Buildings built from glass bottles (Thai Temple example).

Does it matter if the bottle filled with water is exposed to the sun or can it just be incased in the motar or filling the space in the bricks?

The water just provides thermal mass and it need not be exposed to the light.

So, most concrete bricks I see have those two hollows in them. Are they filled with motar during construction? Would buildings significantly benefit from having sealed bottles of water placed in them? (Not sure if bottles that small exist in large quantity.)

You probably want to leave them empty. Water is an excellent thermal mass but a lousy insulator; air is the reverse. So you’d want water in the interior of your house and air in the walls.

Thermal mass is generally a good thing but you really need to understand the whole picture because looking at just one issue can be misleading.

Insulation keeps heat from passing through.
Thermal mass stores heat so it would take longer for the heat to be lost or gained and temperature swings would be slower.

If you have a house with good insulation and extremely high thermal mass then the inside temperature would be the mean of the outside temperature. It would be cooler than the outside during the day and warmer at night.

Not only that but you can pump heat in or out of the building when it is most convenient to you. You can run the A/C at night when it is more efficient. Or you can use solar heating during the day and the temperature would not drop at night.

So, in general terms, thermal mass is good. One good thing about hydronic heating systems is that they provide some thermal mass in the water itself. Running many pipes in the walls and floors for radiant heating is even better as it adds more mass. BUT, a ruptured pipe is a mess. On the other hand a wall full of bottles filled with water adds a lot of thermal mass with no danger of leaks. You just have to seal the bottles well so the water does not evaporate.

They are probably empty. I got to go on a tour on an Earthship in New Mexico. There is a documentary about the architect called Garbage Warrior (awesome doc, BTW). Most of the walls of his buildings use old tires with sand pounded into them, as well ass aluminum cans and bottles. From the inside, the bottles work like stained glass (you can see a picture at the above link where it says “nightly rentals”. It’s quite beautiful and really remarkable solid. The homes are totally off grid.

There’s a YouTube video about them too.

Fianceephone and I are actually interested in building one as a retirement home.

At 1:38 he says the bottles (and cans) don’t serve a insultative purpose. Does that contradict what we’ve been discussing?

In the past they were sometimes filled with cellulose insulation. They are sometimes filled with concrete and rebar for structural purposes, if for example they form a pillar supporting something.

Just to point out the obvious, do not put water in the bottles if the wall will ever freeze, or you’ll end up rebuilding your wall.

One thing I’ve always wondered about these walls - do you cap the bottles? I can’t imagine that you would leave them open, as wasps and other bugs would love it.

Leave enough air space to provide for the expansion if they freeze. I’d think you’d be better off filling the cores with urethane foam, though.