In August 2012, Paul Denys delivered a presentation on The Viability of Heritage Window Technology at an-invitation-only Building Science Summer Camp in Westford, Ma. about the benefits of restoring, rather than replacing, heritage windows. Topics covered include cost and energy savings, materials and technology used in window restoration.
“The reaction was very positive. Steam stripping is a viable choice that most people are not aware of. It does not damage the window and it enables us to harvest antique glass that can be re-used as part of the restoration process.”
Heritage Window Restoration – Paul Denys from Paul Denys
1. Because your windows fit your house.
• Quirky as they might be, your older windows fit your house. Care was taken to match the weight and style of window to the building, the trim, etc. They have expanded and contracted with the seasons. With proper weather stripping they can be made to fit and seal even better. Replacement windows have a rigid structure that fits within your window openings. Old houses move and shift over time and frequently the gaps that open up around replacement windows and the window openings result in more drafts that the original windows.
2. Because you appreciate good craftsmanship
• The true mortise and tenon construction of antique windows is incredibly strong and even when it begins to weaken is easily repaired. Many unique window shapes were created because of the craftsmanship with wood joinery. Antique windows were built to last and not land in landfill.
3. Because you value good materials.
• Antique wood windows are constructed of old growth timber. The wood is much denser and more weather resistant than today’s tree farmed softwoods. Delicate profiles are possible because of the density of the wood. The reason these windows are still around, even with years of neglect, is because the wood is of very high quality requiring no cladding or additional materials to give them weather resistance. Minus all the ugly paint your wood windows are usually quite beautiful, graceful, and strong.
4. Because you love the character of antique glass.
• Even the glass in antique windows tells a story. It may be roundel or cylinder glass, each indicating a certain era of manufacturing. Old glass has varieties of color and texture that are a delight to the eye. Two layers of glass are better than one, and in an antique home that second layer of glass should be the storm window that protects the original window.
5. Because you think a warranty should be more than 20 years.
• Chances are your windows have done their job for fifty or more years already. Sure, they may be a little creaky and may not be as attractive as they once were, but it’s a far better investment to repair a proven performer than to sink money into a new window that only has a 20 year warranty at best. With proper maintenance your antique windows should last another 100 years. Heck, even without maintenance they may last that long! Some are predicting a 400-600 year life span.
6. Because you want to avoid vinyl.
• Poly vinyl chloride (PVC) is becoming one of the greatest concerns in the building industry. Not only does the production of it create an environmental nightmare, but the gases it emits over time are becoming a concern. Heaven forbid your house catches fire, and PVC burned will release toxic amounts of dioxin. If you are concerned about lead, please understand that it is used as a stabilizer in the manufacture of PVC. If you are concerned about our planet’s health you should read up on efforts to reduce the use of vinyl.
7. Because you want more light.
• Replacement windows are set into the window opening, and the sash is smaller than the originals. You get less viewing area and less light. Who wants less light?
8. Because windows are a functional part of your house.
• Weights and pulleys are the best balance systems every invented. There is a prevalent myth that a lot of cold air comes in through the weight pocket. If there is cold air in the weight pocket it’s generally because there is a gap between the outside trim of the house and the siding. It may also indicate a poor seal at the floor joists. Replacing easily serviceable weights and pulleys with vinyl jamb liners or invisible balance systems means installing a system that has a maximum life span of 10-20 years but generally fails in less time. You can’t believe how joyful it is to open and close windows easily with one hand when everything is restored to the way it was designed to work!
9. Because you really can save 30-40% on heating costs.
• According to the Field Study of Energy Impacts of Window Rehab Choices conducted by the Vermont Energy Investment Corporation, the University of Vermont School of Civil and Environmental Engineering and the U.S. Army Cold Regions Research and Engineering laboratory the estimate first year energy savings between a restored wooden window with a good storm window vs. a replacement window was $0.60. Yup, less than a buck. In their conclusions section they noted “The decision to renovate or replace a window should not be based solely on energy considerations, as the difference in estimate first year savings between the upgrade options are small.” Broken glass, failed glazing, no weather stripping – these small and repairable items are what really effect energy efficiency in windows.
10. Because the greenest building is one that is already built.
• Replacement windows are touted as a way to save energy. But when evaluated from the perspective of the entire production, shipping, installation and removal process replacing windows consumes a whole lot of energy, or viewed the other way an older building has a great deal of embodied energy. If the total energy expenditure to manufacture replacement windows is considered the breakeven period stretches to 40-60 years. In the words of Richard Moe, President of the National Trust for Historic Preservation “We can’t build our way out of the global warming crisis. We have to conserve our way out. That means we have to make better, wiser use of what we have already built.” Repairs and restoration work are done by local craftspeople paying local taxes. The use a minimum of materials and resources and a maximum of labor. Restoring windows is the best use of existing materials and the best way to support the local economy.