The Economic & Environmental Reasons to Restore Your Windows
The Importance of Existing Buildings
It is estimated that cities consume more than 75% of the world's natural resources, produce more than 50% of global waste, and emit up to 80% of the world's greenhouse gases. The architecture, construction, and engineering (AEC) industry as a whole is moving towards practices and policies that prioritize reuse of existing structures and materials in order to minimize unnecessary waste, combat rampant consumerism, and reduce dependency on both renewable and non-renewable resources.
A Whole-Structure Approach
The existing materials in your building have a smaller carbon footprint than any new materials available on the market. The introduction of new products and materials to improve the operational efficiency of a building should only occur after careful consideration of all of the impacts associated with the creation of those materials. For smaller buildings, such as single-family dwellings, the environmental impact of retrofit products may be even greater than the impact of doing nothing at all!
Why are Windows Important?
A value of a historic home is equal to the sum of its parts. As original materials are removed from a historic property, it begins to lose its integrity and ultimately its historic value. Historic windows greatly contribute to a property in terms of character and craftsmanship. They were expertly designed and constructed from high-quality materials. Preserving historic windows in place keeps original, high quality materials with the property and out of the landfill.
In historic homes, the windows are an integral part of the design. They were designed to not only be aesthetically pleasing, but were necessary as a functioning component to the building by providing light and ventilation. The loss of original windows also has great potential to negatively impact the appearance of a historic home. Building facades lose proportionality and depth as modern replacements are introduced.
Historic wood windows can certainly be maintained or restored to working order. Preservation of original architectural features, including windows, is encouraged in the City of San Antonio Historic Design Guidelines. Nevertheless, there is an abundance of replacement window products that are too often used by historic home owners seeking to “upgrade” their aging properties.
Why the Replacement Craze?
In an age where energy reduction is at the forefront of every homeowner’s mind, windows are often blamed as the leading culprit of heat gain/loss. The criminalization of “drafty old windows” is nothing new; window manufacturers have long been pointing out the faults of old windows while promoting attractive solutions (their products). New low-e, gas-filled and triple pane replacements may seem like an exciting solution for homeowners coping with their monthly energy bill. Walk into any home-improvement store, and you may be feeling the pressure to replace. Imagine the savings!
In reality, heat gain/loss occurs evenly throughout the home, with windows only accounting for a small percentage of waste. Poorly insulated walls and attics are probably the greater culprit, especially locally. The San Antonio climate offers many days of full sun. While we enjoy these sunny days in the winter, during the hot summer months that same sun bears down on rooftops, turning attics into ovens. Trying to solve an energy problem by only addressing the windows is like trying to hold water in a leaky bucket and only patching a few of its holes.
The Real Costs
Because many historic windows feature single pane glass, a multi-pane, energy efficient replacement will, in fact, reduce heat/gain loss through the windows of a home, and most homeowners experience 5-15% annual savings in energy costs. However, there is a very real economic tradeoff between the costs of replacing windows, their lifespan, and the actual energy savings that must be considered. Studies provided by the National Trust for Historic Preservation indicate that replacement windows offer a relatively low return on investment compared to traditional window maintenance and shading.
In determining the true savings achieved through window replacement, one should assess:
1) The initial replacement costs: The cost of an in-kind (wood) replacement window can range between $700-$1,500 per window. Including installation and general construction costs, homeowners undertaking full window replacement may spend anywhere from $15,000 to $30,000 depending on the quality, glazing options, and number of windows. This figure doesn’t include the costs of retrofitting additional elements of the home to accommodate manufacturer’s stock sizing, like trim, siding, and even framing. Patching in these areas will add to an overall replacement cost estimate.
2) Annual savings: Assuming that full window replacement yields a 15% reduction in annual energy costs, the average homeowner would save approximately $400-$600 per year. However, no assumptions about energy savings should be made until an energy audit has been performed to determine where heat gain/loss is really occurring. Most often, homes lose the most energy through small openings or cracks at floorboards, door openings, and roof eaves. If there are multiple points of air infiltration, that draftiness can be significant! Energy audits help identify key areas where routine maintenance and repair can make a significant difference in air flow.
3) The lifespan of the replacement: Historic wood windows were constructed using high-quality, old growth hardwoods - meaning that the wood was harvested from trees that grew for hundreds, sometimes even thousands, of years before being felled in the late 19th or early 20th century. These materials are extremely durable and naturally resistant to deterioration. In many cases, wood windows in historic properties have withstood the elements for over 100 years. A repaired historic window that is maintained over time can easily last for another 100 years. Replacement windows have a much shorter lifespan, with aluminum or vinyl products on the lower end. Modern wood windows utilize second or third growth trees, which were grown for an average of 20 years (versus hundreds) before being harvested, making them less durable, more rot resistant, and less dense. Even the most reputable window manufacturers only offer limited 10-year warranties on their products for a reason - and they are often not transferrable between owners, and warranties can be voided just for painting them! Keep in mind, when a replacement window fails, the entire factory unit must be replaced again (and again). New replacement products are just that - replacements - meaning they will be replaced again, and again, and again, adding to growing landfill waste.
4) Payback period or return on investment: Assuming an annual savings in the $400-600 range (which is generous), the average historic homeowner would experience a payback period of at least 20 years in order to see a return on investment. The payback period may be greater depending on the size of the home and number of windows that were initially purchased. After more than 20 years, it will most likely be time to replace again!
To recap, consider the hidden costs of buying new to ensure the total lifecycle costs are considered:
Resource Extraction & Manufacturing: The creation of new building products is extremely resource-intensive. For example, vinyl is a petroleum-based product. Consider the environmental impact of mining, extraction, and manufacturing of virgin resources when evaluating the overall sustainability of your choice.
Transportation: From factory to showroom to installation, the transportation costs can be significant. Older materials were often sourced locally and the repair of existing materials by local businesses limits the environmental impacts of transportation.
Limited Warranties: Most replacement products offer limited warranties that can be voided in multiple ways. For example, several replacement window warranties can be voided through painting, improper maintenance or repair techniques, or even just by selling the property (non-transferable clauses). Evaluate warranties carefully.
Replacement Cycle: Historic building elements were constructed with repair in mind and can often be disassembled, spot-repaired, and reassembled using readily available tools. Modern products are sold as standalone elements and can be difficult to repair, or may require specialty components that are contingent upon the original company remaining in business. Consider the lifespan of your product and whether your investment will have to be fully replaced in 15-20 years, creating a continuous cycle of replacement.
End-of-Life Waste: Plastic and composite materials can take up to 1,000 years to decompose in a landfill, making repair and reuse of existing materials and products the most sustainable option overall.
Old vs. new: when it comes to wood, there’s no debate on which is superior! The old growth board on the left has a denser ring structure, making it more durable, straighter, and more resistant to warping, insects, and rot. It’s also more easily repairable and restorable. Consider original hardwood floors: they are not only coveted due to their beauty, but also due to their ability to be sanded and sealed multiple times to last hundreds of years. The same concept applies to wood windows.
Window Repair
In most cases, window repair is not only the more affordable solution upfront, but offers a much greater return on investment than replacement. Repairing and maintaining an old wood window may seem like a daunting task. It is important for historic property owners to familiarize themselves with the anatomy of their windows and standard practices of maintenance and repair. By educating themselves on these practices, repairs can become something that any homeowner can tackle one window at a time (although feel free to obtain the services of a professional!)
Each window should be assessed for its individual performance. Consider the following:
Is the window operable?
Are the any noticeable gaps in between meeting rails, sills or stops?
Do the joints between the rails and stiles seem soft or spongy?
Is the glazing loose or missing?
Is the paint cracked, peeling or faded?
Is there trapped or infiltrating moisture?
Are there any rotted or broken components?
Is hardware intact and functioning?
By identifying and addressing problem areas, any window can be made improved in both efficiency and function. Remember that historic windows were intended to be taken apart so that if one piece fails, only that piece can be replaced. Check out the resources section at the end of this article for guidance on window repair.
Other Solutions
Even windows in the best condition can be made more energy efficient. Heat gain/loss through windows occurs in three different ways: air infiltration, heat transfer (conduction) and solar gain (radiation). There are a number of low cost, reversible and historically appropriate strategies that can be used to reduce heat gain/loss. It should be noted that implementing a combination of any of these techniques can be just as effective in arresting heat gain/loss as a brand new window.
Weather stripping is perhaps the cheapest and easiest solution for improving window efficiency. Proper weather stripping drastically reduces air infiltration at meeting points in the window. This can easily be done by any homeowner and offers a great return on investment.
Storm windows can be used to provide an additional transparent barrier between the outside and inside of a historic home. Their installation creates an insulating air pocket which reduces heat transfer. Storm windows can be hung from the interior of a window and simply clipped or wedged into place (some even use magnets) for easy removal and cleaning. Some exterior storm windows may be appropriate provided that they have a thin frame and are used with either a decorative screen or in a manner that does not obscure any architectural details.
Shades, shutters and screens can all be used to prevent solar gain during the hot summer months or seasons where windows receive direct sunlight. Some interior shades also have insulating qualities that can reduce heat transfer. Solar screens are gaining in popularity, but are only appropriate when installed on the rear of a building as to not have a visual impact from the street.
Interior window films can be applied to reduce the impact of solar gain, and are another affordable, easy solution. A wide variety of products are available, but homeowners should be cautious to avoid films that are deeply tinted or reflective as they have the potential to alter the exterior appearance of the glass.
When You Must Replace
Not every historic building will have repairable windows. In instances where windows have been neglected or poorly maintained over time, original wood windows may have deteriorated beyond repair. When 50% or more of the original window components must be replaced with new material, a full replacement may be considered. Office of Historic Preservation staff is available to meet on your property to help you determine if your windows are repairable or if replacements are appropriate.
According to the Historic Design Guidelines, new windows (when approved) should match the historic or existing windows in terms of size, type, configuration, material, form, appearance, and detail. The Office of Historic Preservation recommends searching through architectural salvage yards or online markets before paying for expensive custom replacements. Only in-kind replacements are recommended; replacing wood windows with cheap aluminum or vinyl alternatives, pictured below, should be avoided.
In instances where original windows are no longer intact or have previously been replaced with inappropriate materials, look for replacements that restore the look and feel of the original construction. Use nearby historic buildings that are similar in style to make your selections. Restoring historically-appropriate wood windows to a property is encouraged by the Office of Historic Preservation and can usually be approved administratively by staff.
Summary
Over 112 million windows end up in landfills each year, and about half are under 20 years old. Historic wood windows were constructed to last 100+ years with old growth wood, which is substantially more durable than modern wood and clad products, and original windows that are restored and maintained over time can last for decades. Replacement window products have a much shorter lifespan, around 10-20 years, and cannot be repaired once they fail. On average, over the lifetime of an original wood window, replacement windows will need to be again replaced at least 4 times. The total lifecycle cost of replacement windows is also much more energy intensive than the restoration of existing windows, including material sourcing and the depletion of natural resources and forests, petroleum-heavy manufacturing methods, transportation, and installation. Finally, window repair and restoration utilizes the local labor and expertise of craftspeople versus off-the-shelf, non-custom composite products. We encourage the repair and restoration of original windows whenever possible for all of these reasons and more!
Resources
Rehabber Club periodically hosts historic window repair and restoration courses. The courses are open to all, and for a small tuition, participants receive hands-on training in window repair. Past workshops have been held at the Fire Station No. 1 and both the Acosta/Halff House and Richter House in Hemisfair Park. To date, over 50 historic wood windows have been restored by course participants. Visit our events page to see our upcoming courses, or sign up for the Rehabber Club emailing list to be among the first to register!
Additionally, we have a list of local window restoration contractors that can repair your windows. Scott’s List is another local contractor source, and the Window Preservation Alliance has a national network of contractors offering their services to property stewards.
Finally, the Office of Historic Preservation is a resource to you. Please reach out with any questions or for a property-specific consultation.
References
The Top Things You Should Know About Retrofitting Historic Windows
Energy Retrofits for Hot-Humid Climates (UTSA Study with Cost-Benefit Analyses)