When we talk about making construction more sustainable, most people think of energy-efficient buildings or eco-friendly materials. But sustainability begins long before the first brick is laid in fact, it starts on the road. That's where A4 emissions come in.

In the Life Cycle Assessment (LCA) of building materials, the A4 stage refers specifically to the transportation of materials from the manufacturer or supplier to the construction site. It's a critical yet often underestimated piece of the environmental puzzle.

What is the A4 Stage in LCA?

LCA breaks down the life of a product into stages from raw material extraction to manufacturing, transportation, use, and end-of-life. The A4 stage is part of what's called the Construction Stage, which includes:

• A4 – Transport to the Construction site

So, A4 focuses purely on the emissions generated from moving the product from the factory gate to the site where it will be used.

Why Do A4 Emissions Matter?

Transportation may seem like a minor blip compared to production, but for large-scale construction projects or materials sourced from afar, A4 emissions can add up quickly.

Key factors influencing A4 emissions include:

• Mode of transport (truck, rail, ship, air)
• Distance traveled
• Type of fuel used
• Load efficiency (how full the transport vehicle is)
• Weight and volume of the material

For example, shipping steel beams across continents by sea creates a different carbon footprint than transporting locally sourced timber by truck.

How Are A4 Emissions Calculated?

The emissions are typically calculated using:

• Emission factors for each mode of transportation (CO₂ per ton-km)
• Material weight
• Distance to site
• Vehicle type and fuel

The formula:

A4 CO₂ emissions = Weight of material (tons) × Distance (km) × Emission factor (kg CO₂/ton-km)

Sample Data for A4 Emissions Calculation by Transport Mode

A4 and Sustainability Decisions

Understanding A4 emissions helps architects, contractors, and clients make better decisions:

• Favour local materials when possible
• Optimize delivery routes
• Use lower-emission transport options (e.g., rail over truck)‍
• Consolidate shipments to improve load efficiency

Final Thoughts: Don’t Skip the Journey

The journey of a construction material from point A to site B can leave a significant carbon footprint. Including A4 in your LCA ensures you’re not just building green in theory, but in practice, from start to finish.

So next time you’re evaluating sustainable materials, remember: It’s not just what you build with, but how it gets there.

Build cleaner. Move smarter. Design for zero.

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Talk to Desapex our Net Zero Energy Consulting, BIM expertise, and Digital Twin solutions turn data into action, empowering your project to lead with both precision and purpose.