It is estimated that buildings, their construction, operation and disposal, account for over 40% of the total energy consumption. This causes the depletion of natural resources and for the production of pollution leading to problems such as global warming and acid rain.
Buildings take energy to construct them. This is called ‘embodied’ energy, which is all the energy required to extract, manufacture and transport a building’s materials as well as that required to construct and ‘finish’ it. As buildings become increasingly energy efficient, the energy required to create them becomes proportionately more significant in relation to that required to run them. Some modern materials, such as aluminium, consume vast amounts of energy in their manufacture. The common building material with least embodied energy is wood. Brick is the material with the next lowest amount of embodied energy, (4 times that of wood). From the perspective of embodied energy, every building, no matter what its condition, has a large amount of energy locked into it. This is yet another factor in favour of conserving and restoring old buildings, and for designing long life, loose fit buildings that easily accommodate change. Also, because the energy used in transporting its materials becomes part a building’s embodied energy, this is a motivation to use local materials.
Smaller is better: Optimize use of interior space. Be energy-efficient: Use high levels of insulation, high-performance windows and tight construction. Use renewable energy: passive solar heating, day lighting and natural cooling. Design water-efficient, low-maintenance landscaping and grey water from sinks, showers etc. can be recycled for irrigation.
Spread the environmental impacts of a building over as long a period as possible to improve durability. Make sure the structure is adaptable to other uses, and choose materials and components that can be reused or recycled in the future.
Because manufacturing is very energy-intensive, a product that lasts longer or requires less maintenance usually saves energy. Where possible, select building materials that will require little maintenance or whose maintenance will have minimal environmental impact. Choose building materials with low embodied energy. Heavily processed or manufactured products and materials are usually more energy-intensive. Locally produced building materials cuts transportation costs, and thus reducing pollution.
Building products made from recycled materials cut energy consumption in manufacturing and save on natural resources. Solvent-based finishes, adhesives, etc. release toxic compounds into the air and should be used to a minimum. Products with excessive packaging, is an energy waste and should be avoided.
It surprises a lot of people to learn that a state-of-the-art, energy-efficient, passive-solar house built today may consume less heating and cooling energy over 30 or even 50 years of operation than was required to build it. To effectively reduce energy use, we will need to focus on embodied energy as well as operating energy.