The document presents new energy efficiency requirements under the 2012 NBC Section 9.36 for wood-frame buildings, focusing on improved insulation and the effects of thermal bridging. Key concepts include effective versus nominal R-values, compliance paths for energy codes, and design guidelines for achieving high energy-efficient building enclosures. It emphasizes the importance of considering details, interfaces, and airtightness to optimize building performance in various climate zones.

1. Implications of the New NBC Section 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

2. 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

3. 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

4. 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

5. 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

6. 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

7. 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

8. 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

9. 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 –
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
WithoutaHRV
Climate
Zone
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
WithaHRV

10. 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
NECB2011
ASHRAE90.1-2010–
ResidentialBuilding
Climate
Zone
Wall (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

11. 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

12. 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

13. 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

14. Insulation Placement & Wall Design Considerations
Interior
Insulation
Exterior
Insulation
Split
Insulation

15. Getting to Higher R-values – Insulation Placement
Baseline
2x6 w/ R-22
batts = R-16
effective
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

16. 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)

17. 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

18. Many Possible Strategies – Wide Range of Performance
Cladding Attachment through Exterior Insulation

19. 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

20. 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

21. 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

22. 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

23. 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.

24. 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

25. 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?

26. 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?

27. 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?

28. 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

29. 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

30. 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)

31. 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)

32. Pitched-Roof, Exterior Insulated Assembly
Materials & Control
Functions
Critical Barriers
Effective R-values

33. Low-Slope Conventional Roof Assembly
Materials & Control
Functions
Critical Barriers
Effective R-values
(Accounting for
tapered insulation
packages)

34. 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

35. Detailing – Colored 2D Details

36. Detailing – Wall to Roof Interfaces

37. Detailing – 2D Window Details

38. Detailing – 3D Window Installation Sequences

39. Graham Finch, MASc, P.Eng
gfinch@rdhbe.com
604-873-1181
Building Enclosure Design Guide Available from
FP Innovations:
http://www.fpinnovations.ca/ResearchProgram/Advanced
BuildingSystem/designing-energy-efficient-building-
enclosures.pdf
Discussion