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Fenestration Forum: October 2013

New windows are typically evaluated for performance characteristics in
laboratories for structural adequacy, resistance to air and water
infiltration, ease of operation, and sometimes resistance to forced
entry.

New windows are typically evaluated for performance characteristics in laboratories for structural adequacy, resistance to air and water infiltration, ease of operation, and sometimes resistance to forced entry. Heritage windows are generally expected to meet the same performance requirements when used in full-scale building restoration or renewal projects. Balancing the various options for bringing buildings with heritage windows up to code, which may include restoration and repair or full-scale replacement, requires an assessment of the various costs involved and definitely represents a challenge. Facility managers often wrestle with the need to ensure functionality and at the same time attempt to protect the heritage components.

When evaluating life-cycle costs and functionality, decision-makers need to assess the various costs of creating, operating, repairing and maintaining the units over their expected service life. These costs typically include the initial capital investment, the associated energy costs and the cost of repair and maintenance including access for cleaning.

There will be an investment required regardless of whether the decision is made to restore the windows or to replace them. Even if a designer or building owner decides to replace the windows, there will be a cost involved in removing and/or salvaging the existing windows and installing temporary protection over the openings. Some repairs will likely be required to the exterior portions of the building envelope as well as the interior trim around the window.

Heritage architects are often engaged during early stages of projects in order to consult on the range of modifications to the original buildings and prepare formal heritage interpretation plans describing the significance and history of the building or site. These plans include a justification for the proposed works, a description of any investigative work required and an assessment of the impact of any usage change. The architect will describe the material to be removed, including its age and significance, and indicate which components are going to be protected. Interested Heritage Committees must be consulted and their feedback included in the plan. The plan also lists the documentation necessary and the skills required to undertake the project.

For large heritage buildings, the range of costs across the various options can be significant. It then becomes an issue of determining the merits of preserving the heritage elements when the cost of either restoration or replacement is considered.

Some of the heritage architects I spoke to pointed out that energy savings resulting from the installation of new windows are often less than those realized from improvements in HVAC equipment, thermal performance of the roof and walls, or improvements to lighting and lighting controls. These same architects said that quite a bit of thought is also given to sustainability, durability, ease of maintenance and repair as well as the ease of operation of the units. In some cases, safety issues must also be addressed.

In many ways, these kinds of assessments can represent subjective evaluations and are difficult to quantify. However, heritage windows are an extremely important part of the building fabric and contribute tremendously to the overall look and feel of a structure. In cases where the windows are part of some significant piece of architecture, professional and skilled restoration of the windows to their original condition would almost certainly be considered good heritage conservation practice. The same would probably be true for stained-glass windows in both religious and university settings.

Once existing windows have been removed and replaced, the decision cannot be reversed. As a result, heritage consultants such as those at the Canadian Association of Heritage Professionals undertake a very thorough and comprehensive review before proceeding. •

Brian Burton is a business development consultant and is serving on the Personnel Committee for the CSA’s Certification Program for Fenestration Installation Technicians. His current interests include adaptive reuse of buildings, overcladding technologies, maintenance of the building envelope and the rapidly growing use of computers in construction. You can contact him at brianburton@live.ca or visit his new website at http://burtons-pen.com