Essential Energy Code Knowledge : Avoiding Last-Minute Permit Hassles

1. Essential Energy Code Knowledge :Avoiding Last-Minute Permit Hassles Bob Zabcik Director, Research and Development NCI Group

2. Essential Energy Code Knowledge Learning Objectives • Understand how the envelope provisions of an energy code work • Understand the difference between U-factor and R-value and know when to use which for compliance • Dispel the myth that R-5 thermal blocks are required for all SSRs • Show that screw-down roofs, while challenged, can still be used in energy code compliant buildings • Tell you the truth about continuous insulation and why it is not required despite what your building official tells you • Better understand the air barrier requirements in the code • Understand how ComCheck can solve most of your problems

3. Essential Energy Code Knowledge • The two primary model building energy conservation codes for commercial construction are: • ASHRAE 90.1 • International Energy Conservation Code, or IECC • Independent documents but IECC depends heavily on ASHRAE 90.1 for U-factor determination of assemblies • IECC also allows ASHRAE 90.1 to be used as an alternate compliance path (C401.2) This is important since ASHRAE 90.1 requirements are generally less stringent due to the update cycle.

4. Essential Energy Code Knowledge Typical Energy Code Structure General Requirements & Definitions Air barrier requirements Mandatory Provisions Set Level of Performance for each system Energy Modeling - Variable performance between systems Prescriptive Path Performance Path Minimum Insulation R-value Maximum Assembly U-factor U-Factor Compliance R-Value Compliance ComCheck software (Most flexible) but not always accepted by permit authorities Envelope Trade-offs

5. Essential Energy Code Knowledge ASHRAE/IECC Construction Types (Roofs)

6. Essential Energy Code Knowledge ASHRAE/IECC Construction Types (Walls)

7. Essential Energy Code Knowledge Difference between R-value and U-factor The thermal conductance of an opaque envelope component is natively expressed as a U-Factor with the units of BTU/(hr-ft2-F). For layers of different materials, the combined U-Factor is calculated by: In order to make this easier, thermal conductance is often restated as an R-value where R = 1/U. Thus, the above equation becomes:

8. Essential Energy Code Knowledge IECC 2012 R-Value Chart

9. Essential Energy Code Knowledge IECC 2012 U-factor Chart Note that there is no requirement for R-5 thermal blocks on the U-factor chart

10. Essential Energy Code Knowledge • What does R-19 + R-11 LS mean? • It refers to a specific assembly accepted by ASHRAE 90.1 to have a U-factor of 0.035 • They know this because a test report was shown to them that had an R-5 thermal block • It also had 5’ purlin spacing (How often does that happen anymore?) • R-19 + R-11 LS is only the baseline system. It is not the system you HAVE to use • Your job is to match the U-factor of the baseline system, not match the system itself!

11. Essential Energy Code Knowledge • This is what that system looks like • Also known as Simple Saver • How much do you really think that little old thermal block affects the performance of this system? • R-5 out of R-30 • Roughly 5% of roof area • 5/30 x 0.05 = 0.8% of total performance • NOT MUCH!!

12. Essential Energy Code Knowledge • This illustrates the biggest problem with R-value charts; they often require assemblies that can’t meet public safety requirements. • Try using a 5’ purlin spacing in a 100 psf snow zone and see what happens (I’m kidding, please don’t) • This is why modeling capabilities are important; you can model anything • The ideal method is to calibrate models versus hot-box tests and use the models to tweak the result to match the project • This is why NCI partners with insulation companies and requires that they have these capabilities to help our customers

13. Essential Energy Code Knowledge Through-Fastened Roofs • The same situation exists with TFRs - Just because the baseline system is an SSR doesn’t mean a TFR can’t be used • However, TFRs compress insulation much more than SSRs, so additional insulation will be required • Often this additional insulation makes the in-place cost of a TFR more than that of an SSR for the same thermal performance • The clip standoff dimension is the key factor. NCI has a 2” standoff clip that results in better U-factors but they must be modeled.

14. Essential Energy Code Knowledge Continuous Insulation ASHRAE 90.1 defines continuous insulation as “Insulation that is continuous across all structural members without thermal bridges other than fasteners and service openings.” Continuous insulation is important because thermal bridges and discontinuities introduced by compressing non-rigid insulations cause the in-place R-Value of the assembly to be less than the tested R-Value of the insulation used.

15. Essential Energy Code Knowledge IECC 2012 R-Value Chart Continuous insulation is identified by “ci”

16. Essential Energy Code Knowledge Continuous Insulation • Just like with roofs, the continuous insulation requirements are part of the base line system, they are not actual requirements • Again, you must match the U-factor of the baseline system, not the system itself. • Use testing/modeling to generate the U-factors

17. Essential Energy Code Knowledge Insulated Metal Panels We have used finite element modeling to determine the U-factor of all IMPs we manufacture Finite Element Mesh Isotherms Temperature Heat Flux

18. Essential Energy Code Knowledge

19. Essential Energy Code Knowledge Air Barriers • Air barriers can be proven in one of three different ways • Material performance to ASTM E 2178 (No joints tested) • Assembly performance to ASTM E 2357, E 1677, E 1680 (roofs) or E 283 (walls) • Whole building testing to ASTM E 779 • We have test data for most panels that exceed the typical assembly requirements • When using them, you must match the tested assembly • Sealed walls • Exterior closures • Stitch Screw Spacing 12” for PBR, 20” for walls

20. Essential Energy Code Knowledge • If you have a whole building test, there are a few extra steps you can take with insulation liner to vastly improve performance • We have used these details on several buildings that have passed with flying colors • COE does not allow insulation liner to function as air barrier unless it meets ASTM E 2178 • PSK from Lamtec meets this requirement

21. Essential Energy Code Knowledge

22. Essential Energy Code Knowledge • Free-for-download application: www.energycodes.gov/ComCheck • Allows user to “trade off” roof and wall systems using weighted average U-factor • Uses U-factor Compliance behind-the-scene but accepts input from either

23. Essential Energy Code Knowledge Can put in cavity and continuous insulation R-value Or U-factor

24. Essential Energy Code Knowledge ComCheck • Can really save you money because it allows you to tune the system such that the building is just barely code compliant. • Case-in-point: Go to a long tab and banded roof system instead of a simple saver by considering the additional insulation given by an IMP or rigid board used on the wall that is there regardless • On a tennis facility with IMP walls, we helped a customer reduce cost $20,000 by doing this and eliminating associated purlin bottom flange angles

25. Essential Energy Code Knowledge Review Learning Objectives • Understand how the envelope provisions of an energy code work • Understand the difference between U-factor and R-value and know when to use which for compliance • Dispel the myth that R-5 thermal blocks are required for all SSRs • Show that screw-down roofs, while challenged, can still be used in energy code compliant buildings • Tell you the truth about continuous insulation and why it is not required despite what your building official tells you • Understand how ComCheck can solve most of your problems

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