While the approach to thermal simulation of vision glazing areas is well documented by groups such as the National Fenestration Rating Council (NFRC), the approach to simulate opaque spandrel panels is not similarly documented. Furthermore, spandrel assemblies are substantially different from conventional opaque wall assemblies (i.e., concrete, steel stud, wood stud, etc.). To address this industry need, RDH in partnership with the Fenestration Association of BC (FENBC) and funding from BC Housing has developed a procedure to determine spandrel panel U-factors using common industry tools and familiar methods. The methodology includes consideration of various spandrel panel arrangements and builds off the existing NFRC 100 simulation methodology. The objective of this procedure is to document a reasonably accurate and practical approach to determine opaque spandrel area U-values with higher precision and uniformity. This allows for both the accurate representation of these systems with regards to code compliance and energy modelling, as well as the fair comparison of competing products. Presented at the 15th Canadian Conference on Building Science and Technology.

1. 1
REFERENCE PROCEDURE FOR SIMULATING
SPANDREL PANEL U-FACTORS
CCBST 2017
NOVEMBER 8, 2017
DANIEL HAALAND

2. 2
Overview
 Who
Developed through FENBC, with funding from BC Housing
 What
A reference procedure for determining spandrel panel U-factors
 Why
Address an identified need for additional guidance on how to
treat spandrel panels
 How
Supplement and extend existing NFRC-100 methodology.

3. 3
Reference Procedure Scope
 This procedure is specifically for the determination of
spandrel U-factors using 2-D thermal simulation only
 Physical testing and validation is outside the scope

4. 4
Energy Code (ASHRAE 90.1 – 2010)
Opaque
NFRC-100
>RIP15.6

5. 5
What does NFRC 100 say?
Spandrel: the opaque areas of a building envelope that
typically occur at locations of the floor slab, columns, and
immediately below roof areas

6. 6
1200mm
What does NFRC 100 say?
A Single
Standard size
Another glazing option
2000mm

7. 7
Spot the “Standard” spandrel…
There is a need for additional
spandrel arrangements

8. 8
Relative Size of Frame Matters
<90% <50%<80%
U-1.53 (W/m2∙K)
U-0.27 (Btu/hr∙ft2∙oF)
Panel to
Frame Ratio
U-Value
U-2.42 (W/m2∙K)
U-0.43 (Btu/hr∙ft2∙oF)
U-0.70 (W/m2∙K)
U-0.12 (Btu/hr∙ft2∙oF)
RIP-8.3 RIP-3.7 RIP-2.3

9. 9
Are Spandrels an “Additional Glazing Option”?
63.5mm (2.5”)

10. 10
Are Spandrels an “Additional Glazing Option”?
63.5mm (2.5”)
152mm (6”)
There is a need for
wider edge distances

11. 11
Moving Toward a New Methodology
Gaps
 Single product size does not
capture product variability
 Edge distance does not
capture the “edge”
Priorities
 Product comparison
 More realistic thermal
performance (U-factor) data
 Leverage existing tools and
expertise

12. 12
Procedure
 NFRC 100 procedure is followed generally, including:
 Products are rated at standard sizes
 Products are separated into frame, edge of spandrel, and center
of panel components; U-Factor x Area
 Boundary conditions, material properties, etc.,

13. 13
Arrangements
Configuration 1 Configuration 2 Configuration 3
Uninterrupted Spandrel
Partially Interrupted
Spandrel
Fully Interrupted Spandrel
2000 mm x 1200 mm
(79 in x 47 in.)
2000 mm x 1200 mm
(79 in x 47 in.)
2000 mm x 203 mm
(79 in x 8 in.)

14. 14
Arrangement 1 – Uninterrupted Spandrel
 Spandrel panel is completely uninterrupted (i.e., a typical
curtain wall arrangement)

15. 15
Arrangement 1 - Uninterrupted Spandrel
 Minimum of 4 cross
sections (if symmetrical)
 Height: 1200mm
 Width: 2000mm
 Edge: 152.4mm (6”)
 A center of panel
(1D or 2D model)

16. 16
1D vs. 2D Center of Panel
Methodology USI-Factor (W/m2K) UIP-Factor (Btu/hr∙ft2∙oF)
WINDOW (1D) 0.265 0.0467
THERM (2D) 0.268 0.0472
% Difference 1.1%

17. 17
Arrangement 2 – Partially Interrupted
 Spandrel panel insulation is
interrupted at a floor slab
 Model to include concrete
slab extending 1 m
 Edge of sill measured from
point of interruption
6” (152 mm)
3’ 3” (1 m)

18. 18
Arrangement 2 – Partially Interrupted
 Minimum of 5 models (if
symmetrical)
 Full cross section
 Remainder of the cross
sectional areas are similar
with additional cross section
at the slab

19. 19
Arrangement 2 – U-Factor Tags
Model includes min. 1000 mm of concrete measured from to inner
most element of the system (e.g., back dam angle, backup wall, etc.)
Edge (152 mm)
Frame (Sill)
Edge of Slab
None
Edge (152 mm)
Frame (Head)
NFRC Exterior
Interior Glazing Film
Interior Frame
Adiabatic
FilmInterior Frame
Interior, Heat Flow
Downwards
ExteriorInsideAdiab
atic FilmInterior
Frame
Interior, Heat Flow
Upwards
ExteriorInsideAdiab
atic FilmInterior
Frame

20. 20
Arrangement 3 – Completely Interrupted
 Completely interrupted
spandrel panel
 High frame to panel ratio

21. 21
Arrangement 3 – Completely Interrupted
 Minimum of 3 models (if
symmetrical)
 Height: 203mm + ½ Frame
 Width: 2000mm
 Edge: n/a

22. 22
U-Factor vs. Edge Distance Validation (Example)
0
0.2
0.4
0.6
0.8
1
1.2
0 50 100 150 200 250
U-Factor(W/m2K)
Edge Distance (mm)
RIP-21
RIP-6
> 300% increase

23. 23
U-Factor vs. Edge Distance Validation (Example)
0
0.2
0.4
0.6
0.8
1
1.2
0 50 100 150 200 250
U-Factor(W/m2K)
Edge Distance (mm)
13% increase

24. 24
U-Factor vs. Edge Distance Validation (Example)
0
0.2
0.4
0.6
0.8
1
1.2
0 50 100 150 200 250
U-Factor(W/m2K)
Edge Distance (mm)
0.17 W/m2K

25. 25
U-Factor vs. Edge Distance Validation (Example)
0
0.2
0.4
0.6
0.8
1
1.2
0 50 100 150 200 250
U-Factor(W/m2K)
Edge Distance (mm)
0.17 W/m2K

26. 26
Reference Procedure

27. 27
Calculation Tool

28. 28
Available Online
http://www.fen-bc.org/content/view/resources-spandrel

29. 29
Next Steps
 Proposed methodology does not capture everything
 Deflection headers
 Adjacent systems
 Etc.,
 But it does
 Provide a consistent & comparable method
 More accurately reflects typical spandrel arrangements

30. 30
Discussion + Questions
FOR FURTHER INFORMATION PLEASE VISIT
 www.rdh.com
 www.buildingsciencelabs.com
OR CONTACT US AT
 dhaaland@rdh.com