1. WDMA Technical Conference Chicago, IL 28 June 2016
BENEFITS OF INTERIOR INSTALLED HIGH PERFORMANCE INSULATING GLASS FOR COMMERCIAL RETROFIT APPLICATIONS – A CASE STUDY
WDMA Technical Conference
Chicago, IL
28 June 2016

2. Outline of discussion
Introduction & Background – 400 Market Street, Philadelphia PA, USA
System Description – Interior Installed Low-e Insulating Glass
Test Configuration & Conditions
Energy Comparison
Surface Temperature Comparison
Cost Comparison
Conclusions

3. Introduction & Background
400 Market Street, Philadelphia PA
12-story office building
Constructed in 1971 with monolithic
clear glazing
After market window film applied to
interior lites
Prepared By: Home Innovation Research Labs
Funded by U.S. Department of Energy,
Project #DE-­‐EE
Presentation prepared collaboratively
between Quanex Building Products and
JE Berkowitz LLC

4. Interior Installed Low-e IGU
Interior IGU construction:
2 lites 5 mm glass
PPG SB60 low-e coating on
surface #3
½” (13 mm) argon glazing gap
Aluminum spacer with PIB
primary and silicone
secondary sealants
Mounted interior of monolithic
lite
Separated by applied flexible
spacer
Interior mechanical trim applied
to existing sill framing

5. Interior Installed Low-e IGU
Overall system center-of-glass U-value = 0.18 Btu/hr-ft2-F
(1.02 W/m2-K)
Overall system Solar Heat Gain Coefficient = 0.44

6. Test Specimen Configuration
Two pairs of side-by-side offices chosen for comparison
Room Dimensions: 10’ x 12’ (3.05 m x 3.66 m)
Glazing Dimensions: 6’ x 6’ (1.83 m x 1.83 m )
Room pair #1 located on 6th floor facing east
Room pair #2 located on 11th floor facing north
One glazing per pair retrofitted after film removal

7. Test Conditions
Air leakage testing demonstrated minimal difference between original and retrofit energy transfer effects due to air leakage are deemed negligible
All rooms isolated from building mechanical (HVAC) systems
Independent heating/cooling equipment in each office to maintain temperature:
Heating demand – 69 F (20.6 C)
Cooling demand – 71 F (21.7 C)
Incandescent lighting utilized to simulate thermal loads from
occupants and equipment
Monitoring conducted from:
Nov 2011 – Oct 2012
Heating
1 Dec 2011 – 29 Feb 2012
Cooling
27 Jul 2012 – 30 Sep 2012

8. Office Energy Use Comparison

9. Building Energy Use Comparison
Energy usage based on monthly utility billing following full building retrofit

10. Building Energy Use Comparison

11. Surface Temperature Comparison
Inside Glass Surface Temperature Profile
East Facing
North Facing
Low-e Retrofit Panel (°F/°C)
Original Single Pane/Film (°F/°C)
Winter, Maximum during day
70-76/21-24
75-85/24-29
65/18
52/11
Winter, Minimum during day
57/14
33-40/1-4
34-37/1-3
Summer, Maximum during day
84/29
/40-43 23
Summer, Minimum during day
72/22
74/23
71/22

12. Installed Cost Comparison
Compares estimated cost of “rip-out and replace” (ROR) retrofit with specified double-glazed IGU to actual installed cost of internally installed low-e IGU for entire building
Does not include additional long-term savings due to triple-glazed system resultant of internally installed low-e IGU vs. double-glazed ROR.
Total Openings: 532
Total Glazing Area: 18.9 mft2 (1759 m2)
System
Installed Cost
Cost per Opening
Cost per Area
Cost Reduction
ROR
$1,879,545
US$3533
$99/ft2 ($1068/m2)
base
Interior Retrofit IGU
$848,891
US$1596
$44/ft2 ($484/m2)
-54.8%

13. Conclusions
Heating energy reductions of between 40% and 60% compared to monolithic glazing with applied film
Cooling energy savings up to 35% compared to monolithic glazing with applied film
Whole building post-retrofit total energy savings of up to 30%
Interior surface temperatures kept closer to room-side temperature year-round; greater condensation resistance in winter and cooler in summer
Less than half the cost of a ‘rip-out-replace’ full glazing replacement
Additional Benefits:
Minimize internal disruption (off hours)
No change to exterior envelope or weatherization
No scaffolding, rigging, etc. for multi-story/high-rise retrofit
Less total time for full building retrofit

14. Questions???
Tracy G. Rogers Quanex Building Products Phone: