What’s up with building codes?

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Cracking the code for sustainable buildings in Minnesota

A critical conversation is underway in Minnesota that will have a resounding impact on the future of our built environment: The state of Minnesota is currently evaluating whether to update our residential building energy code.

Before scrolling away because this topic seems too boring or technical, look around—chances are, you’re in a building right now. Americans spend roughly 90 percent of their time in buildings, which are also responsible for a whopping 40 percent of U.S. greenhouse gas emissions.

Constructing a building is the first and often best chance to determine how much energy it will consume, and building codes (which you will be an expert on in a few short minutes) have an outsize impact on how most buildings are built. This is why building codes are too important to take for granted, especially because residents and local leaders have the power to make a significant impact strengthening the climate- and human-impact of our buildings via the code adoption process. In this post, we will demystify this process and show you how to contribute to the conversation.

To start, most of us already know a few basics about building codes. For example, if you’re selling a house, you likely know that you can’t count basement rooms as bedrooms if they don’t have egress or escape windows. Why is that? Our residential building code requires that basement bedrooms must have escape windows. Or you might be fond of lamenting to friends and family that aspects of your old house are not “up to code,” for example when you find yourself shivering next to a wall with no insulation, or when plugging in a space heater involves a 34-step process to make sure that it doesn’t trip the breaker.

Building codes establish the minimum standards for a building’s quality, safety, energy use, and construction. Constructing a building “to code” means that the building will meet the minimum state requirements, but only that. Building developers and owners can always construct buildings that are more efficient than the code requires, but never less efficient. This is why establishing strong building codes are a critical policy to improve energy efficiency, reduce carbon emissions, and speed the transition to a clean energy economy.

What are building codes?

Modern building codes are highly technical, but the basic concept has been around for thousands of years. In the 1700s B.C., The Code of Hammurabi stated that “If a builder builds a house for someone, and does not construct it properly, and the house which he built fall in and kill its owner, then that builder shall be put to death.”

Today, codes are less…punitive, but they are far more detailed. The Minnesota Building Code contains 18 chapters covering everything from accessibility and elevators to fire protection, electrical, and plumbing.

How many bathrooms does a theater need? It’s in the building code.

How thick does the fireplace hearth need to be? There’s a code for that (minimum four inches).

Don’t understand an acronym in the code? There’s an entire chapter of referenced standards, where you might learn (if you didn’t already know!) that AMCA stands for the Air Movement and Control Association International, which has standardized “Laboratory Methods of Testing Air Curtain Units for Aerodynamic Performance Rating,” a term which has (somehow) not yet been made into this acronym: LMOTACUFAPR. I guess everyone has their limit?

So, who writes these incredibly detailed codes? In most cases, the first draft of the code is a generic, “model” code created by an organization like the International Code Council (ICC). The ICC convenes committees of relevant industries, advocates, non-profits, and state and local code enforcement officials to update a new version of the International Building Code (IBC) every three years.

Like most states, Minnesota uses the IBC as the basis for our State Building Code, which is updated at least every six years by the Department of Labor and Industry (DLI). The adoption process is managed by staff working under a Governor-appointed Commissioner. With input from the public and experts, DLI staff edit the generic IBC to include Minnesota-specific changes, and then publish the updated State Building Code, which exists across 18 chapters of State Administrative Rule.

Like many other areas of regulation, the Minnesota Legislature plays a limited role in managing building code details, instead granting authority to a state agency (DLI, in this case) to administer the code adoption and modification process. The state law regarding building codes addresses three main purposes: 1) the authority of DLI to update and enforce codes, 2) the purpose of building code compliance and enforcement, and 3) where the code is and is not used. While some states allow cities to adopt stricter codes than the statewide standard (called stretch codes), Minnesota law currently prohibits local governments from adopting anything other than the State Building Code.

Does the Building Code apply to all buildings in Minnesota? Not quite. All new commercial, residential, and government buildings must comply with the Minnesota Building Code. However, existing buildings are not required to meet today’s building code unless the owners make renovations. If an owner or contractor seeks proper approval from their local code enforcement office, they will have to bring the specific elements they’re updating up to code. However, this is a narrow requirement—an electrical update in one room will not necessarily require electrical updates in the next room—much less require updates to unrelated aspects of the code such as plumbing.

There are other exceptions as well, including some agricultural buildings and manufactured homes—which are governed by the national Manufactured Home Construction and Safety Standards, administered by the U.S. Department of Housing and Urban Development.

Is the Energy Code different from the Building Code?

We’ve talked a lot so far about building codes, but where does energy fit in? Is there an energy code? Yes! There is an energy code that lives in the building code. The Energy Code simply refers to two chapters in the Minnesota Building Code: Chapter 1322, Residential Energy Code, and Chapter 1323, Commercial Energy Code.

What’s actually in this energy code?

Because almost everything about a building affects how energy is used, the energy code covers many elements, including requirements, standards, and regulations for the building’s:

  • Envelope—in other words, everything that separates the outdoors from the indoors. Think about air leakage around doors, window quality, and insulation requirements for outside walls.
  • Heating and cooling systems, including requirements for ducts, thermostats, system efficiency, and more. This is where HVAC fits in, which stands for Heating, Ventilation, and Air Conditioning.
  • Water heaters and hot water pipe insulation.
  • Electrical wiring and lighting systems.

These specifications also change depending on location. Energy code requirements vary by climate zone, becoming stricter the farther north you move in the United States (this is most notable for envelope and sometimes HVAC requirements—lighting doesn’t change from one zone to another). Minnesota has two climate zones: Southern Minnesota is in Zone 6, and Northern Minnesota is in Zone 7.

IECC Climate Codes

Credit: HomerPro 3.15

There are two model energy codes used in the United States: The International Energy Conservation Code (IECC)—which is part of the International Building Code and written by the ICC—and ASHRAE-90.1, which is written by ASHRAE, the American Society of Heating, Refrigerating and Air-Conditioning Engineers. Every three years, ASHRAE publishes an updated model energy code called ASHRAE-90.1 (a year indicates the specific version of this model code, published in that year, for example, ASHRAE 90.1-2021). Two years later, and on their own three-year cycle, the ICC releases an updated IECC, which is based on the latest ASHRAE 90.1 standard.

Minnesota uses an amended version of the 2012 IECC for residential buildings and the 2018 IECC or ASHRAE 90.1-2016 for commercial buildings.

Why use both the 2018 IECC and ASHRAE 90.1? Isn’t this supposed to establish consistent standards? Well, yes, but the ICC includes multiple compliance options that give building owners and builders flexibility to choose how they follow the code. Since the IECC is based on the latest update to the ASHRAE 90.1 standard, the writers offer it as an alternative compliance pathway. (Even within the IECC, there are multiple compliance pathways—more on that later.)

The simplest indicator of a code’s energy efficiency is the year it was published. For example, ASHRAE 90.1-2019 is more efficient than ASHRAE 90.1-2001 and the 2018 IECC is more efficient than the 2009 IECC. In the figure below, you can see how each iteration of energy code generally improves upon its predecessor, visualized by decreasing energy use on the graph.

Credit: U.S. Department of Energy

The U.S. Department of Energy’s Building Energy Codes Program tracks the estimated efficiency improvements in buildings following the model energy code over time. View this and other energy code infographics here.

Multiplied across the state, the financial and carbon emission savings from the ever-improving energy code are significant. Pacific Northwest National Laboratory (PNNL) estimates that adopting the residential components of the 2021 IECC would save consumers an average $231 in the first year of adoption. The same report estimates carbon reductions of 9,524,000 metric tons over 30 years, “equivalent to the annual CO2 emissions of 2,071,000 cars on the road.” This doesn’t even include the estimated jobs created or increased quality of life from better buildings.

How are building energy codes used?

There are three main stakeholder groups that use energy codes:

  • manufacturers;
  • architects, builders, and contractors; and
  • code enforcement officials.

First, manufacturers use the model energy codes to create products that will meet minimum standard requirements across the country. For example, insulation is rated by R-value, which is the “resistance” to heat transfer through the material. Code regulates the minimum R-values for insulation across the building, and requires that the R-value be displayed on insulation products. To ensure compliance, manufacturers produce insulation that will provide the necessary “thermal resistance,” and ensure that the rating is printed across the product for visibility.

Second, architects, builders, and contractors use products from those manufacturers to design and construct buildings that, at a minimum, meet the code. Not only do builders need to purchase and combine the right set of building materials, they also have to assemble and install them correctly. If all the insulation has the right R-value but is installed with large gaps, the builder hasn’t followed code.

To provide flexibility to builders, there are multiple compliance pathways to choose from: prescriptive or performance-based. These compliance pathways are included in the model codes adapted by states across the country, so industry professionals are generally familiar with the options.

The prescriptive path provides a longer but more straightforward checklist. As long as the builder uses the appropriate R-values and other minimum standard products, and follows appropriate construction techniques, the code official will approve the project.

Example requirements
Residential buildings in Minnesota must have ceiling/attic borders insulated to R-49 or more. (TABLE R402.1.1) The same goes for commercial buildings (TABLE C402.1.3 OPAQUE THERMAL ENVELOPE INSULATION COMPONENT MINIMUM REQUIREMENTS, R-VALUE METHOD a, i)
Regarding air barriers and insulation. “Ceiling/attic: Access openings, drop down stair or knee wall doors to unconditioned attic spaces shall be sealed.” (TABLE R402.4.1.1 AIR BARRIER AND INSULATION INSTALLATION)
“The building or dwelling unit shall be tested and verified as having an air leakage rate of not exceeding 5 air changes per hour in Climate Zones 1 and 2, and 3 air changes per hour in Climate Zones 3 through 8” (R402.4.1.2 Testing.)
As an alternative to insulating floors over crawl spaces, crawl space walls shall be permitted to be insulated when the crawl space is not vented to the outside. (R402.2.10 Crawl space walls.)

The performance path allows more wiggle room on specifics and allows a builder to use a computer model that demonstrates that the overall project meets basic efficiency requirements. This approach could allow, for example, a wall or window that doesn’t meet prescriptive requirements for insulation or air sealing. But if the building team knows they can make up that efficiency in other parts of the building, the performance approach will give them this flexibility.

Finally, local code enforcement officials complete the process by inspecting plans, issuing permits, and conducting inspections on new buildings and major renovations. You can find your local building code officials on the Minnesota State Building Code Jurisdiction Directory. The enforcement of codes could be its own blog post, but suffice it to say that code enforcement is a very important part of the codes discussion.

How are building energy codes updated?

Like a lot of policies in the U.S., codes and their update schedules vary from state to state. While the federal government requires states to consider updates to their state energy code based on new model codes, they are not required to adopt new codes following consideration. Some states, like North Dakota, do not have a mandatory energy code. Some states allow local governments to adopt “stretch codes” that set higher standards in the city or county than the state-wide energy code.

Minnesota has a uniform statewide energy code, which cannot be amended by local governments. In other words, no stretch codes here. Currently, Minnesota statute requires the Department of Labor and Industry to update the State Building Code at least every six years.

While Minnesota has made notable commitments to clean energy and climate policy, our building code represents an under-used policy tool to improve our health, safety, comfort, utility costs, and emissions across the state.

In 2020, DLI considered and declined to adopt the residential provisions of the 2018 IECC. Our residential energy code is currently an amended version of the 2012 code, which means that a lot of energy savings have been left on the table since then, but also that a lot of emissions reductions are possible if we update. In 2022, a new process is underway to consider adopting the 2021 IECC residential provisions, which would dramatically increase the efficiency and resilience of all new residential buildings in Minnesota.

Modernizing our building code will also bring us in line with other states who are leading on climate and energy issues. The U.S. Department of Energy’s Building Energy Codes Program tracks state level energy code adoption and is a great place to learn more about residential and commercial energy codes across the country.

What’s next for energy codes in Minnesota?

Fresh Energy is taking action on multiple levels to improve building energy codes for health, savings, and climate.

First, we participate in the state’s Commercial and Residential Energy Code update processes. DLI is actively evaluating the residential provisions of the 2021 IECC and held a hearing August 23, 2022. Together with our partners, Fresh Energy has prepared comments, testimony, and a coalition to voice strong support for 1) adopting the 2021 IECC and its considerable energy savings potential, 2) advocating against amendments that weaken and reduce the efficiency of the model code, and 3) supporting amendments that strengthen the efficiency and emissions reductions of the model code. The August hearing is just one step in a longer process which will also include technical advisory groups (TAGs), where we will continue to make the case for more efficiency and more savings.

Second, we continue to advocate with state legislators for better building codes and better code adoption processes. A recent win was a change in law that updates Minnesota’s Construction Codes Advisory Council to include an energy conservation expert, which over time should help balance the voices at the decision-making table. Additionally, Fresh Energy has supported the efforts of city leaders across the state to allow a stretch code in Minnesota. This would give cities the freedom to enforce higher efficiency standards than the minimum state standards.

Finally, we hold a voting seat on the International Codes Council Consensus Committee on Envelope and Embodied Carbon. This gives us a voice and a vote to influence not just Minnesota’s own amended codes but the model residential code used across the country.

Phew. I know that was a lot of information. But give yourself a pat on the back for learning a bit about building and energy codes and why they are such an important tool to address climate change. And stay tuned for future buildings-related pieces (did you hear we recently launched a new Buildings program?) from your friends at Fresh Energy.

Like Rome, smart, consequential, and equitable buildings policy will not be built in a day, but we invite you to follow along and take action with us as we start laying the foundation for the future (sorry, I had to get in a few more buildings puns).

Learn more.

Tune in to “Decarbonize: The Clean Energy Podcast” for a conversation with Fresh Energy staff about building codes with Eric Fowler, senior policy associate, buildings and Bri Kerber, policy communications associate.