Building Envelope

1. Building Envelope

2. Outline • Structure of the Subsection • Scope & Application of BE Requirements • Insulation requirements • Nominal vseffective • Appendix Information • Airtightness requirements • Simple trade-off

3. Structure of the Subsection • 9.36.2. Building Envelope • 9.36.2.1. Scope and Application • 9.36.2.2. Determination of Thermal Characteristics & Areas • 9.36.2.3. Determination of Areas of Wall and Fenestration • 9.36.2.4. Calculation of Thermal Resistance for Assemblies • 9.36.2.5. Continuity of Insulation • 9.36.2.6. Above Ground Assemblies • 9.36.2.7. Windows, Doors and Skylights • 9.36.2.8. Below Ground Assemblies • 9.36.2.9. Required Level of Airtightness • 9.36.2.10. Construction of Air Barrier Details • 9.36.2.11. Simple Trade-offs for Building Envelope

4. Scope and Application • Scope & Application of Building Envelope • Addresses heat transfer and air leakage • Applies between conditioned space and unconditioned space, exterior air or ground • Applies between conditioned space and adjoining storage garage, even if storage garage is heated • Testing R-values for materials and components • Calculating wall and fenestration areas • Calculating effective thermal resistanceof assemblies

5. Continuity of Insulation • General Requirement • Insulation shall be installed continuous • Exceptions: • Structural members • Behind recessed heaters, ducts etc (min RSI 2.93) • Behind pipes, cables etc (min. RSI 2.93) • Window-wall interface (min. insulation value of window) • Joint between the foundation wall and the floor slab • Between foundation and masonry veneer (exterior insulation) • If continuity is broken • Overlap 4 times the width of the gap • Insulate 4 times the penetration on either side

6. Required Thermal Characteristics • Opaque assemblies • Minimum effective thermal resistance (RSI = 1/U) for • Above ground assemblies: walls, attics, floors over unheated spaces, etc. • Below ground assemblies: foundation walls, floor slabs, heated slabs etc. • Two compliance options • R-values based on mechanical ventilation (no HRV) @ 2.5 ACH • R-values based on HRV @ 2.5 ACH • Windows, doors and skylights • Manufactured fenestration components: • Maximum overall thermal transmittance (U = 1/RSI), or • Minimum Energy Rating (ER) values (not for skylights) • Prescriptive specifications for site-built windows

7. Code Requires Effective RSI Values • Above-ground Assemblies • Example: 2 x 6 construction - 16” on center • Code minimum effective value RSI 2.93 m²°C/W (R16.6) • Appendix: nominal insulation examples RSI 3.34 m²°C/W (R19) R6.9 R19 framing 23% 77% cavity

8. Look-up Nominal Values • Above-ground requirements • Appendix – lookup tables

9. Look-up Nominal Values • Above-ground requirements • Appendix – lookup tables

10. Look-up Nominal Values • Above-ground requirements • Appendix – lookup tables

11. Look-up Nominal Values • Above-ground requirements • Appendix – lookup tables

12. Calculation of RSI Values • Above-ground assemblies – requirements (example) • Appendix – Calculation • Formula • Methods (isothermal/parallel) • Framing percentages (wood/metal) • Material values (MNECH97,IRC,ASHRAE) • Log walls (MNECH97) framing 23% 77% cavity

13. Windows, Doors and Skylights • U-value – requirements for windows, doors and skylights • Energy Rating (ER) – requirements for windows and doors • Storm doors exempt • Exception for • 1 front door and attic/crawl space hatches: U = 2.6 W/m²K • Garage door RSI = 1.1 m²K/W

14. Windows, Doors and Skylights • Prescriptive alternative for site-built windows • Intended for site-constructed or site assembled windows not tested to CSA A440.2 (NAFS) • Typically in custom-built homes or for specific situations where manufactured units are not available • Requirements are not intended for curtain wall construction

15. Airtightness • Two compliance options • Prescriptive construction details • Considering different approaches (poly, ADA, exterior sheathing) • Addressing typical penetration and junctions • Using tested assemblies • Assembly required to conform to ULC S742 Air Barrier Assemblies • Limited reference: material used does not need to comply with ULC S741 Air barrier Materials • Provide junction details (manufacturers’ instructions)

16. Airtightness • Prescriptive compliance path • General requirements • Compliance, exemptions, cross-references (9.25.3.) • Material values, continuity, sealants • Specific Construction Details • Electrical outlets and switches • Sill plates • Window-wall interface • Overhangs • Party wall details • Chimney and duct penetrations • ICF (top of the wall to attic ceiling)

17. Simple Trade Off • Using “A over R” approach (MNECH97) • 3 Trade-off Options: • Opaque to opaque • Transparent to transparent • Limited to trades within same orientation • Opaque to transparent • Trade reduced window area for reduced attic insulation • Intended for factory constructed houses/buildings (max FDWR 15%) • Overall Limitations • Can’t reduce walls and attic roofs below 55% of required R-value • Can’t reduce other opaque assemblies below 60% of required R-values • Can’t be applied to heated assemblies • Can’t be applied to components and assemblies already exempted areas remain same

18. Questions? www.nationalcodes.nrc.gc.ca Thank you