Energy Efficient Building Enclosure Design Guidelines for Wood-Frame Buildings

Energy-Efficient Building Enclosure Design Guidelines for Wood-Frame Buildings

!   Graham Finch, MASc, P.Eng Principal, Building Science Research Specialist RDH Building Engineering Ltd.

October 29, 2013 – Wood WORKS! Vancouver

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© RDH Building Engineering Ltd.

Program Education Credit Information

Canadian Wood Council, Wood WORKS! and the Wood Solutions Fair is a Registered Provider with The American Institute of Architects Continuing Education System; the Architectural Institute of British Columbia and the Engineering Institute of Canada. Credit earned on completion of

this program will be reported on behalf of members of each CES provider for those who complete a participation form at the registration counter. Certificates of Completion for non-

AIA, AIBC or EIC members are available on request.

This program is registered with the AIA/CES for continuing professional education. As such, it does not include content that may be deemed or construed to be an approval or

endorsement by the AIA of any material of construction or any method or manner of handling, using, distributing, or dealing in any material or product. Questions related to specific

materials, methods, and services will be addressed at the conclusion of this presentation.

Learning Objectives

1.  Learn about the new wood-design resource for architects, builders, and engineers: the Guide for Designing Energy Efficiency Building Enclosures for Wood-Frame Multi-Unit Residential Buildings

2.  Understand how upcoming building and energy code changes will impact typical wood-frame construction practices, and learn the best strategies to design, insulate, air-seal, and detail new wood frame wall and roof assemblies.

3.  Learn about the building enclosure design considerations for heavy timber structures utilizing CLT and post-and-beam components.

4.  Understand the importance of “critical barriers” in building enclosure detailing with examples of wall, roof and window details for highly insulated wood buildings.

Overview

!   Background

!   Overview of the new Guide for Designing Energy Efficient Building Enclosures for Wood-frame Buildings

!   Available as free download from FP Innovations

!   Original 1999/2011 Wood Frame Envelopes in the Coastal Climate of British Columbia - Best Practice Guide (CMHC) !   Emphasis on moisture control on the

west coast

!   2011 Building Enclosure Design Guide – Wood-frame Multi-Unit Residential Buildings (HPO) !   Emphasis on best practices, moisture and

new energy codes

!   2013 Guide (FP Innovations) !   Focus on highly insulated wood-frame

assemblies to meet current and upcoming energy codes

!   Passive design and green buildings

Evolution Wood-frame Building Enclosure Design Guides

!   Energy Codes across North America have incrementally raised the bar to the point where conventional wood-frame assemblies (i.e. 2x6 walls) no longer provide enough insulating value

!   Increased awareness of passive design strategies and green building programs dictate even higher enclosure performance

!   Little guidance on building durable and highly insulated enclosure assemblies and details

!   Desire to build taller and taller more exposed wood-frame buildings (4-6 stories and higher)

!   Increased use of cross-laminated timber & other engineered wood products dictates alternate assemblies

Why a New Building Enclosure Guide?

!   Multi-Unit Residential Buildings are the focus of the guide (and one of most challenging building types)

!   Relevant for other building types as well utilizing platform framing, cross laminated timber, wood frame infill, & post and beam.

!   Also applies to houses

What Types of Buildings & Structures is the Guide For?

!   North American Guide !  Marine, Cold and Very

Cold Climate Zones

!  Energy Code Climate Zones 4 through 7

!  Details used as examples are west coast focused (i.e. rainscreen)

!   Guidance can also be applied to other climate zones (i.e. Far-North or Southern US) with engineering judgement & local experience

Where is the Guide Applicable

!   Chapter 1: Introduction !  Context of Guide

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

Energy Codes

!  US Building and Energy Codes

!  Performance Rating Systems & Green Building Programs

!  Differences between NECB & ASHRAE 90.1

Overview: What is in the Guide

!   Chapter 3: Moisture, Air and Thermal Control !  Building as a System

!  Climate Zones

!   Interior Climate, HVAC Interaction

!  Critical Barrier Concept

!  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


!   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


!   Review of effective R-values & Consideration for Thermal Bridging

!   Energy Use in Wood-frame MURBs

!   Enclosure R-value Targets and Airtightness Requirements !  Canadian Building Codes

•  2010 NBC

•  2011 NECB

•  ASHRAE 90.1 (2001 through 2010 versions)

!  US Buildings Codes

!  Performance Rating and Green Building Programs

Chapter 2: Building and Energy Codes

Canadian Energy Codes –NECB 2011 vs ASHRAE 90.1

Climate Zone and HDD(°C) Wood-‐frame, above-‐grade wall Wood-‐frame roof, flat or sloped:

[R-‐value (RSI)] [R-‐value (RSI)] Zone 4: <3000 HDD 18.0

(3.17) 25.0 (4.41)

Zone 5: 3000 to 3999 HDD 20.4 (3.60)

31.0 (5.46)

Zone 6: 4000 to 4999 HDD 23.0 (4.05)

31.0 (5.46)

Zone 7a: 5000 to 5999 HDD 27.0 (4.76)

35.0 (6.17)

Zone 7b: 6000 to 6999 HDD 27.0 (4.76)

35.0 (6.17)

Zone 8: >7000 HDD 31.0 (5.46)

40.0 (7.04)

NECB 2011

Climate Zone

Wood-‐frame, above-‐grade wall Wood-‐frame roof—insulation

entirely above deck Wood-‐frame roof—attic and other

Effective [R-‐value (RSI)]

Nominal [R-‐value (RSI)]





Zone 1 (A & B)

11.2 (2.0)

13.0 (2.3)

20.8 (3.7)

20.0 ci (3.5 ci)

37.0 (6.5)

38.0 (6.7)

Zone 2 (A & B)

11.2 (2.0)

13.0 (2.3)

20.8 (3.7)

20.0 ci (3.5 ci)

37.0 (6.5)

38.0 (6.7)

Zone 3 (A, B, & C)

11.2 (2.0)

13.0 (2.3)

20.8 (3.7)

20.0 ci (3.5 ci)

37.0 (6.5)

38.0 (6.7)

Zone 4 (A, B, & C)

15.6 (2.7)

13.0 + 3.8 ci (2.3 + 0.7 ci)

20.8 (3.7)

20.0 ci (3.5 ci)

37.0 (6.5)

38.0 (6.7)

Zone 5 (A, B, & C)

19.6 (3.5)

13.0 + 7.5 ci (2.3 + 1.3 ci)

20.8 (3.7)

20.0 ci (3.5 ci)

37.0 (6.5)

38.0 (6.7)

Zone 6 (A & B)

19.6 (3.5)

13.0 + 7.5 ci (2.3 + 1.3 ci)

20.8 (3.7)

20.0 ci (3.5 ci)

37.0 (6.5)

38.0 (6.7)

Zone 7 19.6 (3.5)

13.0 + 7.5 ci (2.3 + 1.3 ci)

20.8 (3.7)

20.0 ci (3.5 ci)

37.0 (6.5)

38.0 (6.7)

Zone 8 27.8 (4.9)

13.0 + 15.6 ci (2.3 + 2.7 ci)

20.8 (3.7)

20.0 ci (3.5 ci)

47.6 (8.4)

49.0 (8.6)

ci = continuous insulation, where denoted

ASHRAE 90.1 - 2010

NECB has higher effective R-value requirements

ASHRAE 90.1-2010 vs NECB 2011 – Effective Dec 20, 2014

Climate Zone

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

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

Window: Max. U-‐value (IP)

8 31.0 40.0 0.28

7A/7B 27.0 35.0 0.39

6 23.0 31.0 0.39

5 20.4 31.0 0.39

4 18.6 25.0 0.42

NEC

B 2

011

AS

HRA

E 90

.1-2

010

–

Resi

dent

ial B

uild

ing Climate Zone

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

Roof (ASc, Cathedral/Flat): Min. R-‐value (IP)

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

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

7A/7B 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

5 12.5, 19.6, 15.6 37.0, 20.8 0.55, 0.35

*7A/7B combined in ASHRAE 90.1 No Zone 4 in ASHRAE 90.1

!   Adoption of IECC and ASHRAE 90.1 varies by State

!   Effective R-value tables provided

!   Airtightness requirements covered !  Washington State

and Seattle (<0.40 cfm/ft2 @75Pa)

!  US Army Corps (<0.25 cfm/ft2 @75Pa)

US Energy Codes – IECC vs ASHRAE 90.1

!   Consideration for “above-code” enclosure performance & green building programs

!   Performance rating and energy modeling considerations

!   Target “high-performance” building enclosure R-values by climate Zone

Performance Rating Programs & R-value Targets

Climate Zones

Wood-‐frame, above-‐grade wall Wood-‐frame roof—insulation

entirely above deck: Wood-‐frame roof—attic and

other:

[R-‐value (RSI)] [R-‐value (RSI)] [R-‐value (RSI)] Zones 1 to 3: hot, cooling dominated

R-‐16 to R-‐22 (2.8 to 3.9)

R-‐25 to R-‐30 (4.4 to 5.3)

R-‐40 to R-‐50 (7.0 to 8.8)

Zones 4 to 5: mixed, heating and cooling

R-‐22 to R-‐28 (3.9 to 4.9)

R-‐30 to R-‐40 (5.3 to 7.0)

R-‐50 to R-‐60 (8.8 to 10.6)

Zones 6 to 8: cold, heating dominated

R-‐28 to R-‐40 (4.9 to 7.0)

R-‐40 to R-‐50 (7.0 to 8.8)

R-‐60 to R-‐80 (10.6 to 14.1)

!   Exterior Climate

!   Temperature & Humidity

!   Rainfall

!   Interior Climate

!   HVAC systems

!   Ventilation

!   Architectural Form & Enclosure Design

Chapter 3: Climate Considerations

!   Deflection, Drainage, Drying and Durability

!  Wetting and Drying Mechanisms

!   Critical Barriers & Continuity !  Water Shedding Surface

!  Water Resistive Barrier

!  Air Barrier

!   Thermal Insulation

!   Rainwater Penetration control fundamentals

Chapter 3: Building Science Fundamentals

!   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

!   Other Approaches

Chapter 3: Air Flow Control – Air Barrier Strategies

!   Relative Humidity control !  Maintaining high interior

surface temperatures !  Reducing thermal bridging

!  Use of better windows

!   Controlling air movement (air barrier systems)

!   Controlling vapour diffusion (vapour retarders)

Chapter 3: Condensation Control

!   Keeping wood dry during transportation and construction and limiting built-in moisture

!   Careful use of impermeable materials/membranes

!   Controlling and accounting for wood-frame shrinkage !  Detailing for differential shrinkage

Managing Construction Moisture & Wood Shrinkage

!   Control of Heat Flow !  Solar Control, 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

Chapter 3: Heat Flow Control & Insulation

!   All Energy Codes now consider effective R-values

!   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 include impacts of insulation installation and thermal bridges !   For example nominal R-20 batts within

steel studs becoming ~R-9 effective, or in wood studs ~R-15 effective

Chapter 3: Effective R-values

!   Framing factors for studs @ 16” o.c = 25% !   Taller wood-frame structures framing factors >30-40%

depending on structural destign

Chapter 3: Wood Framing Factor Impact

Insulation Placement and Assembly Design Considerations

Interior Insulation

Exterior Insulation

Split Insulation

Getting to Higher R-values – Placement of Insulation

Baseline 2x6 w/ R-22 batts = R-16 effective

Exterior Insulation – R-20 to R-40+ effective •  Constraints: cladding attachment, wall thickness

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

thickness

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

attachment

Chapter 3: Insulation Placement – Above Grade Walls

2x6 stud wall Double-‐stud wall 2x4 (or 2x6) stud wall CLT/mass timber 2x4 (or 2x6) stud wall

Interior-‐insulated wall assemblies Exterior-‐insulated wall assemblies Split-‐insulated wall assembly

Cladding Attachment 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

Cladding Attachment through Exterior Insulation

Insulation Placement – Below Grade Walls

Interior-‐insulated wall Exterior-‐insulated wall Interior-‐ and exterior-‐

insulated wall (ICF)

Insulation Placement - Roofs

Interior-‐insulated pitched roof Low-‐slope roof: conventionally

insulated Low-‐slope roof: inverted

!  Whole building energy efficiency considerations

!   Impact of Wall, Window and Roof R-values on overall heat-loss and energy consumption

!   Example calculations of whole building R-values

!   Thermal mass impacts of Heavy timber structures

!   Hygrothermal and Thermal simulation guidance

Chapter 3: Whole Building Energy Efficiency

!  Material selection & guidance

!   Control Functions

!   Critical Barriers

!   Effective R-value Tables

Chapter 4: 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)

!   Wood-frame and Heavy Timber Building Wall R-value Targets !   R-19.6 ASHRAE 90.1 !   R-18.6 to R-20.4 NECB

!   Can only get ~R-16 effective within a 2x6 framed wall

!   Industry shift towards split and exterior insulated wood-frame walls

Exterior & Split Insulated Wood Assemblies





Chapter 4: 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)

!   Double 2x4/2x6 stud, single deep 2x10, 2x12, I-Joist etc.

!   Common wood-frame wall assembly in many passive houses (and prefabricated highly insulated walls)

!   Often add interior service wall – greater control over airtightness

!   Inherently at a higher risk for damage if sheathing gets wet (rainwater, air leakage, vapor diffusion) – due to more interior insulation

Double/Deep Stud Insulated Walls





Chapter 4: Energy Efficient Walls – Exterior Insulated

Wood framing

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

Exterior insulation thickness 3 inches R-‐value (RSI)]

4 inches [R-‐value (RSI)]





3½-‐inch-‐thick CLT panels

R-‐4/inch (0.28/cm)

17.2 (3.0)

20.9 (3.7)

24.4 (4.3)

27.9 (4.9)

31.6 (5.6)

35.0 (6.2)

R-‐5/inch (0.34/cm)

19.8 (3.5)

24.4 (4.3)

28.7 (5.1)

32.9 (5.8)

37.3 (6.6)

41.5 (7.3)

Cross Laminated Timber Construction - Considerations

Cross Laminated Timber Construction – Wall Assemblies

CLT Panel Construction - Unique Details for Consideration

CLT Panel Details Requiring Attention – Panel Joints

Sealants, tapes, & membranes applied on either side can’t address this type of airflow path through the CLT lumber gaps

CLT Panel Details Requiring Attention - Parapets

Airflow increased by stack effect and pressures at parapet corners

Roofing membrane applied, path becomes longer – but doesn’t go away – even if clamped, sealed etc.

CLT Panel Details Requiring Attention - Corners

Airflow path more convoluted – lower leakage rates, but still a consideration

!   CLT panels air-tight as a material, but not as a system

!   Recommend use of self-adhered sheet product air barrier membranes or thick liquid applied membrane on exterior of panels (exterior air-barrier approach)

!   Use of loose-applied sheets (House-wraps) not generally recommended – more difficult to make airtight, perforating attachment, billowing, flanking airflow behind membrane

Guidance for CLT Assembly Air Barriers

!   Structural connections can interfere with air-barrier membrane installation/sequencing and sharp parts can damage materials (applied before or after)

CLT Assembly Air Barrier Considerations

Infill Walls – Post & Beam or Concrete Floor Slabs

Post and Beam with wood-frame infill

Concrete frame with wood-frame infill

!   Interior Insulated

Chapter 4: Below Grade Walls

!   Exterior Insulated



!   Effective R-values

Chapter 4: Pitched-Roof, Vented Attic Assembly

!  Materials & Control Functions


!   Effective R-value Tables (accounting for insulation reductions at eaves)

Chapter 4: Pitched-Roof, Exterior Insulated Assembly




Chapter 4: Low-Slope Conventional Roof Assembly



!   Effective R-values (Accounting for tapered insulation packages)




Chapter 4: Low-Slope Inverted Roof Assembly

!   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)

Chapter 5: Detailing

!   Thermal Continuity !   Air Barrier Continuity

!  Water Shedding Surface and Water Resistive Barrier

Detailing – Materials & Critical Barrier Discussion

!   Details provided for each main wall assembly included !  Split insulated

!  Double Stud

!  CLT

!   And roofs !  Sloped

!   Low-slope

Detailing – From Roof to Grade

Detailing – Colored 2D Details

Detailing – Wall to Roof Interfaces

Detailing – Wall Penetrations

Detailing – 2D Window Details

Detailing – 3D Window Installation Sequences

!   Further reading !  Builder & Design Guides

!  Building Science Resources

!  Energy Codes and Standards

!  Other Research Organizations

!  Design Software

!   References

!   Glossary of Building Enclosure, Energy Efficiency and Wood terms

Chapter 6: Further Reading, References & Glossary

Questions?

! [email protected] - 604-873-1181

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

!   Google: energy efficient building enclosure design guide

Questions / Comments?

This concludes the:

American Institute of Architects Architectural Institute of British Columbia

Engineering Institute of Canada

Continuing Education Systems Program

Energy-Efficient Building Enclosure Design Guidelines for Wood-Frame Buildings

Energy Efficient Building Enclosure Design Guidelines for Wood-Frame Buildings

Engineering

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