Transforming a 1909 St. Paul house into an all-electric green home for the future

Two people stand next to two large condenser units
William Risse and Kristin Mroz stand next to their new heat pump-powered mini-split condensers in December 2023.
Courtesy of Kristin Mroz

In the fall of 2022, Kristin Mroz and her husband William Risse bought a century-old house in St. Paul with an eye toward the future. 

Over the next year and a half, the couple gutted the classic 1909 two-story, removing the gas boiler and replacing it with an air-source heat pump; beefing up insulation and other energy savings measures; and installing new electric wiring and energy efficient appliances. 

Looking up into spray-foam coated rafters
Spray foam insulation covers the rafters of the house in May 2023.
Courtesy of Kristin Mroz

The home is now weatherized to comfortably withstand Minnesota’s harsh winters and humid summers. And it’s 100 percent electric — the couple even had the old gas meter permanently removed from outside the home. 

That’s important because natural gas and other fossil fuels that we currently use to heat our buildings contribute significantly to global carbon emissions.

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As more and more of the electricity generated in the state comes from renewable, carbon-free sources like wind and solar, experts say Minnesotans will need to completely rethink energy use in our homes to take advantage of that renewable electricity.

That means green-home makeovers like this one need to become much more commonplace, if the state is going to meet its goal to eliminate greenhouse gas emissions in the next 25 years to prevent more devastating impacts of climate change.

To help other homeowners, Mroz and Risse documented the steps they took to make their home all-electric, and recently offered a tour of their home to show off the (almost) finished product. 

Heat pumps 

One of the first things noticeable in the bright, cozy home is that there aren’t any radiators — which are practically ubiquitous in most turn-of-the-century homes in Minneapolis and St. Paul.

One of the major steps to electrify the home was to remove the old, inefficient gas boiler, and replace it with an air-source heat pump

Rather than creating heat through combustion of a fuel in a furnace or boiler, a heat pump extracts warm air from outside the home, and moves it inside your home to heat it.

It also works in the opposite direction as an air conditioner — it can take warm air inside your home and deposit it outside the house to cool it. 

A close-up of a floor-mounted air duct vent
Homeowners Kristin Mroz and her husband William Risse installed new air ducts while renovating their 1909 St. Anthony Park home in St. Paul, pictured Jan. 8.
Ben Hovland | MPR News

“I still don’t understand all of it,” admitted Mroz. “Sometimes I tell people that the heating and cooling system that we have is just ‘magic.’ I don’t understand what is inside there that does it. But I know it does it efficiently. And I know that it keeps our home comfortable.”

They explored installing a ground-source heat pump system, which takes warm air from underground to heat the inside of the home. But the bids they received were cost-prohibitive to excavate the system in an established neighborhood. 

Air-source heat pump technology has made huge strides in recent years, Risse said. Newer cold-climate models can extract heat from outside even when temperatures plummet well below zero. 

Contractors in Minnesota recommend installing a backup source of heat. Risse and Mroz have an electric resistance backup system that kicks in automatically when it’s needed. But this winter he said it’s barely been needed. 

“It’s been a very warm winter, but it’s had no issues keeping up,” Risse said. 

They also installed a heat pump water heater. They replaced a gas range with an electric induction stove. And in a small mudroom in the back of the house, they installed a new heat pump dryer.

A close-up of a heat pump-powered dryer
Kristin Mroz and William Risse installed a new heat pump-powered electric dryer in their St. Paul home during recent renovations to convert the house to run entirely on electricity, pictured Jan. 8.
Ben Hovland | MPR News

When they called their utility to ask them to come remove the gas meter outside because they no longer needed it, they said it took a while for them to understand what they were asking. 

“They just kept circling back to us, asking us to fill out a demolition form, as if we were completely demolishing our home. And we’re like, we’re not demolishing the home! We just want the gas meter gone,” said Risse. 

He also climbed up to the roof last winter to tear down the chimney, brick by brick. The house didn’t have a fireplace, and the chimney was no longer needed to vent furnace exhaust outside.

“A benefit of electrifying the home was that we could get rid of the chimney. We didn’t need it. So it ended up saving us that much more space,” Risse said. 

A partially demolished interior
Demolition in full swing in January 2023.
Courtesy of Kristin Mroz

To the studs

One of the hardest decisions the couple made was to remodel the entire house at once. They ripped the house down to the studs so they could redo the electricity and plumbing and better insulate.

A man stands in a kitchen wearing a respirator
William Risse starts demolition of the old kitchen in November 2022.
Courtesy of Kristin Mroz

They realize not everyone can do that — they were able to live in their previous home while they did the work. But they knew that by doing that important work inside the walls, they would give the house at least another century of life. 

Opening up the walls also allowed them to install ductwork for the heating and cooling system. And they were able to use spray foam insulation all around the walls and roof. Even on a cold winter day, the third floor attic — where they added nine inches of insulation — feels warm and comfortable. 

“Before we insulated anything and all the walls were open, you would come up here, even on a 50 degree day, and it would be blazing hot,” said Risse. 

“And then we reinsulated the whole house with that spray foam, and there was very little temperature variation between the floors. It’s pretty amazing what it does."

It’s not the new, shiny appliances that make the most difference in building a green home, Mroz said, but rather the grunt work — the efficiency improvements — that save the most money and the most energy. 

“Efficiency is the first step in doing anything, because you want to make sure that whatever you are doing for heating and cooling, or if you’re adding solar, that you’re sizing it to the right system, and the more you can do to improve the insulation and your air sealing, the more money you’re going to save in the long run,” Mroz said. 

They were surprised they didn’t have to replace the widows. Instead they restored the existing windows, and added some missing storm windows — saving them money. 

Building for the future

The couple also replaced their electric box in the basement to handle the larger electric load in their home; and to accommodate even more load in the future. 

They plan to add a charger in their garage for their electric Chevy Bolt, and they say they also eventually plan to install solar panels on their roof. 

One big recommendation they have for homeowners considering similar projects is to find a contractor who understands how to electrify a home, or, at least, someone willing to learn alongside you. 

“We knew we wanted to try to do this, we didn’t really know how,” Mroz said. “But our contractor was willing to do that research for us and find other subcontractors to do the work.”

A person stands next to an open electrical panel
Homeowner Kristin Mroz shows off the updated electrical panel in her electric-powered house in the St. Anthony Park neighborhood of St. Paul on Jan. 8.
Ben Hovland | MPR News

In the end, they poured a lot of sweat equity into their new home. They anticipate the changes will save them money in the long run — especially as the state and federal government roll out a host of tax credits and rebates for green energy programs. 

But they didn’t make all these changes just to save money. They wanted to reduce carbon emissions, and also improve their indoor air quality. 

"We know it’s the right thing to do. We wanted an older home, and we knew that it wouldn’t be as efficient as something newer,” Mroz said. “But it had character, and we wanted to give life into something that can continue to live for the next 100 years.”