passive heat storage, tile
My house was somewhat designed by the previous owner to get passive solar heat, it is orientated to the south, it has skylights on south that let the low winter sun penetrate deeper, it was built with a lowered floor area all along the length of the first floor for a thick tile job to store some heat.
None of these measures were implemented as well as they could have been, the skylights for example let in an awful lot of summer heat that I don't want, they would have been better if they were dormer windows so that the glass was more upright and so would select winter vs summer sun. The back wall should have had 2 layers of drywall vs one layer to store more heat. And, the owner installer when they tilled in the mid seventies filled part of the lowered floor area with 3/4 inch particle board to save work, which meant that the mortar bed was not as thick as it was designed to be. They did use 3/4 inch thick tile.
Some tiles have broken over time, and I can't match it, so I had to replace it. So I ripped out the particle board and now have a thick mortar bed, today just finished the deck mud and it is over 2 inches thick, total thickness is 2 5/8" of mortared and tile over about 120 sq foot area down the length of the house.
Photo is mortar bed in progress, the stuff applied is deck mud, it is like building a sand castle, it is mostly sand
Tue, 12/06/2022 - 12:04
passive heat storage result
It may not look like much, but this is 28.5 cubic feet of solid thermal mass, when the sun is out in winter, it is low in the sky and hits this walkway in the back of the room. The mass continues into the kitchen so far as storage goes, but the sun does not hit back there, they are connected mass, so the heat should transfer there. kitchen also has messed up tile, that area will be redone this summer and also have the particle board taken out to give it the mass the house was designed for, the kitchen is a bit less than half as much cu ft of thermal storage. there is also some mass by the wood stove of course, tile behind and under. Under the wood stove is 20sq ft, but only half as thick and not connected or in the direct sun for direct passive storage, behind the wood stove is 44sq ft, don't know how thick, I don't think very thick. Both will smooth out temperature over time, so store radiant heat from wood stove and excess air temperature in the room without direct solar gain.
So, the tile job just in the living room is 28.5 cubic feet, assume kitchen at half that , 14.3 so total of right under 43cut ft, a 55gallon metal barrel full of water is 7.35243 cu ft. So more than 5 barrels of mass. Water and stone store and release heat differently, see the link the the passive solar house book on the other thread.
Mon, 01/02/2023 - 10:56
Tile heat storage?
Do you have any idea how much heat that comes in the top is lost out the bottom? (I'm assuming that there's just dirt or cement slab underneath the grout under the tile.) An acquaintance of mine has been trying to promote a new building material for below-grade insulation that's made of sintered crushed glass ("foamed glass aggregate"). You would use it like ordinary crushed stone, but it's about half the density, and better thermal insulation. However, a quick web search couldn't quantify the thermal insulation... I mean, it seems plausible, but I didn't find data.
Fri, 01/06/2023 - 19:59
I know exactly
I know exactly what is underneath and it is not dirt or a slab. What is underneath the mortar is 1.5 inches thick of Douglass fir wood, you can see that wood in the photos. underneath that is a crawlspace, so air for another few feet. This used to have fiberglass insulation under the wood, but I had to throw that away last spring due to smoke damage from the fire. The crawlspace was also a "conditioned crawlspace" meaning that insulation and thermal break area is at the walls of the crawlspace now and nit right under the floor. I have a lot of perforated. radiant barrier unused and I am going to put that under the floor, even though it is a conditioned crawlspace. SO, then it will be tile, thick mortar bed, 1.5 inches of Doug fir lumber, 3.5 inches of airspace, a radiant barrier, a couple feet deep of airspace with insulated walls at the house perimeter.
As far as heat loss underneath, well, wood does some conductive heat transfer, but it doesn't touch the soil, so really there is no conductive heat loss out of the floor system, under the wood there is effectively no air movement as the crawlspace is sealed, so no convective heat loos. There will be some radiant heat loss, but less will radiate down than up into the room as wood radiates much more poorly than the tile. This is why I will most likely add the radiant barrier. Although, the idea of a conditioned crawlspace is to have the crawlspace itself part of the conditioned (heated) part of the house, like a really short basement. I will most likely transition to something in between, where there is a small air connection (vent) to the house but leave it to be colder than the house proper.