OUR CRAZY HOUSE
Design
My husband, Chris, designed the house. He pulled elements from many sources and integrated them into a cohesive whole. We moved in at the end of 2010; it feels GREAT to finally be HOME.
The house is round or, more accurately, a 48 sided figure. This provides the minimum outside area for the maximum interior space to improve energy efficiency. It is also located atop a ridge where conditions are often windy. The round shape funnels the wind around at high speeds. The casement windows are designed to catch some of this cooling breeze in the summer, bringing it into and then out of the house again. The round shape also was a nice match for the atrium greenhouse. Most importantly, it's kinda cool.
The house is round or, more accurately, a 48 sided figure. This provides the minimum outside area for the maximum interior space to improve energy efficiency. It is also located atop a ridge where conditions are often windy. The round shape funnels the wind around at high speeds. The casement windows are designed to catch some of this cooling breeze in the summer, bringing it into and then out of the house again. The round shape also was a nice match for the atrium greenhouse. Most importantly, it's kinda cool.
Off Grid
The house relies on a photovoltaic (solar) panel system for electricity. It is a one kilowatt system with a battery bank and inverter, as well as various electronics to help control and monitor the flow of electricity. The system is fully installed and functioning as of November, 2010 and has performed flawlessly through the present day. Backwoods Solar, www.backwoodssolar.com, designed and sold us the system, which Chris installed. The Backwoods staff has been wonderful in terms of answering questions and offering further support. We highly recommend them!
A few elements, such as the well pump and livestock fences, run directly off their own panels, without integration into the larger system.
After living off-grid for several years, I am surprised at how easy it is! You have to use common sense, but we have had no problems at all, and conserving electricity occasionally in the winter has been an invitation to read instead of watch a movie. It has been a very positive experience, and the power never goes out!
A few elements, such as the well pump and livestock fences, run directly off their own panels, without integration into the larger system.
After living off-grid for several years, I am surprised at how easy it is! You have to use common sense, but we have had no problems at all, and conserving electricity occasionally in the winter has been an invitation to read instead of watch a movie. It has been a very positive experience, and the power never goes out!
What Is It Made Of?
The structure is pine logs. The roof is locally harvested and rough cut cedar decking topped with rigid insulation and EPDM (rubber pond liner) with a living roof above. The exterior walls are earth bags to windowsill height and straw-clay slip above, and the wall between the atrium and the interior is made from pine posts, waste styrofoam (packaging from the windows, etc.), and straw-clay slip. The floor is a compressed earth and gravel base with stone (like a stone patio) which is sealed with a natural product: Bioshield Resin Floor Finish www.bioshieldpaint.com . The inner non-load-bearing walls are traditional frame and drywall. The walls (including the drywall) are plastered with earth plaster and lime plaster, inside and out. The house is earth bermed to windowsill height. All the doors and most of the door hardware are reclaimed; all the windows are new, double pane www.pella.com There is no concrete. There is no foundation.
Atrium
The central atrium greenhouse is separated from the rest of the house with walls and doors in the interior. However, the main entrance path travels though it, and it is walked through often. Our dwarf citrus, figs, aloe, banana tree, pineapples, and various herbs love the greenhouse. Our outside water plants live in buckets in the greenhouse during the winter months. It is also be a natural, warm haven during the day in the winter.
The dome was purchased as a kit from Growing Spaces http://www.growingspaces.com. The picture shows the dome skeleton under construction. It has windows that automatically open and close with the temperature using wax cylinders. There is also a door leading to the roof. However, its most important function is as a trap for warm air to use to warm the rest of the house. We can also grow subtropical plants like this pineapple and banana tree.
The dome was purchased as a kit from Growing Spaces http://www.growingspaces.com. The picture shows the dome skeleton under construction. It has windows that automatically open and close with the temperature using wax cylinders. There is also a door leading to the roof. However, its most important function is as a trap for warm air to use to warm the rest of the house. We can also grow subtropical plants like this pineapple and banana tree.
Heating System
In short, the house is heated by circulating air from the top of the atrium, either directly into the living space, or through the floor in the cooler months. This moderates the house temperature and a wood burning cookstove is the main heat source. The house is also very well insulated. Temperatures in the winter would not get below 45 degrees inside without any supplemental heat. In fact, it usually stays in the low 60's. With the wood burner we can keep a comfortable temperature (low 70's) all winter with 1 1/2 cords of wood during a cold winter. (We also have integrated the woodstove into our plumbing system to provide hot water to the house on cloudy winter days.) On sunny days, our vacuum tube solar hot water heater on the roof provides hot water and the atrium provides all the necessary heat for the house. So on sunny days in the winter, no fire is required. During extended cold, cloudy spells, however, we are very happy for the woodstove.
A more detailed description of the heating system follows. Warm air from the top of the atrium is drawn through a pipe through use of a small solar powered fan. We can control whether the warm air goes directly into the living room, or it can travel through the earthen floor of the house, around the perimeter. The pipe acts as a heat exchanger; the heat can travel through the pipe and warm the surrounding earth. It need not be efficient because it is 200 feet long and the air will move quite slowly. This system can be used as soon as temps begin to cool in the fall, before you would normally turn on a heating system. The house is fairly highly insulated for this region to minimize daily fluctuations in temperature.
A technical point that helps the temperature stabilization of the house is the watershed umbrella. Outside the house, rigid insulation is buried horizontally in the earth berm, 2 feet below the surface, sloping downward parallel to the surface of the berm. This insulation is topped with layers of plastic sheeting and then 2 feet of earth. A french drain is installed at the perimeter of the watershed umbrella to keep the area around the house quite dry. Since dry earth moves temperature at the rate of approximately 1 foot per month, while wet earth moves it much faster, this system effectively increases the mass of the house exponentially.
A more detailed description of the heating system follows. Warm air from the top of the atrium is drawn through a pipe through use of a small solar powered fan. We can control whether the warm air goes directly into the living room, or it can travel through the earthen floor of the house, around the perimeter. The pipe acts as a heat exchanger; the heat can travel through the pipe and warm the surrounding earth. It need not be efficient because it is 200 feet long and the air will move quite slowly. This system can be used as soon as temps begin to cool in the fall, before you would normally turn on a heating system. The house is fairly highly insulated for this region to minimize daily fluctuations in temperature.
A technical point that helps the temperature stabilization of the house is the watershed umbrella. Outside the house, rigid insulation is buried horizontally in the earth berm, 2 feet below the surface, sloping downward parallel to the surface of the berm. This insulation is topped with layers of plastic sheeting and then 2 feet of earth. A french drain is installed at the perimeter of the watershed umbrella to keep the area around the house quite dry. Since dry earth moves temperature at the rate of approximately 1 foot per month, while wet earth moves it much faster, this system effectively increases the mass of the house exponentially.
Cooling
. . . is very important in Tennessee! Our breezy location and a total of 20 windows all around the house keeps us well-ventilated. The atrium is totally ventilated in the summer. Fairly broad overhangs minimize summer heat gain through the windows.
After living with the solar system for a little while, it is apparent that our photovoltaic system could support a small, portable A/C unit in the dog days of summer (which is also when we take in the most solar power)! So far, we have not needed it though, as the house has not exceeded 83 degrees, during the very hottest periods when outdoor temps exceed 100. More generally, the interior stays in the 70's during the summer days.
Another advantage of the dome atrium is that domes create natural air currents that can be quite strong. In the words of Buckminster Fuller, "Domes suck." That is, they suck air into them when vented from the top, so the dome can actually be used to create gentle ventilation through the house on a still day.
The picture above shows the windows installed atop the earth bag wall before the straw clay slip wall was built between the windows.
After living with the solar system for a little while, it is apparent that our photovoltaic system could support a small, portable A/C unit in the dog days of summer (which is also when we take in the most solar power)! So far, we have not needed it though, as the house has not exceeded 83 degrees, during the very hottest periods when outdoor temps exceed 100. More generally, the interior stays in the 70's during the summer days.
Another advantage of the dome atrium is that domes create natural air currents that can be quite strong. In the words of Buckminster Fuller, "Domes suck." That is, they suck air into them when vented from the top, so the dome can actually be used to create gentle ventilation through the house on a still day.
The picture above shows the windows installed atop the earth bag wall before the straw clay slip wall was built between the windows.
Mass
The house is simply massive. We estimate that well over 10 tons of material are part of the house. The mass has the effect of moderating temperatures - making the house slow to warm or cool. It also makes the temperature remarkably even within the house, from room to room. It has the effect in the winter of having a cooler air temperature *feel* warmer than I am accustomed to feeling in a traditional house in which the air temperature may be 60, but the floor on my bare feet is 50 and the walls are 55, etc.
The picture above shows the earth bag walls under construction.
The picture above shows the earth bag walls under construction.
Water
. . . is provided by a well with solar pump. It pumps whenever there is enough sunlight to power the panel at a slow steady rate into a 5,000 gallon tank which is uphill of the house. We share the water system with a neighbor. The drop from the tank to our house provides our water pressure. Plumbing is polyethylene to the house and pex within.
We also installed outdoor hydrants every hundred feet or so along the water line to allow ready access for irrigation, watering animals, etc.
The picture shows our two oldest kids, the PV panel for the well pump, and the water flowing on the first day we tested it.
Interior
The house has 4 modest bedrooms, 2 bathrooms, a living/kitchen/dining room, a playroom/guest room, a small office, and a mud room/entrance.
The roof structure is exposed. The interior walls are finished with lime plaster. All doors were reclaimed - many from a single "deconstruction," complete with vintage doorknobs. There are three shelves laminated in place on the interior wall that go all around the house. They are organically shaped and very useful.
The roof structure is exposed. The interior walls are finished with lime plaster. All doors were reclaimed - many from a single "deconstruction," complete with vintage doorknobs. There are three shelves laminated in place on the interior wall that go all around the house. They are organically shaped and very useful.
Our Philosphy of "Natural" Building
So, just what is a "natural" building? It can be many different things, depending on your priorities and the choices you make accordingly. We are not purists, and there are certainly non-natural, human-made materials in the house. When confronted with a choice of what material to use, we considered the energy footprint of the item, including method of manufacturing, how long it would last, how well it would accomplish it's job (impacting whether or when it would need replacement), and recyclability or compost-ability. We also considered more typical issues like cost and time to obtain and install. We found that the "right" answer was not always clear. We did our best to stay true to our values while honoring practicality as well. I'm sure every person building such a home would make their own set of decisions that would differ from ours.
A priority was using natural materials. We estimate there are over 10 tons of natural materials in the house, all translating into thermal mass as well! We did not use any concrete in the house because of the very high energy requirements to manufacture. However, we did use rubber cement to attach the rigid insulation to the roof because a windstorm was coming and we had little choice if we didn't want to lose it all down the hill! We used a type of rigid insulation that is recyclable; however, it is still a manufactured, unnatural product. It's performance outdid anything remotely natural and it should never need to be replaced. We used polyethylene pipe instead of PVC because it is safer and also recyclable, even though it was significantly more expensive. We are still making choices, and I'm sure we'll also find that we'd do it differently in some areas, years from now.
A priority was using natural materials. We estimate there are over 10 tons of natural materials in the house, all translating into thermal mass as well! We did not use any concrete in the house because of the very high energy requirements to manufacture. However, we did use rubber cement to attach the rigid insulation to the roof because a windstorm was coming and we had little choice if we didn't want to lose it all down the hill! We used a type of rigid insulation that is recyclable; however, it is still a manufactured, unnatural product. It's performance outdid anything remotely natural and it should never need to be replaced. We used polyethylene pipe instead of PVC because it is safer and also recyclable, even though it was significantly more expensive. We are still making choices, and I'm sure we'll also find that we'd do it differently in some areas, years from now.