Building Homes With a Smaller Footprint

Residential construction accounts for a significant share of global carbon emissions — from the energy-intensive production of cement and steel to the decades of heating and cooling that follow. Low Carbon House explores the materials, methods, and design strategies that are transforming how we build.

The Carbon Cost of Building

Every home carries two carbon burdens. Embodied carbon is locked into the materials at construction — the CO₂ released when limestone is heated to make cement, when iron ore is smelted into steel, or when sand is melted into glass. Operational carbon accumulates over the building's lifetime through heating, cooling, lighting, and appliance use.

A typical single-family home generates 50 to 80 tons of embodied carbon before anyone turns on a light. Understanding where those emissions come from is the first step toward reducing them.

Lower-Carbon Materials

• Cross-laminated timber (CLT) — Engineered wood panels that can replace concrete and steel in mid-rise construction while sequestering carbon
• Hempcrete — A bio-composite of hemp shiv and lime binder that insulates, regulates moisture, and stores carbon
• Rammed earth — Ancient technique updated with modern engineering, using locally sourced soil with minimal processing
• Recycled steel — Electric arc furnace steel made from scrap produces roughly a quarter of the emissions of virgin steel
• Low-carbon concrete — Blended cements using fly ash, slag, or calcined clay to reduce clinker content by up to 50 percent

Design Strategies

Passive House Standards

Ultra-insulated envelopes, airtight construction, and heat recovery ventilation can reduce heating and cooling energy by 90 percent compared to conventional homes.

Right-Sizing

Smaller homes use fewer materials and less energy. Thoughtful floor plans can deliver comfort and functionality in significantly less square footage.

Adaptive Reuse

Renovating existing structures avoids the embodied carbon of demolition and new construction entirely.

Why It Matters

• Buildings account for nearly 40 percent of global energy-related CO₂ emissions — the sector must decarbonize to meet climate targets
• Material choices made at design stage lock in emissions for decades — early decisions have outsized impact
• Low-carbon building often costs less over the lifecycle — energy savings offset higher upfront material costs
• Codes are tightening — jurisdictions worldwide are introducing embodied carbon limits for new construction

The greenest house is one that considers its carbon impact from foundation to rooftop. Start here to learn how.