Implications of the New NBC Section 9.36

Moving Towards More Energy Efficient Wood-Frame Building Enclosures

Graham Finch, MASc, P.EngPrincipal, Building Science Research Engineer RDH Building Engineering Ltd.Vancouver, BC

RCIC 2013 Edmonton – April 30, 2013

Presentation Outline

New Building Enclosure Energy Efficiency Requirements Under New 2012 NBC Section 9.36

Highly Insulated Wood-frame Enclosure Assemblies

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

New Section 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

Prescriptive, Trade-off and Energy Modeling Paths for Compliance

Effective R-values vs Nominal R-values

New NBC Section 9.36 Energy Efficiency Requirements

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

Nominal R-values = Rated R-values of insulation which do not include impacts of how they are installed

For example R-20 batt insulation or R-10 foam insulation

Effective R-values or Real R-values = Calculated R-values of assemblies/details which include impacts of installation and thermal bridges

For example nominal R-20 batts within steel studs 16” o.c. becoming ~R-9 effective, or in wood studs ~R-15

Nominal vs Effective R-values

Thermal bridging occurs when a conductive material (e.g. aluminum, steel, concrete, wood etc.) provides a path for heat to flow around insulation

The bypassing “bridging” of the less conductive material significantly reduces its effectiveness as an insulator

Examples:

Wood framing (studs, plates) in insulated wall

Steel framing in insulated wall

Conductive cladding attachments through insulation (metal girts, clips, anchors, screws etc)

Concrete slab edge (balcony, exposed slab edge) through a wall

Window frames and windows themselves

Thermal Bridging

Effective R-values account for thermal bridges and represent actual heat flow through enclosure assemblies and details

Heat flow finds the path of least resistance

Disproportionate amount of heat flow occurs through thermal bridges

Often adding more/thicker insulation can’t help

Required for almost all energy and building code calculations

Energy code compliance has historically focused on assembly R-values – however more importance is being placed on details and interfaces & thermal bridges

Airtightness also as important

Why Thermal Bridging is Important

Increased emphasis on continuous insulation, higher effective 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 Rating (ER) Tables for Windows, Doors, Skylights

Prescriptive airtightness requirements (no blower door yet)

HVAC duct sealing/insulation, minimum equipment efficiency

Domestic Hot Water, minimum equipment efficiency

Energy modeling option & Trade-off options

New NBC Section 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)

ClimateZone

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

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

Roof –Attic: 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

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ClimateZone

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

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

Roof –Attic: 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

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HR

V

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

ClimateZone

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

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ing Climate

ZoneWall (Mass, Wood, Steel): Min R-value

Roof (Attic,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 calculation of effective R-values of some assemblies (to help transition from nominal R-values)

Sufficient for most wood-frame /ICF wall assemblies

No provisions for cladding attachment/ thermal bridging

Guidance: Effective R-values within NBC 9.36

Wall Assembly /Insulation Rated R-value

Effective Wall R-value **

Studs at 16”, 25% F.F.*

Studs at 24”, 22% F.F.*

2x4 w/ R-12 batts 10.7 -

2x4 w/ R-14 batts 11.5 -

2x6 w/ R-19 batts 15.5 16.1

2x6 w/ R-22 batts 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 – Effective R-values

Effective R-value targets above ~R-17 essentially means that standard practice of batt insulation in 2x6 stud frame wall is inadequate

Shifts code minimum baseline wall assembly to:

Insulated/Foam Sheathing

Sprayfoam?

Exterior/Split Rigid Insulation

Double/Deep Stud

Structurally Insulated Panels (SIPs)

Insulated Concrete Forms (ICFs)

Beyond 2x6 Framed Walls

Insulation Placement & Wall Design Considerations

Interior Insulation

Exterior Insulation

Split Insulation

Getting to Higher R-values – Insulation Placement

Baseline2x6 w/ R-22 batts = R-16effective

Exterior Insulation – R-20 to R-40+ effective• Constraints: cladding attachment, wall thickness• Good for wood/steel/concrete

Deep/Double Stud– R-20 to R-40+ effective• Constraints wall

thickness• Good for wood,

wasted for steel

Split Insulation–R-20 to R-40+ effective• Constraints: cladding

attachment• Good for wood, palatable for

steel

Insulation outboard of structure and control layers (air/vapor/water)

Thermal mass at interior where useful

Excellent performance in all climate zones

Cladding Attachment biggest source of thermal loss/bridging

Not the panacea, can still mess it up

Exterior Insulated Walls

Steel Stud Concrete Heavy Timber (CLT)

Key Considerations:Cladding Attachment

Wall Thickness

Heat Control: Exterior

Insulation

Air Control: Membrane on

exterior of structure

Vapor Control: Membrane on

exterior of structure

Water Control: Membrane on

exterior of structure (possibly surface of insulation)

Exterior Insulation Assemblies

Many Possible Strategies – Wide Range of Performance

Cladding Attachment through Exterior Insulation

Minimizing Thermal Bridging through Exterior Insulation

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 Considerations - Split Insulation Assemblies

Key Considerations:Exterior insulation type

Cladding attachment

Sequencing & detailing

Heat Control: Exterior and stud space

Insulation

Air Control: House-wrap

adhered/sheet/liquid membrane on sheathing, sealants/tapes etc. Often vapor permeable

Vapor Control: Poly or VB paint at

interior, plywood/OSB sheathing

Water Control: Rainscreen cladding*,

WRB membrane, surface of insulation

Split Insulation Assemblies – Exterior Insulation Selection

Foam insulations (XPS, EPS, Polyiso, ccSPF) are vapor impermeable

Is the vapor barrier on the wrong side?

Does your wall have two vapor barriers?

How much insulation should be put outside of the sheathing? – More the better, but room?

Rigid mineral or glass fiber insulation are vapor permeable which can address these concerns

Vapor permeability of WRB and air-barrier also important

Risk is dependant on interior conditions (RH) and potential for air-leakage, and on exterior conditions (rain/RH) and potential 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 airtightness

Higher risk for damage if sheathing gets wet (rainwater, air leakage, vapor diffusion)

Double/Deep Stud Insulated

Key Considerations – Double Stud/Deep Stud

Key Considerations:Air-sealing

Rainwater management/detailing

Heat Control: Double stud cavity fill

insulation(s)

Air Control: House-wrap/membrane on

sheathing, poly, airtight drywall on interior, OSB/plywood at interior, tapes, sealants, sprayfoam. Airtightness 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 Multi-Unit Residential Buildings in Marine to Cold Climates

Builds off of Previous Building Enclosure Design Guides & CMHC Best Practice 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: Introduction

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 Rating 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 Interaction

Critical Barriers

Control of Rainwater Penetration

Control of Air Flow

Controlling Condensation

Construction Moisture

Controlling Heat Flow and Insulation

Whole Building Energy Efficiency

Computer Simulation Considerations for Wood-frame Enclosures

What is in the Guide?

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

What is in the Guide?

Air Barrier Systems (Fundamentals, Materials, Performance, testing)

Sealed Poly/Sheet Membranes

Airtight drywall

Sprayfoam

Sealed-Sheathing Approaches› Unsupported sheet membranes

› Supported sheet membranes with vertical strapping

› Sandwiched membranes behind exterior insulation

› Self-Adhered and liquid applied membranes

Air Flow Control – Air Barrier Strategies

Control of Heat Flow

Minimizing Conductive Losses, Minimizing Air Leakage

Placement of Insulation within assemblies

Wood framing factors

Types of insulation, R-values and typical uses

Thermal bridging and effective R-values

Heat Flow Control & Insulation

Material selection & guidance

Control Functions

Critical Barriers

Effective 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)]

R-12 (3 inches) [R-value

(RSI)]

R-16 (4 inches) [R-value

(RSI)]

R-20 (5 inches) [R-value

(RSI)]

R-24 (6 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 selection & guidance

Control Functions

Critical Barriers

Effective 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)]

3-inches [R-value

(RSI)]

4-inches [R-value

(RSI)]

5-inches [R-value

(RSI)]

6-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 Functions

Critical Barriers

Effective R-values

Low-Slope Conventional Roof Assembly

Materials & Control Functions

Critical Barriers

Effective R-values(Accounting for tapered insulation 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 Installation Sequences

Graham Finch, MASc, P.Enggfinch@rdhbe.com604-873-1181

Building Enclosure Design Guide Available from FP Innovations: http://www.fpinnovations.ca/ResearchProgram/AdvancedBuildingSystem/designing-energy-efficient-building-enclosures.pdf

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