A message from our President

The Importance of Low Solar Glass

Windows are a big deal. The type of window you select and how it functions matters. A lot! If you’ve ever been in a room where the sun’s rays are directly hitting the glass, then you can relate to how uncomfortable it can be to spend time in that room. In construction, we refer to this as uncontrolled, or intermittent, heat gain. Managing these uncontrolled heat gains are the driving factor causing oversized cooling loads, meaning your air conditioner, ducting, and bulkheads all have to be larger than necessary in order to supply this larger volume of air to cool your home.

Putting heavy curtains up might help, but if you’ve got a room with a nice view, or you want to keep an eye on what’s happening in the back yard, then this is not a great option. It also doesn’t reduce the HVAC sizing, because we assume there are no curtains.

When selecting new or replacement windows, I recommend looking for a Solar Heat Gain Co-Efficient (SHGC) of under 0.25. This will significantly reduce the excess solar gain, improve your electricity bills for cooling, and provide greater comfort for your family.

For example, when the BC heat dome resulted in nearly 600 deaths over a very short period of time, the vast majority of those who passed away were in their residence and succumbed to the effects of heat stroke. In the majority of cases, this was due to the homes in the region not being equipped with air conditioning. This heartbreaking scenario could happen anywhere in lower Canada, should we be subject to a heat wave and a power outage.

This is one reason why I have personally put significant effort into getting changes to the building codes here in Canada, to permit windows that reduce these solar gains. In addition, when I have the opportunity to speak to other members of the building industry, this is a subject I constantly come back to. Unfortunately, the industry has not kept pace with the need for windows with low solar glass. I recently had the opportunity to demonstrate window performance to a number of high-performance builders and industry stakeholders. Even amongst net zero home builders, we are one of the very few that use low solar glass.