Which combination of materials is noted for relatively low embodied energy in green construction?

• A. Concrete, glass, and steel.
• B. Rammed earth, reclaimed wood, and recycled-content steel.
• C. Vinyl siding, asphalt shingles, and foam insulation.
• D. Plastic laminates, aluminum foil, and ceramic tile.

Answer: (B)

Embodied energy in building materials is the total energy used to extract, process, manufacture, transport, install, and dispose of them. Materials that require little processing, come from local or reused sources, or use recycled content tend to have lower embodied energy. Rammed earth uses mostly on-site soil with minimal processing, so the energy invested to prepare it is low. Reclaimed wood gives new life to existing timber, avoiding the energy needed to grow, harvest, and process new lumber. Recycled-content steel is made from scrap steel, which typically requires far less energy than producing steel from virgin ore. When combined, these materials collectively minimize the energy footprint across their life cycle, making this mix relatively low in embodied energy for green construction.

The other options rely more on energy-intensive materials: cement-based components like concrete and high-temperature processes for glass and new steel drive up energy use, while petroleum-derived materials such as vinyl, asphalt, foam, and certain plastics also require substantial processing and transport energy. Aluminum-containing products and ceramic tiles similarly involve energy-demanding production.