National building energy codes that prioritize energy efficiency may help curb climate change, but they can also be notoriously difficult for states and cities to adopt.
This year, as part of an expanded effort to support states and cities in adopting residential and commercial energy codes, the Building Energy Codes Program under the U.S. Department of Energy's (DOE's) Building Technologies Office released a compilation of national and state cost-effectiveness reports, fact sheets, and technical briefs in conjunction with their official energy savings determinations.
Also new this year were individualized reports for 20 major cities.
With the support of Pacific Northwest National Laboratory (PNNL), DOE was able to issue the determination of the new residential energy code to fulfill the legislative requirements in less than six months, a historic, record-setting timeline.
Buildings contribute 35 percent of annual greenhouse gas emissions in the United States-and they're also around for a very long time-so making sure they're as efficient as possible when constructed can significantly reduce their environmental impact and slow the course of climate change. For occupants, more energy-efficient buildings mean substantial improvements in the comfort, performance, resilience, and sustainability of homes and office spaces. And even lower utility bills.
Building energy codes represent an opportunity to reduce utility bills by $138 billion and prevent 900 million metric tons of CO2 emissions in residential and commercial buildings over a 30-year span, benefiting states, local governments, households, and businesses alike.
Climate goals require urgent action
Historically, the supporting documents have not been released until a year or more after the energy savings determinations are made. But with the Biden administration's ambitious plan to reach net-zero carbon emissions by 2050, it's becoming increasingly important to provide states and local governments with appropriate support in adopting the latest model energy codes and drastically lowering the emissions coming from their buildings.
The energy savings determinations included an extensive analysis, conducted by PNNL's Building Energy Codes team, to quantify how recent editions of the national model codes improve energy efficiency for buildings subject to the code.
And this year's newest energy model codes pack a punch.
The analysis indicated that commercial buildings subject to the updated codes could see energy savings of 4.7 percent compared to previous editions of the model energy codes. For residential buildings, overall potential energy savings were calculated to be 9.4 percent over the previous edition of the code.
DOE is required by law to issue the determinations no later than 12 months after the revised national energy model codes publish, which include ANSI/ASHRAE/IES Standard 90.1-2019 for commercial buildings and the 2021 International Energy Conservation Codes for residential buildings.
Secretary of Energy Jennifer Granholm announced new building energy code determinations and the release of the supporting documents during the National Energy Codes Conference in July.
The quicker the determinations are issued, the sooner states can adopt the new measures into their state building codes and the sooner builders can start following the new codes.
In fact, states only have two years to certify that their codes meet or exceed the most recently determined national model energy codes.
"Having all these supporting documents available is important to help them make that timeline," said Michael Rosenberg, chief scientist and lead for PNNL's Building Energy Codes Program.
PNNL completed the energy efficiency analysis in record time
For PNNL's energy code experts, the model code determinations and release of the supporting documents was the culmination of nearly six months of virtually nonstop work including thousands of energy simulations.
A team of 27 researchers and engineers delivered DOE a total of 177 publications including technical reports and fact sheets in under six months-an effort that would normally be completed within a two-year period.
"That set a record we haven't come close to before and required extraordinary determination and diligence from the code's team," said Rosenberg.
To get an accurate picture of the impact the residential and commercial code changes will have on the country and on individual states, PNNL's analysis considers construction costs, utility rates, building types, and state income tax across 16 different U.S. climate zones.
"It's a big, complicated, and very involved energy simulation process. We model changes using 16 prototype commercial buildings and 32 residential buildings in 16 different climate zones," said Rosenberg, which can be time-consuming, considering there were 120 changes in the commercial code alone.
But PNNL's work advancing energy-efficient building codes doesn't stop once the determinations are issued, and the reports have been published. PNNL's team of energy code experts are available to provide technical assistance to states in adapting the model codes to suit their specific needs and energy goals.
