Buildings: Embodied Energy
A building's embodied energy - the energy expended to create it, and later remove it - can be minimised by constructing it from locally available, natural materials that are both durable and recyclable, and by designing it to be easy to dismantle, with components easy to recover and reuse or recycle.
Distinguish a building's embodied energy from the energy required for its ongoing operation - eg for lighting, ventilation, heating and cooling, and building maintenance.
A building's embodied energy can be minimised by constructing it from locally available, natural materials that are both durable and recyclable. And by designing the building to make it easy to dismantle, and its materials and parts easy to recover and reuse.
Using locally available materials minimises transport costs.
Durable materials extend the life of the building, thus reducing its yearly embodied energy (its embodied energy divided by the number of years it exists or is used).
Recyclable materials allow two buildings to share some of their embodied energy, and so get more building-years for the same energy input.
Buildings that are easy to dismantle require less energy to pull down. Components easy to recover and reuse allow new buildings to avoid the extra energy costs of new components.
Embodied Energy as Cumulative Energy Demand
Embodied Energy. RMIT - Greening the Built Lifecycle
Embodied energy, or "cumulative energy demand", represents the sum of all the energy inputs into a product system, from all stages of the life cycle. For building materials this is usually extraction of materials, processing, transport and manufacture, and sometimes including capital equipment and services supplied to the product system in question. For a full product system or service the use and disposal phase may be included in the value.
Embodied Energy - Buildings
Embodied Energy. Your Home Technical Manual. Australian Greenhouse Office
A building's embodied energy is the energy consumed by all of the processes associated with the production of the building, from the acquisition of natural resources to product delivery. This includes the mining and manufacturing of materials and equipment, the transport of the materials and the administrative functions.
Embodied energy may include:
- The energy used to transport the materials and workers to the building site.
- The upstream energy input in making the materials (such as factory/office lighting, and the energy used in making and maintaining the machines that make the materials, etc.).
- The embodied energy of urban infrastructure (roads, drains, water and energy supply).
The materials incorporated into a building include:
- The materials used to construct the building shell.
- The materials used to complete the building such as bathroom and kitchen fittings, driveways, outdoor paving, etc.
Embodied energy can be the equivalent of many years of operational energy.
The single most important factor in reducing the impact of embodied energy is to design long life, durable and adaptable buildings.
Embodied energy content varies greatly with different construction types.
A higher embodied energy level may be justified if it contributes to lower operating energy. For example, large amounts of thermal mass, high in embodied energy, can significantly reduce heating and cooling needs in well designed and insulated passive solar houses.
Different calculation methods produce vastly different results (by a factor of up to 10). For best results, compare figures produced by a single source using consistent methodology and base data. What is important is to consider the relative relationships and try to use materials that have the lower embodied energy.