Covington Window Study
Baker Hunt Arts & Cultural Center
This presents the findings of a comparison of two window options for the Baker Hunt Mansion, (1) replacement windows, versus (2) restoration of the original windows plus the addition of historic-look storms.
Windows are a consistent topic of discussion on Covington’s Urban Design Review Board. Residents believe replacing their historic windows will be cheaper and more energy efficient. Preservation research finds the opposite. To help provide clarity, Progress with Preservation, a local Covington organization, decided to do a comparison of window options. At the same time, Baker Hunt was considering what to do about its window situation. Baker Hunt graciously agreed to allow Progress with Preservation request a window restoration and historic storm window bid for the Mansion, to compare to an existing bid for window replacement previously submitted to Baker Hunt by Anderson.
The Importance of Windows
Windows are character-defining features of a building. Their size, placement, proportion, style, and material composition contribute to how a building looks and feels. Window are integral aspects of architectural design.
A window has four basic functions: admitting light to the interior spaces, providing fresh air and ventilation to the interior, providing a visual link to the outside world, and enhancing the appearance of a building.
Original Windows versus Replacement Windows
When comparing historic windows to replacement windows, in addition to visual appeal, historic windows have many benefits.1
1. Old windows are built with high quality materials. Wood windows made before 1940 are likely to be made from old growth wood. Old growth wood has distinct physical chacteristics that make it superior to new materials. The wood is denser and more durable, rot resistant, and dimensionally more stable than modern wood. Wood used to make windows constructed prior to the 1940’s was also most likely harvested locally, making it better suited for local climate conditions.
The Baker Hunt Mansion was built in 1840 with additions made through the end of that century. Its windows are from old growth wood. An examination of the windows by Joe Clark, Clark Brothers (Window Restoration Company) found that most of Baker Hunt’s windows are in fairly good condition. In general they need relatively minor repairs, weather stripping, repair of broken glass, and general maintenance. A few windows on the front of the Mansion, on the third floor, are in worse condition and will need more significant work.
2. Old windows fit their openings. Historic windows were made and custom installed to fit their specific window openings. Each opening is usually a little bit different, especially because natural materials react to their environment. For example, wood typically shrinks during dry weather and will swell with increased humidity. Older windows may have shifted and changed with their openings as the building aged. After 100 plus years windows may no longer be exactly square, but they still fit the opening.
If new stock replacement windows are installed in historic openings there is very little chance that they will fit well. The resulting gaps around the windows will be just, if not more, drafty than the historic window they replaced.
The Anderson bid that Baker Hunt has is for custom windows, expertly installed. This gives these replacement windows a better chance of fitting in their openings than stock replacement windows.
The historic storm bid from Allied is for custom storms to fit the existing openings.
3. Old windows can be repaired. Traditional windows are made from individual parts. Each piece, the rails, stiles, muntins, stops, sill, stool, jamb, etc… can be individually repaired or replaced in kind. Vinyl, aluminum, fiberglass, and composite windows are manufactured as a unit, and the components generally can not be repaired. When a part fails or the insulated glass seal breaks, or the vinyl warps, the entire unit must be replaced.
The Anderson replacement window bid is for a wood-plastic composite window frame, which is a mixture of wood, vinyl, and an epoxy adhesive. The glass is a double-pane, low-e argon blend insulating glass.
4. Old windows perform well and are energy efficient. A growing body of studies is demonstrating that a historic wood window that is properly maintained, weather stripped, and has a storm window can be just as energy efficient as a new window. While additional testing will provide more evidence, many people find that using a window-storm combination is even more efficient than having a new double pane window unit alone. This is because the air space between a historic window and the storm provides several inches of added insulation.
Restoring Baker Hunt’s original windows and adding historic-look storms will save Baker Hunt $50,000 versus the cost of Anderson Replacement Windows. The scope of work for both options is detailed in
Obviously, initial cost is an important factor, but not the only cost component to consider. Energy efficiency, maintenance, and life of the windows are also important elements of total cost.
In terms of energy efficiency, the insulation value of the wood sash on Baker Hunt’s original windows is about the same as the insulation value of the Anderson composite frame, per Anderson’s bid materials. The difference in insulation values comes in the glass.
Windows lose and gain heat by conduction, convection, radiation, and air leakage. The rate of heat loss is indicated in terms of the U-value — the lower the U-value the greater a window’s resistance to heat flow and the better its insulating value.
The Anderson bid implies the U-value of its windows is ~.30. A second source, the Efficient Window Collaborative, confirms that Andersen windows with similar performance descriptions to the Baker Hunt bid have a U-value of 0.28 – 0.32.
Baker Hunt’s original windows are single pane, clear glass. An estimate of the U-value of these windows is .84 to .91, per the Efficient Window Collaborative and the Colorado Energy Department. With the addition of a storm window the U-value will drop to .49 – .50.
Therefore, the Anderson replacement window will have a better insulating value than the original windows plus storm. What is this worth?
Per the National Trust, on average, replacing windows with new higher quality replacement windows (when properly installed) could save you about $50 month on your heating or cooling bills (in a 24-30 window average home). A typical replacement window fails within 20 years. And per Walter Sedovic, CEO Walter Sedovic Architects (historic preservation and sustainable design), 30% of the time a replacement window will be replaced within 10 years.
Anderson has provided a warranty of 20 years on the glass, 10 years on the components and 2 years on labor and service.
Anderson’s bid is for 73 windows, so theoretically 2.5 – 3.0 times the heating/cooling cost estimate savings above. Assuming a savings of $150/month in heating and cooling, it would take more than 27 years for the Anderson windows to pay back the difference versus the original window restoration plus storms, more than 7 years longer than the replacement windows are likely to last.
Replacement windows often make a claim of “maintenance free”. However, experts agree that replacement windows are not maintenance free. This maintenance free claim is most often used with companies that sell vinyl and aluminum windows. These windows simply can not be maintained or repaired. When a part fails or the insulated glass seal breaks, or the vinyl warps the entire unit must be replaced. Anderson’s bid also makes a claim of maintenance free.
Historic homes were built with energy efficiency in mind. High ceilings, transoms over doors, windows that open, exterior or interior operating shutters, thick masonry walls, and roof overhangs are all important energy saving elements in these homes.
It is estimated that between 15-30% of heat/cooling is lost through windows. Therefore focusing on windows alone will not solve the issue. Most heat loss in a building goes through the roof and other gaps in the walls and foundation. The National Trust for Historic Preservation has written a brief, “Conserving Energy in Historic Buildings” and recommends the following energy saving measures: weather stripping doors and windows, and caulking open cracks and joints to reduce air infiltration; insulation in accessible attic spaces; storm windows; basement and crawl space insulation; and duct and pipe insulation.
Baker Hunt can identify where it is losing most of its heat/cooling by conducting an energy audit – something that local or state energy agencies frequently offer for free. Alternatively, or in addition, Black & Decker sells a thermal leak detector for about $50. This tool can help pinpoint where heat is being lost. And finally, proper thermostat control, based on building use, can also be a significant energy saver.
Assuming that the Board decides to restore the original windows and add historic storms there are three remaining decisions to be made: type of storm; color of storm; and what to do with the stained glass windows.
As was mentioned, in the back of the Mansion the Board has the choice of using triple track storms versus the fixed-in-place historic storms. Triple-track storms on the back of a building in the Historic Licking Riverside Overlay Zone will be approved by the Urban Design Review Board. Aside from a lower cost, the additional benefit of the triple track storms are ease of use for ventilation. Baker Hunt should seriously consider choosing the triple-track option for the back of the Mansion.
The storm window bid includes the standard colors of white, off-white, black, brown, or bronze. The storm color should match the color of the window rails, stile, and mutins. This part of the windows is currently painted grey/black. Black would likely be the appropriate storm window color choice.
The stained glass windows are currently obscured from the outside by a protective glass and wire mess. The original intent of the stained glass windows was that they be viewable from both the interior and exterior of the home. Therefore the restoration and storm window bids assume the removal of the existing protection and replacement with a clear Allied fixed-in-place storm. We recommend proceeding with this plan, however it is a choice that the Board should be aware of.
In terms of cost, visual character consistency, and life, restoring the original windows and adding historic storms is the better choice for Baker Hunt.
Progress with Preservation is grateful to the Board for the opportunity to perform this comparison and would be happy to answer any questions or talk with the Board directly.
Sincerely, Lisa Sauer
Progress with Preservation
1. Scope of Work Summary
2. What Replacement Windows Can’t Replace: The Real Cost of Removing Historic Windows
1 The benefits outlined here are attributed to the National Trust for Historic Preservation.
Scope of Work
Anderson: Replacement of windows in 73 openings, 1 door opening, and 2 storm doors. Interior storm panels are being provided for certain windows not being replaced because of their art glass or curved glass shape. The architectural appearance of the new units will duplicate the appearance of the existing units as closely as possible. Value engineering of some windows will change their functionality in order to reduce cost, but will not adversely affect their appearance. Several of these windows are on the third floor, and none of the others are currently operable.
The installation technique to be used calls for all interior and exterior trim components to remain in place. We plan to use the least invasive installation process will be in accordance with Renewal by Anderson’s specifications. Installation will be performed by Renewal by Anderson’s own factory trained technicians. No sub-contractors.
Because of the complexity of many of the window units lead time will be approximately 6-8 weeks. Installation should be completed in 5-7 days.
The installed price includes the removal and disposal of the old units (unless you wish to retain them for some reason), setting the units, insulation and caulking. The units will come pre-finished white, so there is no painting included in the proposal. We were informed that a member of the Baker Hunt staff could perform any touch-up that may be required.
Clark Brothers: Repair the sash and frames, re-rope, replace broken/cracked glass, re-glaze, all as necessary based on individual condition of each window. Remove existing storm windows and screen guides, scrape, sand, spot prime and apply 1 coat of paint to the exterior of all of the windows (sash to the blind-stop), replace broken parting bead as necessary, replace missing or defective weather striping, and service the operation of the double-hung and casement windows.
- 65 Double Hung Windows
- 14 Casement Windows
- 11 Fixed Sash
- 4 Bowed Sash
- 1 Circle Sash
- 6 Single Hung Windows
Allied Installations: Furnish and Install Custom Size Aluminum Historic Storm Windows per basic specs:
- Clear DSB Glass
- 1/8” Plex for Bowed Windows
- White Color (Board can choose from standard color selection of white, off-white, black, brown, bronze)
- Circle Top Windows
- Option is to use triple track storm windows where possible, historic as required