|
|
An earth-mass home is generally thought of as being built into a hillside, or at least partially enveloped by the earth. (This is one good option, as Mark will attest - pictured here is the earth-mass home he has lived in for 15 years). However, "earth mass" just means having a large portion of your home connected directly to the earth; this can be right under your floor if insulation does not break the connection.
Earth mass is like having a big hot water bottle in your home - a hot water bottle heated by passive solar. For passive solar to be effective, the home must have enough mass to hold the incoming heat.
A home with earth mass surrounding one to three sides can be extremely efficient. This type of structure obviously limits or eliminates windows on the earth sides. However, the south side will have large windows (this is the passive solar) which will bring plenty of light into the home. Skylights and refractory light tubes are also used to bring natural light into the "earth" sides of the home.
Straw bale homes are becoming more popular both for their energy efficiency as well as their beauty and flexibility of design. Straw is essentially a waste product of the grain harvest; sometimes it can be used as mulch, but more often it is simply burned. A straw bale home has moderate mass and fantastic insulation, making these homes inexpensive to heat. The bales are finished with a type of plaster or stucco and have a pleasingly organic look when finished; the walls will not be completely smooth as in a standard drywall house. A poorly-built straw bale house may be susceptible to moisture, so it is important to choose a builder with attention to detail and plenty of experience. (Ahem...!)
If you are planning your straw bale dream home, keep in mind that the outer walls will be thicker than standard walls (about 22 inches thick). In a moister climate, such as our home state of Wisconsin, we highly recommend using large overhangs or sometimes porches or even trees to protect the outer walls. And we always recommend building small!
We have used many different types of earth-based finishes on our homes, including 100% natural earthen plasters, fiber-cement stuccos and lime/cement-based plasters. All of these work, but each has its advantages and disadvantages. Natural earthen plasters are fantastic but trickier to apply and prone to cracking. Cement bases are easier to deal with and less likely to crack. Any type of finish can be used to add custom details to the interior or exterior, such as wall sconces, built-in ledges, window seats, and unique wall designs.
We are also experienced in earthen-plaster floors, which are similar to plastered walls but coated in a laminate for protection and smoothness.
Concealed-fastener metal roofs
Light, fire resistant, and long-lasting, metal is the best material we have found for roofs. We always use "concealed-fastener" roofing, which simply means that the fastener is located beneath the roofing material to eliminate leakage. Metal roofs come in standing seam sheets or shingles, and can be painted for aesthetic purposes.
Rammed earth is a high mass, low insulation type of building. Earth is packed in a temporary form system, or in permanent forms like nylon bags or tires (popularized by the Earthship), which are then stacked and covered.
Wood can be a beautiful and convenient building material. Unfortunately, modern civilization is using our wood resources faster than they can be renewed. We suggest using only sustainably-harvested lumber, now available at many retailers in the United States (lumber is certified as sustainable by the non-profit Forest Stewardship Council.) We also prefer to avoid treated lumber whenever possible; instead we make use of certain tree species that are naturally more resistant to rot.
But the most important point about building with wood today? Build small, and use wood sparingly.
All homes need some form of air exchange, but it is especially important in the high-mass or high-insulation homes described above. We use an ultra-efficient air exchange system that runs the incoming air through underground pipes to temper the air before it enters your home. After passing through the outgoing air as well, there is almost no temperature difference between the fresh air coming in and the stale air going out.
