The science-behind-better-building-enclosures-chicago
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ROXUL® Building Science, Dörken Systems and RDH Building Science Laboratories’ John Straube discussed and shared in resolving common problems related to building design and construction. This full day 5 CONTINUING EDUCATION LEARNING UNITS seminar covered: Key building science principles Critical design strategies for improved energy efficiency, Examples of best practice details and specifications, Emerging issues and trends.
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The science-behind-better-building-enclosures-chicago
- 1. 17-10-03 1 Presenter: Dr John Straube P.Eng. Principal, RDH Building Science Assoc. Professor, University of Waterloo The Science Behind Be0er Building Enclosures Energy Design Centre Energy Design Centre Energy Design Centre Rough Outline • Review of Basics • Control func@ons / layers /barriers – Rain – Air – Heat • Issues & Trends… throughout – Look forward to future needs/demands • Best prac@ses and case studies
- 2. 17-10-03 2 Basics of Enclosure Design Performance? • More than on-@me, on-budget, to code – Safe – Healthy – Comfortable • A growing clamor for…. – Durable – Low-energy – Maintainable – Faster Design/ Construcion – All weather construc@on • All delivered “affordably”, reliably, predictably
- 3. 17-10-03 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. 17-10-03 4 Building Components • Func@on 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 consump@on – 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. 17-10-03 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. • Some@mes, interior par@@on also are environmental separators (pools, rinks, etc.) Enclosures No. 9 / Building Enclosure Components Enclosures No. 10 /
- 6. 17-10-03 6 Enclosure Loadings • The separa@on func@on generates loads • Load: any event, phenomenon or characteris@c 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. Sea0le ≠ Sacramento Miami ≠ Minneapolis Edmonton ≠ Vancouver
- 8. 17-10-03 8 Climate Zones Enclosures No. 15 / Climate Load Modifica@on • Building & Site (overhangs, trees…) – Creates microclimate • Building Enclosure (walls, windows, roof…) – Separates climates – Passive modifica@on • Building Environmental Systems (HVAC…) – Ac@ve modifica@on – Use energy to change indoor weather Building Science Enclosures No. 16 /
- 9. 17-10-03 9 Basic Func@ons 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 • Distribu@on – a building func@on Functional Layers Basic Enclosure Func@ons • 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. 17-10-03 10 Basic Enclosure Func@ons • 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 – Con@nuous air barrier • Heat – Con@nuous layer of insula@on • Vapor – Balance of wepng/drying • Finish – Interior and exterior surfaces for people Functional Layers Other Control Func@ons . . . • Support • Control – Fire • PenetraBon • PropagaBon – Sound • PenetraBon • ReflecBon – Light • Diffuse/glare • View • Finish Functional Layers
- 11. 17-10-03 11 History of Control FuncBons • Older Buildings – One layer does everything • Newer Building – Separate layers, . . . separate func@ons Basic Enclosure Func@ons • Support – Resist & transfer physical forces from inside and out • Control – Control mass and energy flows • Finish – Interior & exterior surfaces for people • Color, speculance • Pa0ern, texture Functional Layers
- 12. 17-10-03 12 Building Science Enclosures No. 23 / Finish vs. Control Confusion What is a high performance enclosure? • High levels of control • But, poor con@nuity limits performance • & Poor con@nuity causes most problems too: – E.g. air leakage condensa@on – Rain leakage – Surface condensa@on – Cold windows • Thus: con*nuity + high levels of control
- 13. 17-10-03 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. 17-10-03 14 27 1. Air / Rain Barrier 2. Structural Support 3. Rain Shedding 4. Insula@on Design Information older than I am.
- 15. 17-10-03 15 The world is complex enough Choose to make it simpler PAGE 6 The “Perfect Wall” • Finish of whatever • Control con@nuity 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 insula@on, radiant barriers – Vapor control layer • Retarders, barriers, etc • Structure can be anything 30 Addi@onal Fire Control may be needed Addi@onal Sound Control op@onal
- 21. 17-10-03 21 Window Building Science Enclosures No. 42 / Building Science 2008 Enclosures No. 43 /
- 25. 17-10-03 25 Rain Control Water Control Layers WRB / Drainage Plane, etc. Approach • If it does not get wet, it wont leak – Exposure, deflec@on • 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, ven@la@on, vapor permeance, – Moisture tolerant materials
- 29. 17-10-03 29 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 What is a Rainscreen • Drained? • Vented? • Do we need a ½”mm? 1” gap? • Do cladding joints need to be sealed
- 30. 17-10-03 30 60 “Rainscreen?” or “Drained” System • Rain shedding • Drainage gap • Water control layer • Must integrate with flashing, drainholes • Overlap everything • No holes Flashing must be waterproof Building Science 2008 – Rain Control 61
- 31. 17-10-03 31 Building Science .com Sub-sill flashing Self-adhered membrane Formable self-adhered membrane Liquid applied membrane Pre-formed flashing system
- 32. 17-10-03 32 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 Building Science Windows and Curtainwalls No. 6580 Window Air-Vapor & Water Control Air & Water Control Vapor Permeable!
- 33. 17-10-03 33 Window Corners 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
- 37. 17-10-03 37 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 insula@on, radiant barriers – Vapor control layer • Retarders, barriers, etc • Finish – interior and exterior 78 Fire Control may be needed Sound Control op@onal Driving Forces Ref. Straube and Burne0. Building Science for Building Enclosures.
- 39. 17-10-03 39 Exterior Air Barriers • Exterior air barriers are o`en water barriers – Water control must remain the primary focus • Exterior Air barrier o`en must bevapor permeable air barrier – Put most or all of the insula@on outboard – Energy c.i. values are not enough R- outboard ABS Con@nuity 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
- 41. 17-10-03 41 Fully-adhered membrane • 86 Fully-adhered is preferred • Most of the damage, with none of the air leakage 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
- 45. 17-10-03 45 Heat Flow • Why control flow of heat – Comfort! – Condensa@on control – Opera@onal energy savings – Meet code How to control heat flow • Insula@on – Thickness – Con@nuous! • Air@ghtness – Air barrier systems – Con@nuous! • Solar control – Shading, window coa@ngs, lower window area
- 46. 17-10-03 46 Choices: Insula@on Materials • Materials Examples Moisture Fire Vapor Permeance Air Permeance Mineral fiber Fiberglass, stone, slag Tolerant Non- combus@ble high high Organic Fiber Cellulose, co0on, wool, straw Sensi@ve Combus@ble high high PlasBc foam Polystyrene, polyurethane, polyisocyanurate Tolerant Combus@ble Low-medium low Mineral foam Foamglass, pumice, airkrete, aerogel Tolerant Non- combus@ble low low Choices: Forms of Insula@on Form InstallaBon Limits to use Loose poured or blown may se0le, easily compressed Bac fric@on fit held in place by fric@on, easily compressed Roll fric@on fit / mechanically a0ached as for ba0s Board mechanically, adhesively a0ached resistant to mechanical pressure Spray spray in place s@cks to adjoining surfaces, resilient
- 49. 17-10-03 49 Thermal Bridging Thermal control • ASHRAE 90.1... requires studs to be accounted for • Steel studs and floor slabs are thermal bridges
- 50. 17-10-03 50 Building Science 2008 Insula@on and Thermal Bridges No. 104/65 Find the thermal bridge Trends - MeeBng Energy Code Wall R-value Targets with Exterior InsulaBon or 2x8 Studs • Prescrip@ve effec@ve R-value targets in many areas bumped to R-20 range (from ~R-16 in previous codes): – 2x8 framing (w/ R-28+ ba0s) • Limited if cavity full of framing, services and @e- downs etc. – 2x6 with 1-1.5” (R-4+) of exterior insula@on ~R-16 ~R-20 ~R-20+
- 51. 17-10-03 51 • Discon@nuous 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 inspec@on and worker effort into air sealing But performance far from op@mal Energy Code Challenges with Mid-rise Wood-frame Buildings • Mid-rise wood-frame buildings will typically have less room for stud space insula@on (studs, @e- downs, services etc.) – Creates challenges to mee@ng prescrip@ve R- value requirements without exterior insula@on
- 53. 17-10-03 53 Building Science Insula@on and Thermal Bridges No. 110/65 Find the thermal bridge Thermal Bridging Building Science 2008 Hot • Steel is 400 Bmes more conducBve than wood • Steel studs are about 40 Bmes thinner Bac Cold R=4+ R<0.3 3.5” wall
- 55. 17-10-03 55 Thermal Bridges • Balconies, etc • Exposed slab edges 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
- 56. 17-10-03 56 Exterior InsulaBon 1. Cladding acachments 2. Windows and doors 3. Balconies and canopies Much easier to get conBnuous Challenges for c.i. • Limits insula@on choice – Can’t use natural fibers as insula@on • Moisture tolerance! – Needs to be self-suppor@ng/semi-rigid – Fire performance needs to be designed • Can use foam plas@c but requires care • Cladding aLachment • Window / door alignment
- 57. 17-10-03 57 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 ASHRAE 90.1 “Clear Wall” best case Building Science Insula@on 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
- 58. 17-10-03 58 Impact of Insula@ng 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 Allows fast drying in both direc@ons
- 61. 17-10-03 61 Building Science 2008 Enclosures No. 126 / Building Science 2008 Enclosures No. 127 /
- 67. 17-10-03 67 Many Cladding Acachment 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 More info • Available on-line Google “RDH TB-11”