Embodied energy refers to energy consumed in the creation of an item, such as a material, product or entire building. The embodied energy is measured by its Gross Energy Requirement for manufacturing, application, maintenance and obtaining raw materials/product. Although the Gross Energy Requirement (GER) of an item is the most accurate measure, it is incredibly difficult and laborious to calculate.
Of the Building (e.g. Residential Dwelling): Energy required is dependent on the site conditions as well as the builders/trades methods, energy habits and tool efficiency. Variable from site to site.
Of the Material (e.g. Aluminium):Dependant on the energy requirements of the supplier’s factory and equipment. E.g. lighting and machinery running cost. Variable between suppliers.
Of the Building (e.g. Residential Dwelling): A higher embodied energy level can be justified if it contributes to lower operating energy.
Of the Material (e.g. Aluminium): Suppliers may have better research and development over their competitors to create the same material more efficiently.
Of the Building (e.g. Residential Dwelling): A product like hardwood timber cladding may have lower embodied energy to get to site than a timber-plastic composite, but perhaps not once maintenance over 100 years is factored in.
Of the Material (e.g. Aluminium): Maintenance of factory machinery should be factored in to the GER. Variable between suppliers.
Logistics of Obtaining Raw Materials / Products
Of the Building (e.g. Residential Dwelling): Each site is in a different location from another. A product manufactured and imported from overseas will have greater embodied energy than an identical product manufactured locally.
Of the Material (e.g. Aluminium): Depending on the methods, energy habits, equipment efficiency and mine conditions, each supplier will have very different energy requirements for raw material.
Since the GER is so difficult to quantify, the easier, but less accurate measurement is the Process Energy Requirement (PER). The PER is a simpler measurement that considers average energy outputs for bringing a product, material or building to market, often ignoring highly variable energy requirements like logistics. For this reason, it is important to use the PER as a guide towards making better environmental decisions rather than using the PER as a definitive answer to your buildings embodied energy.
If the eco house upgrade is chosen, The Rubix Collective makes sure calculated estimations are made in our design and specifications to lower the energy impact of construction and maintenance.
CSIRO has found that the average house contains about 1,000GJ of energy embodied in the materials used in its construction. This is equivalent to about 15 years of energy used to ‘run’ the house.