On July 5th, 1976, Ottawa Architect Alistair Ross issued a set of drawings for tender for The Sussex Condominium at 40 Boteler Street. Almost forty years later, we completed a major renovation to the building, replacing the original sliding windows.

When we first reviewed the sliders, it was evident that there had been significant ingress of water over time. We determined that on the windward (North-facing) sides of the building, the wind pressure was sufficient to fully compress the sliders against their seals, leaving a large unprotected gap. Our initial recommendation was that the sliding windows should be replaced. It is worth noting that while the units which faced the prevailing wind had to contend with wind- driven rain entering their units, those units on the leeward side were faced with the less easily quantified effect of suction, drawing heated or cooled air through their windows.

After numerous design iterations, mainly trying to find a way of retaining the original aluminum framing, it was eventually agreed that the windows should be replaced in their entirety. As simple as it may sound, it was quite a challenge since the changes to both regulatory codes and best practice in the intervening decades meant that the whole window installation detail had to be re-designed. Working with Buchan Lawton Parent as our building envelope consultant, we did extensive site investigations both inside the building and out to determine the manner in which the existing windows were installed and how best to install the newer, much deeper window frame, taking advantage of all advances in building science.

By early 2015 we were finally ready – and on May 05 2015 the first of the new frames was shipped to the site.

The last windows were installed by the end of September, barely five months after the start of construction – on time delivery despite several weather delays. As they are fundamentally better sealed than the old windows, we anticipate that the new windows will improve the energy efficiency of the building. A common comment from unit owners has been that the new windows reduce the noises from the street making the units considerably quieter than before. The Condominium Board is monitoring their utility bills; it will be interesting to see if there is a noticeable reduction over this first winter.