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What Is The International Energy Conservation Code (IECC)

By Tobias Roberts Rise Writer
Jun 2, 2021

The Energy Information Administration (EIA) reports that residential electricity, standard in virtually every home in the United States, accounted for 41 percent of household end-use energy consumption in 2019. To appreciate the amount of energy our homes use more fully, let's take a further look at the numbers.

  • Again, in 2019, the average annual electricity consumption for a US residential utility customer was 10,649 kilowatt-hours (kWh), an average of about 877 kWh per month.
  • To stay cool in the summer months, US residential customers used 236 billion kWh of electricity in 2020.
  • There are an estimated 122.8 million households in the United States.
  • Based on the average of 10,649 kWh of annual energy consumption, our homes require well over 1.3 trillion kWh of electricity every year.

Though our society is making strides in the necessary transition towards renewable energy technologies, we are still a long way from a fossil-fuel-free energy future. Lamentably, coal, oil, and natural gas continue to dominate our national energy grid. The EIA states that of the 4.13 trillion kilowatt-hours (kWh) of energy produced in 2019, the electricity sector emitted 1.72 billion metric tons of carbon dioxide (CO2). This amount is about 0.92 pounds of CO2 emissions per kWh.

These statistics show that our homes' energy consumption continues to be a significant contributor to global climate change. Even the most progressive carbon-zero pledge by local, regional, and national governments worldwide tends to push the "deadlines" several years into the future. There is a lot of warranted excitement in the solar, wind, and other renewable electricity industries. But, the fact of the matter is that fossil fuels will most likely continue to dominate the electricity industry in the coming years and decades.

Given this reality, focusing on the energy efficiency of our homes is an absolute necessity if we are to reduce the carbon footprint of our houses meaningfully. In this sense, energy codes are one of the best regulatory tools that can affect significant changes in overall energy use and the corresponding greenhouse gas emissions.

In this short article, we will look at how the International Energy Conservation Code (IECC) plays a fundamental role in helping to increase energy performance and thus reduce the carbon footprint of our residential and commercial buildings.

Image Credit: SBC Mag

What Is The International Energy Conservation Code (IECC)?

Our homes and businesses are responsible for upwards of 40 percent of the energy the United States uses. That figure is slightly less in Canada, with just over 30 percent of Canada's energy footprint going to buildings in 2009. Reducing demand for residential energy can have a significant impact in helping cities, states, provinces, and countries around the world achieve their carbon reduction pledges. In the United States and dozens of other countries worldwide, the International Energy Conservation Code is the model energy code. The code thus sets and regulates minimum efficiency standards for both new construction and major remodels. The efficiency standards associated with the IECC set benchmarks for a structure's walls, floors, ceilings, lighting, windows, doors, duct leakage, and air leakage.

The IECC is considered to be a "model" because legislation dictates that building codes are regulated explicitly by legislation on a state-by-state basis. There is no "national energy code" in the US or Canada. This reality makes sense because of the drastic differences in climate, temperature, and other contextual factors that will affect a building's energy and thermal performance. The level of required insulation in a home in northern Minnesota is undoubtedly different than a home located in the mild climate of Alabama.

However, just because state legislation regulates building codes does not mean that there is no national standard or benchmarking process. Every three years, state and regional officials and politicians, together with leaders and experts in energy-efficient building techniques and materials, meet to propose and vote on proposed changes to the IECC model code. Because building techniques and materials continue to improve energy efficiency and thermal performance, these periodic meetings allow state building codes to update and incorporate the best building technologies and practices effectively. The IECC only seeks to offer a standard of best practices for energy efficiency. Other model codes, such as the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) code, offer regulatory guidance for minimum levels of volatile organic compounds (VOCs) and other information related to indoor air quality.

It is also important to mention that in 2015, the IECC consolidated with the International Residential Code (IRC) on issues related to energy. Builders and contractors generally prefer the IRC because the IRC addresses all relevant building topics, including structural considerations, plumbing, electricity, etc. This consolidation allows builders only to have to "carry" one codebook. Today, Chapter 11 of the IRC code book carries the same guidance code considerations as the IECC recommendations. The IECC and IRC offer States a constantly revised, well-vetted, and feasibly implementable building energy code.

Who Developed the IECC? 

The International Code Council initially created the International Energy Conservation Code in 2000 to offer minimum design and construction requirements for energy efficiency. The predecessor to the IECC was the Model Energy Code (MEC). However, this code was less widely adopted, primarily because energy-efficient building techniques were still a fringe movement at that time.

For almost 20 years, the MEC and IECC were lucky to only accomplish around 1 to 2 percent gains in energy efficiency yearly. Most of the energy efficiency recommendations were minor and inconsequential as slight improvements in building techniques and materials could not keep up with the explosion in the size of the average new home. You can read more here about how the size of your home plays a vital role in energy efficiency and other sustainability considerations.

IECC State Adoption Map
IECC State Adoption Map. Image Credit: ICC

Who Uses the IECC?

Although significant efficiency gains have all but stalled since 2015, the almost universal adoption of the IECC is reassuring. According to the International Code Council, the International Energy Conservation Code is in use or adopted in 49 states, the District of Columbia, the US Virgin Islands, NYC, and Puerto Rico. Unlike the United States, Canada does have a national building code. The Model National Energy Code for Buildings (MNECB) was developed back in 1997 through collaboration between provinces, utilities, industry, the National Research Council of Canada (NRC), and Natural Resources Canada. 

IECC Progress Graph
IECC Progress Graph. Photo Credit: Energy Efficient Codes Coalition

How Often Are New Versions of the IECC Released?

As we mentioned above, the IECC releases new versions of its model code every three years. However, it wasn't until the 2009 iteration of the IECC that the code began to advocate for significant energy efficiency gains. During that year's revision, the Energy-Efficient Codes Coalition (EECC) brought together several essential players and stakeholders in the sector. Together, they lobbied for a 30 percent (or more) energy-efficiency boost to the IECC recommendations. You can see a graph that details the percentage gains in energy efficiency code regulations here.

The 2012 iteration of the IECC, commonly referred to as "The 30 Percent Solution," was the first comprehensive efficiency proposal ever offered before the International Code Council. Unfortunately, continued progress in code-regulated efficiency gains was effectively postponed as anti-efficiency lobbyists stopped further measures from being implemented during the 2015 and 2018 code cycles. According to the Energy Efficient Codes Coalition, "these lost opportunities for efficiency gains in the 2015 and 2018 IECCs set us behind and have cost homeowners and business owners thousands in lost revenue due to buildings being constructed to weaker standards than is feasible today." Since the 2012 code, the IECC has only created nominally more energy-efficient standards, even though energy-efficient building techniques and materials are continually hitting the market.


What Are the Updates to the 2021 IECC?

The 2021 IECC, fortunately, made some ambitious changes. These changes will hopefully increase the energy efficiency of residential structures since the International Code Council appraised that the new code requires buildings to be around 10 percent more energy efficient than the previous edition. The Department of Energy finds that the residential provisions of the 2021 edition of the International Energy Conservation Code are 9.38 percent more efficient than the 2018 edition and reduce greenhouse gas (GHG) emissions by 8.66 percent.

Some of the changes in the 2021 IECC include:

  • Increase in the R-value of wood frame insulations in Climate Zones 4 and 5.
  • Increase in ceiling insulation in most Climate Zones.
  • Addition of provisions for installing exterior lighting controls, including motion detectors.
  • The climate zone map was updated to align with ASHRAE 169.

Unfortunately, the 2021 iteration of the IECC has still not embraced the leading recommendations for energy-efficient building practices and materials. In the United States, the Biden Administration has mentioned the key role energy codes play in reducing carbon emissions. The national goal of achieving a 50-52 percent reduction in greenhouse gas emissions compared to a 2005 baseline by 2030 will require more ambitious changes to the 2024 IECC.

Some of the changes we hope to see in the 2024 and subsequent editions of the IECC include:

  • Pathways for zero energy and carbon zero homes
  • Electric vehicle charging stations in homes
  • All-electric homes
  • Guidelines/standards for renewable energy use
Hudson Passive House Alpen High Performance Products
Hudson Passive House. Photo Credit: Alpen High Performance Products

How Does the IECC Compare to Other High-Efficiency Building Practices?

To continue to improve the model code standards, the IECC would do well to look towards more motivated energy-efficient standards such as the Passive House Standard. The passive house standard is widely considered to be the worldwide leader in energy efficiency. For example, the PHIUS 2.0 requires a ceiling insulation R-value of 116 for Climate Zone 8. In contrast, the IECC 2021 version only requires an R-value of 60.

Also, the Passive House Standard has a much more rigorous focus on specialized window treatments to limit unwanted heat loss and heat gain. The focus on highly airtight building envelopes is also notoriously missing in the IECC codes. Despite the advances in the most recent IECC iteration, more exacting standards like the PHIUS 2.0 will probably be necessary for the US residential building sector to achieve the greenhouse gas emissions targets set forth.

Disclaimer: This article does not constitute a product endorsement however Rise does reserve the right to recommend relevant products based on the articles content to provide a more comprehensive experience for the reader.Last Modified: 2022-01-19T04:13:31+0000
Tobias Roberts

Article by:

Tobias Roberts

Tobias runs an agroecology farm and a natural building collective in the mountains of El Salvador. He specializes in earthen construction methods and uses permaculture design methods to integrate structures into the sustainability of the landscape.