Polar Vortex

We learned that phrase  in 2014 when Doug and I were living through our first full winter in Underhill House. Now we are experiencing another one. 

The National Weather Service warned that “this is the coldest air many of us will have ever experienced” here in the upper Midwest. Like 2014, this arctic blast comes with clear skies and full daytime sun. And like in 2014, Underhill House is performing like is was designed for this weather because in a way it was. We wanted a house that would take the least amount of fuel to heat through our Wisconsin winters. 


Our daughter, architect Della Hansmann, (who now specializes in helping new homeowners revitalize their midcentury ranch houses. Check out what she’s doing here.) designed Underhill House with:

  • Straw-bale insulation
  • Passive-solar design
  • Thickly-insulated foundation walls
  • Lots of concrete and water for thermal mass
  • Solar-hot-water in-floor heat

We faced the 2014 Polar Vortex with excitement and some trepidation. This time – just excitement. We know from experience what Underhill House can do.

So with the Polar Vortex pushing temperatures lower than in 2014 we are once again snug and cozy with absolutely  no fuel required during the sunny part of the day. In fact we make enough additional heat during the day to coast through these evenings of way-below-zero temps.


Great for putting a bit of heat precisely where it’s wanted.

For a short while this morning, I kept my feet warm in my downstairsoffice with a tiny electric heater that I keep under my desk. It’s there for the cloudy days, and is usually all I need. But this morning, I soon turned it off as the sun streamed in through the window and the solar hot water panels heated the floor.  We won’t light a fire in the stove till after the sun sets, and the insulated curtains are pulled down.

As for the propane back-up that we use to heat the house when we’re away and when it’s cloudy, that got turned OFF at dawn this morning, the coldest day of this century. 


All day, the sun pours in, building up heat in the concrete floor. Side note: notice our winter indoor clothesline, which both dries our clothes and humidifies the house nicely.

Instead, passive solar heat stabilized the house temperature and then began warming us up from a morning low of 62 degrees to about 64 at 9:45 AM. After that, the solar hot water panels had warmed up enough to begin circulating to our 165 gallon heat exchange tank full of water, where copper coils sent the heat out to our floors. By noon it was a comfortable 68 degrees indoors, even though it was still about 15 below zero outside. 

By 4:00 PM, about an hour before sunset, the house was a toasty 69 degrees, and the water in the heat exchange tank had warmed up from an overnight low of 70 degrees to 104 degrees even though it had been sending heat to our concrete floors all day long. That water is a lot of good thermal mass!


Our hot water solar panels greeting the morning sun.

Just think! We raised the temperature of the equivalent of 33 five gallon buckets of water from room temperature to 104 degrees on a day with a high temperature of minus 14 degrees outside. All this while, the system was sending a lot of additional heat to the concrete floors for evening warmth.

Clearly, we enjoy our energy-efficient homestead’s capabilities, but there are some things anyone can do to save some significant heating costs. For starters, we keep the bedroom cooler. Shutting off its heating loop kept it at no higher than 63 degrees. We also shut the door and closed the heating loops to the guest bedroom and 2nd bathroom. Those rooms spent the day in the upper fifties. 

One new gadget we’re using to stay safe as well as stay warm this polar vortex as opposed to the one five years ago is our infrared thermometer that lets us point it and read surface temperatures. This allows us to shut off heat to our guest bathroom, monitoring temperatures around the water pipes to make sure they don’t get close to freezing. The lowest the pipes got was the mid forties at dawn. Safe enough for me.  

Our biggest issue was bundling up adequately to go out to feed the birds.  (In winter, our feathered friends can add 10% of their weight in fat every day and then burn it all up to survive the night.)


Roxie’s a sport about wearing foot protection.

While we were out we also added some insulation over the outdoor hose spigots, knocked some ice off the stove hood exhaust vent louvers and exercised our daughter’s energetic dog Roxie, a dobie mix who’s got to run every day no matter how cold it gets. An Alabama rescue, she’s getting to experience  the novelty of serious subzero temps.

Overnight the outside temperatures got down to minus 30 last night, and they’re predicted to drop even further tonight, but we feel confident we’ll be fine with our combination of insulation, thermal mass and temperature monitoring.  

It’s good to know we can weather this weather so easily.  Stephen Vavrus, a senior scientist at UW-Madison’s Center for Climatic Research thinks climate change could actually lead to more such cold snaps for places like Wisconsin.

This week’s frigid weather is a result of a disruption in the polar vortex, a mass of cold air that normally swirls above the north pole. A sudden warming of the stratosphere 20 miles above the Earth can cause those swirling winds to slow, allowing a “lobe” of cold air to slip down into the middle latitudes — covering places like Wisconsin, he said. 


Bottom line?  We had a 3-hour-long wood fire last night as the temperature plummeted to minus 30, and we’ll have another one tonight when its predicted to get colder yet. We’ll send a little propane to the boiler for about 6 hours in the wee hours, and we shut off about a quarter of our living space, letting it drift down into the mid fifties by the morning. 

Minimal compromises.  We were cozy through the bitterest cold our warming climate is likely to throw at us.

Cozy and a bit bemused by the whole experience.

Why aren’t all new houses being built incorporating at least a few of the concepts that keep us comfortable? Just orienting appropriately to the sun and making minimal design changes can dramatically improve heating and cooling efficiency.


Because of all the extra bundling up, I got out about one minute too late to catch the last sun of the day warming our house.  No matter. We’ve stored enough heat for the night.

BTW, if you’re into photovoltaic electricity generation, we have a relatively small 9-panel PV array that generated 2 surplus kW of electricity over the last two days, so in addition to pumping water to the floor heating loops,  antifreeze to the hot water panels, powering the refrigerator the freezer the lights and the electronics, we sent a little electricity over to our nearest neighbor across the road. Feels good.

How are you weathering this Polar Vortex? 

5 replies

  1. Encouraging to know the possibilities and to learn about the efficiency with which your house allowed you to endure these bitter temperatures. Fun stuff!
    Mark Hirsch

    • Thanks Dan. Last night was even colder: 40 below. Again this morning, we turned off the propane as soon as the sun came over the ridge and are having a comfortable day. It’s clouded over, so we won’t collect quite so much warmth. How was the Polar Vortex at your place?

  2. It’s always a pleasure to read your posts, Denise. And this one is dear to our hearts! We may contact your daughter about our 50s ranch, too.

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