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Things to consider When Upgrading To Energy-Efficient Windows

January 23, 2023

Up to 25% of the total heat loss from a house can be attributed to windows and doors. It is possible to repair windows and doors, but there are times when it is preferable to replace them with more energy-efficient alternatives. In order to save energy and increase comfort, proper installation and maintenance are also crucial. Here’s how you can replace or upgrade your windows.

Energy-Efficient Windows

You have a variety of choices for improving your windows’ energy efficiency. Latch, crank, and lock repairs can be made, and windows can also be updated with caulking, weatherstripping, glass, and storm protection options. Sometimes replacing the entire window assembly with new, high-performance and certified windows or inserts is the best option. Inserts, such as new sash and glazing units, can be good choices if the frames are still in good condition, particularly for houses with a historic designation.

Replacing Glazing, Sashes, and Windows

Homes with properly fitted energy-efficient windows are more comfortable because they have fewer draughts and a warmer interior side, which prevents condensation. Many of the following characteristics will be present in energy-efficient windows:

  • double, triple, or even four times the glazing
  • glass inert gas with a low emissivity (low-E) rating, such as argon or krypton in a sealed unit
  • spacer bars with a heated edge or low conductivity
  • insulated windows and doors
  • excellent airtightness

Your best option will be to replace all or a portion of the window if your inspection uncovers major issues with the glazing, sash, or entire unit.

You can purchase a replacement sealed glazing window insert, for instance, if the glazing is simply a single pane of glass or is in poor condition. It could be time to replace the unit if the frame is damaged.

Checking for Damage

Examine each window for evidence of deterioration, including rot, mould growth, and/or stains on or near the glass, as well as the putty, paint, weatherstripping, and the functionality and state of the hardware. While some windows may just need modest air sealing maintenance, others may need to be significantly upgraded or even replaced. Examine all moveable joints and the area around the frame for air leaks.

Interior Caulking

Applying a continuous film of caulk around the window trim where it meets the wall, at the trim’s mitered joints, and between the trim and the frame will help to prevent window air leakage. Make sure the caulk can be painted, is of high quality, and is meant for indoor use.

If a window leaks a lot and the trim is simple to remove and reinstall, remove the trim, fill the space with insulation, and then reinstall the trim. Small gaps may only require insulation before caulking. Either a backer rod with caulking or low-expansion foam may be necessary for larger gaps.

Apply a layer of red technical tape to the connection between the wall and window frame to prevent further air leakage. As the tape cannot be painted and red adhesive may remain when extra tape is removed, be sure it will be masked by the trim.\


Reduce air leakage by weatherstripping windows around the sash. If the windows don’t need to be opened and aren’t used as escape routes, they can be caulked and locked. If storm windows are used, make sure to seal the interior window more firmly than the exterior window to prevent condensation issues.

There are numerous kinds of weatherstripping available. Be sure to not only choose weatherstripping based on price, because less expensive products are typically less reliable and efficient.

Double-hung and Single-hung Windows

Weatherstripping should be applied to the sides, top, and bottom of the moveable sash of double-hung and single-hung windows. Air leaks surrounding the fixed area of the window should be caulked.


A suitable option is thin plastic V-type weatherstripping. With the mouth of the V facing the outside, open the window and slide the stripping between the sash and the frame. If you first take out the top and bottom sashes, you can do the work more effectively.



Marvin experts are experienced in working with architects, builders and homeowners to ensure your vision becomes a reality.

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