In the 1990s, Canadian housing largely used windows made from porous materials that were not airtight or watertight, especially in the case of double aluminum sliding windows, which peaked in popularity during the 60s and 70s. Because of their advanced age and outdated technology, many of their components were no longer consistent with current standards.

A convincing benchmark

The Canada Mortgage and Housing Corporation (CMHC) addressed the issue, which resulted in the June 1998 publication of benchmark results comparing the refurbishing of such windows against their replacement. The project was carried out in five different Montreal buildings that were built between 1964 and 1975. The windows were evaluated before and after refurbishment.

In addition to the general work involved in window refurbishment, the majority of weatherstripping, window heads and jambs were replaced by new high-performance components. In some cases, the foam lining, which compresses the upper rails, was replaced by a “plastic sleeve-type model”, which provided superior sealing performance and longer service life. The refurbishment of each window required between 45 and 60 minutes of maintenance work.


Once refurbished, the windows were capable of reducing air leakage by 54% to 83%. Furthermore, they became compliant with type A-2 window standards, as required by the Canadian Standards Organization (CSA) under its A-440 standard. In other words, the refurbishment of these windows provided significantly better energy performance, equivalent to similar new models.

Cost comparison

Based on the refurbishment method used in this study, the average cost for refurbishing a window was determined to between $110 and $130. By comparison, replacing the same window would cost between $900 and $1,000. The same test set approach also showed the cost of replacing all 500 windows of a typical building to be $475,000, whereas the cost of refurbishing the same windows would amount to less than $76,000.


The test set demonstrated not only a substantial improvement in energy performance from refurbished windows and doors, but also the tremendous savings of choosing refurbishment over replacement. Thus, the authors of this study reached the following conclusion: “This improvement method is to be recognized and considered as a viable alternative to window replacement.”

*This study is entitled “Reconditionnement des portes et fenêtres coulissantes existantes” (Refurbishment of Existing Sliding Doors and Windows). It is available at the CMHC, in Ottawa, under the following reference numbers:

  • DMA : 96-81
  • PC : RD-0102-A

The following five apartment buildings were included in this study :

Built in 1972
Test performed in October 3, 1997

La Cité
Built in 1975
Test performed in August 5, 1997

Le 5150 avenue McDonald
Built in 1972
Test performed in July 22, 1997

La maison de convalescence St-Georges
Built in 1964
Test performed in July 29, 1997

Le Riviera
Built in 1967
Test performed in June 12, 1997

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