color, speculance • Pa1ern, texture Functional Layers
- 12. 17-06-13 12 Building Science Enclosures No. 23 / Finish vs. Control Confusion What is a high performance enclosure? • High levels of control • But, poor conAnuity limits performance • & Poor conAnuity causes most problems too: – E.g. air leakage condensaAon – Rain leakage – Surface condensaAon – Cold windows • Thus: con*nuity + high levels of control
- 13. 17-06-13 13 Ideal Enclosure • Water control – No leaks (that cause damage) • Air Control: Limit leaks – Assembly: 0.2 lps/m2 @ 75 Pa 0.04 cfm / ft2 at 0.3 wg – Material 0.02 lps/m2 @75 Pa 0.004 cfm / ft2 at 0.3 wg • Thermal Control – Effective R-value? Beware thermal bridges • Vapor Control – No damaging diffusion-related accumulation 25 Protect the Air-water control layers from UV/temp if they are polymer based Building Enclosure Resources – Guides, Research Reports and Videos
- 14. 17-06-13 14 27 1. Air / Rain Barrier 2. Structural Support 3. Rain Shedding 4. InsulaAon Design Information older than I am.
- 15. 17-06-13 15 The world is complex enough Choose to make it simpler PAGE 6 The “Perfect Wall” • Finish of whatever • Control conAnuity 1. Rain control layer • Drained with gap (shown) • or Perfect barrier • or Storage 2. Air control layer • Air barrier system 3. Thermal control layer • Aka insulaAon, radiant barriers – Vapor control layer • Retarders, barriers, etc • Structure can be anything 30 AddiAonal Fire Control may be needed AddiAonal Sound Control opAonal
- 25. 17-06-13 25 • Water • Air • Thermal Rain Control Water Control Layers WRB / Drainage Plane, etc.
- 26. 17-06-13 26 Approach • If it does not get wet, it wont leak – Exposure, deflecAon • When rain hits, direct it away – Drips, surface texture, protected joints – Drainage gaps, flashing, weeps • If you are not perfect, provide some drying – Color, sun, venAlaAon, vapor permeance, – Moisture tolerant materials
- 29. 17-06-13 29 Three Approaches Building Science 2. Exclude (Perfect Barrier) 3. Drain (Drained/Screened) 1. Store (Mass) Cladding Thermal Control Support Water-Air-Vapor Control Rain Control: Drained System Walls oGen use drained approach • Rain shedding • Drainage + flashing • Must integrate with flashing, & drainholes • Overlap everything • Avoid holes J
- 30. 17-06-13 30 What is a Rainscreen • Drained? • Vented? • Do we need a ½”mm? 1” gap? • Do cladding joints need to be sealed 60 “Rainscreen?” or “Drained” System • Rain shedding • Drainage gap • Water control layer • Must integrate with flashing, drainholes • Overlap everything • No holes
- 32. 17-06-13 32 Sub-sill flashing Self-adhered membrane Formable self-adhered membrane Liquid applied membrane Pre-formed flashing system 64 Double-glazed vinyl, wood, or fiberglass framed window with nailing flange Low expansion spray foam or sealant, connects DELTA® -VENT SA air barrier to window. Do not seal full cavity to allow drainage from sill flashing. Back dam installed with framing; alternate install sloped sill DELTA® -FLASHING sill flashing. Overlap vertical DELTA®-VENT SA min 2" (50 mm) DELTA®-VENT SA fully-adhered air and water resistive barrierContinuous vapor permeable thermal insulation (EPS and semi-rigid MFI) Install ties over DELTA® -VENT SA to minimize penetrations. Ties are installed over DELTA® -FLEXX-BAND patch to seal around fasteners. Brick, stone, or concrete sill with drip edge Sealant with backer rod No fasteners through lower window nailing flange to allow drainage from sill flashing Cavity insulation (fiberglass batt, cellulose, ocSPF) and vapor control as required (see "Vapor Control") Alternate air sealing detail: use sealant and backer rod to seal between window frame and rough opening. PAGE 36
- 34. 17-06-13 34 Jamb 67 Continuous vapor permeable thermal insulation (EPS and semi-rigid MFI) Double-glazed vinyl, wood, or fiberglass framed window with nailing flange Low expansion spray foam, connects DELTA®-VENT SA air barrier to window Rough opening wrapped with DELTA® -VENT SA fully-adhered air and water resistive barrier Cavity insulation (fiberglass batt, cellulose, ocSPF) and vapor control as required (see "Vapor Control") Sealant behind nailing flange Sealant for rain penetration control and visual finish Pressure EqualizaAon: Theory Theory: “If you get pressure equalizaAon, no water will be driven across the cladding” Pressure (of total) Water control layer and air barrier with a few leaks
- 35. 17-06-13 35 Pressure EqualizaAon: Limits Water control layer Bad VenBng Air Barrier Leaks Pressure (of total) Pressure EqualizaAon: Reality Air-Water control layer Good Air Barrier • If you get perfect pressure equalizaAon … • all air pressures is across the water control layer, so • if water is on drainage plane it will be driven through any holes by air pressure! Reality: “Cladding leaks because of gravity, and window/ penetraAons dump water on drainage plane
- 36. 17-06-13 36 Pressure • Too much focus on air pressure differences • Not enough focus on amount of water, gravity laps, and drainage paths CauAonary Tale • Tall, sloped walls • Cladding acted like open joint, looked closed Tested and passed ASTM 508-14 PER standard.. VerAcally.
- 39. 17-06-13 39 Air Control Air Barriers Air Control: Air Barrier Systems • Support – structure is anything that works • Control con*nuity – Rain control layer • Perfect barrier • Drained with gap • Storage – Air control layer • Air barrier – Thermal control layer • Aka insulaAon, radiant barriers – Vapor control layer • Retarders, barriers, etc • Finish – interior and exterior 78 Fire Control may be needed Sound Control opAonal
- 40. 17-06-13 40 Driving Forces Ref. Straube and Burne1. Building Science for Building Enclosures. Exterior Air Barriers • Many more penetraAons and details with interior air barrier approach (old Canadian, modern PassiveHouse) • Exterior is preferred today.. 80 <john@buildingsciencelabs.com> <john@buildingsciencelabs.com>
- 42. 17-06-13 42 ABS ConAnuity is Key 83 *Structural and mechanical penetrations must be addressed. *Also address interior service and mechanical penetrations (lighting, electrical, etc.) Interior Air Barrier Approach Exterior Air Barrier Approach Interior connection to air barrier at ceiling/attic floor Complex transition at floors and interior walls Connection to below-grade air barrier components Parapet / Low-slope roof all exterior connection No interruption at floors and interior walls Connection to below-grade air barrier components Accessories Materials Components BRAND BRAND Air Barrier Whole Building AirBghtness
- 44. 17-06-13 44 Fully-adhered is preferred • Most of the damage, with none of the airleakage 87 negative pressure gust positve pressure gust housewrap balloons outwards air flows from interior into stud space housewrap pressed tight to sheathing air flows out of stud space to interior PAGE 10 Fully-adhered preferred •
- 45. 17-06-13 45 BTW
- 48. 17-06-13 48 How to control heat flow • InsulaAon – Thickness – ConAnuous! • AirAghtness – Air barrier systems – ConAnuous! • Solar control – Shading, window coaAngs, lower window area Choices: InsulaAon Materials • Materials Examples Moisture Fire Vapor Permeance Air Permeance Mineral fiber Fiberglass, stone, slag Tolerant Non- combusAble high high Organic Fiber Cellulose, co1on, wool, straw SensiAve CombusAble high high PlasBc foam Polystyrene, polyurethane, polyisocyanurate Tolerant CombusAble Low-medium low Mineral foam Foamglass, pumice, airkrete, aerogel Tolerant Non- combusAble low low
- 49. 17-06-13 49 Choices: Form of InsulaAon Form InstallaBon Limits to use Loose poured or blown may se1le, easily compressed Bad fricAon fit held in place by fricAon, easily compressed Roll fricAon fit / mechanically a1ached as for ba1s Board mechanically, adhesively a1ached resistant to mechanical pressure Spray spray in place sAcks to adjoining surfaces, resilient
- 52. 17-06-13 52 Thermal control • ASHRAE 90.1... requires studs to be accounted for • Steel studs and floor slabs are thermal bridges Building Science 2008 InsulaAon and Thermal Bridges No. 104/65 Find the thermal bridge
- 53. 17-06-13 53 Trends - MeeBng Energy Code Wall R-value Targets with Exterior InsulaBon or 2x8 Studs • PrescripAve effecAve R-value targets in many areas bumped to R-20 range (from ~R-16 in previous codes): – 2x8 framing (w/ R-28+ ba1s) • Limited if cavity full of framing, services and Ae- downs etc. – 2x6 with 1-1.5” (R-4+) of exterior insulaAon ~R-16 ~R-20 ~R-20+ • DisconAnuous thermal and air barrier Building Science Enclosures No. 106 / Tolerable because: -We use vapor permeable water barrier -wood is not a horrible thermal bridge -put a lot of inspecAon and worker effort into air sealing But performance far from opAmal
- 58. 17-06-13 58 Interior InsulaBon Floors, roofs, slabs cause penetraBons 1. Intermediate Floors 2. Baconies, ProjecBons, Shades 3. Parapets 4. Window and Door perimeter 5. Internal Walls to External Walls 6. At Grade Hard / impossible to get conBnuous Exterior InsulaBon 1. Cladding adachments 2. Windows and doors 3. Balconies and canopies Much easier to get conBnuous
- 59. 17-06-13 59 Challenges for c.i. • Limits insulaAon choice – Can’t use natural fibers as insulaAon • Moisture tolerance! – Needs to be self-supporAng/semi-rigid – Fire performance needs to be designed • Can use foam plasAc but requires care • Cladding aLachment • Window / door alignment ASHRAE 90.1 “Clear Wall” best case R-11 3.5in R-13 3.5in R-19 6in R-21 6in R-11 3.5in R-15 3.5in R-19 6in R-21 6in ClearWall 5.5 6.0 7.1 7.4 8.4 10.0 12.9 13.8 Nominal 11 13 19 21 11 15 19 21 0 5 10 15 20 25 R-value ClearWall Nominal Steel Studs Wood Studs Wood Studs Simple framing
- 60. 17-06-13 60 ASHRAE 90.1 “Clear Wall” best case Building Science InsulaAon and Thermal Bridges No. 119/65 R-11 3.5in R-13 3.5in R-19 6in R-21 6in R-11 3.5in R-15 3.5in R-19 6in R-21 6in ClearWall 5.5 6.0 7.1 7.4 8.4 10.0 12.9 13.8 Nominal 11 13 19 21 11 15 19 21 0 5 10 15 20 25 R-value ClearWall Nominal Steel Studs Wood Studs Impact of InsulaAng Sheathing From : Bombino and Burnett , Pennsylvania Housing Research Center 15 R-value (ft2.o F. hr/BTU) 10 5 0 Exterior Insulating Sheathing R -value (ft 2.o F. hr/BTU) 12 .1 30 Rcc Ravg (steel framming ) 20 25 55% 6.6 68% 9.9 14.6 17 .1 74% 12 .6 19.6 78 % 15 .3 22.1 81% 17 .8 24 .6 83% 20.4 27.1 85% 22 .9 0.0 2.5 5.0 7.5 10.0 12.5 15.0 steel stud wall stud spacing stud depth interior sheathing insulating sheathing exterior sheathing Buy R5 Get R6 Buy R10 Get R12.2
- 66. 17-06-13 66 Orchards Passive House, Portland Prefabricated Modular Passive House w/ 6” Comfortboard
- 70. 17-06-13 70 Light-weight claddings Building Science.com Enclosures No. 139 / Many Cladding Adachment OpBons Ver*cal Z-girts Horizontal Z-girts Crossing Z-girts Galvanized/Stainless Clip & Rail Aluminum Clip & Rail Long Screws through Insula*on Non-Conduc*ve Clip & Rail Thermally Improved Clip & Rail