Improving envelope performance: Influencing the design process early - June blog

Twinsburg, Ohio
707 Fifth office tower
by Helen Sanders, Ph.D
707 Fifth office tower
Featuring a curved, triple-glazed, curtainwall system, the 707 Fifth office tower in downtown Calgary, Alberta, serves as an example of high-performance fenestration and high energy efficiency. In spite of its cold climate, the 27-story, 564,000-square-foot building met its energy targets, due in part, to the durable, warm edge spacer that separates the three panes of glass, creating an insulating barrier at the perimeter of the IGU to improve thermal performance. Photo: Steve LeBlanc, Contract Glaziers

Last month, we explored reasons why the fenestration systems installed in California do not seem to reflect the relative stringency of the fenestration systems in the prescriptive compliance path of the state’s Title 24 building energy code. One of reasons discussed relates to the widespread use of the performance code compliance path, which can allow higher performing internal systems to be traded off with a lower performing envelope. This month, I sat down (virtually) with two leaders in California’s glazing contractor community – Matt Kamper of Woodbridge Glass Inc./Werner Systems Inc. and Nick Bagatelos of Bagatelos Architectural Glass systems – to dig deeper into the underlying dynamics.

According to Bagatelos, since cost is often the main driver, the typical outcome is the least expensive, minimally code compliant building. The installation of lower performing envelopes appears to be driven by the fact that using a more efficient mechanical system and high efficiency lighting is less expensive than investing in higher performance fenestration. This can lead to buildings with fenestration performance lower than the prescriptive requirements even when using higher than prescriptive window areas. This issue is not just isolated to California. As discussed in previous blogs, the performance paths of IECC and ASHRAE 90.1 used elsewhere in the country results in the same dynamic. But is it just about cost, or are there other drivers at play? continue reading click here.

(the full blog, as well as previous posts, are hosted on

Do you have a challenge for us?

Constant innovation is what makes us tick. If you have a conundrum, let us work together to find the perfect solution.