It’s Time to Update the Energy Code to the Best One Yet

Credit: DOE

Building energy codes set minimum energy efficiency requirements for new and renovated residential and commercial buildings, which means buildings meeting the most updated code versions use even less energy to keep the lights on and their inhabitants comfortable. Cities and states are getting serious about updating the efficiency of their building energy requirements, and the process has begun for developing a new model code incorporating today’s latest energy technologies.

In most of the country, electricity is generated by burning fossil fuels, such as gas and coal, that produce climate-harming pollutants. If our buildings consume less energy from the start, it reduces the amount of pollution associated with heating and lighting them over their century-long lifespans. The DOE found that, taking into account the fact that states adopt the model building codes at varying rates, energy codes with modest updates over the years could save consumers $126 billion on their utility bills from 2010 to 2040. This equates to a carbon pollution reduction of 841 million metric tons, equivalent to the greenhouse gases emitted by 177 million passenger vehicles driven for one year or the carbon dioxide emissions from 245 coal power plants for one year.

The building code is a crucial yet commonsense tool to reduce their owners’ energy bills and make buildings better, more comfortable, and more efficient: it’s never cheaper or easier to add more insulation or better windows and building systems than when the building is under construction.


Our friends at the New Buildings Institute have proclaimed 2019 as the “Year of Energy Codes”—and we have to agree. We’ll be blogging all year about developments in the building energy code throughout the country but today we’re discussing a process that will run the course of the year: development of the 2021 International Energy Conservation Code (IECC). 

What is the IECC?

The International Energy Conservation Code (IECC) is the model building energy code updated every three years through a stakeholder process involving code officials, builders, efficiency advocates, and other interested parties. Once the model code is developed, it’s then up to cities and states to adopt it. The IECC is used by more than 40 states, although not all are using the latest version. It also is recognized by the Department of Energy (DOE) and cited in federal law.

The energy codes apply to new buildings and major renovations, and ensure that your new home will have enough insulation in the attic and walls, high-quality windows, and that the energy-using systems in your home function efficiently. A home built to the 2018 code uses less than half of the energy as a standard home constructed in 1975—and there’s still room for improved efficiency and resiliency.


NRDC submitted seven proposals to the IECC, but we’ll be supporting many more. We work closely with groups like the Energy Efficient Codes Coalition to develop and advocate for proposals that make the energy code more efficient, saving energy and money for consumers and businesses.

Here’s a quick rundown of our proposals.

Zero Energy Appendix

NRDC and the New Buildings Institute collaborated on a proposal to create a new, optional appendix for code compliance. Complying with this path of the code will result in a new residential building that over the course of a year produces as much energy as it consumes, through a mix of aggressive, yet achievable, levels of energy efficiency combined with on-site generation of renewable energy such as through rooftop solar panels.

Lighting and Lighting Controls

This proposal requires every residential light bulb to produce at least 70 lumens per watt, which is equivalent to a LED bulb. It also requires lighting controls, such as dimmers or occupancy sensors, on most fixtures to help reduce lighting electricity consumption.


This proposal improves the U-factor of residential windows, meaning all windows will need to be more efficient.

Water Heating

This proposal requires builders to choose from one of six water-heating options in homes. Some, but not all, of the options use even less energy than current federal standards.

Energy Rating Index Score Improvement

The Energy Rating Index path of the code, which gives builders flexibility to comply with the code by meeting an efficiency score, was made less stringent in 2018. This proposal improves the efficiency of the ERI path, with scores based on the values already being achieved by builders in 2017. NRDC may also support other proposals that improve the efficiency of the ERI score even further.

Electric Readiness

This proposal requires a home to be constructed with 240-volt receptacles located within close proximity to a gas- or propane-fired dryer, water heater, and/or cooking equipment, to accommodate future electric appliances/equipment. (Electric appliances produce less pollution within the building and if powered by electricity generated from wind and solar, have no emissions.) The proposal also requires water heaters to be located in a space big enough to accommodate a future highly efficient electric heat pump water heater.

Hot Water Design Compactness

This proposal gives builders credit for constructing a home with compact hot water design, meaning the hot water heater is centrally located and pipe runs are short. This saves water and energy, as hot water gets to the outlet sooner with less waste.

Credit: DOE

Want to get involved?

There are lots of ways you can influence the efficiency of the energy code, and we’ll check in throughout the year with ideas of how to be involved.

Register to vote

If you work for a state or local government, you may be eligible to vote on the final code proposals. While that voting won’t happen until November, there are steps you need to take now. The most important thing is make sure your agency, department, or unit is a member of the International Code Council (ICC). The deadline for registration is March 29. If you’re not a member by then, you won’t be able to vote on proposals for the 2021 IECC.

Spread the word

If you’re already registered to vote, make sure others are too! In previous code cycles, of the more than 100,000 potential governmental officials eligible to vote in across the nation, only about 20,000 registered to vote with the ICC, and only about 500 cast votes for the IECC. If just 500 more had cast votes, today’s energy code would already be more efficient.

Strong building energy codes are a slam dunk for energy efficiency: they save consumers money and they help mitigate the impacts of climate change. Better energy codes mean better buildings, fewer carbon emissions, and more energy savings for consumers. Efficiency is one of the most effective tools to fight climate change, so more efficient buildings are more important than ever. Let’s work together and make cleaner, more efficient buildings the reality.

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