What is Embodied Energy?
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Embodied energy refers to the total energy consumed during the extraction, processing, manufacturing, and delivery of materials used in construction. This calculation typically measures energy from cradle-to-site, encompassing every step of a material’s lifecycle up to its incorporation into a building. Some broader definitions may also include transportation, construction processes, and end-of-life disposal or recycling.
Why Embodied Energy Matters
Embodied energy contributes significantly to a building’s environmental footprint. While much focus has historically been placed on reducing operating energy (the energy used during a building’s lifespan for heating, cooling, and lighting), studies have shown that embodied energy can equal or exceed decades of operational energy consumption. For example, the materials in an average house can represent the equivalent of 15 years of operational energy.
Embodied Carbon and Related Terms
The term embodied carbon measures the greenhouse gas emissions (e.g., CO₂, methane) released during material production. This is expressed as CO₂e (carbon dioxide equivalent) and accounts for other gases with higher global warming potential (GWP). For instance, methane has a GWP of 25, meaning it has 25 times the impact of CO₂.
It’s important to note that a zero carbon building refers to a structure that produces as much energy onsite as it consumes, a concept tied to operational energy rather than embodied energy.
Reducing Embodied Energy
To minimise embodied energy, architects, designers, and manufacturers can:
- Choose materials with lower embodied energy (e.g., locally sourced, recycled).
- Design for durability and ease of material separation.
- Optimise construction processes to reduce waste.
- Incorporate materials made using renewable energy sources.