It has been nearly half a decade since the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE), the American Institute of Architects (AIA), the International Code Council (ICC); the Illuminating Engineering Society (IES); and the U.S. Green Building Council (USGBC) signed a memorandum to better align green building goals through ANSI/ASHRAE/ICC/USGBC/IES Standard 189.1, the International Green Construction Code (IgCC), and the LEED certification system.

For years, these groups had been working on their owner green building standards and frameworks. That started to change in 2009, when USGBC, ASHRAE, and IES teamed up to released Standard 189.1: Standard for the Design of High-Performance Green Buildings, Except Low-Rise Residential Buildings. It marked a momentous step forward, as the standard established minimum requirements for the siting, design, construction, and plans for operation of high-performance green buildings. Though loosely modeled around the categorical framework of LEED, Standard 189.1 provided the industry with a true model standard for green building rather than to some sort of guideline or volunteer rating system. Though many municipalities across the U.S. have local ordinances requiring LEED, Standard 189.1 offered a document more conducive to amendment and adoption as code for a wider range of jurisdictions.

However, by 2012 the ICC released its first edition of the IgCC, which was similar in breadth and scope to Standard 189.1, but harmonized with the organization's widely utilized international model codes (i.e., the "I-Codes"). Recognizing the duality in the marketplace, and to help circumvent potential regulatory complications, the 2012 (and the subsequent 2015) version of the IgCC included Standard 189.1 as a project compliance option.

A bit confusing, yes; and the duality (and seeming competition) of Standard 189.1 and IgCC was compounded by pre-existing LEED mandates in various cities. This was the impetus for the August 2014 Memorandum of Understanding. As a result in 2015, ICC was added as an additional cosponsor of the 2017 edition of Standard 198.1, which served as the technical content of the 2018 IgCC.


At last, we're seeing the fruits of the ICC/ASHRAE/USGBC strategic alignment

At a moment when LEED is pivoting toward an increasingly more stringent certification model based on an integration of strategies and measured performance (utilizing the emerging arc platform), the 2018 IgCC is poised to fill the necessary role of setting a minimum standard for energy and environmental design.

This is why the IgCC is important. In the spirit of the acronym, LEED will continue to lead. For cities and institutions struggling with LEED mandates, the 2018 IgCC may be considered. For a jurisdiction looking for a model standard from which to codify green building, The 2018 IgCC may be more appropriate than a volunteer rating system.

The 2018 IgCC is the first fully integrated edition of the IgCC to be developed cooperatively by ICC and ASHRAE. It retains the general LEED-like structure of Standard 189.1 That is intentional. USGBC’s fingerprints are all over Standard 189.1 and subsequently the IgCC. This is part of a broader effort toward transforming the building design and construction industry.

As traditional codes evolve to include sustainability measures, green building codes such as IgCC will compliment and expand on the traditional codes to set holistic and rigorous minimum standards for green building with clear and specific requirements including provisions that provide safe and substantial construction in a manner that is harmonized with LEED. As this aggregate of codes set minimum standards, LEED as a volunteer third-party certification systems will provide a pathway to help projects exceed the minimum requirements and provide opportunities for leadership through high-performance design and construction. This past November at Greeenbuild, two months after the release of the 2018 IgCC, USGBC raised the bar beyond Platinum certification by launching LEED Zero, a complement to LEED that verifies the achievement of net zero goals through measured data regarding carbon emission, (source) energy, (potable) water, and waste (via TRUE Zero Waste certification).

Market transformation will require an increasingly positive environmental impact by our building projects. Traditional building codes and model green building codes must continue to advance and integrate over time as LEED and other rating systems ratchet up in stringency and become more sophisticated. Illustration courtesy of USGBC.



Let's be clear: 2018 IgCC is not LEED-Lite

As the advancements of LEED shift it toward ongoing measured performance, the 2018 IgCC signals the future manifestation of what our industry has always understood as a prescriptive "credit-driven" process to realize a green building project. But from this point forward, such a system will persist as an evolving model building code with normative language that lends itself to enforcement. The 2018 IgCC is not a watered-down concession to LEED. The 2018 IgCC is quite stringent in many regards. If adopted without amendment,  it would codify:

  • Rainwater management provisions requiring infiltration, evapotranspiration, rainwater harvesting, collection and use.
  • Water consumption measurement devices with remote capability.
  • Envelope and mechanical requirements beyond the minimums set forth by ASHRAE Standard 90.1-2016.
  • Mandatory provisions governing acoustical control for the building envelope, interior spaces and the design of the mechanical systems.
  • A total construction waste threshold of 42 cubic yards or 12,000 pounds, per 10,000 square-feet of floor area for new building projects.
  • Specific requirements for building functional performance testing, a building project commissioning process, and measurement and verification.
  • A limited degree of provisions with regard to building project programming, equipment purchasing, facility operation and maintenance policy, and staff training requirements.


The message from the green building design and construction community is clear: we are united and the future of green building will rest on robust, comprehensive standards that will require project teams and owners alike to take a more vested role in the design, construction, operations, and maintenance of our built environment.