Your Window on Energy Savings

Bob Alf Construction

Better windows can save money, brighten your mood, and freshen your air, but beware OF the advice of a window salesperson or your neighbor.

Windows are a hot topic, especially now that the US government is offering a sizable tax credit for home energy improvements.1 Yet the countless types of windows that are now available, plus the complexity of installation can leave you a bit vulnerable. Sales and installation folks are often very busy so their tendency may be to lead you toward the fastest and highest margin options, not the options that are best for you and your house. Beyond these cautions, this article provides a path toward a less confusing and better prioritized investment in windows. An understanding of industry terms will be crucial, so refer to the “Glossary” as necessary.

Window Myths and Traps

Before diving into an understanding of window options, it’s first helpful to understand some common myths and traps. See the chart below.

Myth / Trap

The Truth

Myth: Windows are so expensive you should spend your energy improvement budget on something else

Many homes now have very efficient furnaces and boilers, well-insulated walls, and well-sealed attics. This may leave windows and doors (about 25-30 percent of total wall surface) ridiculously inefficient. Usually, improving your energy envelope, including windows and doors, should be done before replacing your furnace.

Trap: New windows can be installed for under $200

Watch for advertisements for very low cost (and most likely cheaply made) windows and installation. It is better to install several good, well-built, efficient windows than a bunch of bad windows.

Trap: “The Shrinking View”

Some homeowners receive “totally new windows” only to find that these new windows were installed into the old frames, thus reducing visible glass size by almost 10 percent. For some, this surprise reduction in daylight might be a mood altering experience (especially during winter months).

Trap: What you can’t see (e.g. rot), can’t hurt you

Some new windows have been inserted within old frames that had rot; this rot was covered up by the new window frames. This can result in more extensive wall rot and more costly repairs. Make sure your window professional inspects every existing window for rot (especially at sill) before they recommend a specific window for you.

Trap: No maintenance is best

This is often the loudest claim by sellers of inexpensive vinyl windows. There are almost always downsides to a cheaper window. Vinyl is considered toxic to manufacture and to dispose of (expected life is only 25-30 years). Vinyl also expands and contracts much more during seasonal changes and this can result in failure of the caulk that seals the window to the exterior trim or siding. Consider other options that are low maintenance.

Myth: My storm windows give me lots of energy efficiency

Storm windows were designed to protect your main windows from weather and bugs, not to provide thermal insulation. Most should have weep holes at the bottom to allow rain and condensation to escape to the outside. Those weep holes prevent significant insulating value and should be left open to serve their important purpose. Minor energy efficiency is gained by storms as they can reduce the rate of airflow through the main windows by blocking wind currents, etc.

Know YOUR Reasons for Getting New Windows

The following are some reasons for getting new windows. You should rank these and consider them before approving a final order for new windows:

  • Rot: The frame and/or sash of the old window is rotting thus putting the entire wall system at risk.
  • Function: The sashes don’t open or fully open and close as they might be painted shut and/or have broken sash cords.
  • Glass Cleaning: New windows can generally be tilted in for very easy cleaning. If you choose full screens, there would no longer be storm window glass to clean.
  • Energy Efficiency: Older single-pane windows are often R-1 (U-1.0) and leak air. Moderately efficient windows are about R-3 (U-0.33) and highly advanced windows are R-4 (U-0.25) to R-9 (U-0.11). Old windows often have uninsulated wall cavities used for sash weights. It is tough to have an advanced thermal envelope with old windows that utilize sash weights. Generally, building scientists consider the thermal envelope (windows included) a higher priority than many other energy conservation strategies.
  • Sun Block: Newer windows are much better at blocking UV rays that can damage interior finishes and are better at reducing radiant heat gain.
  • Aesthetics: Old windows may be in such terrible, ugly shape that you cannot look at them any longer.

Type of Upgrade

Full Replacement

Full Inserts

Sash Packs

Interior Insulation Panel

Costs per opening—materials plus labor (1)

$1000-$2000 including new trim inside/out




Best choice if…

  • Rot in old frames
  • Maximum energy efficiency needed
  • Existing frames and trim in good shape
  • Easy tilt/removal needed
  • Budget concerns
  • Existing frame and trim in good shape
  • Serious budget restrictions
  • Fall install and spring removal not a big deal
  • Historical windows

Don’t choose if…

  • A cheaper option meets your requirements
  • Reduced glass size is a concern
  • Max energy efficiency needed
  • Rot in old frames
  • Easy tilt/release needed
  • You want casement-type windows (i.e. crank-out type)
  • Old frames or sashes rotted
  • Sashes don’t operate to allow summer venting
  • You need NEW windows. Buy 1-2 per year


  • Fully tear out old
  • Waterproof- gasket opening
  • New exterior trim (usually)
  • Often requires repair & touch-up paint of walls/siding
  • Remove storms and sashes
  • Old frames stay in place
  • Minor pieces of new trim needed
  • Remove storms and sashes
  • Old frames stay in place
  • Minor pieces of new trim needed
  • Usually just add 4 mounting screws




Low-Moderate: Tilt-in or removal for cleaning is tougher

Very Low: Must remove panel to clean or operate window

Energy savings

Highest: Can seal between windows & structural lumber

Medium-high: Use low-expansion foam to fill old sash-weight cavities

Medium: Use low-expansion foam to fill old sash-weight cavities


Other green considerations

  • Advanced options: Triple-pane (R-5;U-0.2); Suspended Film (R-9; U-0.11)
  • Fiberglass frames better
  • Vinyl: don’t do it
  • If wood, consider FSC-certified
  • Fiberglass frames better
  • Vinyl: don’t do it
  • Consider FSC-certified wood
  • Consider getting full-screen to allow better summer venting
  • Don’t install on outside of window
  • Don’t caulk exterior storms to create a type of insulation panel

Window Options

Choose Type of Upgrade First

More important than considering what brand of window to buy, first choose one of the four upgrade types above that meets your reasons for getting new windows. The majority of window improvement contractors appear to be pushing full inserts. This means you receive an entirely new window system (frame plus sashes) inserted into the old window frame. This may be perfect for you if you have considered all of the other types of upgrades. Many salespeople push the type of window which provides them with the highest margin and lowest risk, and this may not be what’s best for you. Construction coaches and some of the better general contractors can independently assess your situation and potentially save you significantly in the end.

Choosing a Window Brand and Installer

Few window salespeople will give you objective information to allow brand comparisons. Start by making a list of brands available locally and then do your own research on these brands. Consumer review publications may have recent articles to help you. Green remodelers often have subscriptions to “green products” review services and may be able to help. If this process is too daunting, consider hiring a green construction coach or green remodeler with long-term ties to the community (i.e. one who exhibits or presents at the Living Green Expo, is a member of the Green Building Council, etc.).

Once the brand has been chosen, you can consider having an experienced green remodeler or window factory contractor do the installation. Regardless of which type of installer, be sure to do the following background work:

  • Is there at least one on-site worker who has experience with 20 installations or more?
  • Does the installer have deep roots in the green remodeling community? Others may have poor environmental practices (no recycling of on-site waste, etc.).
  • Is there an “enforcement action” by the State of Minnesota Department of Industry & Labor?
  • Find out how they control dust during the project.
  • Check the Better Business Bureau for unresolved complaints
  • Obtain a copy of their insurance certificate showing you as “Certificate Holder.”
  • Once the project is fully completed, make sure you receive a “waiver of lien” so that the installer cannot later file a claim against your property.

Education and involvement can have a big impact on window improvement decisions. Take the time to educate yourself and make a fully informed decision. Otherwise, the flow of business as usual may carry you on a path that is best for others, but will bring unknown consequences for you and the environment.

Bob Alf is a St. Paul based construction coach and sustainable remodeler found at

Glossary of Window Terms

Casement: Style of window that generally has one sash with a hinge on one side and “cranks” open. Maximum ventilation is approximately 90 percent of the full window unit. It is easier to meet building codes for fire exits, offers improved ventilation, and is slightly more energy efficient than a double-hung window.

Casing (aka “trim”): Trim covering the window frame edge on both the outside and the inside. It sits flat on the wall and covers the gap between the window frame and the wall surface (drywall or plaster). The exterior trim is often factory-attached to new “full replacement” windows, while the interior trim is usually custom-fit after the window has been installed.

Double-Hung: Style of window where there are two sashes that slide up and down vertically. Maximum ventilation is approximately half of full window unit.

Sash: A piece of glass plus the “sash frame” in which it is embedded, which generally moves to open and close the window. Old sash frames are often made of wood. However, more recently sash frames have been constructed from wood with a metal cladding on the outside.

Window Frame: The rectangular frame into which sashes are mounted. It is usually mounted within the wall and often the bottom piece (sill) juts out past the exterior siding. Often made of wood but also can be metal-covered wood or made of other materials including fiberglass.

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