Sustainable design in architecture

The World Commission on Environment and Development has put forth a definition of sustainability as “meeting the needs of the present without compromising the ability of future generations to meet their own needs” (from Our Common Future, 1987). Fundamentally, sustainability in architecture is three-fold: environmental sustainability (the most familiar), economic sustainablity and social sustainability. There are many types of sustainable designs in architecture, and many ways of designing sustainably. Environmental sustainability refers to the general problems of energy needs, waste load (and emissions), urban transport, poverty, urban population growth, biodiversity loss, undervaluation of natural areas.

General principles
Sustainable design in architecture considers: life quality, environmental quality, human health, building health, energy efficiency and cost. And these topics are related to economy of resources (especially energy, water and material conservation), life cycle design (concerning the pre-building, building and post-building phases), and humane design (considering preservation of natural conditions, urban design site planning and design for human comfort). Consequently, its mains features are the following: i.	Adequacy of buildings to the environment and human needs. ii. Efficient and rational use of energy. iii. Obtention of environmental comfort through the optimized use of renewable resources.

Passive Design is presented as a system used in architecture to obtain environmental conditioning by natural processes. This system uses solar radiation, breezes and winds, material characteristics, orientation, trying to minimize the use of heating or cooling systems in order to reduce energy consumption, providing comfortable conditions in interior and exterior spaces. The most effective design measures are:

-Thermal insulation. The minimization of transmission losses of the building envelope (conservation) is the main goal in order to reduce consumption.

-Natural ventilation. Control of air flows is important both for comfort and for energy saving.

-Thermal mass. The incorporation of materials with high thermal mass retains heat effectively.

-Orientation. Proper orientation of the building increases the possibilities of solar caption and wind potential.

-Passive solar systems. Their main applications are related to “direct solar gain” and “heat storage”.

Incorporation of efficient equipment, substitution of alternative energy sources for non-renewable energy sources and usage of local products are other important topics to consider in relation to sustainable design.

Sustainable designs in residential architecture
Some sustainable designs for residential construction include Straw-bale housing, Earth-bag housing, Micro housing, Earth Sheltered homes, Sod houses, and Hybrid homes.

Straw-bale housing is typically a house that is utilizing the construction qualities of Hay, or straw bales. They are a natural insulator, don't burn well due to absence of oxygen in the strawbale, and no insect, or vermin voluntarily eat straw. Often, People building strawbale homes plaster the outside of the straw bale, and build the walls on the inside by sectioning the straw bales, and attaching OSB, or Drywall to the inside.

The Earth-bag design technique has been utilized for hundreds of years. It typically consists of filling Berlap, or polypropolene sacks with sand, or earth. It doesn't work well as an insulator, but if covered with an adequate roofing system, will be good for years. If the walls are angled, and covered with earth, sod can be grown on the walls, which will give the walls natural protection form the elements. Earthen bag houses are also generally resistant to bombs, and bullets, which is a good trait for developing countries, or countries at war.

A popular method of green building is the usage of locally produced materials, or renewable resources such as bamboo, and cordwood. Earth has even taken to the walls of various homes across the country, through the usage of Cob walls, adobe, stucco, and waddle & daub. Dirt, or plaster don't serve as great insulators, but the heat-retentive walls help cool the house during the day and warm it during the night.