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New Ideas about Old Windows (II)

In a previous issue of Foundations, the lifecycle environmental costs associated with the disposal and replacement of historic wooden windows were contrasted against the gains in energy efficiency that could be achieved through the installation of new, energy efficient windows. Given the energy and resource losses caused by disposing an original window and fabricating a new one that has a shorter predicted lifespan, the energy savings achieved by window replacement are not as clear cut as window manufacturers might have you believe. There are, however, additional considerations when deciding whether or not to replace old wooden windows. This article considers the factors of cost, maintenance and ease of operation for old wooden windows compared with new windows.


It goes without saying that if reduction in cooling and heating costs is the primary motivation for window replacement, homeowners would be wise to invest money toward retrofits that will recoup the cost of the retrofit quickly through savings in their household energy bill. Building researchers refer to this rate of recouping costs as the “return on investment” (not to be mistaken for the phrase used by real estate professionals when referring to costs recovered through the sale of a house).

In a review of different window replacement and retrofit options, recent studies have found that the average return on investment (ROI) for window replacement was lower than the average ROI that could be achieved through window retrofit options such as the installation of insulated cellular shades or the installation of an interior storm window.1,2,3 In these studies, high performance replacement windows did offer energy savings, but the savings were only marginally better than those achieved by retrofitting the existing window and they came at a much heftier price tag. In addition, the payback period for installing new windows has been estimated to range between 40 and 100 years — longer than the lifespan of many replacement windows! 1,3,4

To maximize the impact of home renovations on energy bills, experts recommend that homeowners take a more holistic view of the main sources of energy consumption in the home. For homes built prior to WWII, an aging furnace or boiler, and uninsulated walls, attics, and basements contribute significantly more to their total energy bill than do older windows (see Figure 1).4 For these homes, energy efficiency improvements such as replacing an older furnace, air sealing, filling the wall cavity with insulation, insulating attics and insulating the tops of basement walls, are likely to have a significantly greater impact on a home owner’s energy bill than window replacement.

In contrast, heat loss from windows and doors in newer homes with insulated walls comprises a significantly higher proportion of the total heat lost. A breakdown of the relative contribution of energy retrofits to your total heating bill for houses of different styles and ages can be found on the Canadian Mortgage and Housing Canada website.

Maintenance and Repair

There is no question that old windows require maintenance. Wooden frames and storm windows require repainting or touch ups once every five years or as needed. If the glazing putty that seals the joint between the glass and the frame become brittle or cracked, it may need replacing. The counterweight mechanism that permits easy opening and closing of the windows may require a new pulley rope if the original rope is broken.

The good news is that the materials required for maintenance of wooden windows are relatively inexpensive and readily available at most hardware stores. And while maintenance can be time consuming, the level of skill required for most maintenance is relatively low. Do-it-yourselfers can find resources for conducting their own maintenance and minor repairs at the end of this article and in Part I of the series published in a previous issue.

Repair or restoration of damaged wooden windows is more labour intensive and may require the help of a contractor familiar with restoration. Contact the Waterloo Municipal Heritage Committee for a list of local contractors who are familiar with window restoration.

Handy homeowners may seek guidance on window repair from the US National Park Service brief on window repair or from back issues of Old House Journal or Edifice Magazine.

In contrast to old wooden windows, new windows are generally advertised to be “maintenance free”. Critics of the maintenance free claim argue that new windows are often unrepairable and are usually thrown out and replaced when they fail. According to the Siding and Window Dealers Association of Canada, “more than 75% of vinyl window manufacturers in Canada do not test their windows for air infiltration, water leakage and strength, according to government standards”5 which casts additional doubt on any maintenance free claim.

Provided that the window frame has not failed, window sash repair kits may be available for new window units if those window models are still being manufactured. Sash repair kits cost somewhere in the order of $250-300 for a window measuring 30 inches wide by 60 inches tall.6

Ease of Operation

New windows have a number of features absent in old wooden windows that make them easier to use. Cleaning, for example, is significantly easier with the tilting features available for many new windows. For older windows that don’t tilt, they must be cleaned from the outside using a ladder, or disassembled from the inside for cleaning. Both options can be time consuming and the latter option requires a certain degree of skill that many homeowners simply do not possess.

Perhaps the most onerous chore in the operation of old wooden windows is the seasonal installation and removal of exterior storm windows. The purchase and installation of interior rather than exterior storm windows can provide an alternative to this task. Interior storms are often designed to adhere to a magnetic strip affixed to the inside of the window and windows can be installed and removed from inside the house without the use of special tools or ladders. Although interior storm windows do not protect the wooden window from the elements, they do offer the same energy saving functionality.


Recent awareness of household energy use, combined with government incentive programs for energy efficient retrofits have made windows a target for homeowners seeking to reduce their environmental impact or save money on their energy bills. But decisions to replace historic windows in absence of information on the range of energy conservation techniques, the hidden costs of disposal, and the return on investment for new windows may result in poor decisions that fail to achieve the homeowner’s environmental or financial goals. This article aims to provide homeowners with a broader range of considerations that are important when considering the replacement of historic windows.

1 Saving Windows, Saving Money: Evaluating the Energy Performance of Window Retrofit and Replacement. (2012). A report by the Preservation Green Lab in partnership with the National Centre for Preservation Technology and Training, Cascadia Green Building Council, and Ecotope.
2 Baker, P. (2012). Measure Guideline—Wood Window Repair, Rehabilitation, and Replacement. Prepared for Office of Energy Efficiency and Renewable Energy,
U.S. Department of EnergyResearch, Report # RR-1203.
3 Shapiro, A. M. and James, B. (1997). Creating Windows of Energy-Saving Opportunity. Home Energy Magazine, Sept/Oct issue. Website: www.
4 Sims, C. (2006). Repair or replace. Windows in historic buildings: Arriving at a sustainable solution. Heritage, Summer, p. 40-49. Website: http:// heritage%20canada.pdf.
5 Siding and Window Dealers Association of Canada, Windowwise Program, 2012.
6 Peter Yost, Director of Residential Services for the non-profit US site BuildingGreen

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