The 2018 Building Energy Code Holds the Line for Efficiency

Credit: DOE

The newest building energy code, which will govern how much energy and money is saved by new home and commercial building owners, was recently approved by code officials—and by and large, they voted to uphold the great efficiency gains made in past code cycles.

The International Energy Conservation Code (IECC) is the model building energy code recognized by the Department of Energy (DOE) and cited in federal law. It is updated every three years through a stakeholder process involving code officials, builders, efficiency advocates, and other interested parties. The process for developing the newest code has been underway for more than a year: proposals for the 2018 IECC went through multiple rounds of hearings and public comments before building code officials from around the country got the final vote. Once the model code is developed, it’s then up to state and local jurisdictions to adopt and enforce the codes. The IECC is used by more than 40 states.

What are energy codes, anyway?

Building energy codes set specific requirements for the energy use of a building at the time of construction or during a major renovation. Codes are important because it’s much easier and less expensive to make energy efficient improvements while a home is under construction. Once something like insulation or windows is installed in a home, it’s likely to be a decade or more before they are replaced, and codes help make sure that efficient choices are made from the start. Codes have proven to be an incredibly effective tool to reduce energy use in homes and businesses, saving Americans money and reducing harmful pollution. A home built to the 2012 code uses about half of the energy as a standard home constructed in 1975—but there's still room for improved efficiency.

Americans spend more than $200 billion each year on their energy bills and a recent Department of Energy report found that a modest 4 percent to 5 percent increase in the stringency of the building energy code could cumulatively save consumers $126 billion on their energy bills from 2010 to 2040. Those are real savings for building owners and occupants and the reduced energy use from such improvements as more efficient windows or thicker insulation also helps avoid the pollution from fossil fuel-fired electricity generation that fuels climate change.


We didn’t see much in the way of big efficiency gains during this code development cycle. But, code officials were able to hold the line for efficiency, and that’s a particularly big deal this time around. The building code was under attack at every step of this year-long process. There were many proposals that would have significantly weakened the code and allowed more opportunities for energy waste, but nearly all were defeated. This alone is cause for celebration given that many of these proposals only needed a simple majority to pass, which proves what we knew all along: code official understand the importance of energy efficiency.

Successful proposals that strengthen the code

There were only a few successful proposals that will make homes and businesses more efficient in the 2018 code. On the residential side of the code, these will clarify how the Energy Rating Index (ERI) path of the code is calculated to ensure consistency for consumers, require a minimum level of efficiency for homes that meet the code with renewable energy, and mandate the installation of more efficient windows in most climate zones. Commercial buildings (including large multifamily buildings) will be required to have more efficient showerheads.

Why were there so few efficiency gains? Well, the Residential Technical Advisory Committee, appointed by the International Code Council (ICC) to hear and make the initial recommendations for proposals, was downright hostile to code energy efficiency improvements this code development cycle. That matters because of the ICC voting rules: a recommendation by the committee to disapprove a proposal means that 2/3 of code officials would have to vote to overturn the committee decision. It was an uphill battle for anything efficiency-related, so we weren’t surprised that only a few proposals passed that actually strengthen the code. But the ones that did are still worth celebrating! 

RE166-16 – Reference to ANSI/ICC/RESNET 301 Standard in the ERI Path, and RE 173-16 – Modified ERI Numbers an On-Site Generation Backstop

Here’s an example of where proposals that are “in the weeds” make a big difference in the real world. RE-166 links the Energy Rating Index (ERI) to the industry-standard ANSI/ICC/RESNET Standard 301, while RE173 adjusts the ERI compliance numbers and requires a minimum level of efficiency for homes using renewable energy. The figure at right shows the HERS Index, which is defined in Standard 301. Lower scores mean lower energy use.

These two proposals were among the highest-profile issues decided during this code development cycle, and we’re happy to say that code officials agreed with NRDC, Leading Builders of America, the insulation industry, and other efficiency advocates who supported a broad compromise. By passing these two proposals together, there is increased certainty in the ERI path of the code that customers will receive a high-quality home. Furthermore, if builders use renewable energy to comply with the ERI path of the code, then they must first meet a more stringent thermal envelope backstop. This means that a home must be efficient and designed to use less energy first, before renewable energy is added, resulting in less energy use and less energy waste. It would be silly, for example, to allow a home to be built that doesn’t have much insulation, or has inefficient single paned windows just because it has solar panels on top—so these successful proposals prevent that from happening. These proposals promote both energy efficiency and renewable energy in homes, which are both key to a sustainable clean energy future. 

RE 31-16 – More efficient windows in homes

Credit: DOE

While RE-19 (which NRDC supported) did not pass, a nearly identical proposal submitted by NAHB to make windows more efficient did pass. As a result, windows in climate zones 3-8 (everywhere but the most southern parts of states in the south and southwest) will need to be as good as—or better than, in some areas—the previous version of ENERGY STAR.

There were a handful of other proposals that passed that will have a positive impact on the code, including proposals to insulate heated concrete slab, adding a new type of fan to a mechanical ventilation system table, and a few small clarifying proposals.

Credit: EPA

On the commercial side of the code, CE 175-16 Part 1 was successful. This sets the maximum flow rate of showerheads in commercial buildings at 2.0 gallons per minute, which is the level specified by the EPA Water Sense program since 2010. More efficient faucets not only save water (which has become increasingly important in California and many other drought-stricken areas of the country) but also cuts down on the energy used to heat and pump that water.

Proposals that would have weakened the code

Given the anti-efficiency positions of the Technical Advisory Committee, playing defense was the name of the game for the efficiency advocates during this code cycle.  Thankfully, our efforts were largely successful!

The most impactful proposals that were defeated t would have increased air leakage in homes and allowed for builders to take credit in the performance path for efficiency gains between the minimum federal standard HVAC equipment and the type of equipment they install, and instead install less insulation or less-efficient windows. The increased air leakage proposal was a clear rollback of the code, and the equipment trade-off proposals would have created a huge free-ridership loophole given that more than 90 percent of installed equipment is already more efficient than the minimum standard.

A number of other proposals, including one that would have allowed efficient lighting to replace other longer-lived improvements in the performance path of the code, and administrative proposals that would have changed key definitions to weaken the intent of the code, were also defeated.

These bad proposals would have raised consumer utility bills, in many cases without them knowing about it ahead of time, as most of the impacted systems are not visible to the occupant.

Proposals that weaken the code

There were just a few proposals that passed that will have a negative impact on the efficiency of the code. One exempts log homes from the residential thermal envelope requirements, which means those homes will likely not be as well-insulated or sealed as their non-log-home counterparts. Another allows for certain types of small multifamily buildings to be tested for compliance with the code in batches, rather than testing each individual unit. The rationale was that these units should be built identically, but this opens up the possibility of not every unit complying with the code.

Given the large number of proposals that could have dramatically weakened the code, the ones that passed should have a relatively minor negative impact in terms of decreasing energy efficiency requirements.

Proposals that would have strengthened the code

The vast majority of proposals were voted down by code officials. Unfortunately, that included many that would have increased the energy efficiency of the code, including proposals for more efficient water heaters, more efficient lavatory faucets in homes, stronger building envelope requirements, and proposals for both residential and commercial buildings that would have required a 5 percent improvement in efficiency through a choice of flexible upgrades. These were all good proposals that NRDC supported, and we’ll keep pushing for them in the future.

Next Up

The votes have to be certified and confirmed by the ICC Board of Directors, which will happen in the upcoming months. The final version of the 2018 IECC will be published sometime in mid-to-late 2017, after which the Department of Energy will analyze the energy savings of the new code. With each new edition of the IECC, DOE is required by statute to issue a determination as to whether the updated edition will improve energy efficiency. States will begin adopting the code when it goes into effect in early 2018.

While efficiency advocates didn’t get everything we wanted during this code cycle, we made good progress on some important issues. There’s room in future codes for much more cost-effective energy efficiency, and in the meantime we’ll be working with states and local jurisdictions to find the best possible outcomes as they adopt new codes.