Meeting Residential Energy. Construction. Copyright Materials. Loren Ross, P.E. Manager, Engineering Research American Wood Council

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1 Meeting Residential Energy Requirements with Wood-Frame Construction Loren Ross, P.E. Manager, Engineering Research American Wood Council Copyright Materials This presentation is protected by US and International Copyright laws. Reproduction, distribution, display and use of the presentation without written permission of the speaker is prohibited. American Wood Council Copyright 2015 American Wood Council. All rights reserved. 1

2 The American Wood Council is a Registered Provider with The American Institute of Architects Continuing Education Systems (AIA/CES), Provider # Credit(s) earned on completion of this course will be reported to AIA CES for AIA members. Certificates of Completion for both AIA members and non-aia members are available upon request. This course is registered with 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. 3 Polling Question What is your profession? a) Architect b) Engineer c) Code Official d) Building Designer e) Other 44 Copyright 2015 American Wood Council. All rights reserved. 2

3 Learning Objectives On completion of this course, participants will: Be familiar with R-value and U-factors and how to calculate them. Understand the three prescriptive compliance energy paths recognized by the code and understand how to use them in singlefamily design. Be familiar with allowable trade-offs in the IRC and IECC. Be familiar with available design aids offered by AWC. 5 Outline R-values and U-factors Compliance Paths Trade-offs Example Problems Design Aids Questions? 6 Copyright 2015 American Wood Council. All rights reserved. 3

4 R-Value versus U-Factor R-Value Measure of resistance to heat flow Material and Product Specific Labeled on Product or ASHRAE Handbook of Fundamentals Can be Summed U-Factor Measure of heat flow Assembly Specific Derived from sum of R-Values Area Weighted 7 R-values to U-Factors: Parallel Path Method Item R-Value Stud Path Cavity Path Air Film 0.68 X X 2 Gyp. 1/ X X 1 Stud 2x X 4 Insulation 13 X 3 OSB 7/ X X 5 Vinyl Siding 0.62 X X Air Film 0.25 X X Path R-Value Sum U-Factor of Path Stud Cavity Copyright 2015 American Wood Council. All rights reserved. 4

5 R-values to U-Factors: Framing Factors Projected Area of wood / Total Projected opaque wall area = Framing Factor Framing Factor Headers 3-4% Studs 16 o.c % Studs 24 o.c % 9 Polling Question What is the definition of framing factor? a) Projected wood area / projected opaque wall area b) Projected wood area / total wall area c) 25% for all buildings d) Other 1010 Copyright 2015 American Wood Council. All rights reserved. 5

6 R-values to U-Factors: Parallel Path Method 25% 75% Path Sum U-Factor Stud Cavity % Framing Factor (0.1430)+0.75(0.064) = R-Values to U-Factors: Table Method The same value can be found in DCA 7 Appendix A 12 Copyright 2015 American Wood Council. All rights reserved. 6

7 Compliance Paths Same options for the IRC and IECC IRC Part IV Energy Conservation N through N IECC Residential Provisions Chapters 1 through 5 13 Compliance Paths R-Value [R ] Simple Cavity or Cavity and Continuous Only Least Flexible U-Factor [R ] Similar to R-value, only Assembly based Trade-offs only within the Assembly Total UA Method [R ] Most Complex of Prescriptive Trade-offs between Assembly Types Method of DCA 7, REScheck 14 Copyright 2015 American Wood Council. All rights reserved. 7

8 Compliance Path: R-Value 2012 IECC 15 Compliance Path: R-Value 2012 IECC h. First value is cavity insulation, second is continuous insulation or insulated siding, so 13+5 means R-13 cavity insulation plus R-5 continuous insulation or insulated siding. If structural sheathing covers 40 percent or less of the exterior, continuous insulation R-value shall be permitted to be reduced by no more than R-3 in the locations where structural sheathing is used to maintain a consistent total sheathing thickness. 16 Copyright 2015 American Wood Council. All rights reserved. 8

9 Compliance Path: U-Factor 2012 IECC = U-Factor 17 Compliance Path: U-Factor 2012 IECC 2x4, R-13 Wall Non-compliant! Path Sum U-Factor Stud Cavity % Framing Factor Copyright 2015 American Wood Council. All rights reserved. 9

10 Polling Question Is a 2x4, R 13 wall compliant in Climate Zone 1 and 2 with the 2012 IECC? a) Yes, but only using the R value path b) No, its U factor is too high c) Whatever REScheck says d) All of the above 1919 Compliance Path: Total UA Alternative 2012 IECC = Uref Aassembly Uact A UA assembly 20 Copyright 2015 American Wood Council. All rights reserved. 10

11 Trade-offs: Total UA Alternative 2012 IECC Energystar.gov 21 Trade-offs: Window and Wall For a 30 by 40, two-story, house with 16% window area: Total Wall Area: (30 )(8 )(2)(2) + (40 )(8 )(2)(2) = 2240 ft 2 Window Wall Area: 2240 ft 2 x (0.16) = ft 2 Opaque Wall Area: 2240 ft 2 x (0.84) = ft 2 Reference UA of Proposed Home: Window UA: ft 2 x (0.35) = Opaque UA: ft 2 x (0.057) = Total UA: = Proposed Home: Window UA: ft 2 x (0.30) = Proposed Opaque UA: = Proposed Opaque U: /1881.6= Copyright 2015 American Wood Council. All rights reserved. 11

12 Trade-offs: Window and Wall Trade-offs: Window and Wall 24 Copyright 2015 American Wood Council. All rights reserved. 12

13 DCA 7 Background on compliance paths U-Factor Calculation U-Factors for various assemblies (Appendix A) OSB, Plywood, Fiberboard b 16 o.c. & 24 o.c. 2x4 & 2x6 R-13 through R-24 cavity insulation Tables for UA trade-offs for fenestrations and walls for 2012 IECC (Appendix B) 25 DCA 7 Appendix A 26 Copyright 2015 American Wood Council. All rights reserved. 13

14 Framing Factor vs. U-Factor Framing Factor U-Factor 2x4 w/ R-13 2x4 w/ R x6 w/ R-20 25% % % % Max. Improvement Cavity Cavity + Continuous Cavity 27 DCA 7 Appendix B 28 Copyright 2015 American Wood Council. All rights reserved. 14

15 DCA 7 Appendix B 29 DCA 7 Appendix B 30 Copyright 2015 American Wood Council. All rights reserved. 15

16 DCA 7 Calculator For ios, Android, and Silverlight 31 Polling Question How familiar are you with AWC s website? a) Never been there b) Only go there for education c) Familiar with publications and calculators d) It s my homepage 3232 Copyright 2015 American Wood Council. All rights reserved. 16

17 DCA 7 Calculator, Silverlight Insert state specific values! R-values show in the calculator are the performance needed after compression of the insulation! 33 DCA 7 Calculator, Silverlight 34 Copyright 2015 American Wood Council. All rights reserved. 17

18 Future Plans/Desires for the Calculator 2015 IECC Reference Values State Specific Reference Values U-Factor Calculator l Moisture Criteria 35 Take Home Messages... R-values and U-factors are related but require calculation to go from one to the other There are three prescriptive compliance paths in the IRC and IECC The paths trade-off between simplicity and flexibility Modern energy codes have tightened opaque envelope requirements Leveraging the UA Alternative method can alleviate requirements AWC has online aids for determining U-factors and using the UA Alternative method at 36 Copyright 2015 American Wood Council. All rights reserved. 18

19 Questions? This concludes The American Institute of Architects Continuing Education Systems Course 37 Copyright 2015 American Wood Council. All rights reserved. 19