Residential Design and Construction offers over 75 workshop and professional development opportunities to enrich residential design and construction professionals’ design and technical skills. Nationally and internationally recognized industry leaders team with Boston’s best to share their knowledge and expertise.

Before you replace your old windows, review the information, collected from the workshop panelists and tradeshow exhibitors, as presented below!

1. 10 Things I Hate About Your Renovation
An RDC Conference Workshop that presented three strong views on common and avoidable mistakes made in renovating older homes. An architect, an historic renovation contractor, and the former Executive Producer of “This Old House” took on such topics as window replacement, insulation, kitchens and baths, materials, taste, and additions deft and otherwise. The panel discussion was conducted by;

2. Testing the Energy Performance of Wood Windows in Cold Climates
A Report to The State of Vermont Division for Historic Preservation, Agency of Commerce and Community Development by Brad James, Andrew Shapiro, Steve Flanders and Dr. David Hemenway, 115 pages.

• Replacing a historic window does not necessarily result in greater energy savings than upgrading the window.
• The decision to replace or renovate a window generally should be made on the basis of considerations other than energy cost savings.
• Exterior storm windows can reduce air leakage by 45%-75%.
• Weather-stripping also can significantly reduce air leakage.
• Energy loss attributable to windows is about 20% of whole house loss.

3. Creating Windows of Energy-Saving Opportunity
Shapiro & James, Home Energy Magazine Sept.- Oct. 1997
Andrew M. Shapiro is an energy engineer with the Vermont Energy Investment Corporation in Burlington, VT. Brad James is a master's degree candidate at the University of Vermont. Steve Flanders of the U.S. Army Cold Regions Research and Engineering Laboratory assisted with project oversight.
Windows are where we often look to improve the energy performance in old homes. But don't rip out those old sashes yet. A field study in Vermont suggests that "remove and replace" is not necessarily the way to go when it comes to old windows.

• In comparing various types of renovations and replacements, the largest energy cost savings was projected for replacing a loose single-pane window with a double-glazed low-e window ($20/year/window). Replacing a tight, weather-stripped single-pane window with a double-glazed low-e window reduced energy cost about $5.30/year/window.
• The second largest energy cost savings came from installing a storm window over a loose window ($16-$19/window).
• Weather-stripping a loose window saved $14-$15 per window per year.
• Installing an interior low-e storm window over an average single-pane window offers energy cost savings similar to replacing the window with a double-glazed low-e window ($6.20 vs. $6.80/year), but at a much lower cost.
• Replacing just the sash of a window offers little energy cost savings over retaining and renovating the sash ($14-$15/year vs. $15/year).

4. Windows: Understanding Energy-Efficient Performance
Paul Fisette, Director of the UMASS Amherst Building Materials & Wood Technology, 2003
An update on how today's high-tech windows work and what to look for when you make your next purchase.

When we choose windows for a new home or remodeling project, appearance is usually our first consideration. Most often we choose casement, awning, double-hung or fixed glass based on personal taste - not because they provide a tighter seal or the best natural ventilation. Convenience is important too. An entire industry is built around the tilt-out window. Liking a window's appearance is a fuzzy proposition. But performance and cost are absolute. They are important values deserving thoughtful consideration.

• 30% of house’s heating and cooling energy may be lost through windows.

5. Replacing Windows, Energy Star Remodeling Guide
Replacing windows is rarely cost-effective based solely on energy-savings. However, if you are planning to replace your windows because of maintenance or aesthetic reasons, make the most of the opportunity and consider ENERGY STAR Home Sealing. You’ll get new windows, comfort, and energy cost savings.

ENERGY STAR labeled windows, doors, and skylights are twice as efficient as the average windows manufactured just 10 years ago. They help cut your heating and cooling costs and can make your home more comfortable without compromising cost, comfort, versatility, or style. These high-performing windows are available in every operator type, including single- and double-hung, casement, horizontal slider, fixed, picture, and patio slider. And, they are manufactured with most common frame materials, including aluminum, fiberglass, vinyl, and wood.

6. How to Save Energy When You Fix Up the Outside of Your Not-So-New House Retrofit Best Practices Guide, January 2004 Oak Ridge National Laboratory

• Storm windows cost much less than replacement windows but can potentially save nearly as much energy, especially those with low-e coating.
• Replacing single-paned wood frame window with double-paned vinyl window reduces window heat loss by 48%; installing low-e interior storm window instead reduces heat loss by 46%; installing low-e exterior storm window, 35%.

7. Household Air Leakage Pie Chart U.S. DOE website, Energy Savers page

8. Wiser Window Retrofits
Home Energy Magazine, July/August 2002

• Case Product U-factor SHGC Notes glass temp. at 0 ° F outside
• 2 Single-pane + exterior storm U=0.49 R=2.04
• 3 Single-pane + low-e storm U=0.38 R=2.68
• 7 Double-pane wood/vinyl clear glass U=0.50 R=2
• 8 Double-pane wood/vinyl low-e U=0.40 R=2.5

• Replacement windows rarely have the lifespan of the original window because the materials are inferior: fast growth wood, finger joinery, corrodible fasteners all contribute to a short life.
• Thermal pane glass works as long as the gaskets/seals are intact. Most glass has a warranty for 20 years or less.
• Operating hardware for new windows is more complex and sometimes proprietary. What happens when a jamb liner gives out in 10 or 15 years and the parts are no longer available?
• Replacing windows costs a bundle. A full window replacement, including the frame, involves casing removal and sometimes finish wall removal.
• Let's put forward a scenario:
  
  

Windows account for somewhere between 20% and 30% of your building's energy loss. So, take 25% of your yearly heating bill (heat loss through windows), then take 10% of that number (improved efficiency with a low-e double-glaze replacement window over an old window with a storm window).

The result is the amount of money you could expect to save in energy use. If you replace 25 windows at a cost of $300/window, the Total Installation Cost = $7,500.

ROI? Let's assume $5,000 in annual heating and cooling costs... then 25% of $5000 goes out the windows = $1250. Now, 10% of that is what you will save in energy use or, $125. So...it takes 60 YEARS to earn your money back! (not accounting for inflation)

Of course, your sucessors will have replaced your "replacement" windows at least once by then.

9. In Defense of the Old
John Leeke, Smart HomeOwner magazine Mar/Apr 2002
A preservationist makes the case for saving old windows when possible.

10. Save Your Wood Windows
A report by John Leek covering traditional methods and the latest in modern high-tech materials and techniques. Learn how to avoid falling under the spell of the window replacement salesman. Fifteen specific step-by-step treatments to repair weathered sills and deteriorating sash. 59 pages, 119 illustrations.

View sample pages or, read a review.

11. What Replacement Windows Can’t Replace: The Real Cost of Removing Historic Windows
Walter Sedovic and Jill H. Gotthelf, APT Bulletin: The Journal of Preservation Technology Vol. 36 April '05, pp. 25-29
APT Bulletin articles showcase cutting-edge preservation techniques, as well as innovative applications of established restoration technologies. All those concerned with historic structures-architects, conservators, engineers, contractors, craftspersons, educators, developers, property owners, historians, apprentices, and students- will learn about how to treat historic buildings and landscapes more intelligently, thus affording properties longer, more viable lives. No other journal has published so long and so well in this field. Sustainability looks even better through a restored window.