Heat being heat. [PD] Wikimedia

Heat being heat. [PD] Wikimedia

Of course it’s not that simple. It’s all about mass. And the mass of one house can be arranged quite differently from the next. It’s particularly the hot mass you need to keep in mind.

The Umpteenth Law of Thermodynamics says every speck of matter  in the universe is trying to arrive at the same uniform temperature. Hot things are forever shedding heat, and cold things are forever absorbing it. We try to arrange our homes in a way that prevents heat from radiating out into the cold air, snow, trees, cars, and the black universe. But heat escapes nonetheless.

And the warmer your house is, the faster heat will pulse outside to achieve harmony with coldness. That’s why it saves energy to turn the thermostat down when you’re sleeping or working: The closer the inside temperature is to the outside temperature, the less ambitious the heat is about cooling off.

The big, fat caveat, especially here in Maine where many old houses still hiss and thump along with steam heat, is that mass messes up the thermodynamics (which weren’t particularly tidy to begin with). Steam has to heat up hundreds of pounds of cold, iron radiator before much heat can pass into the air and the walls and the toilet seat. Same goes for radiant heat in concrete floors: The heating mass takes a long time to cool off; then a long time to heat up.

Even so, turning the thermostat up and down for an old steam system doesn’t make the furnace work any “harder,” or burn more fuel in the long haul. It truly does save energy (money), says the Department of Energy–about 1% savings per degree if you turn down for eight hours a day.

The problem is that you may not love the sluggish changes in temperature that result from a massive heating system: By the time the bathroom gets warm in the morning, it’s time to go to work.

The cool news is that new thermostats are much better at physics than I am. Brainy new appliances can continuously calculate the ideal timing of your furnace’s bursts of effort.



Kublai Khan. Wikimedia pd

Kublai Khan. Wikimedia pd

I’ve been watching the Marco Polo series on Netflix not for the melodrama and frontal nudity, but for the real estate considerations. Primarily, how did Kublai Khan not freeze his funny little hairdo off? How warm can you really make a ger?

Pretty warm, apparently. Thanks to sheep.

The Mongolian ger, aka yurt, is a lightly-woven basket, covered with layers of felted wool. The ger is modular from the get-go, as befits a culture of sheep-followers. Accordingly, the insulation also is easily adjusted. The basic unit of insulation is a flexible version of foam insulation board, known as felted wool. The raw material is mined from a sheep, then whacked into dense sheets about an inch thick. This oily product is water and wind-repellent, and has an R-value of a bit under 1. In the winter, you pile on as many as you want. Three inches of felt mat provide an R value similar to your double-pane window (2). The old balloon-construction houses of Maine only managed R-4 or -5.

But insulation is only part of the story. Materials also lose heat through radiation. Glass is a fantastic radiator, shedding your household heat out into the winter air. Felt, according to research by a bunch of sheep, yak, camels, llamas, and goats, is not.

And air infiltration is important as well: That old Maine house has sprung so many leaks since it was built that you may as well just leave a door open all winter. The circular, even spherical, shape of the ger sheds cold wind instead of fighting it; and apparently the oily felt itself is remarkably windproof. (Modern gers have a canvas cover that helps, too.)

So Khan & Co. weren’t exactly roughing it on the Mongolian grasslands. Plus, if Netflix’s account is to be believed, no Mongolian ever spent a night alone.