Code compliance has been cited as one of seven major barriers to the adoption of high-performance façade systems. While lack of stringency in model codes and slow speed of adoption hold back high-performance façade adoption, poor code enforcement prevents the installation of facades that at least meet the legal minimum performance.
The Façade Tectonics Institute’s (FTI) report to the U.S. Department of Energy dug into the reasons for this lack of enforcement:
Code Officials have Insufficient Training, Resources and Time to Enforce Fenestration Requirements
Many cities rely on building permit fees to fund code enforcement and those fees are constrained to manage affordability to meet full enforcement needs. As a result, the budget is seldom available to hire and train sufficient staff. Understandably, available resources prioritize immediate life-safety compliance (fire, structural) over energy efficiency performance.
Where Enforcement is Solid
Enforcement of building envelope provisions is much tighter in places where adequate funding is provided, such as Seattle.
Duane Jonlin, a code official at the City of Seattle, said the city’s code office is funded by Seattle City Light, the local utility and a major driver of its leadership in energy code stringency and enforcement. This utility views the energy code development and enforcement as an energy efficiency program and funds it as such. Washington legislation requires utilities to invest in energy efficiency programs.
Seattle City Light provides 50% funding for six full-time engineers and a department leader. The City of Seattle code office can review building energy simulations and façade details. It also provides funding to develop increasingly more stringent energy codes and to participate in national model code development.
Elsewhere, FTI reports, “Washington, D.C. has a special tax levy to support code enforcement, and New York City also has dedicated funding.”
Code Review is Not Required for Contractors to Prove Their Systems and/or Glazing Details Meet Code Requirements
Fabricators interviewed for the FTI research noted that project drawings from contractors and/or architects often do not meet code. While the fabricators point out the gaps in code, the relevant party is not motivated to fix them because there is typically no code enforcement via a glazing detail or systems review. This compliance gap is closed in cities where code enforcement is funded effectively.
National Fenestration Rating Council (NFRC) Certification Enforcement
Unit windows that are shipped complete from the manufacturer typically have an affixed NFRC label indicating its certified performance at a defined model size. Certification follows NFRC’s Product Certification Program (PCP). It is easy for a code official to determine code compliance by looking at the labels during a site inspection (assuming the labels have not been removed).
However, the performance of commercial fenestration products, such as those that are constructed on-site, is certified using a different NFRC program (Component Modeling Approach and site-built program), which generates a label certificate. The label certificate is part of the project paperwork, not attached to the product itself. It often lists the performance of many products and configurations used in the building design.
The U.S. model code–International Energy Conservation Code (IECC)–requires that for fenestration: “U-factors, SHGC [solar heat gain coefficient] and VT [visible transmittance] shall be determined by an accredited, independent laboratory, and labeled and certified by the manufacturer with a label affixed to the product or a label certificate specific to the products in the project.” To improve clarity, the 2024 version was updated to specifically include “label certificate” as well as “label affixed.”
Despite the requirement by model codes of fenestration labeling and certification, the site-built fenestration certification program is neither followed nor enforced. This leads to potential discrepancies between what is installed and what is required by code.
In some cases, the code official is given a simulation report completed using the NFRC-approved software by the fenestration manufacturer to demonstrate compliance, such as a “bid report,” instead of having performance validated by NFRC and an official NFRC label certificate generated.
Other barriers to the use of NFRC certification in commercial site-built fenestration are:
- Custom curtainwall systems required physical testing to rate them, which was costly and did not align with project schedules.
- NFRC ratings have not been effective at capturing the performance of common spandrel arrangements in curtainwalls and window walls, which can cause thermal bypass.
New NFRC Commercial Fenestration Program
NFRC is gearing up to launch a new version of the commercial product program that makes it easier and faster to determine the performance of different combinations of frames, edge of glass and center of glass performance. It also provides data for the model size and for project-specific sizes and configurations. Testing requirements for custom curtainwall are removed as simulation becomes the approved process.
While it will be easier to generate the correct performance data for the site-built systems, the requirement to have these values validated by NFRC and to generate an official label certificate remains. Enforcing this part of the program will be important.
Both the City of Seattle and the State of California already enforce complete NFRC label certificates for site-built fenestration, yet most jurisdictions do not. Widespread education is key to improving awareness among code officials. The updated NFRC program is slated to be launched this year.
Compliance Using the Whole Building Performance Path: Building Simulation Validation
Vancouver has moved to compliance through energy simulation only and has taken steps to validate the inputs used by simulators in its building energy models. It has also issued modeling guidelines and rules for code compliance, including for spandrel thermal simulation, which is a known challenge. This ensures appropriate simulation quality consistency and a level playing field. These guidelines have now been adopted at the provincial level to improve code compliance.
Despite these rules, compliance is only confirmed at the site plan approval stage. According to University of Toronto professor of building science Ted Kesik, compliance gaps can occur at the building permit stage. At the permit stage, only the basic code requirements are checked, and letters of attestation from consultants are used to confirm compliance. Performance gaps, he notes, are driven by thermal bridging and air leakage, which underscores the need for mandatory enclosure commissioning and air-leakage testing.
How to Improve Compliance?
Jurisdictions like Seattle, Vancouver and California have already demonstrated a roadmap to improved code compliance for façades. The key elements are:
- Appropriate funding for code offices – this would allow them to have the bandwidth and capabilities in-house to assess energy code compliance, including simulation assessment and envelope system detail review;
- Education for code officials on certification and labeling of fenestration as well as envelope assembly details, thermal bridging and air leakage;
- Rules and guidelines for building energy simulation, with compliance confirmation from knowledgeable code officials; and
- Codes requiring complete performance demonstration—Building commissioning and air leakage testing are important. The latest versions of the model code broaden air leakage testing requirements across more buildings and climate zones, and local jurisdictions, such as Massachusetts, through its widely adopted stretch energy code, are implementing them in advance of model code requirements.