Why wonky building codes could be key in reducing state’s climate impact

Updated 7:17 a.m.

When it comes to combating climate change, glistening solar panels, whirring wind turbines, lightning-quick electric vehicles, clean hydrogen electrolyzers and other cutting-edge technologies garner a lot of the buzz.

But experts say changes in building codes, the obscure, wonky, highly-technical rules that govern how our homes and apartment buildings are designed and constructed, can play an outsized role in reducing the state’s greenhouse gas emissions — especially when multiplied over thousands of new homes, year after year.

Simply by adopting the latest model energy code, the U.S. Department of Energy estimates that Minnesota could reduce carbon dioxide emissions by 9 million metric tons, and save an estimated $1 billion in energy costs.

While Minnesota has made huge progress in reducing greenhouse gas emissions in electricity generation, the state’s buildings still consume an enormous amount of energy, and now contribute about 40 percent of the state’s climate-warming emissions.

“Part of the challenge that we face is that residential emissions are still rising. We are still adding more climate warming emissions from the residential sector,” said Eric Fowler, senior policy associate with the clean energy advocacy group Fresh Energy.

Emissions from homes and buildings grew 14 percent in the past 15 years, according to the Minnesota Pollution Control Agency — largely because most buildings in the state are heated by natural gas or oil.

Advocates say stricter energy building codes can play a significant role in reducing emissions by requiring all builders to meet the same minimum efficiency standards. Fowler says that will help our homes and buildings “sip” energy rather than “guzzle” it.

But some builders’ organizations worry the benefits of those efficiency upgrades may not be worth the up-front costs.

“Our question becomes the return on investment,” said Grace Keliher, executive vice president of the Builders Association of Minnesota. “How much is it going to cost and what kind of equipment is going to have to be purchased to reach that level?”

Green homes

While building energy codes set minimum requirements for how much insulation or what kinds of windows to install, many builders across the state already build green homes that exceed those standards.

In Duluth, Rachel Wagner, owner of Just Housing, designed a home built last year called “the Evergreen House,” a 1,500 square foot home that is built to generate as much energy as it consumes — a so-called “net zero” home.

At first glance it looks like a normal house inside, until Wagner points out some subtle differences, such as window sills that are 10 inches deep.

“And they’re so deep because the walls are so deep,” explains Wagner, because she designed the home with twice as much insulation in the walls as the state’s current building code requires.

“The other thing I want to point out is that we’re all standing here in our socks,” Wagner said, on a chilly, foggy late April day. She said that’s because there’s also extra insulation in the attic, and under the floor.

The home is three times as airtight as required by the current code. And it’s outfitted with high efficiency mechanical equipment like an electric air source heat pump for heating and cooling.

“And the net result of all of those things was to create a house that requires about 30 percent of the energy that the exact same house would have required every year, had we just built this house to code,” said Wagner. “So we reduced the energy load on this house by 70 percent.”

And that doesn’t even count the solar panels on the rooftop. Add those to the equation, and this house produces as much energy as it consumes.

Clean energy advocates say for Minnesota to meet its ambitious climate change goals, the state has to build more homes like this one.

That’s where energy building codes come in. While there are developers like Wagner building green homes, Rep. Larry Kraft, DFL-St. Louis Park, says stronger codes would require all builders to meet the same minimum efficiency standards.

Last year he authored a bill that strengthened the state’s commercial building energy code. He’s introduced a bill this year to require residential homes built by 2038 to be 70 percent more efficient than a 2006 baseline.

“And the really important thing about code is that it lays it out so the industry can see what’s coming,” Kraft said. “So it’s not an abrupt shift. It’s saying, OK, we’re going to do this in a responsible fashion.”

Kraft’s bill would require Minnesota to update its code every three years. Currently the state uses a version of a model code approved in 2012.

The state is already on its way to meeting the targets set in Kraft’s bill. Nick Erickson, senior director of housing policy for Housing First Minnesota, a builders’ trade group, says new homes built today have already made enormous efficiency gains in the past 20 years.

Erickson argues from a climate perspective, policy makers should focus instead on older homes.

“That is where we have the largest greenhouse gas emissions, less efficiency, and frankly, the low-hanging fruit,” Erickson said. “From a cost-benefit perspective on climate, that is where the attention really should be focused, because our new homes are performing much better than our existing homes."

Keliher, with the Builders Association of Minnesota, told lawmakers that increased costs to comply with stricter efficiency codes “would have a dramatic impact on our ability to build affordable housing.”

Advocates of stricter codes point to a net-zero, affordable housing complex built in Northfield last year that cost about 7 to 8 percent more to build than a development built to code — and that was for a net-zero development, stricter than what’s proposed.

Sam Friesen, a small home builder based in Grand Rapids, testified to the Legislature that he’s devised a method of building homes using larger studs and more insulation that dramatically improves efficiency at only a one percent cost premium.

Richard Graves, director of the Center for Sustainable Building Research at the University of Minnesota, said it will take time to scale up supply chains and expertise to meet the 2038 target, if it’s approved by lawmakers.

“It’s going to really require capacity building, educating builders, educating owners and designers,” Graves said. “It’s one thing to do one project here and there, but how do you scale that so everybody can do it, is the real challenge between now and 2038.”

In Duluth, green builder Rachel Wagner acknowledges that it costs more to build highly efficient homes. She estimates it costs roughly an extra $10 a square foot to make a 1,500 square foot home 70 percent more efficient.

“But the cost of not doing this is far greater than the upfront cost of making these changes now,” Wagner argues.

“I’m sort of fond of saying, if every millionaire lived in a zero-energy home, we still wouldn’t make a meaningful dent in climate emissions,” Wagner added. “We are only going to be able to address the impact that housing and buildings have on climate change by fundamentally changing the way that we build housing. And the easiest place to start with that is with new homes.”

Correction (May 8, 2024): The story has been updated to clarify the cost and rate of efficiency estimated by Wagner.

• New online tool allows for close-up look into Minnesota’s changing climate future
• Report finds Minnesota outpacing the country in carbon-free electricity
• Minnesota’s energy future