Massive items on coasters?

Seems like if you have a well-sited and -designed house with equator-facing windows, during winter you want to have a lot of thermal mass on the equator-facing side, just inside the windows. It heats up as the sun shines on it through the windows. You then want to move this thermal mass to wherever it's most needed once the sun is set, so it can gradually release its heat there. Then it can be pushed back into the sun at dawn.

Similarly, during summer you want the thermal mass to be in the pole-facing part of the house getting cold at night, then bring it to the hot part of the house (or wherever it's needed) to act as a heat sink and otherwise cool down the air around it while ambient temperatures are hotter.

Are heavy marble cabinets on coaster wheels, and stuff like that, a thing that people do to achieve this?

Maybe you don't even need to push them around constantly, you can set them to a cold-season position and leave them there half the year, then do the same for their warm-season position? (A moveable wall with large thermal mass?)

Could I be doing this already with items I already have? Are you?

Possible? Certainly.

The foundation supporting the structure would have to enormously robust, to support the stresses when moving without turning the mass into a pile of rubble. Unless it was a pebble heater pile of rubble, which I suppose would readjust all by itself.

Casters? The weight is enormous. I can't think of how to do that in an economical way, unless it's on the chassis of an old truck.

Personally, I would put it on sacrificial skids, drag it around with a come-along or other winch, and lubricate the skids with desert type powder sand (non-sharp sand) or move it on snow/ice. I move all sorts of heavy stuff this way in winter.

Edit: you could go full Ancient Egypt, moving the mass on rollers disguised as fence posts. I have done this too, though I confess Pyramids are beyond me.

I live in a tiny house so this mass could not be bigger than a refrigerator, preferably smaller.

I know that appliance rollers and refrigerator casters are available here in the USA.

Here is an example I found:

https://www.amazon.com/Profile-Casters-Commercial-Refrigerators-Swivels/dp/B07R1L5DJ2/ref=sr_1_8

https://www.amazon.com/Furniture-Dolly-Moving-Wheels-Lifter/dp/B0B187CQC6/ref=sr_1_6

I am fortunately using the thermal mass of my concrete slab foundation which works for both heat and cold.

A thought: you could save a lot of wear and tear on floors, not to mention effort, if you used water as the mass. Say, for instance, you have a black-painted water tank next to an equator-facing window, connected to a tank wherever you need heat by pipes. Then all you need to move the mass is some form of pump system.

Thanks for the replies so far! It was one of those idle late-night thoughts I had to get out...maybe you know the ones.

Douglas, you seem to have in mind something much heavier than what I did. I've heard of people using well-placed marble countertops and solid clay interior walls as thermal mass. I think these would be supportable by most standard foundations, especially slab-on-grade. Anne mentioned a refrigerator-sized object filled with water, which is similar to what I was thinking of too. They certainly make industrial casters that can handle such a thing. What if it had steel tracks too, set into the floor? (Ideally ones that could be easily vacuumed out to remove dust and debris before moving the mass.)

Anne, I think any slab definitely ought to be used toward thermal mass if possible! Intelligent siting and window placement are probably enough in your tiny house situation, and maybe would be for many somewhat larger houses on slabs too. (Bungalos and other smallish homes, maybe even larger ranch homes if they are broad east-to-west and skinny north-to-south.) But I was thinking about in larger homes with more squarish footprints, or ones with no slab at all.

Elno, my thoughts went also to water, though I'm not sure about the energy needed to pump it...might be simpler/cheaper just to pump the warmed-up or cooled-down air from near the thermal mass via ductwork. Thus I thought if I could just push something 20 or 30 feet along a track and be done... Anyway, I recently saw a video where a guy had built a house whose south-facing window walls were in fact water tanks (not the whole wall, but the lower third of them; the upper two-thirds were regular windows). But he didn't do any pumping or moving of the water.

What do y'all think of moving the thermal mass semi-daily vs. semi-annually?

A trombe wall as rolling furniture-very out of the box thinking!

Inside a home proper, I'm doubtful there are enough advantages to moving the mass vs moving the heat, at least on a daily basis.
Everything is inside the buildings envelope, so emitting stored heat in the "wrong" location isn't an issue.
Having thermal mass where you want it seasonally does seem more worthwhile.
If you are intent on letting summer sun into your living space , it would be good to able to remove any thermal mass from that space during the summer.
That said, shade in the form of overhangs , curtains, shutters or blinds could prevent solar gain just as well and should be in use if you are trying to be thermally  efficient .



The best use case I can think of is in a house with a low thermal mass attached sunspace.
These are like attached greenhouses but they exist primarily to harvest heat for the homes they are attached to.
Normally the heat is transferred from the sunspace into the building envelope continuously during the day.

For our use, the thermal mass would sit inside the sunspace all day, soaking up heat.
After sundown, it would be rolled inside to emit the stored heat.

Even in this case, moving heated water  from a solar collecting pond in the sunspace to a radiator inside the building envelope would be much easier.

Ultimately I don't think moving solid thermal mass makes sense,but thermal mass furniture  is a useful idea in rooms recieving direct sunlight during the winter.

Water makes a good thermal mass that can help heat a house though there are substances that can be heated quicker than water.

I am parcal to the RMH water heating though that is probably not a moveable option.

I wonder if the container was filled with something like sawdust would be easier to move and heat as quickly or quicker than water?

I do like the track idea to make moving easier.

We have some rocks on top of our downstairs wood stove. If it's cold upstairs, sometimes my son "delivers" one to me to put my feet on. It's a *lot* of work, for not a huge amount of benefit, but if I'm just sitting down for lunch, it fits the motto of "heat the person, not the room".

So figuring out how many BTU's would be in play would be worth it. Let me add some random thoughts:
Water: 1.  if the system could be designed to, you might only have to pump it one way and let it gravity feed back.
2. Upside of water is that it's a thermal pig. Downside is expansion, contraction, changing states (humidity or risk of freezing).

Other Materials: 1. some heat up faster, others slower. Choosing the right materials could change the effect in the directions you want.
2. If you want a fast exchange narrow mass (think wall) would do so much faster than that refrigerator shape that's been mentioned.
3. Time vs output. 10 bar fridges on wheels would take longer to move than one big freezer size. However, that also opens the possibility of putting the smaller objects in different places both to heat up and to cool down.

It's a great thought exercise and in the right climate I wouldn't be at all surprised if someone couldn't get a system that would work to a measurable extent.

So what if we built it like a black board?
We could insulate one side and put glazing on the other.
In between a big slab of black countertop.
The glass side is pointed at the sun.
The insulated side has a table top  surface and our silverware, cups and plates are cleverly attached.
For meals we fold the glass side face down and it warms our legs as we eat.

The hardware catalogs all list the weight that casters are designed for.  If you want to run them near max, you need either a very flat, stiff floor, or a bit of flex in the mountings, so that they always share the load.  Large casters are available, but you might want to consider wheels salvaged from road vehicles as a cheaper option.

I live in a passive solar heated house, and have lived in similar houses for the past 25+ years. This is a cold climate, 10,500 feet high, but not as far north as Ohio. To give some benchmarks to compare winters, our pond skating season is about 6 to 8 weeks long, and pipes have to be about 3 feet deep to reliably prevent freezing.

None of the passive solar houses I've lived in have had any method to move heated mass into the interior of the house in the evenings. In my current house, the main methods are:

• The walls are made of rammed earth, mostly 1.5 feet thick, which is the main heat storage. The external walls have 4 inches of styrofoam embedded in them.

• We design the houses so the rooms you want to have warm are along the south side, and the middle and north side are the "thermal buffer zone": corridor, dry composting toilet, stairwell, storerooms. The bedrooms, kitchen, bathing bathroom and living room are on the south side.

• In my current house and one of the houses I previously lived in, we attach a plastic greenhouse sheet on a frame on the south side of the house from October to May, and remove the plastic for the summer. It's UV-resistant greenhouse film, lasts a good 5 to 7 years, and end up getting holes and tears due to physical damage, not UV breakdown. It allows me to have herbs and leafy greens and flowers in winter, and it pumps hot air into the house during sunny days, especially when somebody is home and can keep all the doors and windows open between the greenhouse and the house.

• Trombe walls work in my current house upstairs, and in some of the buildings I worked in previously. In my house, the greenhouse is only on the ground floor, so the upstairs bedrooms have half trombe walls. These are 6-inch thick concrete walls about 6 or 8 inches inside of the floor-to-ceiling windows. I like half-trombe walls up to only 3 or 4 feet high, so you get a direct view out the upper half of the window. Especially in winter, I use white woolen curtains (very low tech: I bough a bolt of woven white wool cloth and made simple long curtains with it), and I open them int eh daytime, and close them for the night. The trombe wall is painted black on the south (exterior-facing) side, of course, so it gets pretty toasty, and then the wool curtain hangs over the whole window, between the wall and the window.

• I'll admit, the house gets chilly on some Jan or Feb nights, and I've thought of putting a black container of water in the window and using it as a hot water bottle in the evenings. I'd prefer to have something small enough to hoist around, and, say, stick under the desk for my feet while I work. Currently I have 1 square meter of floor heating (400W) in the living room that we use from late Dec to early Feb, and I preheat the bed with an electric blanket (130W) before getting in bed for roughly the same season. But I have single glazing in the bedroom (the half-trombe-wall big window) so a good double glazed window would probably make that almost unnecessary.

A decent passive solar heated house shouldn't need too much shifting thermal mass around. In the US, plumbing is high quality so I think water with automated circling on a timer would be good. Where I live in India I don't want unnecessary plumbing in my earthen house, because plumbing is dodgy at best.