It’s no secret that the demands of commercial glazing are growing continuously more stringent. Here’s one specific development I’ve been keeping my eye on: the latest version of the ASHRAE 90.1 Energy Efficiency standard is beginning to see increased adoption among states and municipalities in the U.S. This broadly necessitates a 5- to 15-percent reduction in U-factor from previous versions of the standard, along with new limitations on solar heat gain.
Meanwhile, key stakeholders recently agreed on requirements for the 2019 version of the standard, and we will be seeing stringency increase even more. Tom Culp, technical code consultant for the National Glass Association (NGA), presented on this topic at the recent GlassBuild show in Las Vegas, and manufacturers and glaziers should be paying attention.
In his talk, Culp highlighted not just the increasingly stringent thermal performance demands within the standard, but the ongoing battle over window to wall ratios. This is something our industry has wrestled with in the past, and we’ve successfully fought off efforts to limit the amount of glazing in new structures by highlighting the benefits that can come with quality views and daylighting that can increase total occupancy comfort. But now, efforts to curb glass in the building are happening indirectly. Culp notes that potential restrictions on the performance path in the proposed ASHRAE 90.1 2019 limiting envelope tradeoffs could have the side effect of artificially limiting window area, even if the energy efficiency is unaffected.
Meanwhile, other new steps in stringency are hitting our industry. Recently, mayors of the C40 cities declared their intention to become carbon neutral by 2030, and that has major implications for new building construction in some of the world’s most prominent metropolitan areas. If carbon neutrality is to be attained, architects and builders will be exploring all possible avenues to make it happen, and limiting the amount of glass could potentially be one of them.
Of course, I believe in the value and utility of highly glazed buildings. And I think the best weapons against any effort to curtail the amount of glass in newly constructed buildings are simple: the continued demonstration of excellent thermal efficiency and performance, and continued advocacy around the benefits that come with a highly glazed building.
Today’s glass can hit efficiency and performance targets when the right components and technology are used. Whether it’s low-E coatings, double and triple glazing or spacer systems with proven performance, thermal excellence is attainable. Meanwhile, the benefits glass can bring to an environment through daylighting are clear. World Building Design Guide states that daylighting “helps create a visually stimulating and productive environment for building occupants” while helping to save on lighting costs. The challenge—and the responsibility—for designers and glass manufacturers is to ensure that daylighting can be accomplished without undesirable side effects like heat gain/loss, glare and more.
There’s real value in what our industry brings to the indoor space. We need to continue advocating and proving what’s possible when the right technology and expertise come together.