Built Over 40 Years, Proven in Practice: The Evolution of a Forensic Methodology

Most conversations about curtain wall performance start after something has gone wrong. Ours started four decades ago with a more fundamental question: How do you determine which criteria matter most when selecting the appropriate design for a glazing assembly?

That question led to the identification of 21 distinct performance and design criteria that should be evaluated and weighted as part of the selection process. Of those 21 criteria, four emerged as the primary focus of the thesis.

What the Work Really Comes Down To

At Miami Curtain Wall Consultants, the work is to blend architecture seamlessly with anticipated performance and the requirements of engineering, to the point where you can’t easily tell where one discipline ends and the other begins.

Over more than four decades, we have refined our own procedures for understanding what really matters in a curtain wall or window wall assembly. Out of all the variables a project team could examine, our experience has narrowed the field to 21 subcategories that encompass the original categories. Think of an entire library, and the twenty or so books you could point to that genuinely changed how you see the world. The same principle applies to envelope performance: a focused set of categories carries most of the weight.

We call the methodology Turning 21. It has become a forensic tool that has been applied over 15,000 times in actual situations in the field. The methodology has proven effective.

Where It Started: A 1986 Thesis

The framework didn’t appear overnight. Its foundation is a thesis on the performance of exterior glazing assemblies, written at the University of Florida and published in 1986, at a time when an ASTM subgroup was seeking input on how to evaluate and weigh the performance criteria that go into the selection of a curtain wall system.

The work was developed under serious review:

Bertram Y. Kinzey, Jr., senior faculty at the University of Florida and both an architect and an engineer, guided the research over two years as thesis coordinator.
A. A. “Sac” Sakhovsky of Construction Research Laboratory reviewed the work through its development and signed off before it could be defended.
The manuscript cited the leading authors and contributors to glazing research of the era, and was published at the University of Florida.

From Thesis to Tool

About 15 years ago, after a career spent observing how glazing assemblies actually behave in the field, including extensive work on hurricane claims and latent defect matters, that original body of work was distilled down to the 21 data points that experience showed mattered most.

From there, the tool kept evolving:

It has been applied across hurricane and 558 claims and refined through use, including the development of histograms to evaluate whether patterns of conditions are present.
It supports both extrapolation and interpolation from large sets of field data.
It works alongside a database structured around the same categories and subcategories, built with the help of a strong team.
While it began with glazing, the underlying logic extends to roofing, waterproofing, and cladding, because factors like deformation of structural elements hold true across disciplines.

Probability, Not Anecdote

Architects and engineers work with statistical probability every day. Every chart used to size a beam, a column, or a duct reflects data demonstrating a high likelihood that a system will perform. Turning 21 applies that same logic to envelope evaluation: rather than relying on anecdotal reactions, it organizes observations into quantitative information that speaks to both the architectural and engineering expectations of a system.

The goal is evidence that remains traceable under audit or scrutiny, conclusions that can be examined, questioned, and supported by the underlying data.

From Venice to Publication

John Medina contributed a scientific paper describing this performance evaluation approach to the Performance-Based Façade Design (PBFD) 2026 conference in Venice, Italy. The paper will be published in the next PBFD/ASTM publication in September 2027. Forty years after the original thesis, the conversation returns to the same organization that helped prompt it.

The takeaway: durable answers about glazing performance come from focused, quantitative evaluation refined over time, not from first impressions. If your team is navigating questions about glazing or building envelope performance, connect with our team to discuss your project.