Passive Solar Design with Earthen Homes
During a long and cold winter, many of us might wonder if it is possible to stay warm without the benefit of a fossil fuel powered central heating system. The U.S. Department of Energy estimates that close to 50% of all the energy used in American homes is for heating and cooling purposes.
While it is nice to be able to walk barefoot in one’s home during the dead of winter, that luxury comes with a price that most of us don’t consider.
The Energy Information Administration (EIA) notes that residential carbon dioxide emissions have been steadily growing at a rate of around 1% per year. While most household appliances and home energy implements have become much more energy efficient (think LED lighting), the amount of energy used to heat and cool a home has continued to rise.
As we continue our steady march towards peak oil, we need to seriously begin to consider how we are going to stay warm once cheap and abundant fossil fuels are no longer an option. In Europe alone, over 40,000 people died in 2015 due to extreme cold temperatures. When the electricity goes out, most people have absolutely no idea how to stay warm. Our dependence on fossil fuel energy, then, is not only dangerous for the planet but also a threat to our survival.
What is Passive Solar Design?
Our earth travels around a ball of fire that is continuously emitting enormous amounts of heat and energy. The sun is perhaps the most underutilized source of energy. We spend millions of dollars to develop technologies to dig fossil fuels out of the ground, refine them, and burn them when every day our homes receive between 8 and 16 hours of direct exposure to the largest source of energy in our solar system.
Passive solar design is simply the process of designing a home to best take advantage of the sun’s energy and warmth. With the incorporation of earthen elements into the home, a properly designed passive solar design system can provide adequate heat for an entire home with only occasional need for extra heating (from wood stoves, for example) during long, extreme cold spells.
The Four Principles of Passive Solar Design
1. Angle your home towards the path of the sun (south in the northern hemisphere and north in the southern hemisphere). In winter, the sun drops in the horizon. Without sunlight directly overhead, the only way to take advantage of that sun is through angling your home so that it receives the most direct sunlight.
2. Build large windows on the sun-facing part of your home that allows for maximum solar gain. Building large windows on the sun-facing side of your home will allow for the sun to heat your home during the day. Since windows also can let heat escape from your home, it’s important not to build too many windows (or none at all), on the cold side of your home (north facing wall in the northern hemisphere and vice versa). If you live in an extremely cold climate, double pane windows can add an extra layer of protection and insulation.
3. Build lots of thermal mass into your home so that the sun’s heat can be stored overnight. It would do little good to design your home to capture the sun’s rays if you had little way to “store” that heat. Certain earthen materials are known as thermal masses because they can absorb the heat of the sun and hold it for long periods of time. The rock or brick mantles of fireplaces follow from the same principle. The heat generated by the fire is “sucked up” by the rock or brick so that even after the fire subsides, these thermal masses continue to slowly release the heat from the fire. Some options for thermal mass materials to capture the sun’s heat include earthen floors, adobe or cob walls, or stonework and masonry.
4. Insulate well, especially on the cold side of your home. Once you get the sun’s heat into your home and stored in a thermal mass, you want to make sure to keep that heat in your home for as long as possible. Insulating your home, especially on the cold sides of your home (north and east in the northern hemisphere), is important for passive solar design. One of the best insulative building materials is with straw bales.
Passive Solar Design to Free Yourself from Dependence on Fossil Fuel Energy
When combined with passive solar design, a well-built earthen home may very well be able to heat itself with nothing more than the warmth of the sun. Finding alternative ways to stay warm in the coming post fossil fuel age is a task we shouldn’t take lightly. Passive solar design and earthen construction are two methods, that when combined, offer a completely natural heating system.