Rapidobe

For a couple of months, at weekends, we have been building a new room north of the bedrooms.

Its primary purpose is as a thermal battery. When it gets real warm in the house (through the solar gain of our south windows), we open up the door to the new room. There is a lot of thermal mass in the walls of the room, so it stores the heat well. There is a large bench across the north wall, which serves as a giant thermal mass.

The North Room is also a barrier between the outside and the interior of the rest of the house. It has made a huge difference in the nocturnal temperature drop in the bedrooms, which stay about 60 degrees when it is 30 outside, with no fire.

Its secondary purpose is as a storage room. We built a table and shelf unit to house my sewing machine, fur operation, fabric, etc. Abe will be putting some of his mushroom and fodder stuff in there. Also tools, boxes, spare mattress will be moved in there shortly, now that it is finished.

We used a system Abe developed for the walls. We call it Rapidobe (Rapid-Adobe). We put posts into the ground, every two feet, in two parallel lines (each side of the wall). To these we attached a mesh and tarp, in a U shape, from one set of posts to the other. We then filled the bag with dirt that we dug out of the hill, tamping it as we went - this took a day and a half for thirty feet of four feet tall wall. We then put a gypsum plaster on the interior of the wall, and will put a concrete stucco on the outside when the risk of freezing passes. The plastic mesh acts as reinforcement for these plasters.

The main advantages to Rapidobe are speed and low-cost. The tarp that forms the big bag is a recycled billboard vinyl (cheap or free). We cut many of the posts from our property, and the dirt was right under our feet. It is basically a big bag of compacted earth, which is extremely cost effective for a wall material.

Instead of digging the hill down all the way to the level of the floor, we dug it down to a shelf height, 3 feet wide. Seeing as the room is for storage, the shelf seemed like a good idea, saved some digging time, and has added to the thermal mass of the room. The long, Rapidobe wall sits atop this shelf.

The east wall is styrophone insulation with lathing attached to both sides, stuccoed, like a SIP. It has a metal frame that is welded to the door and to the roof.

The west wall is a temporary plywood and frame wall. We will be adding to that area of the house one day when we do the "west wing", so it just has to block out most of the weather for now. It is tarped on the outside.

The roof is metal. We had wanted to do a living roof, but with such a dry year. the desire to add to our catchment area was pretty strong. Metal was fast and easy. It has styrophone insulation underneath it.

All in all, it turned into a really nice room. It is now painted and ready to move into. Guess what we're doing for Christmas?!

For more photos, click here.

Temperature Controls

Because we live off the grid, energy and water efficiency are a priority. We have thus designed the house to use as much natural heating and cooling as possible.

First of all, the insulation helps keep the inside temperature constant. For example, when it rains at night here, the temperature outside can drop 20 degrees, while inside it will only drop 3 degrees.

Secondly, we have built eaves on the south side that allow sun to enter the back of the room in winter, when the sun is low and the warmth is needed. However, in summer, when it's hot and the sun is high in the sky, no sun comes into the room. Seeing as most of the south side of the house is window (all double-glazed), this will significantly help our temperatures. The excessive windows also help with minimizing the need for turning on lights. Even on a super cloudy day, no light is needed.

Thirdly, we have buried the north wall of the house up to about 5 feet. This is where the kids' rooms will be, up a flight of 8 stairs. The buried wall has incredible thermal mass, thereby helping to keep the interior temperature constant.

Fourthly, before filling in the dirt on the north side of the house, we buried pipes that loop from the living room to the kitchen. Because the temperature underground remains pretty much constant year round (like in a cave), they will be much cooler than ambient summer temperature and even warmer than a cold winter's day. We can put a small DC fan on one end, and cool air will come out the other, making it an extremely energy efficient air conditioning. Furthermore, we will be installing ceiling fans in a couple of the rooms, for any super hot, still days.

Fifthly, when we lay the brick floors, we will be putting pipes under the brick, whose water will be heated by solar water heaters that we are going to install on the south side above the kitchen. This will also be our source of hot water for the kitchen and bathroom.

We haven't yet seen a winter in this house, but we are very happy with how it performs in summer.