Building Materials can be obtained from the Earth at the site without or with less of the expense of manufacturing and transporting them. Stabilized earth, adobe blocks, rammed earth, earth floors, sod roofs, and mud surfacing are examples of on site, low cost building material potentials. It is important to understand the value of plant life on Earth. This relationship of sun and plants that created the biosphere around the Earth allows man and animals to survive. Biomass is the plant and animal material produced by photochemical reaction.
Free oxygen is added back by the chemical process during combustion.
Chemically, a wood fire is the reversal of nature's growth process but at a much greater speed. Care must be taken to provide complete combustion, otherwise pollutants will be released into the air. Methane is a colorless, odorless, flammable gas which is formed by the decomposition of organic waste products of living organisms on Earth. Methane, the main component of natural gas, can be used as a heating fuel and for illumination. In addition, its by-product can be used as fertilizer.