Because of its small size, a tiny house is generally already more efficient than a large one—there is less square footage to heat and keep cool, among other factors. There are ways we can increase this efficiency. My earthbag tiny house has a very modest solar setup and I almost always have power to spare. The reason is that I use natural forces to provide my needs whenever possible. Here are some of the methods I’ve used:
Gravity-fed water. We have a large rainwater tank at the top of our property and it is probably at least a fifty to 75 foot drop from there to the tiny house. This provides good water pressure, good enough to run my battery-powered, on-demand hot-water heater. This keeps me from needing a pump and using the energy that would require.
I use air temperatures and thermal mass for refrigeration. One feature I made sure to add to the tiny house was a fridge and root cellar window combo. The top part is open to the outside and helps cool food in the colder months. The bottom part is bermed and uses thermal mass to stay cool year-round. Our average earth temp here is 58 degrees so while the root-cellar window won’t make anything frosty, it’s a big improvement over our air temps in the summer months. It’s basically just a root cellar integrated into the living space for easy access. I put thick foam insulation on the inside of the fridge doors to isolate the inner temps from the outer. Usually, in modern structures, we use all of the energy to cool a space (fridge) within a warm space (house) within a cool space (outdoors)–that’s a huge waste of energy!
I use window placement in line with the prevailing winds to help dehumidify the tiny house. Because we used a spot originally excavated for a root-cellar, the tiny is at the bottom of a north-facing slope. As you probably already know, south-facing is the desirable orientation (in the Northern-hemisphere) for passive solar gain and the natural drying that comes with it. Our climate is very wet where I live so drying is extremely important. A moist structure can lead to mold growth and a host of other serious issues. One part of my solution has been to orient the windows so that the wind coming through our valley creates a cross-breeze in the house. It’s amazing how quickly a dry winter wind can dehumidify the entire house, much faster than an electric dehumidifier.
The tiny is kept comfortable by thermal mass and a wood stove. Earthbag walls intrinsically have a lot of thermal mass. Eventually, the tiny house will also be bermed in the back, as earthships are. This will bring more temperature stabilization in all seasons. A small wood stove is plenty to keep the structure warm. I plan on building some cob around the wood stove as well to make a pocket of warmed thermal mass inside, just as rocket mass heaters do.
Plenty of windows and glass in the front french doors means no need to use artificial light during the day—another power saver.
I built the tiny house because of an urge I was having to simplify my life. By using natural forces to provide my necessities and comforts, I can have a very modest solar array that is mostly used for high-efficiency LED lighting and charging my devices, such as the laptop I’m typing this on. Natural forces such as gravity and thermal mass will not fail you. There is no danger of them breaking as all electronic and mechanical devices eventually do. The use of them doesn’t add any carbon to the atmosphere and doesn’t worsen climate change. They’re also really easy to incorporate into any structure. If more and more of us become aware of possibilities like these, they become part of the mainstream culture. Humans aren’t generally intentionally ignorant, we are just unaware of certain options.
My next blog post will likely focus on the fridge and root cellar window. In many areas, it’s a great option for zero power refrigeration. Thanks for reading! Morgan.