moving towards more energy efficient wood frame building enclosures

Implica(ons of the New NBC Sec(on 9.36

Moving Towards More Energy Efficient Wood-‐Frame Building Enclosures

!   Graham Finch, MASc, P.Eng Principal, Building Science Research Engineer RDH Building Engineering Ltd. Vancouver, BC

RCIC 2013 Edmonton – April 30, 2013

Presenta<on Outline

!   New Building Enclosure Energy Efficiency Requirements Under New 2012 NBC Sec(on 9.36

!   Highly Insulated Wood-‐frame Enclosure Assemblies

!   Building Enclosure Design Guide for Highly-‐Insulated Wood-‐frame Buildings

!   New Sec(on 9.36 -‐ Whole Building Energy Efficiency Requirements for Part 9 houses

!   Reference to NECB 2011 for other buildings (Part 3)

!   Building Enclosure (Envelope), HVAC, Hot-‐Water Components

!   Prescrip(ve, Trade-‐off and Energy Modeling Paths for Compliance

!   Effec(ve R-‐values vs Nominal R-‐values

New NBC Sec<on 9.36 Energy Efficiency Requirements

2010 NBC Updated in December 2012 – New Sec8on 9.36. Energy Efficiency

!   Nominal R-‐values = Rated R-‐values of insula(on which do not include impacts of how they are installed !   For example R-‐20 ba\ insula(on or

R-‐10 foam insula(on !   Effec(ve R-‐values or Real R-‐values =

Calculated R-‐values of assemblies/details which include impacts of installa(on and thermal bridges !   For example nominal R-‐20 ba\s

within steel studs 16” o.c. becoming ~R-‐9 effec(ve, or in wood studs ~R-‐15

Nominal vs Effec<ve R-‐values

!   Thermal bridging occurs when a conduc(ve material (e.g. aluminum, steel, concrete, wood etc.) provides a path for heat to flow around insula(on

!   The bypassing “bridging” of the less conduc(ve material significantly reduces its effec(veness as an insulator

!   Examples: !   Wood framing (studs, plates) in insulated wall !   Steel framing in insulated wall !   Conduc(ve cladding a\achments through insula(on

(metal girts, clips, anchors, screws etc) !   Concrete slab edge (balcony, exposed slab edge)

through a wall !   Window frames and windows themselves

Thermal Bridging

!   Effec(ve R-‐values account for thermal bridges and represent actual heat flow through enclosure assemblies and details !   Heat flow finds the path of least resistance !   Dispropor(onate amount of heat flow

occurs through thermal bridges !   Ofen adding more/thicker insula(on can’t

help !   Required for almost all energy and building

code calcula(ons !   Energy code compliance has historically

focused on assembly R-‐values – however more importance is being placed on details and interfaces & thermal bridges

!   Air(ghtness also as important

Why Thermal Bridging is Important

!   Increased emphasis on con(nuous insula(on, higher effec(ve R-‐values

!  Minimum R-‐value Tables for Above & Below Grade Enclosures (Walls, Roofs, Floors) – dependent on whether HRV present in house (minor tradeoff allowance)

!  Maximum U-‐value (minimum R-‐value) & Minimum Energy Ra(ng (ER) Tables for Windows, Doors, Skylights

!   Prescrip(ve air(ghtness requirements (no blower door yet) !   HVAC duct sealing/insula(on, minimum equipment

efficiency !   Domes(c Hot Water, minimum equipment efficiency !   Energy modeling op(on & Trade-‐off op(ons

New NBC Sec<on 9.36 Energy Efficiency Requirements

New NBC/NECB Climate Zone Divisions

•  >7000 HDD

•  6000 to 6999 HDD

•  5000 to 5999 HDD

•  4000 to 4999 HDD

•  3000 to 3999 HDD

•  < 3000 HDD

Wall, Roof & Window Requirements for Alberta (NBC 9.36)

Climate Zone

Wall -‐ Above Grade: Minimum R-‐value (IP)

Roof – Flat/Cathedral: Minimum R-‐value (IP)

Roof – AXc: Minimum R-‐value (IP)

Window: Max. U-‐value (IP) / Min. ER

8 21.9 28.5 59.2 0.25 / 29

7B 21.9 28.5 59.2 0.25 / 29

7A 17.5 28.5 59.2 0.28 / 25

6 17.5 26.5 49.2 0.28 / 25

With

out a

HRV

Climate Zone

Wall -‐ Above Grade: Minimum R-‐value (IP)

Roof – Flat/Cathedral: Minimum R-‐value (IP)

Roof – AXc: Minimum R-‐value (IP)

Window: Max. U-‐value (IP) / Min. ER

8 17.5 28.5 59.2 0.25 / 29

7B 17.5 28.5 59.2 0.25 / 29

7A 16.9 28.5 49.2 0.28 / 25

6 16.9 26.5 49.2 0.28 / 25

With

a HRV

Wall, Roof & Windows (NECB 2011/ASHRAE 90.1-‐2010)

Climate Zone

Wall – Above Grade: Minimum R-‐value (IP)

Roof – Flat or Sloped: Minimum R-‐value (IP)

Window: Max. U-‐value (IP)

8 31.0 40.0 0.28

7B 27.0 35.0 0.39

7A 27.0 35.0 0.39

6 23.0 31.0 0.39

NEC

B 2011

ASHR

AE 90.1-‐2010 –

Reside

n<al Building Climate

Zone Wall (Mass, Wood, Steel): Min R-‐value

Roof (AXc, Cathedral/Flat): Min R-‐value

Window (Alum, PVC/fiberglass): Max. U-‐value

8 19.2, 27.8, 27.0 47.6, 20.8 0.45, 0.35

7B 14.1, 19.6, 23.8 37.0, 20.8 0.45, 0.35

7A 14.1, 19.6, 23.8 37.0, 20.8 0.45, 0.35

6 12.5, 19.6, 15.6 37.0, 20.8 0.55, 0.35

*7A/7B combined in ASHRAE 90.1

!   Some guidance (Table A-‐9.36.2.6.(1)A provided for calcula(on of effec(ve R-‐values of some assemblies (to help transi(on from nominal R-‐values)

!   Sufficient for most wood-‐frame /ICF wall assemblies

!   No provisions for cladding a\achment/ thermal bridging

Guidance: Effec<ve R-‐values within NBC 9.36

Wall Assembly / Insula<on Rated R-‐value

Effec<ve Wall R-‐value **

Studs at 16”, 25% F.F.*

Studs at 24”, 22% F.F.*

2x4 w/ R-‐12 baes 10.7 -‐

2x4 w/ R-‐14 baes 11.5 -‐

2x6 w/ R-‐19 baes 15.5 16.1

2x6 w/ R-‐22 baes 16.6 17.4

2x6 w/ 2pcf sprayfoam (R-‐5/in, R-‐27.5)

18.3 19.3

2x6 w/ 2pcf sprayfoam (R-‐6/in, R-‐33)

18.6 19.8

*Studs at 16” o.c.=25% total Framing Factor (F.F.) and Studs at 24” o.c. =22% total framing factor. This includes typical framing arrangements of studs, sill and top plates, window headers, corners, built-up studs etc. ** All values calculated using three-dimensional thermal modeling calibrated to hot-box testing

Typical Wood-‐frame Wall Assemblies – Effec<ve R-‐values

!   Effec(ve R-‐value targets above ~R-‐17 essen(ally means that standard prac(ce of ba\ insula(on in 2x6 stud frame wall is inadequate

!   Shifs code minimum baseline wall assembly to: !   Insulated/Foam Sheathing !   Sprayfoam? !   Exterior/Split Rigid Insula(on !  Double/Deep Stud !   Structurally Insulated Panels (SIPs) !   Insulated Concrete Forms (ICFs)

Beyond 2x6 Framed Walls

Insula<on Placement & Wall Design Considera<ons

Interior Insula(on

Exterior Insula(on

Split Insula(on

GeXng to Higher R-‐values – Insula<on Placement

Baseline 2x6 w/ R-‐22 ba\s = R-‐16 effec<ve

Exterior Insula(on – R-‐20 to R-‐40+ effec<ve •  Constraints: cladding a\achment, wall thickness •  Good for wood/steel/concrete

Deep/Double Stud– R-‐20 to R-‐40+ effec<ve •  Constraints wall

thickness •  Good for wood,

wasted for steel

Split Insula(on– R-‐20 to R-‐40+ effec<ve •  Constraints: cladding

a\achment •  Good for wood, palatable for

steel

!   Insula(on outboard of structure and control layers (air/vapor/water) !   Thermal mass at interior where useful !   Excellent performance in all climate zones !   Cladding A\achment biggest source of thermal loss/bridging !   Not the panacea, can s(ll mess it up

Exterior Insulated Walls

Steel Stud Concrete Heavy Timber (CLT)

!   Key Considera(ons: !   Cladding A\achment !  Wall Thickness

!   Heat Control: Exterior Insula(on

!   Air Control: Membrane on exterior of structure

!   Vapor Control: Membrane on exterior of structure

!  Water Control: Membrane on exterior of structure (possibly surface of insula(on)

Exterior Insula<on Assemblies

!  Many Possible Strategies – Wide Range of Performance

Cladding Aeachment through Exterior Insula<on

Minimizing Thermal Bridging through Exterior Insula<on

Longer cladding Fasteners directly through rigid insulation (up to 2” for light claddings)

Long screws through vertical strapping and rigid insulation creates truss (8”+) – short cladding fasteners into vertical strapping Rigid shear block type connection

through insulation, cladding to vertical strapping

Key Considera<ons -‐ Split Insula<on Assemblies

!   Key Considera(ons: !   Exterior insula(on type !   Cladding a\achment !   Sequencing & detailing

!   Heat Control: Exterior and stud space Insula(on

!   Air Control: House-‐wrap adhered/sheet/liquid membrane on sheathing, sealants/tapes etc. Ofen vapor permeable

!   Vapor Control: Poly or VB paint at interior, plywood/OSB sheathing

!  Water Control: Rainscreen cladding*, WRB membrane, surface of insula(on

Split Insula<on Assemblies – Exterior Insula<on Selec<on

!   Foam insula(ons (XPS, EPS, Polyiso, ccSPF) are vapor impermeable !   Is the vapor barrier on the wrong side? !  Does your wall have two vapor barriers? !  How much insula(on should be put outside

of the sheathing? – More the be\er, but room? !   Rigid mineral or glass fiber insula(on are

vapor permeable which can address these concerns

!   Vapor permeability of WRB and air-‐barrier also important !   Risk is dependant on interior condi(ons (RH) and poten(al for

air-‐leakage, and on exterior condi(ons (rain/RH) and poten(al for water leaks

!   Double 2x4/2x6 stud, Single Deep 2x10, 2x10, I-‐Joist etc… !   Common wood-‐frame wall assembly in many passive houses !   Lends itself well to pre-‐fabricated wall/roof assemblies !   Interior service wall – greater control over interior air(ghtness !   Higher risk for damage if sheathing gets wet (rainwater, air leakage,

vapor diffusion)

Double/Deep Stud Insulated

Key Considera<ons – Double Stud/Deep Stud

!   Key Considera(ons: !   Air-‐sealing !   Rainwater management/detailing

!   Heat Control: Double stud cavity fill insula(on(s)

!   Air Control: House-‐wrap/membrane on sheathing, poly, air(ght drywall on interior, OSB/plywood at interior, tapes, sealants, sprayfoam. Air(ghtness on both sides of cavity recommended

!   Vapor Control: Poly, VB paint or OSB/plywood at interior

!  Water Control: Rainscreen cladding*, WRB at house-‐wrap/membrane, flashings etc.

!   Energy-‐Efficient Building Enclosure Design Guide for Wood-‐frame Mul(-‐Unit Residen(al Buildings in Marine to Cold Climates

!   Builds off of Previous Building Enclosure Design Guides & CMHC Best Prac(ce Guides

!   Focus on durable and highly insulated wood-‐frame assemblies to meet current and upcoming energy codes

!   Guidance for taller and alternate wood-‐frame structures (ie post & beam, CLT) up to 6 stories

Building Enclosure Design Guidance

!   Chapter 1: Introduc(on !  Context

!   Chapter 2: Building and Energy Codes across North America !  Canadian Building and Energy

Code Summaries & R-‐value requirements

!  US Building and Energy Code Summaries & R-‐value requirements

!  Performance Ra(ng Systems & Green Building Programs

What is in the Guide?

!   Chapter 3: Moisture, Air and Thermal Control !  Building as a System !  Climate Zones !   Interior Climate, HVAC Interac(on !  Cri(cal Barriers !  Control of Rainwater Penetra(on !  Control of Air Flow !  Controlling Condensa(on !  Construc(on Moisture !  Controlling Heat Flow and Insula(on !  Whole Building Energy Efficiency !  Computer Simula(on Considera(ons for Wood-‐frame Enclosures


!   Chapter 4: Energy Efficient Wall and Roof Assemblies !  Above Grade Wall Assemblies

•  Split Insulated, Double Stud/Deep Stud, Exterior Insulated •  Infill Walls for Concrete Frame

!  Below Grade Wall Assemblies •  Interior and Exterior Insulated

!  Roof Assemblies •  Steep Slope & Low Slope

!   Chapter 5: Detailing !  2D CAD (colored) and 3D build-‐sequences for various typical

enclosure details

!   Chapter 6: Further Reading & References


!   Air Barrier Systems (Fundamentals, Materials, Performance, tes(ng) !   Sealed Poly/Sheet Membranes !   Air(ght drywall ! Sprayfoam !   Sealed-‐Sheathing Approaches

›  Unsupported sheet membranes ›  Supported sheet membranes with

ver(cal strapping ›  Sandwiched membranes behind

exterior insula(on ›  Self-‐Adhered and liquid applied

membranes

Air Flow Control – Air Barrier Strategies

!   Control of Heat Flow !  Minimizing Conduc(ve

Losses, Minimizing Air Leakage

!  Placement of Insula(on within assemblies

!  Wood framing factors !   Types of insula(on,

R-‐values and typical uses !   Thermal bridging and

effec(ve R-‐values

Heat Flow Control & Insula<on

!  Material selec(on & guidance

!   Control Func(ons !   Cri(cal Barriers !   Effec(ve R-‐value Tables

Energy Efficient Walls – Split Insulated

Wood framing

Nominal stud-‐space insulation [R-‐value (RSI)]

Exterior insulation

None [R-‐value (RSI)]

R-‐4 (1 inch) [R-‐value (RSI)]

R-‐8 (2 inches) [R-‐value (RSI)]





2x4 R-‐12 (2.1)

10.7 (1.9)

15.0 (2.6)

18.8 (3.3)

22.5 (4.0)

26.2 (4.6)

29.7 (5.2)

33.2 (5.8)

R-‐14 (2.5)

11.5 (2.0)

15.8 (2.8)

19.6 (3.4)

23.2 (4.1)

27.0 (4.8)

30.5 (5.4)

34.0 (6.0)

2x6 R-‐19 (3.3)

15.5 (2.7)

19.8 (3.5)

23.7 (4.2)

27.3 (4.8)

31.0 (5.5)

34.5 (6.1)

38.0 (6.7)

R-‐22 (3.9)

16.6 (2.9)

21.0 (3.7)

24.8 (4.4)

28.5 (5.0)

32.2 (5.7)

35.7 (6.3)

39.2 (6.9)

!  Material selec(on & guidance

!   Control Func(ons !   Cri(cal Barriers !   Effec(ve R-‐value Tables

Energy Efficient Walls – Double Stud/Deep Stud

Wood framing

Nominal fill insulation [R-‐value/inch (RSI/cm)]

Gap width between stud walls No gap [R-‐value (RSI)]

1-‐inch [R-‐value (RSI)]

2-‐inches [R-‐value (RSI)]





Double-‐stud 2x4

R-‐3.4/inch (0.24/cm)

19.1 (3.4)

22.9 (4.0)

26.5 (4.7)

30.0 (5.3)

33.4 (5.9)

36.9 (6.5)

40.3 (7.1)

R-‐4.0/inch (0.28/cm)

20.5 (3.6)

25.1 (4.4)

29.4 (5.2)

33.4 (5.9)

37.4 (6.6)

41.5 (7.3)

45.4 (8.0)

Pitched-‐Roof, Exterior Insulated Assembly

!  Materials & Control Func(ons

!   Cri(cal Barriers !   Effec(ve R-‐values

Low-‐Slope Conven<onal Roof Assembly

!  Materials & Control Func(ons

!   Cri(cal Barriers !   Effec(ve R-‐values

(Accoun(ng for tapered insula(on packages)

!   2D CAD details (colored) provided for typical details for each wall assembly type (split insulated, double stud, exterior insulated) plus some for infill walls

!   3D sequence details provided for window interfacing (split insulated, double stud, exterior insulated)

Detailing

Detailing – Colored 2D Details

Detailing – Wall to Roof Interfaces

Detailing – 2D Window Details

Detailing – 3D Window Installa<on Sequences

!   Graham Finch, MASc, P.Eng [email protected] 604-‐873-‐1181

!   Building Enclosure Design Guide Available from FP Innova(ons: h\p://www.fpinnova(ons.ca/ResearchProgram/AdvancedBuildingSystem/designing-‐energy-‐efficient-‐building-‐enclosures.pdf

Discussion