(Yeah, I typed this offline and then logged on just long enough to squirt it onto the blog)
People talk up thermal mass as if it’s the answer to keeping warm in winter. And it certainly has its charms – the Secret Lair has next to none, and while it’s easy to heat up it also easily goes back to cold. Winter mornings in the Lair are no big treat, it’s shiver in a coat until the fire builds up to heat the iron, and the iron heats the air. Truth is the more I insulate the Lair, the less unpleasant the winters become overall. Which is why I look back on winters in Michigan, where I grew up, with ironic nostalgia. Michigan has its flaws as a place to be from, but they do have central heat and lots of insulation there.
People have told me over and over that what I need is more “thermal mass.” That is, I should pile rocks or something around my woodstove to catch and hold the heat overnight. It’s not a bad idea at all, in fact I did a little of that last winter and plan to do it again now: I’ll take all my leftover tiles from the floor job and stack them neatly in the corner behind the stove. I can’t stack rocks around and under the stove, as someone suggested, because I have to be able to pull it out to clean the stovepipe – I’m not giving that up. But I can do a little of it, and will. I’ve got lots of heavy ceramic tiles left over, since I bartered D&L’s entire surplus and they had lots. I had enough tiles to floor three Lairs.
It’s of D&L I want to write because Monday L said something bearing directly on the subject of thermal mass. She said – on September 26 in a latitude not known for long, vicious winters – “We’ll probably need to start running the pellet stove this week.”
Regular readers know that D&L built a house with lots of thermal mass. 4000 square feet of thick adobe under the floor. Every interior wall – even the closets! – eighteen inches thick, made of earthbags. Exterior walls of strawbales coated inside and out with adobe. They’re lounging around in robes and slippers at five in the morning while I’m shivering in layered sweatshirts and my canvas coat, praying for the fire to catch. It takes a long time for all that mass to dump its stored heat, and it’s great while it lasts.
But there’s a downside. D&L burn fuel constantly in winter, not in spite of all that thermal mass but because of it. They don’t dare let their house get cold. It would be really hard to warm it up again.
I’m not saying this because I think thermal mass is a bad thing. It’s better in summer than winter. This last June I suffered through several 100+ degree days – indoors. D&L’s house never got warmer than 80, and rarely that warm. Oh, it was great – when I visited I didn’t want to leave. And in winter it certainly smooths out the temperature cycles. But somebody’s always got to be there to stoke the fire, or refill the pellet hopper or the propane tank. If you ever let it get cold, it would be the work of several days to warm it up again.
So I’m not saying thermal mass is a bad thing, not at all. But it’s also not an unmixed blessing. If I ever left during winter I could drain the pipes and let the cabin go to ambient temperature, knowing it would only take an hour or two to warm up. If they ever do it, they’ll need to hire me to run their stoves for them while they’re gone.
That’s exactly the deal with this log home. It took me a while to figure it out, but I know now that if I let the logs get too warm in summer (if we ever have another warm summer, of course), I’ll never get the indoors temperature down again until winter. It gets cool at night, even on the hottest days, but it isn’t cool enough, long enough to reduce the temp of the logs. I have one thermometer on an outside wall just so I can keep track of that.
In the winter, I can’t let the logs get cold either. Same principle. I don’t have central heat, just radiator type space heaters and the upstairs wood stove. It really doesn’t take much to make the indoor temp fairly comfortable, as long as I don’t let it get much below 55 degrees at night. I mostly heat the rooms I actually use the most, but I watch the temperature in other rooms carefully as well, especially if it is below zero outside.
I do notice that the rooms with the most stuff in them change temperatures more slowly. All the stuff absorbs heat, and can conserve it for a while. I also have double pane windows that seal tightly. One pane cracked badly in the office and I can feel the difference. It leaked cold air. Will have to get it replaced. Eventually. In the meantime, the duct tape over the crack is cleverly covered with a drape. 🙂
Not thermal mass, but on-line time:
Next month when your bandwidth resets, check this out:
https://en.support.wordpress.com/xml-rpc/
Offline editing for WP blogs. Writing and posting is probably a small percent of your on-line time, but every little bit helps.
Beg,borrow,barter,but a more efficient wood burning stove is the solution for sure. I have been heating a 1,400 sq.ft. House for close to six months out of the year for longer than I care to think about and it’s all about the stove. I load it up,shut it down and it’s still going in the morning. I know your burning pallet wood but still,you should not have to start over every morning.
I have been following your blog for some time and really enjoy your perspective on things.
Thanks Joel. Good perspectives.
When I have options, I favor layered (like defense). Space that can “breath”. Opened to ambient, or closed up. Move up in a structure when it’s cold, and down when it is hot. In more extremes of temperature, retreat to smaller area within, where temperature can be easiest controlled. Small enough, and well insulated, body heat can be enough. For me, hot places are the toughest. Tunneling maybe…
Joel have you thought of putting some plastic sheeting over the inside of the windows to stop some of the heat loss. One thing we have done a few years ago was get interior storm windows. They fit the inside the window perfectly and change them from double to triple pane. If you could scrounge some plexiglass I’m sure you could make a frame that would fit the interior of the window and help keep in the heat.
Here is an explanation about how they work.
http://www.windowsaver.com/
Here is how to make one on the cheap.
http://www.builditsolar.com/Projects/Conservation/PaulAcrylicStorms.pdf
I’ve wondered just how much insulation on the outside of walls it would take to make a large quantity of thermal mass work well. It seems like one of those things that looks terrific on paper, but in real life, not so much.
I’d think that a two-piece system might make it work: solar hot water – with large insulated tanks fed by an equally large solar array – piped through the mass to constantly maintain a minimal acceptable ambient temperature, say 62-64F, coupled with on-demand air heating to supply the last 7-9 degrees F might work, assuming enough exterior insulation. Reverse the piping process for summer, using ground-cooled water (usually around 52F) tempered with solar-heated water to maintain the mass at 68-70F.
Then again, if it did work well – or at least work well in a budgetary sense – one would see it in use everywhere because thick poured concrete walls are relatively inexpensive; in actuality the only places one sees thick masonry walls seems to be in midieval castles where that was the available building material and the cheap feudal labor to build them. It appears even the rabid greenie cults haven’t jumped on this particular bandwagon.
As a short time apartment dweller in a unit that probably had a single layer of tin foil (with holes!) for exterior wall insulation, I simply wore a sweater inside with warm up pants and called it good. Coldest nights had 50 degree interiors because I simply refused to use the heater (and was rewarded with $10 a MONTH electrical bill) and the coldest time was dashing from fresh shower to bedroom. My Grandfather’s words – JUST LEAN INTO IT.
Joel’s tile for his floor is interesting. I’ve wondered how it will affect the ambient temperature in the Lair in cold weather. Seems possible that if there’s still air infiltration and the floor isn’t very well insulated from underneath complete with plastic vapor barrier perhaps covered with wood it will be very very cold in winter except for a small area around the wood stove. In summer LB will enjoy lying on the cool surface. It will be interesting to hear how the tile floor works over time. Joel’s description of what happens in D & Ls house is interesting because I would have thought a space with that much mass and very little infiltration would give up heat very slowly and reach an equilibrium where it would take a long time to cool down more.
“Seems possible that if there’s still air infiltration and the floor isn’t very well insulated from underneath complete with plastic vapor barrier perhaps covered with wood it will be very very cold in winter except for a small area around the wood stove. ”
The new backing board will have some insulating quality. and the combination of backing board and tile layer will certainly stop any air infiltration that was getting through the original floor. Therefore the Lair should be more snug than before on a cold winter day.
A tile floor almost always feels colder to the feet because of the way its thermal mass transfers heat to your flesh, but that doesn’t mean that it somehow cools down the entire house in the winter time.
Welcome to the last day of September! If Joel’s new Internet account rolls over by the calendar month, he should be out of “Internet Jail” sometime Saturday.
“If Joel’s new Internet account rolls over by the calendar month, he should be out of “Internet Jail” sometime Saturday.”
The second round of “Special High Intensity Training for Adaption to Internet Disruption” may be ending soon?
This won’t help you with your stick-built Fortress of Chickentude, but for D&L, what’s the ground temperature about 4′ down? My bet is that it’s a fairly pleasant 70-75 degrees, and doesn’t vary much year round. Now if they were to berm their house up to about that depth, with the berms being about that thick as well, they would have very little reason to worry about outside temperature. “Earth sheltered” houses are funny that way…
I believe that Ian’s house qualifies as “earth sheltered”, so Joel should be able to offer us a very informed comparison between high-mass stucco, earth sheltered, and his own stick-built Lair.
“If Joel’s new Internet account rolls over by the calendar month, he should be out of “Internet Jail” sometime Saturday.”
Hopefully! because I feel like we’ve been in detention out here too. Mornings just aren’t the same without Joel to go with the coffee.
I just got in from Alaska, 2404 miles from door to door. Just skimming the posts here tonight.
Maybe someone already mentioned this, and I missed it while skimming.
But I wanted to comment on thermal mass. Joel, a stock pot simmering gently, which will hold a lot of heat overnight, releasing it slowly, and meanwhile, will give you bone broth or deliciously simmered stock for soups. When the nights were cold and I lived up higher in the mountains, the stock pot on the stove (a 3-gallon stock pot) kept a lot of lingering warmth, and a few days of roasted bones and a bouquet garni simmering away is just the best stock for sipping, for soups, and mostly for the availability of essential amino acids that are often missing from other foods. Bone broth. Perfect way to recycle and revalue the heat from a wood stove! Check it out. I hope you have a nice stock pot with a lovely lid. If not, I may have an extra one.
I am road weary. I drove in from White Court AB today. But lovely weather and nice people along the way. Canadians, eh?
I see I have a lot of catch-up reading to do. Good to see everyone here.
But time to get some sleep.
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Amen! 🙂
That ‘amen’ was hoping Joel is back on regular band width or whatever it is by tomorrow.
Oh yahooooooo!!!! It’s October 1. Joel, where are you?
Are we there yet?