Green Buildings-part 1

A clay and bottle wall from the Earthship Brighton

Cob Homes

Cob homes are made from a mixture of sand, clay and straw, with just the right moisture content to build-up walls without using a form. Cob homes are considered to be a very workable construction method due to the ability to create and construct curved walls, pillars and many other shapes. This construction method was very popular in England and Wales from the 13th century until the late 18th century when bricks became available. Cob homes offer reasonable insulation, are usually allergenic, cheap to build, and offer the opportunity to make a unique home.

Earthships

Earthships are a modern, funky, low impact approach to building. The Earthship construction philosophy is attributed to American builder Michael Reynolds who started working with recycled materials. A popular Earthship building construction is based on a U shape so the building can take advantage of natural heating and cooling from the sun and shade.

An Earthship design generally has retaining walls made from recycled tires, empty aluminium cans or glass bottles. The frame is packed with earth and stacked up as building blocks. Often a wood frame is used to guide construction and interior and exterior walls are finished with plaster. Earthships tend to also incorporate additional environmental and energy saving features such as rain catchment, greywater retrieval, indoor gardening and passive solar.

Earthbag Building

Just as the name suggests, these buildings use bags filled with earth or some other mixture and are layered to form walls. The earthbags need some stabilization wire between the layers to keep the bags in place and a finishing layer of plaster. Earthbag structures are very sturdy, able to withstand floods, earthquakes and even bullets. They offer good insulation properties and are very cheap to build in terms of cost, but like most self-constructed buildings, handmade buildings can be quite labour intensive.

Earth Shelter Homes

You don’t have to be a hobbit to live in an earth-sheltered home; in fact these funky, eco-friendly homes are becoming increasingly popular with the mainstream. Earth Shelter homes are usually constructed with a concrete and steel reinforced dome-like structure. They have three sides and are bermed or covered with several feet (a couple of metres) of earth. Earth Shelter buildings have a wide range of eco-benefits including; reduced heating cost, especially with a south facing passive solar thermal design, sound reduction and electromagnetic emission protection. Earth Shelter homes are considered to be more harmonious with their environment as they provide a continuum of greenspace.

Packed Earth/Rammed Earth

The Packed Earth or Rammed Earth construction method has been used for thousands of years and is making a comeback with eco-conscientious builders. Rammed Earth houses are constructed using a wooden (or other rigid material) frame; dampened earth is then mixed with (roughly) 1-10% cement content to create earth walls. The ‘earth’ component of the walls is made from a mixture of compacted gravel, sand, and clay. Rammed Earth houses offer great insulation, are low allergen, soundproof, and offer earthquake and electromagnetic emission protection. Construction costs are often comparable to a traditional house.

Passive Solar

Passive Solar homes use the energy from the sun to heat the home and to also minimize heat loss through the interior and exterior design. Placement of windows is carefully considered during the construction stage and of particular importance is the high insulation used in walls and the roof. Often, more than one form of green building practice is used in solar designed homes, including passive solar water heating and solar photovoltaic energy generation. Green roofs, rammed earth and earth-shelter homes are also ideal candidates for passive solar home designs. These homes have less than 20% of the heating costs of regular designs.

Straw Bale

Straw bale dwellings are a popular, cheap and easy to construct housing option. They are built by stacking bales to form structure walls; bales can operate either as load bearing walls or act as excellent insulation against heat flow and sound. Once the bale walls are constructed, most builders opt to cover the straw with a plaster coating. Bale construction operates to keep a dwelling cool in summer and warm in winter. Strawbale buildings can remain sturdy and liveable up to an estimated 100 years.

Yurts

Yurts are often referred to as Mongolian Cloud Houses. These Asia Minor dwellings have long been a favourite with hippies and nomads around the world. Originally used as a weather proof, transportable nomadic dwelling, the modern yurt can be anything from an outdoor office, fitness room, or an in-law suite to housing for year round living, in all but the most extreme winter weather climates. Yurts have a reinforced lattice construction, stiffening rings and roof spars over which is stretched weatherproof fabric. The circular design maximizes interior space and a wide range of add-ons are available for weather protection, passive sunlight use and water catchment. Yurts can last over ten years with low maintenance and are extremely economical to build/purchase. A number of companies offer ready to ‘move in’ yurts for sale.