Codes and Standards

How to use IgCC and Standard 189.1

The 2018 edition of the International Green Construction Code unifies several energy-efficiency and green building codes and standards.
By Bill Kosik, PE, CEM, BEMP; DNV GL, Oak Brook, Ill. June 10, 2019

Learning objectives

  • Understand the history of the International Green Construction Code, including the connection to ASHRAE 189.1. 
  • Learn the differences between ASHRAE 90.1 and the energyefficiency compliance language in the IgCC. 
  • Identify the parts of the IgCC that are written around the USGBC’s LEED for New Construction. 


Design professionals have myriad standards, guidelines and bestpractice documents available to them when working on a new or renovated building projects. However, the final word on certain aspects of the design comes from the building codes adopted by the authority having jurisdiction; these are the laws that govern how a building is designed, constructed and occupied.  

Codes and regulation are not meant to be a design “cookbook” or cover every single aspect of building design and construction; they are foundational in ensuring the required life safety provisions are in place and to safeguard against conditions that threaten public health and general welfare of the building occupants.  

Ithe early 20th centurylocal officials in the United States began adopting formal building codes. Several reasons prompted this: deadly fires, structural collapse and tragedies due to earthquakes and other natural disasters. Over the subsequent decades, as building materials and construction technologies advanced, codes advanced to address practices in the industry and new information coming from building research.  

Standards organizations (independent from the local municipalities) published uniform or model building codes that are regularly reviewed by experts in the industry and amended as necessary. While model codes create consistency when used in different locationsmunicipalities can issue additions or revisions to the code based on local conditions or special circumstances. 

Figure 1

Courtesy: DNV GL

Energy-efficiendesign becomes priority 

From 1948 to 1972, the building design and construction industry saw major advancements in the development of building codes. The oil crisis of 1973-1974 (also known as the OPEC oil embargo) is arguably the most important catalyst that jump-started energy efficiency improvements in buildings. Federal and state governments (and the general public) had a front-row seat and saw firsthand to the consequences of unstable worldwide energy supplies.  

In response to the oil crisis and calls for energy efficiency initiatives in general, one of the first programs developed by the federal government is the 1977 U.S. National Energy Plan. This plan was developed as a blueprint identifying energy efficiency as a priority because “conservation is the quickest, cheapest, most practical source of energy.” This plan became the basis for many other building energy use reduction programs. 

Also, during this time period, one of the most widely used building energy efficiency standards was published for the first time: ASHRAE Standard 90-1975: Energy Conservation in New Building DesignAt that time, there wasn’t a comprehensive national standard, so this was the first opportunity for many architects and engineers to understand the impacts of their designs on energy use and the importance of improving energy efficiency. It wasn’t until the late 1990s/early 2000s that state and local municipalities began incorporating energy conservation codes into their suite of building regulations and adopted a formal energy conservation code.  

Since its initial release, the standard has been renamed to ASHRAE Standard 90.1: Energy Standard for Buildings Except Low-Rise Residential Buildings and has been put on a three-year maintenance cycle. For example, ASHRAE’s 2013 version of Standard 90.1 improves minimum energy efficiency by approximately 37% from the 2004 edition of Standard 90.1 for regulated loads. It is typical that each new release of the standard will contain significant energy efficiency requirements.  

Environmental sustainability 

In 1993, an organization called the U.S. Green Building Council was formed during a period of growth in the environmental movement. The founders of the USGBC understood the importance of the relationship between buildings and the natural environment, including human healthAt that time “green building codes” did not exist, certainly not ones that could address the nuances of environmentally sustainable design and construction processes, including compliance procedures.  

On a more basic level, there were no agreed-upon standards to define terminology such as “environmentally responsible” or green building.” This lack of industry consensus provided opportunity for an organization to step up and lead the way in the development a new industry standard.  

Fast-forward to 2018 and USGBC has more than 94,000 participating LEED projects in 165 countries and territories. The USGBC has several different types of rating systems based on the type of construction and the type of building, as well as rating systems for residential, city and communities. USGBC’s experience and deep knowledge of the built environment that is environmentally and fiscally responsible would ultimately play an important role in developing holistic code that addresses building, energy efficiency and environmental responsibility. 

Figure 2

Courtesy: DNV GL

Enter IgCC 

The International Green Construction Code has been in existence for more than a decade and, like many codes and standards, it has evolved to respond to the building design and construction industry recommendations and lessons learnedBefore the 2018 edition of the IgCC, ASHRAE Standard 189.1: Standard for the Design of High-Performance Green Buildings was used as a mechanism for a voluntary compliance path.  

Standard 189.1 had its first public review in 2007 and was published in 2010. In the 2018 edition of IgCC, Standard 189.1 has been wholly incorporated into the IgCC, resulting in a unified code that will help municipalities in the adoption and enforcement of a green building code. Provisions for environmental sustainability also are tightly integrated in the code 

The USGBC’s contribution to the IgCC resulted in requirements that are built using the LEED rating system as a templatewhile the IgCC requirements differ from the LEED recommendations in language and technical details, USGSC’s spirit and philosophy on the built environment has been maintained. In fact, the USGBC is acknowledging project design and construction teams that are complying to certain IgCC measures. 

The IgCC is truly a ground-breaking code, closing the gap between the green building and traditional building codes, merging different documents/processes that historically have been fragmented. This is accomplished through the IgCC’s integrated, wholebuilding approach in developing codecompliant language; the IgCC is the first model code to incorporate measures for efficiency and sustainability over the course of design, construction and operations for a building project (including the site). The resulting code material, technical data and regulatory framework is available in assisting governments and municipalities as they endeavor to develop a building code based on the IgCC.  

The IgCC establishes minimum requirements for green and high-performance buildings, providing baseline benefits and a foundation for applying green complementary and voluntary systems. The IgCC is written in code-ready language, setting forth minimum criteria for high-performance building projects. The IgCC is sometimes referred to as a green construction code that, like most building codes, ensures the safety, health and welfare of the general public, but simultaneously encourages innovation and promotes the use of low-impact materials and construction techniques. Currently Standard 189.1 is referenced in: 

Figure 3

Courtesy: DNV GL

IgCC basics 

The following information is meant as an overview to familiarize the reader with the IgCC; it is not meant as a thorough examination nor a critical analysis of the code. The IgCC has wide application to many building projects, specifically: 

  • New buildings and their systems. 
  • New portions of buildings and their systems. 
  • New systems and equipment in existing buildings. 
  • Relocated existing buildings and temporary structures where specified in the code 

Structure and content  

The IgCC is divided into 11 chapters and 11 normative appendices: 

  1. Scope and administration
    • Administration and enforcement of the code. 
    • Types of buildings that fall under the code’s purview. 
    • Duties and powers of the code official.  
    • Rights and privileges of the design professional. 
    • Other administrative points. 
  2. Reserved. 
  3. Definitions, abbreviations and acronyms: This chapter is of importance because the generally understood meaning of a word may not be the same as the meaning in the code. 
  4. Reserved. 
  5. Site sustainability: This chapter defines the requirements for site analysis, selection and development. Topics range from development on flood plains to the environmental impacts of transportation options. 
  6. Water use efficiency: Minimizing the use of potable and nonpotable water is the central theme presented in this chapter. It focuses on items such as water consumption of irrigation systems; flow rates of plumbing fittings and fixtures; and metering, collection and analysis of water consumption. This chapter also outlines specific requirements for reducing water use in heating, ventilation and air conditioning systems, such as optimizing the cycles of concentration for open cooling towers based on the total hardness of the makeup water. Also, in particularly humid locations, the condensate from the evaporator coil in air conditioning units must be collected for reuse.  
  7. Energy efficiency: The primary technical document referenced in this chapter is the ASHRAE 90.1-2016 energy standard. An important provision of this chapter appears in the opening sections: “Building projects shall be designed to comply with Sections 5.4, 6.4, 7.4, 8.4, 9.4 and 10.4 of ANSI/ASHRAE/IES Standard 90.1.” Buildings also must dedicate space for future on-site energy systems such as wind, photovoltaic, geo– and solarthermal. An exception to this is if there is a commitment made to purchasing products complying with the Green-e Energy certification program  
  8. Indoor environmental quality: The aim of this chapter is to ensure the health of the occupants; it has provisions requiring the proper amount of natural light, acceptable temperature and moisture levels and volatile organic compound emissions among others. 
  9. Materials and resources: This chapter focuses on the environmental and human health impacts of materials, including resource conservation, reduced life cycle impacts of building materials, impacts on the atmosphere, product transparency and waste management.” Some of the specific items covered under this chapter are construction waste, refrigerants, recycling in occupied buildings and proper disposal of lamps and ballasts. There is also a performance option that requires a life cycle assessment of the proposed facility. 
  10. Construction and plans for operation: This chapter contains requirements for monitoring moisture levels and indoor air quality during construction. Also included: stipulations for operational planning in preparation for facility startup, testing and commissioning. 
  11. Appendices A through K: Some of the appendices are normative and others are for informational purposes only, providing additional information and resources for the user. 
  • Normative A: Climate zones and prescriptive building envelope and duct insulation tables; includes a mandatory reference to ASHRAE Standard 169: Climactic Data for Building Design Standards. 
  • Normative B: Prescriptive equipment efficiency tables for the alternate reduced renewables and increased equipment efficiency approach. Mandatory equipment efficiency information for the different types of mechanical equipment used for heating and cooling. 
  • Normative C: Performance option for energy efficiency. Mandatory reference to ASHRAE Standard 90.1 for modeling requirements. 
  • Normative D: Building concentrations: mandatory criteria to estimate building concentrations of materials for individual VOC concentrations. 
  • Informative E: Building envelope tables: not referenced in the body of the code and is therefore not part of the code. 
  • Informative F: Integrated design: not referenced in the body of the code and is therefore not part of the code. 
  • Informative G: References: not part of the code but includes potentially useful source documents that may be consulted. 
  • Informative H: Option for energy efficiency using the International Energy Conservation Code prescriptive compliance path. Not referenced in the body of the code and is therefore not part of the code. This approach allows the use of the prescriptive provisions of the IECC without directly relying on the energy provisions of ASHRAE Standard 90.1. 
  • Informative I: Additional guidance for functional and performance testing and the commissioning process. This is not referenced in the body of the code and is therefore not part of the code. 
  • Informative J: Option for residential compliance using the National Green Building Standard. Not referenced in the body of the code and is therefore not part of the code.  
  • Informative K: Addenda description information: not referenced in the body of the code and is therefore not part of the code. 
  • Annex 1: This annex contains pertinent information from ASHRAE Standard 169 for assessing climate zones. 
Figure 4

Courtesy: DNV GL

IgCC and LEED 

“The IgCC addresses site sustainability, water and energy efficiency, indoor environmental quality, materials and resources, building commissioning, construction and plans for operations and maintenance for new and certain types of existing buildings, building sites and building materials, components, equipment and systems.” — 2018 International Green Construction Code. 

This excerpt provides a clear indicator of the integrated approach in the IgCCwith the technical content based on ASHRAE 189.1 and the environmental sustainability compliance language based on the LEED rating system. While there isn’t an absolute one-to-one correlation between LEED and the IgCC, many of the of code sections are based directly on LEED and the overarching concepts and philosophies 

Keep in mind that the IgCC is not a substitute for LEED; to get a certification for a building project the LEED rating system must be used. However, the USGBC is taking steps to have additional recognition for LEED projects that use the IgCC. The USGBC released a comparison of the LEED rating system and 2018-IgCC called “Alignment of LEED and the 2018-IgCC.”  

Figure 5

Courtesy: DNV GL

Comparison/Integration with ASHRAE 90.1-2016 

Chapter 7 of the IgCC, energy efficiency, defines the scope as “ requirements for energy efficiency for buildings and appliances, for on-site renewable energy systems and for energy measuring.” While there are many provisions in the IgCC that are taken directly from or based on ASHRAE 90.1-2016, there are also numerous energyefficiency requirements in the IgCC that differ from the requirements in Standard 90.1. Comparing a sampling of provisions between the two documents, three situations exist: 

  • Items in the IgCC that are not in Standard 90.1. 
  • Items in Standard 90.1 are modified for inclusion in the IgCC. 
  • Provisions in the IgCC that completely supersede parts of Standard 90.1. 

In the IgCC where sections or tables meet one the situations listed above, there are clear instructions and descriptions of what needs to be done, helping the user to better understand how to move forward. These are some of the items in the IgCC that meet one of the above scenarios: 

  • Centralized, automated demand-response system with monitoring and control for fan speed, lightingtemperature, etc. 
  • Requirements for on-site renewable energy that can be reduced by using highefficiency HVAC equipment. 
  • Modifications and additions to provisions for HVAC systems, such as 10% reduction in fan power over 90.1. 
  • Demandcontrolled ventilation. 
  • Updated requirements to reflect changes in Standard 90.1 (such as climate zone 0). 
  • Updated lighting tables with improved efficiencies. 
  • Energy Starcompliant office equipment and other appliances. 
  • Updated equipment efficiency tables. 
  • Informative appendix applicable to revised envelope requirements. 
  • Energy Performance option uses performance cost index. (This addendum updates Performance Option A of Section 701.5.2 (7.5.2) to be consistent with recent changes to the Performance Rating Method as published in Standard 90.1-2016.) 
  • Carbon dioxide CO2e (equivalent) emission factors for different energy sources. 
  • Deleted energy performance option B. (Performance Path B in 189.1-2014 was deleted in part by  changes to the Performance Rating Method published in Standard 90.1-2016, which made significant structural changes to the performance compliance path on which the requirements in Standard 189.1 are heavily based.”). 
  • Added new informative appendix with an energy compliance path using the IECC. 
  • Appendix F, while not part of the code, provides an overview of the integrated design process, which is particularly important when using the IgCC. 
  • Provisions for functional testing and commissioning. 

At first glance, the IgCC might look like a building code consisting of a collection of existing standards and guidelines, each used as one part of the process. Instead, the 2018 edition of IgCC is a completely new product developed on the principals of whole building design where all stakeholders provide strategies and tactics for their area of interest and interact with other stakeholders. While documents from the American Institute of ArchitectsASHRAEInternational Code CouncilIlluminating Engineering Society and USGBC shape the primary technical content of the code, the way they are woven into the code leads to a truly integrated design, construction and operations process. 

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Bill Kosik, PE, CEM, BEMP; DNV GL, Oak Brook, Ill.
Author Bio: Bill Kosik is a senior energy engineer at DNV GL and an industry-recognized leader in energy efficiency for the built environment with an expertise in data centers. He is a member of the Consulting-Specifying Engineer editorial advisory board.