Window Replacement: Understanding Your Options

Window ReplacementThere are many reasons why Owners may decide that it’s time to replace their windows. These can include any combination of:

  • water leakage
  • air leakage / cold drafts
  • excessive condensation and mould/mildew growth on interior surfaces
  • poor occupant comfort
  • excessive noise from outside
  • high energy bills
  • look old

BUT – don’t rush into a window replacement project. The presence of any of these conditions do not necessarily mean that your windows need replacement. Many Owners can extend the life of their windows through improved maintenance or targeted repair projects, such as renewing exterior seals and caulking, replacing weatherstripping, and even temporarily removing the windows to improve the concealed barriers.

BUT – if you’ve made the decision to replace your windows, there are many options that will affect the performance and owner satisfaction of the new windows. Owners should consider getting sound advice from someone who can independently evaluate the condition of the windows, present the repair or replacement options available for the specific building, and assist the Owners in getting the best value for their money.

Some of the options available for new windows that impact performance are discussed below.

Frame Types: The most common window frame materials used in multi-family buildings are vinyl, aluminum, and fibreglass. Vinyl windows are generally the lowest cost option, and have great insulating value; however, vinyl windows may need additional reinforcement when used on high rise buildings, and may not be suitable in some applications due to their combustibility. New aluminum windows are thermally broken, meaning that they are designed to reduce the heat flow through the frames when compared to older aluminum windows. Although they are generally not as well-insulating as vinyl windows, aluminum windows are very strong and durable, and suitable for a wide variety of applications. Fibreglass windows tend to be a premium (and more costly) product that combines strength, durability, and thermal performance.

Glazing: Most new windows contain double-glazed insulating glass units – this means that there are two panes of glass separated by a spacer bar, and the space between the glass is usually filled with air or a low-conductivity and inert gas like argon. These units provide improved insulating value and reduced noise transmission when compared to old single-pane windows.

The other option that is gaining popularity is triple-glazed units, which contain three panes of glass. While triple-glazed windows have a higher cost, these units expand on the benefits of double-glazed units by providing even better insulation and noise reduction.

Should noise be a problem, but you don’t want to consider the extra cost of triple-glazing, differential pane thicknesses (meaning the two panes in a double glazed unit are different thicknesses) can also help to reduce noise transmission at a nominal increase in cost.

Low-E Coatings: Most new windows will contain a low-emissivity (called “low-e”) coating on one or more of the glass surfaces, which further improves the insulating effects of the glass units. Different coatings can have different effects on the glass, such as increasing or decreasing the heat gained from the sun (used to reduce heating costs in the winter, or control over-heating in units with a lot of windows), adjusting how much visible light comes through to control glare, or blocking UV to reduce fading of furniture and interior finishes.

In summary, while there are baseline products available based on minimum building and energy code requirements, there are many options that will provide improved performance. The extra initial cost of some of these upgrades can be daunting for homeowners; however, many of these upgrades will pay for themselves in only a few years based on energy savings and incentives. Further, the improved occupant comfort due to reduced exterior noise and heat loss can be significant.

Straight payback on replacing windows is many many years, if based purely on energy savings. However, if the windows are beyond their ability to be maintained and/or greater comfort is required, and the decision has been made to replace the windows, then paybacks on upgrades from baseline window replacement products can be less than 5 years, particularly if product incentives are considered.

There is a lot to consider when deciding whether to replace windows or not; and, when the decision is made to replace the windows, then there is a lot to consider when deciding what replacement windows to use. There are many good sources of information and advice in the market, and the time should be taken to make the right choices.

This article was prepared by Nichole Wapple, a Project Manager at Sense Engineering. Sense Engineering is a consulting firm which provides Restoration Consulting, Capital Planning (including Depreciation Reports) and Warranty Review services, predominantly to owners and managers of existing strata, multi-res, and commercial properties in the BC Lower Mainland. Go to


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