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Preservation Tech Notes: Windows 1 Planning Approaches To Window Preservation

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Preservation Tech Notes: Windows 1 Planning Approaches To Window Preservation



Charles E. Fisher
Preservation Assistance Division
National Park Service

This standard includes the bulk of information contained in the
original Preservation Tech Notes developed by the National Park
Service and the Center for Architectural Conservation at Georgia
Tech.  The Preservation Tech Notes are case studies of exemplary
projects designed to provide specific examples of sound
preservation techniques.  To obtain a complete copy of The Window
publications, including figures and illustrations, please contact:

         Historic Preservation Education Foundation
         P.O. Box 77160
         Washington, DC  20013-7160

The Window Handbook, jointly prepared by the National Park Service,
Preservation Assistance Division and the Center for Architectural
Conservation at Georgia Tech, also contains all of the Tech Notes
on Windows and is available for purchase from the Historic
Preservation Education Foundation for $32.00.  The Window Workbook
is available for $49.00.  The two publications together can be
purchased for $72.00.

Chicago, Illinois


The Marquette Building, constructed in 1895, is one of Chicago's
finest commercial buildings. Individually listed in the National
Register of Historic Places, the building incorporated the then-
recent structural innovation of the steel frame with a design that
brought much acclaim to the architectural firm of Holabird and
Roche.  Though the site was slated for redevelopment in the 1970's
and the occupancy rate fell to ten percent, a decision was made in
1978 to renovate the building for prime office and retail space in
Chicago's Loop.

The modified Chicago-style windows, which fill the bays between the
structural piers, are one of the most prominent features of the
building's facade.  The large glazed area in each bay consists of
two narrow double-hung sash flanking either a large central fixed
light or a pair of fixed lights.  Careful evaluation of the window
repair and replacement options showed that preserving the historic
windows was the most cost-effective treatment.  The project
demonstrated that proper planning can control rehabilitation costs
- as well as lead to the preservation of historic windows.


The Marquette Building is a 16-story building with 290,000 square
feet of net rentable floor space and fronts on Dearborn and Adams
Streets.  While the building has nearly 350 double-hung windows
principally on the upper three floors and throughout the northern
facade facing on an alley, the 182 Chicago-style windows are of
greatest interest here because of their style, prominence, and
large size.  Although the windows vary in size, most measure about
12' wide by 8' high.

Constructed out of good quality mahogany, the windows were still in
sound physical condition despite over ninety years of exposure to
Chicago's winter weather and years of neglect due to deferred
maintenance.  While some of the sills needed repair, the windows
primarily needed to be repainted and to have some interior trim
replaced.  Recaulking around the frames was necessary, but
otherwise there was very little air infiltration.  The windows had
already proven to be very durable and, except for periodic
painting, long-term maintenance was expected to be minor.  The
project architect, Walter C. Johnson, AIA, of Holabird and Root,
estimated the life of the windows to be in excess of another ninety
years.  Even with this information, the architect and owner still
had other factors to consider in examining alternatives for the
repair or replacement of the windows.


One added consideration for the proposed window work was an
outgrowth of the energy and analysis done for the building.  The
new heating and cooling system (HVAC) chosen as a result of the
study consisted of a variable volume air system for cooling and a
hot water radiation system using perimeter finned tube units.

Based on current operating expenditures and projected energy costs
supplied by the local power company, it was determined that by
having the windows closed all the time, savings could be achieved
as a result of purchasing smaller capacity HVAC units and having
lowered operational costs.


In conjunction with the HVAC analysis, three window alternatives
were considered:

    -    Repairing the existing windows and fixing them closed;

    -    Modifying the existing windows by installing insulated
         glazing for improved thermal performance; or

    -    Replacing the existing windows with high-quality,
         aluminum units with insulating glass that matched the
         appearance of the original.

Criteria for evaluating the three alternatives related to
aesthetics, window performance and economics:

1.   The historic character of the large office windows had to be

2.   Only high quality materials and workmanship would be used in
    any work on the windows, consistent with the goal of creating
    prime office space;

3.   As a result of the decision previously reached concerning the
    new HVAC system for the building, the windows had to be fixed

4.   While specific requirements were not established at the outset
    for the energy efficiency of the windows, a project goal was
    to have the overall building performance standards established
    by the American Society of Heating, Refrigerating and Air-
    Conditioning Engineers, Inc. (ASHRAE); and

5.   Any changes to the windows in order to improve energy
    performance needed to be cost-effective.

With these criteria established, the three window treatments were
then examined in detail.


Repair work needed on the large windows consisted of: (1) repairing
ten units where the vertical mullion dividing the two large fixed
panes had been changed to accommodate interior partition
alterations; (2) installing a fiberglass wrap on approximately 5%
of the wood sills where deterioration was a problem; (3) installing
approximately 1,000 linear feet of new casing trim on the interior
to match original trim that was damaged or that had been removed as
a result of later partition alterations; (4) repainting the
exterior and interior woodwork; and (5) reconditioning the chains,
pulleys, sash weights, and hardware in case the windows ever needed
to be opened.  The estimated cost of this work was $65,000,
including the repair and reinstallation of fixed frames and glass
in 28 windows where a material hoist and trash chutes were locating
during the rehabilitation.


A new estimate was made of the cost-effectiveness of installing
insulated glazing in both the existing fixed panes and the double-
hung sash throughout the building.  The insulating glass would be
installed by cutting back the interior stops.  Such a window system
would lighten the load on the mechanical system by reducing
seasonal heat losses and gains.  This window work would achieve
further savings by reducing energy consumption and permitting
installation of a small HVAC system.  Construction costs, however,
were estimated to be $860,000.


Only good quality, high performance replacement windows were
considered because the architect sought to avoid some of the
recurring problems associated with hangers, connectors, and weather
stripping.  The estimated cost of aluminum replacement windows that
matched the appearance, size and configuration of the existing
windows was nearly $1,600,000.  This estimate included the cost of
removing the existing windows and installing metal substitutes that
had a thermal break and insulating glass.


The windows in the Marquette Building at first glance would seem
prime targets for alteration or replacement in order to improve
their energy performance.  Installing matching replacement units
with thermal glass or adding interior storm glazing both could have
been undertaken without significant alteration to the visual
appearance of the windows, yet the historic windows would have been

After an in-depth study of the repair, modifications, and
replacement alternatives in which such factors as energy costs,
construction costs, and finance charges were considered, the
architect determined that the most cost-effective solution was to
repair the existing windows.

Double glazing, achieved either through adding insulated glazing or
as a result of new replacement units, would have improved the
energy efficiency of the windows and the building, yet would have
been expensive and, in this case, unnecessary.  Assuming the worst
conditions for infiltration, insulating glass would have resulted
at best in energy savings of 10% in heating costs and 15% reduction
in cooling costs.  Building management decided to save the money
since there was no pay back.  Furthermore, even without additional
glazing being added to the windows, the overall building exceeds
the energy utilization and building performance standards of
ASHRAE.  In the future, if conditions change, the addition of
insulating glass could be accomplished with little problem.

Repair work on the windows was conducted at the site working one
floor at a time.  Wood stops were removed, and the windows taken
out of those frames needing repair.  The hardware was cleaned and
repaired, or replaced where missing.  Only about 7% of the windows
and trim required any major work.  Most of the required work was
due to the use during rehabilitation of two fixed windows per floor
for trash removal and the material hoist or where later partitions
intersecting the windows had damaged the wooden trim.  The wood
stops were then reattached using screws in order to facilitate
future window work that might arise.

To prevent tenants from opening the windows, a screw was secured
through the decorative extension on the stiles of both the upper
and lower sash.  The work was done on schedule and within the
original cost estimates.


In many rehabilitation projects involving historic buildings, the
original windows are mistakenly identified as obsolete and, as a
result, are needlessly replaced.  Too often the replacements do not
satisfactorily suit the intent of the original design and thus
severely alter the historic character of the structure.  Where this
occurs, substantial Federal tax incentives for historic
preservation may be jeopardized.

This and other rehabilitation projects have shown the value of
careful and objective evaluation of existing window conditions.
Sound planning can result in window decisions that take into
account good preservation decisions and the realities of the



-    Marquette Building
    140 South Dearborn Street
    Chicago, Illinois


-    Bankers Life and Casualty Company
    Chicago, Illinois

PROJECT DATE:  1979-1982


-    Walker C. Johnson, AIA
    Project Architect
    Holabird & Root
    Architects, Engineers and Planners
    Chicago, Illinois

    Holabird and Root Mechanical Engineers


-    Total rehabilitation cost was $17,000,000 and the window
    repair cost, exclusive of the storefronts was $65,000.

                             END OF SECTION