The Glass Advocate

Education, advocacy and technical content from the NGA
Tom Culp
November 20, 2019
COMMERCIAL, RETAIL, FABRICATION : FROM THE NGA

Challenges and Opportunities in the Battle for the Wall

Between 2010-2014, the industry successfully fought off attempts to significantly reduce the amount of window area prescriptively allowed in the building standards, which many called “The Battle for the Wall.” Five years later, how’s the battle going?

As a result of the initial battle, the various committees learned two key points. First, reducing window area is counter to the design of high-performance buildings and will harm occupant health and wellbeing by reducing access to daylighting and quality views. Second, the industry is resolved to fight against these harmful changes. Consequently, there have been no serious attempts to reduce window area in the prescriptive requirements of ASHRAE 90.1, IECC, or the green codes (ASHRAE 189.1 and IgCC) since the initial battle.

The industry has worked with the committees to advance fenestration requirements while still being cost-effective and practical. The most recent example is the comprehensive update to the U-factor and solar heat gain coefficient requirements and alignment between ASHRAE 90.1-2019 and the 2021 IECC. Additionally, the green codes have taken the issue of occupant health and well-being seriously by greatly expanding the daylighting requirements in the most recent edition and proposing a minimum views requirement for the next edition. 

Does that mean the battle for the wall is over? Obviously not, when we see headlines from New York City about “banning glass and steel skyscrapers” like we did earlier in the year. We also heard an architect recently claim that “curtain wall is dead in Massachusetts starting January.” 

What is going on? First and foremost, there is nothing in the New York City code or anywhere else that “bans” glass skyscrapers, and no, curtain wall is not dead. That is unhelpful, untrue rhetoric that also ignores the positive contribution of high-performance glazing to energy efficiency, daylighting, occupant health and well-being, and real estate values. However, it is true that there is a growing threat to highly glazed buildings in some indirect ways. 

The threat is coming in two areas. First, as fenestration requirements are advancing, so is everything else in the code—lighting, HVAC, hot water, controls, etc. As the overall baseline code requirements advance, there is less room to make trade-offs. Second, there is a recent effort to develop “envelope backstops” that require a minimum level of envelope performance no matter what else is done in the building. The backstops would limit how much high-efficiency HVAC, lighting and hot water systems can be used as a trade-off against envelope components, including window area. These new backstops will not be in ASHRAE 90.1-2019 or 2021 IECC, but are being enacted in certain locations: New York City, Massachusetts and Washington state. 

Where is the opportunity? The solution for the threats to the industry is to promote high-performance façades with advanced glazing, framing and shading systems to enable higher window areas. Not only does this offer higher performance, but also higher value-add. One problem has always been short-term value-engineering to remove higher performance features. Developers understand the financial value of offering superior views. If they want to keep that, they will no longer be able to cut out these features.

The second opportunity is also coming from some of the same places as the threats: New York City and Washington state. The same initiatives that are imposing envelope backstops are also imposing carbon emission or energy use limits on existing buildings. Starting in 2024 with progressively tighter requirements by 2030, building owners must report energy usage annually, and pay substantial fines (essentially a carbon tax) for exceeding limits or not reporting. This will create a large incentive to upgrade existing buildings with glazing and window replacement, and secondary glazing systems. 

Yes, the battle continues, but on a different front. The threat is to business as usual, but not necessarily to glazing area for those who adapt and jump on the opportunity to promote high-performance façades and pursue existing building prospects. 

Tom Culp is technical code consultant for the NGA and owner of Birch Point Consulting LLC.