This time of year, you might think that replacing old, drafty windows is the only way to keep your home warm in the winter. Think again!
Switching to new energy-efficient windows can be expensive — ranging from $8,000-$15,000 or more for a typical home. Despite windows accounting for more than 30 percent of a typical home’s heating losses regardless of their age, you can improve your home’s comfort and lower your energy bills by sealing air leaks, repairing windows and investing in better insulation.
If your primary windows are in fairly good condition, attaching storm windows — in particular, low-emissivity or “low-e” storm windows — can boost energy efficiency and comfort at about a quarter of the cost of a total replacement. Whether you are a professional home performance contractor or a do-it-yourself homeowner, follow these five simple steps for making your windows more energy efficient.
STEP 1: PREPARING YOUR EXISTING WINDOWS
To determine whether you should add storm windows, check each existing window to ensure there is no missing glass, rotting wood, broken parts, or egregious air and water leakage. If there are obvious leaks around the frame of the window, some weatherization and rehab may be necessary before installing the storm windows.
You or your contractor can learn more about energy-efficient and durable window rehabs from the comprehensive Wood Window Repair, Rehabilitation & Replacement Guide. And check out Savings Projects for step-by-step guides to caulking and weatherstrip your windows.
If your window is in good condition — but you are still concerned about comfort, heat loss and air leakage — consider mounting a low-e storm window as an exterior attachment or as an interior panel to your existing window.
Any well-constructed and well-installed storm window can reduce air infiltration through the window, whether it’s coated or not. However, low-e coating (a nearly invisible layer on the glass) reduces conduction and radiation heat losses even further and can improve overall energy savings by 10-15 percent more than standard storm windows without the high-performance coating.
In fact, the incremental cost of using low-e glass versus clear glass storm windows is well worth the investment. A recent Energy Department study that examined storm windows in various U.S. climate zones found that low-e storm windows are cost-effective in all climate zones, with an average payback of two to four years.
STEP 3: WHERE TO FIND LOW-E STORM WINDOWS
While some big-box retailers stock standard sizes of storm windows, to ensure a good fit with your existing window, storm windows should typically to be custom ordered. Low-e storm windows should also be customized and are available for order from both independent window dealers and big-box retailers. The Building America Programs’ Solution Center provides guidance on making accurate measurements of your primary window to ensure a good storm window fit.
Several regional utilities offer rebates and incentives for purchasing and installing storm windows. While some utilities may not specifically include storm windows as part of their incentive programs, they may generally include it under building enclosure/insulation or window categories.
Ask your local utility about incentives for low-e storm windows, and check energy.gov/savings.
STEP 5: KEEP YOUR STORM WINDOWS UP ALL YEAR ROUND
Although storm windows and panels can always be removed, they also can be mounted as permanent installations. Unlike your grandmother’s storm windows, modern storm windows are operable windows that can be left in place year-round, with sashes and insect screens that can be opened in the summer.
When compared to not installing storm windows at all, low-e storm windows can help save 12-33 percent in a year heating and cooling costs — a finding that is based on Energy Department field tests and case studies. That means if your annual heating and cooling expenses are about $1,000, installing storm windows would likely save $120-$330 each year — or even more if your existing windows are leaky.