embodied energy!

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source: csiro Australia

What is Embodied Energy?

Embodied energy is the energy consumed by all of the processes associated with the production of a building, from the acquisition of natural resources to product delivery, including mining, manufacturing of materials and equipment, transport and administrative functions.

How is Embodied Energy Related to Carbon Dioxide Emissions?

CO2 emissions are highly correlated with the energy consumed in manufacturing building materials. Furthermore, cement and aluminium are higher than average and glass is lower. On average, 0.098 tonnes of CO2 are produced per gigajoule of embodied energy.

Why is Embodied Energy Important?

The energy embodied in existing building stock in Australia is equivalent to ten years of the total energy consumption for the entire nation. Choice of material and design principles have a significant, but previously unrecognised, impact on energy required to construct a building. Embodied energy is one measure of the environmental impact of construction and the effectiveness of any recycling, particularly CO2 emissions.

How Much Does Embodied Energy Vary Between Materials?

The embodied energy per unit mass of materials used in building varies enormously from about two gigajoules per tonne for concrete to hundreds of gigajoules per tonne for aluminium. Using these values alone to determine preferred materials is inappropriate because of the differing lifetimes of materials, differing quantities required to perform the same task and different design requirements.

How Do We Compare The Embodied Energy Impact of Materials?

In choosing between alternative building materials or products on the basis of embodied energy, not only the initial materials should be considered but also the materials consumed over the life of the building during maintenance, repair and replacement. As buildings are becoming more energy efficient in their operation, the embodied energy is approaching half the lifetime energy consumption.

Do Reuse And Recycling of Materials Reduce Embodied Energy?

The reuse of building materials commonly saves about 95% of embodied energy which would otherwise be wasted. Some materials such as bricks and tiles suffer damage losses up to 30% in reuse. The savings by recycling of materials for reprocessing varies considerably with savings up to 95% for aluminium but only 20% for glass. Some reprocessing may use more energy, particularly if long transport distances are involved.

How Does Embodied Energy Compare With Annual Operating Energy?

The embodied energy of a building is a significant multiple of the annual operating energy consumed, ranging from around 10 for typical dwellings to over 30 for office buildings. Making buildings such as dwellings more energy efficient usually requires more embodied energy thus increasing the ratio even further.

How Much Embodied Energy Is There In a House?

The simpler, lighter clad houses generally have a lower embodied energy value in total and per unit floor area, due to fewer materials being used in construction and lower embodied energy coefficients for those materials. Embodied energy of houses ranges from about 4.5 GJ/m2 to 5.5 GJ/m2 mainly depending on floor type, material of cladding and number of storeys.

note!!: the presented figures above are precise to the Australian situation only, other continents may have different outcomes due to differrence in industrial processes and infrastructure.

Nevertheless the calculation principles are very adaptible too foreign situations.

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