Ever since reading the line “In a hole in the ground there lived a Hobbit,” and its subsequent paragraph, I’ve been more than a little obsessed with the idea of Hobbit homes, especially after I learned that, yes, people can actually live in their own hole in the ground. The proper term for these types of homes are “earth sheltered homes” and which, as it turns out, ICF’s lend themselves well to.
For those who are new to what we at Open Range Construction, Ltd. do, we build with ICFs or insulated concrete forms. Like in the name, ICFs insulate a building rather like a foam cup insulates hot chocolate. ICF blocks are made of expanded polystyrene foam and once they are stacked to form the walls of the home, they are filled with concrete. While the completed ICF home is near indistinguishable from your average stick frame (traditionally built) home, it is sturdier, longer lasting and disaster resistant. ICF homes are also more sustainable with a lower carbon footprint than stick frames, and are also energy efficient, which saves homeowners not only energy but also money, and the energy savings offset the initial cost of the building in the long term.
Earth sheltered homes have many of the same benefits due to being partially or fully covered by earth. This natural covering gives the home thermal mass, which helps to regulate its temperature year round, reducing the need for heating and cooling. The earth covering also gives these homes a degree of resistance to tornadoes and high winds, as well as helps to sound-proof the house from outside noises. As far as cost goes, according to energy.gov, they will be much more cost effective in regions with low humidity and more extreme temperatures (Coloradans, I’m looking at you), however, like with ICF, energy savings will generally be higher. These homes also require less outside maintenance, especially if they have living roofs.
By using ICFs in an earth sheltered home rather than concrete or another building material, you are able to increase the effectiveness of these preexisting benefits and make up for some of the home’s weaknesses. For example, while the earth has high thermal mass, it does not insulate well. ICFs on the other hand, provide high insulation. This in combination with the home’s thermal mass and strategic window placement (passive solar) will help to further decrease energy costs and create a more sustainable home.
There are two main types of earth sheltered homes: underground and bermed (of which there are two subtypes). Underground homes are often entirely subterranean and work well on flat properties. These homes also do well to have open or atrium floorplans and skylights in order to give them a more open feeling and increase ventilation and light access to the whole house.
Bermed homes on the other hand, can be built above or partially below grade and are more often what we see when looking at photos of Hobbit homes. “Elevational” bermed designs have one exposed elevation of the house (often the front) and three earth-covered sides. The roof may or may not be covered. Like with Mr. Baggins’ home, the exposed elevation most often needs to face South so as to maximize the amount of heat and sunlight that filters into the house. Skylights on the northern side of the house can help add ventilation.
Penetrational designs have earth covering the entire house, which is bermed up over and around it. These designs can have windows and openings on all sides of the house, which allows for cross ventilation and more opportunities for natural light to penetrate the home.
Now just because I’m obsessed with the idea of building a home that would make any hobbit of the Shire proud, doesn’t mean that earth sheltered homes have to look anything like them. Earth sheltered homes can come in many shapes, sizes and styles, even everyday houses from off the street if your concern is resale value. Regardless of style, earth sheltered homes generally seem to be designed in such a way so that they are less visibly intrusive to the surrounding environment.