Polar vortex over Chiberia

Two new terms entered my vocabulary over the past week.

The term “Polar vortex” was a hard one to miss while watching the local weather forcast with all its glorious record freezing temperatures. While the numbers did sound glorious, the temperatures felt anything but.

“Chiberia” emerged on social media sites – a playful combination of Chicago and Siberia.

Bottom line, it hasn’t gotten this cold in about 20 years. On Monday (01/06/2014) daytime high temperatures outside the house didn’t get above -10 Fahrenheit (-23 Celsius).

Putting things to the test

Extreme temperatures like these are a good, and somewhat nerve wracking, test for our deep energy retrofit. Small mistakes or weaknesses would have made themselves known pretty quickly, such as a frozen or burst water pipe, or if the boiler can’t keep up heating the building.

None of that happened and I would dare to say we passed that test.

I was a little concerned about keeping the 1st floor (where we are now staying) warm enough. Keep in mind that the second floor is not yet conditioned. The insulation between the 1st and 2nd floor has only an R-value of 22, and mainly serves to reduce sound transmission.

Temperatures on the 2nd floor kept hovering around freezing. It didn’t get much colder up there thanks to the wall insulation (R-10)  and attic insulation (R-65). That kept the temperature delta between the 1st and 2nd floor at a reasonable 40 degrees Fahrenheit.

Heating cycles

What I did noticed on the 1st floor is a distinctly different cycling of the heating system compared to the garden unit.

The thermal mass of the radiant floor slab in the garden unit may lead to three or four heating cycles in a 24 hour period in very cold weather. Each heating cycle takes 30 minutes to one hour to recharge the thermal mass in the radiant floor slab.

The 1st floor is a very different story with it’s steel radiators. These have nowhere near the thermal mass of a floor slab, and as a consequence, the heat cycles on and off about every hour to hour and a half. But with less thermal mass to recharge, the system runs for only five to ten minutes before turning off again.

Despite the cycling differences, I suspect that over a 24 hour period, the heat runs roughly the same amount of time in each unit (two to four hours over 24 hours).


A big contributor to comfort during the heating season is stable temperatures. While we were living in the garden unit, we treasured the temperature variance that rarely exceed four degrees Fahrenheit (typically 63 on the low end and 67 the high end).

I am delighted to find a similarly stable temperature range, and with that comfort, on the 1st floor. There is a difference though – again related to thermal mass. Because there is not much thermal mass in the steel radiators, we can let the 1st floor cool down to 62 degrees Fahrenheit during night time. That wasn’t possible with the radiant floor slab in the garden unit, even with the thermostat set to 62.

I am splitting hairs! It is comfortable, and the drifting snow that starts piling up against the windows makes it feel even more comfortable.


I guess that means that our replacement windows do their job. Did I mention the replacement windows…?

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About Marcus de la fleur

Marcus is a Registered Landscape Architect with a horticultural degree from the School of Horticulture at the Royal Botanic Gardens, Kew, and a Masters in Landscape Architecture from the University of Sheffield, UK. He developed a landscape based sustainable pilot project at 168 Elm Ave. in 2002, and has expanded his skill set to building science. Starting in 2009, Marcus applied the newly acquired expertise to the deep energy retrofit of his 100+ year old home in Chicago.

One thought on “Polar vortex over Chiberia

  1. Great to hear that everything works and that your careful attention to details is paying off.
    Good to know that you have it warm despite the extreme weather.

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