Insulate With an Earth Berm

Not long ago, I was faced with the problem of trying to improve the heating and cooling efficiency of concrete block house, a structure whose walls had an R-factor of about 3!

My family and I had purchased such a home (the manner of construction is common around Gainesville, Florida) and found it uncomfortable. The walls were almost always chilly in winter, and did little to alleviate heat buildup in summer. When our average heating/cooling bills exceeded $150 per month, necessity inspired me to come up with an easy, inexpensive solution to the problem: a wall-length earth berm.

Instead of dumping huge amounts of money into expensive products such as fiberglass or foam insulation, I could use natural materials for our home’s “remodeling”: earth, grass, and wood. (The only “refined” product used was tar, which we applied along the lower five feet of the outer side and back walls.)

In order to berm the perimeter of our 1,400-square-foot dwelling, we hauled in 40 tons of dry earth and packed it against the three tarred walls. The exposed upper wall surfaces–as well as the front of the building–were covered with rough cypress boards.

We soon had grass sprouting on the face of the slopes and found that an afternoon’s sprinkling during the summer transforms the earthen mounds into active heat sinks. In the winter we let the soil dry out, which lessens its ability to conduct heat and thus makes for good insulation.

As a result of our earth berm system, the inside of the house is much less subject to temperature fluctuations even when it’s extremely hot or cold outside. Our heating and cooling expense has dropped about 40% since we finished the project, and we estimate the $1,000 spent on the conversion will be retrieved in less than three years!