Picture a group of guys sitting around a table, smoking expensive cigars and drinking Heineken, and talking about what they would build in a new green, sustainable house if they had the opportunity…and money. There’s some humor here. These guys are smoking cigars and talking about building environmentally friendly houses. Lots of ideas were bantered-about, but one guy actually, the following week, produced his plans for building an incredible house for his ‘retirement’-a home that he says could be passed-down throughout generations. A home that is entirely sustainable, as ‘green’ as it gets, and would out-last conventional homes by decades, without the usual expense of reconditioning and remodeling. We didn’t believe him…at first.
At first I thought this was a joke, but it is real. This guy is going to build a ‘rammed-earth’ home. It’s going to be more expensive than the conventional home initially, but the savings will come later. He calls it his ‘forever generation of families home’ that will last well past his demise, and one that his family will never sell. Needless to say, he got our attention.
Rammed-earth homes-or buildings-aren’t new. They have been around for hundreds of years, having been used in Europe, south America, and in the arid areas of the U.S., including California, Montana, Idaho, Arizona, New Mexico, Oregon and Washington. In essence, rammed-earth homes have 14-20 inch walls where earth is compacted between formwork to make a homogeneous mass wall. It’s been used for centuries and is catching-on as sustainable and beautiful building material. The concept is this: Buildings consume 45 percent of our energy use in Canada and the United States. With energy costs at an all time high and mass environmental awareness forcing change, buildings are the primary place we can impact global warming. In this age of peak oil and historic oil spills, we can transform the built environment now through proven ecological and sustainable alternatives. One of these alternatives is to use the very ground we live on to build the walls of our buildings. Check this out: Here are some of the statistics he provided our group about this unique process:
The combination of heat retention from the mass of rammed earth and insulation makes rammed-earth homes suited for various climates. In fact, heating and cooling is efficient and there is little or no maintenance with rammed-earth homes. It insulates 13.5 times more than a concrete wall of the same thickness. Insulated rammed earth also has incredible thermal capacity, capturing and storing energy through passive solar design.
Most buildings have a life expectancy of less than 50 years. This cycle exhausts energy and resources and creates a toxic waste stream by constantly rebuilding. As well, there are no building codes or standards that require buildings be disaster resistant, healthy (containing no toxic materials) or meet other important benchmarks of a quality construction such as energy efficiency, environmental impact and durability.
Fire and Earthquake resistance
Rammed-earth’s green design is low to no impact, using sustainable, locally sourced and ecological building materials. Durable stabilized, insulated rammed earth walls are virtually fire, water and earthquake proof.
In Australia, rammed earth walls have a four-hour fire rating, the highest for Australian codes. Fire tests to AS 1530.4 – 1985 on a 300mm-thick rammed earth wall with 6 percent cement gave 240/240/240 for structural adequacy, integrity and insulative capacity. This means the wall is still standing strong after four hours in a fire!
Designed to withstand seismic events in Zone 5 (San Francisco and Los Angeles), the compressive strength of a rammed-earth building typically falls between 10–30 MPa (1,450––4,500 psi), making it highly seismically resistant. Many rammed-earth homes have achieved more than 6,000psi with only 10 percent cement and regularly exhibit the same strength as concrete with a fraction of the cement. Because the bending moment increases with the cube of the wall thickness, comparing a 24” rammed-earth wall and 8” concrete wall, the rammed-earth wall is 13.5 times as strong.
Comparing resources required in building construction, a typical five-acre treed parcel supplies wood for 20 wood-framed houses, while a five-acre gravel pit has sufficient suitable earth to build rammed earth walls for more than 5,000 houses. Further, no precious topsoil is lost when building with rammed earth.
Improved Air quality
Many homes and buildings continue to be constructed with forced or recycled air, inadequate ventilation, temperature fluctuations, uncontrolled humidity, and poor sound quality. Rammed-earth buildings are excellent at controlling humidity through the humidity flywheel effect. Bringing more than double the mass to a building, which in turn doubles the thermal and humidity flywheel benefits, rammed-earth buildings result in better air quality and moisture control, maintaining an interior relative humidity in the low 50s, which is ideal for human comfort and an impossible humidity for mold to grow.
We spend 90 percent of our time indoors and needlessly surround ourselves with carcinogens and other toxins. Lumber manufacturers douse most building wood with toxic fungicides to prevent mold growth. Often, the built environment is layered with chemicals and provides ideal habitat for mold, which contribute to asthma, multiple chemical sensitivities, immune system deficiencies and other health issues. Besides being bad for your health, such measures don’t always stop carpenter ants, termites and dry rot from slowly consuming wood houses.
Why does a typical wood wall contain elements like volatile organic compounds (VOCs), phthalates, fungicides and urea formaldehyde? Doesn’t the Building Code ensure that only healthy materials can be used? No, the Building Code is there to ensure the minimum level of safety in buildings and, at this point in time, toxic materials aren’t deemed to be a safety issue.
Unlike most building materials, rammed earth walls are non-toxic and maintenance-free, requiring no sealants or finishes, which preserves indoor air quality. Rammed-earth builders use an integral admixture that seals the wall all the way through, reducing the need for ongoing maintenance. In addition, rammed-earth buildings eliminate toxins from wall assemblies, creating interior spaces that are healthy to inhabit. This is true not only of the wall itself, but also through the exclusion of interior and exterior finishes that can contain many of the most toxic and environmentally destructive components found on a construction site. Amazing.
Rammed-earth homes incorporate traditional ceilings and roofs. Our guy says that he plans on topping-off his home with high performance reflective insulation, making it the most energy efficient and sustainable home that (he imagines) can be built. He plans on installing ecologically smart window film, and solar attic fans and electric systems.
When he finished his talk, the room was silent. Just a bunch of guys with cigars hanging out of their mouths…jealous and dreaming of our own rammed-earth homes in the future.