1. Historic Windows:
Don't replace, retrofit for energy savings
Gulf Coast Green 2013
May 2, 2013
Session 3
Alexis McKinney AIA, LEED BD+C
Bailey Architects
alexism@baileyarchitects.com

2. “Gulf Coast Green” is a Registered Provider with The American
Institute of Architects Continuing Education Systems (AIA/CES). Credit(s)
earned on completion of this program 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 program 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. Course Description
While windows can be a low performer on a historic building they are not
the lowest hanging fruit when improving the building’s energy
performance. Once larger issues such as sealing ductwork, adding
insulation, and upgrading the HVAC system are complete windows can
contribute to measurable energy savings. Recent studies have documented
energy savings from window retrofits when compared to high performance
window replacement. The retrofit options studied in five different climates
include weatherstripping, exterior storm window, interior window
panel, insulating cellular shade, combination of exterior storm window and
cellular shade, interior surface film, and a new high performance
replacement window. Historic windows are highly durable using old growth
or higher quality materials, easily repairable, reduce waste and avoid
production of materials for new windows.

4. At the end of this program, participants will be able to:
1. Describe the positives and negatives of different historic
window retrofit options for the gulf coast region.
2. Compare the return on investment of window retrofit versus
high performance window replacement.
3. Understand the benefits of retaining historic windows during a
building renovation.
4. Understand the components in wood and steel windows and
the strategies available to maximize energy savings.
Learning Objectives

5. Preservation = Sustainability
Preservation V. Sustainability
rather than

6. Common Window Myths
• A new window is better than an old window.
• Old windows are bad for building performance.
• High performance windows have quick energy payback
because they are energy efficient.
• Old windows cannot be easily fixed and are expensive.
Bust the Myths!
• Avoid common Preservation beliefs
• Use science based proof
• NO generalities

7. Windows Provide:
• Maintains historic character
• Occupant control – operable
• Passive ventilation
• Fresh air – operable, screens
• Sun shading – awnings
• Natural day lighting
• Occupant views
• Glare control
• Privacy
Jefferson County Courthouse, 1932Camp Mabry Bldg 1, 1918

8. Windows Critical to Character
• Dominant visual element of the
building exterior.
Jefferson County Courthouse, 1932
MFAH, 1953, 1974

9. National Park Service considers windows significant to a
building if:
After
Windows Critical to Character
• Original to the building
• Are of the original design
intent
• Are of the period style or
building type
• Are from period of significant
change to the building
• Examples of exceptional
design or craftsmanship
Before

10. U.S. Energy Information Administration
• HVAC costs account for 40% - 60% of residential and commercial energy
use.
• 10% of air loss is due to windows in a typical American home..
• Other components contributing to energy costs in commercial and
residential buildings
• Under-insulated walls and roofs,
• Un-insulated wall and roof penetrations,
• Doors (air infiltration)
• Foundations
• Air leaks at any opening
• Un-insulated ducts
Energy Use

11. Select Low Hanging Fruit First
Low rise buildings, 1-3 floors, receive 80% of their heat gain on the roof.
Roof and floor insulation upgrades offer the biggest return on investment.
Consider other energy efficient options first before windows:
• Air sealing
• Improving the efficiency of the HVAC system
Insulate
Roof & crawl space
insulation

12. • New windows consume 2-3 BTUs from production. Energy payback can be
40 years and up.
• Manufacture new materials,
maybe not be recyclable (vinyl)
• Construction waste fills landfills
Embodied Energy

13. • Compared residential retrofit strategies in 5 climate zones for
cost, energy, and carbon savings.
Preservation Green Lab & Cascadia Green Building Council; 2012
Saving Windows, Saving Money: Evaluating the Energy
Performance of Window Retrofit and Replacement
• Studied Strategies
– Weather stripping
– Exterior storm window
– Insulated cellular shade
– Exterior storm window & insulating
cellular shade
– Interior surface film (used on exterior
in hot climate)
– New, high performance replacement
window

14. Pros
• Improves air tightness around the sash.
• Inexpensive materials: Spring metal,
compressible tape, sealant bead, or felt.
• Easily installed by homeowner.
Cons
• Requires regular maintenance
• Must be continuous
Fort Bend County Courthouse
Weatherstripping

15. Pros
• Exterior applied window unit for
improved energy performance &
storm protection.
• fixed or operable with screen.
• Improves energy
performance, extends the life of
the historic window.
• Blocks noise infiltration.
Cons
• Changes exterior window
appearance.
• Drainage maintenance.
NTHP
Exterior Storm Window

16. Pros
• Improves thermal performance.
• Not visible from exterior.
• Easier to install than exterior panel.
• Glass or plastic with UV prevention.
Cons
• Mostly fixed panels not allowing
access to window or ventilation.
• Can reduce visibility
• Condensation issues!
Montpelier Mansion
Interior Storm Panel

17. Pros
• Improved thermal performance
• Daylight control & privacy
• No change to historic window
• Common interior appearance
• Manual, motorized, wireless options
• More layers of cells = more efficient
Cons
• Dependent on operator
• Can reduce visibility and day lighting
Bob Vila
Insulating Cellular Shades

18. Pros
• Reduces solar heat gain
• Reduces UV by 99%. Prevents fading
• No change to historic window
• Prevents shattering of impacted glass
• Applied to existing glass
• Maintenance free
• Low-e coating can be applied to
existing glass
Cons
• Film can appear reflective or reduce
light transmission at higher levels
• Reduces winter solar heat gain
Solutions.com
Interior Surface Film

19. Pros
• Predictable performance; tested
• Easily specified and calculated for
energy modeling.
• Warranty
Cons
• Changes appearance of window
• Cannot be repaired in the future
• Expensive
• Removes original material from
building
• Limited lifespan
High Performance Window

20. Retrofit options achieve performance in the same range of new windows in
all climate types.
Findings:

21. NTHP
Exterior storm window and cellular
shades or an interior window
panel achieved the same annual
energy savings as a high
performance window in Atlanta
(hot, humid climate).
Findings:

22. Findings:
Window replacement maximized average energy cost savings and CO2 savings
but not by much.
Energy Savings $29/yr
NTHP

23. Findings:
Window replacement maximized average energy cost savings and CO2 savings
but not by much.
CO2 Savings 734 lb/yr
NTHP

24. Findings: Return on Investment
• Most retrofit options had a better return on
investment than window replacement.
• Insulating cellular shades had highest ROI of 5.2%
• Replacement windows ROI of 1.8%
• If weatherstripping and window film are installed
by the homeowner the ROI is 20 – 30%
NTHP

25. Common types of windows:
Steel
Local Example:
Jefferson County Courthouse, Beaumont
1932 Art Moderne
14 stories
Architect: Fred C. Stone & Augustin
Babin
1909 Neo-classical, “Texas Renaisance”
3 stories + dome
Architect: C.H. Page
Wood
Local Example:
Fort Bend County Courthouse, Richmond

26. Components of wood windows:
• Tight joints
• Glass tight in sash with flexible putty
• Weatherstriping between sash and
frame forming seal
• Correctly sized sash weights
• Sash cord
• Hardware: sash lock & handle
All components necessary for a
functioning window

27. Components
of wood
windows:
Wood Window Repair, Rehabilitation, and Replacement
Exterior Interior

28. Steps to repair wood:
• Evaluate the condition interior and
exterior (signs of water
damage, termites, unsound wood)
• Remove paint
• Remove & repair sashes. Repair glazing
putty. Protect the glazing.
• Repair the frame & sill while sash is
removed. Install new sash cords.
• Install weatherstripping (sash & frame).
• Repaint.
Final condition should be
“sound”. The goal is not
perfection

29. Components of steel windows:
• Gang operation controls & parts
• Solid steel sash & frame
• Glass tight in sash with flexible putty
• Tight fitting sash lock
• Weatherstripping

30. Steps to repair steel:
• Remove paint
• Replace severely corroded parts. Repair
minor corrosion
• Apply high performance coating or new finish
• Reglaze sashes with flexible putty
• Install weatherstripping
• Adjust existing or new
hinges, locks, operating arms and latches or
operation.

31. • Get blower-door test. Discover
where air is leaking. Fix the
problem.
• Install insulation
• Replace HVAC system
• Repair existing windows
• Install cellular shades and
weatherstripping
• Save money
• Install exterior or interior storm
windows
• Conduct routine maintenance
Avoid
Save the existing windows= Save energy

32. • Historic windows can be repaired by non-
technical skilled labor (homeowner or
facilities).
• Unlimited lifespan.
• Prevents construction materials filling
landfills.
• Avoids production of new materials.
Save the existing windows= Save energy

33. Resources
Saving Windows, Saving Money Evaluating the Energy Performance of
Window Retrofit and Replacement. Preservation Green Lab; 2012.
Technical Preservation Guidelines: Upgrading Historic Building windows.
Caroline Anderson, U.S. General Services Administration, April 2009.
The Repair of Historic Wooden Windows. John H. Myers, National Park
Service Preservation Brief 9, 1981.
The Repair and Thermal Upgrading of Historic Steel Windows. Sharon C.
Park AIA, National Park Service Preservation Brief 13, 1984.
Measure Guideline: Wood Window Repair, Rehabilitation, and
Replacement. U.S. Department of Energy; December 2012.
Windows: Energy Efficiency Facts and Myths. Shanon Perterson
Wasielewski; 2004.

34. Alexis McKinney AIA, LEED BD+C
Bailey Architects
alexism@baileyarchitects.com
This concludes The American Institute of Architects Continuing
Education Systems Course
Thank you for your time
Any Questions??