I live in an earthbag house near Utley, Tx. The walls are about 16-18 inches thick with the plaster on. Our winters are generally pretty mild (this last snow historic snow storm excepted), and our summers are brutal and miserable. Think 90% of the humidity you would associate with Houston or New Orleans but without the regular afternoon showers to break the heat. I would have to say that my earthbag home is very comfortable in my climate.
For summer cooling: The house is sunk into the ground on a slight hill. The bedroom is about three feet below grade, the other side of the house only about a foot. The ceilings are over ten feet high, which helps a lot as well. A great deal of our warm season cooling comes from keeping the front door open (sometimes with the screen sometimes without depending on the bugs) all night whenever the night time lows are going to be below 65 or so, which will happen often
enough up through May or so. The cool air passively pours into the house which is the lowest spot it can go, and cools the walls and tile floor in the process. I also have a box fan that I hang in front of the front door, it definitely looks silly but I can blow the hot air out the south less bermed side, and open the bathroom door on the north side and draw cooler air from the perpetually cooler back porch. All that being said I still have two window unit ACs, one for the whole house minus the bed room, and one just for the bedroom. With some lifestyle and ventilation adjustments I think we could get on without them if we really had to but when the low for the night is 80 degrees and the humidity so high it'd be a stretch. Think an 80 degree fog, yuck!
For winter heating: There is a
greenhouse attached to the front of the house, inspired by earthships but not quite as integrated as that. Most of my windows face out into the
greenhouse. During the heating season I simply turn my fan around and blow hot air from the greenhouse into the house. It doesn't work as well for heating as it does for cooling since the heat wants to rise, but it still makes a very appreciable impact with very little electricity usage. The other form of active heating we have is one little space heater and one electric blanket. The bedroom is tucked into the earth deep enough that heating it has never been too much of an issue. When we had our historic winter storm last month we lost power for three days in temps ranging from 5-25 degrees with no sunshine and six inches of snow on top of the greenhouse roof. That was easily the toughest test our home as a survival tool has ever faced. It was not uncommon for it to be below freezing inside the homes of people in our neighborhood, but when the electricity finally came on briefly and I could turn on the space heater to see what it's thermometer read we only got down to 49 inside! Still unpleasant, but no broken pipes. As a bonus, our water tanks are higher than all the end use points, so once I thawed the one foot of pipe that was above ground the water gravity fed through the filters and we had water again too even when the electricity was still spotty.
There are two things I would say that have limited the comfort level. The first was humidity. I was advised by people on this site to not put any sort of vapor barrier or plastic in, under, or around my earthbags, even below grade. I am very glad that I listened! The house was unfinished when hurricane Harvey dumped a foot of rain on us and blew all the tarps off, but everything dried out just fine in the sun. Another time before the floor was finished and everything was graded outside a pile of dirt for construction blocked a drain in the driveway and caused a waterfall to come flowing down the steps and left an inch of mud near the stairs. Still very annoying and prevented me from tiling the floor until everything could dry out, but not a disaster because everything could freely drain into the rubble and french drain underneath. All that being said there have been some humidity issues, especially in the back, north east corner with the bedroom so far below grade. At one point our furniture in there started getting moldy! The house is square, and the straight walls have five foot buttresses, which means that I already had at least five feet of overhang on all sides. I added an extra 8 feet of porch on the north side and an extra four on the east and that has all but solved the humidity issues. We still have a dehumidifier in the bedroom but it's almost never used. The second thing that has limited the house's performance is draftiness. It all comes down to how well you build those window and door forms at the beginning of the build. The windows were very easy to install, and if something wasn't quite square, just cob it up! The doors however, were a different story. Have you ever tried to fit a rectangular object into an opening that is just a touch of a rhombus? Our door forms shifted during the build, not enough for us to notice at the time, but painfully obvious when it was time to put the doors in. There are three normal doors and one sliding glass door into the greenhouse. The glass door I had to chip and chop away at the earthbags to get into place, and the other three I had to frame up and are still very drafty. It's bad enough that when the weather is a touch warmer later this year I'm just going to take two of the doors out completely and cob up the openings. Done with the drafts!
Hope some of this helped!
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