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Ecow: Assessment and Comparison of Environmental Impacts of Geotechnical Works

This calculation module enables the assessment of environmental impacts, including greenhouse gas (GHG) emissions for all works involving interaction with the ground (earthworks, foundations, retaining structures, ground improvement, etc.).
Ecow also makes it possible to perform multi-criteria analyses by comparing the environmental impacts (climate change indicator as well as other indicators) of several geotechnical design options. As such, it serves as a useful decision-support tool within an eco-design approach.

The objectives of this module are as follows:

  • Encourage the calculation of GHG emissions related to geotechnical works,
  • Provide an intuitive interface suitable for engineers both in the design phase and the construction phase,
  • Enable quick comparison between different project alternatives.

Warning

Ecow does not allow the evaluation of GHG emissions for an entire development or construction project, since geotechnical activities represent only part of the total emissions. The scope is limited to works involving interaction with the soil.

Methodological Approach

LCA Principle

Life Cycle Assessment (LCA) is a methodology used to evaluate the environmental impacts of a "product" throughout its entire life cycle. LCA can be applied to a construction project by accounting for all material and energy flows, from the extraction of raw materials to demolition and material recycling.

LCA is a standardized method, with its general framework and guidelines defined by international standards ISO 14040 and ISO 14044. At the European level, CEN (European Committee for Standardization), through Technical Committee TC 350, is developing a series of standards proposing a system for assessing the contribution of construction elements to sustainable development, based on a life-cycle approach.

Five stages are distinguished in the life cycle of a construction product:

  1. Production phase: acquisition of raw materials, transport to the processing plant, and manufacturing of the finished product.
  2. Construction phase: transport of the product to the construction site, and installation processes.
  3. Use phase: service life (use, maintenance, repair, replacements, energy and water consumption).
  4. End-of-life phase: deconstruction, transport, treatment, disposal.
  5. Benefits beyond the life cycle: reuse, recovery and recycling.

Database Structure

LCA leads to the creation of an Environmental Product Declaration (EPD). These declarations represent the environmental identity card of products and are valid for 5 years.

Stakeholders must comply with NF EN 15804.

Tip

NF EN 15804 is a European standard defining the framework for environmental declarations of construction products.

The Ecow module relies on an updated database of EPDs.

Significant differences exist between amendments A1 and A2, especially in indicators and units. Consistency is required for comparisons.

Indicators (NF EN 15804 +A1) Unit
Climate change kg CO\(_2\) eq
Ozone depletion kg CFC 11 eq
Acidification kg SO\(_2\) eq
Eutrophication kg (PO\(_4\))3- eq
Photochemical ozone formation kg Ethene eq
Abiotic depletion (elements) kg Sb eq
Abiotic depletion (fossil) MJ
Water pollution m3
Air pollution m3

Environmental indicators according to NF EN 15804 +A1

Indicators (NF EN 15804 +A2) Unit
Climate change – total kg CO\(_2\) eq
Climate change – fossil kg CO\(_2\) eq
Climate change – biogenic kg CO\(_2\) eq
Climate change – land use kg CO\(_2\) eq
Ozone depletion kg CFC 11 eq
Acidification mol H+ eq
Freshwater eutrophication kg eq P
Marine eutrophication kg eq N
Terrestrial eutrophication mol eq N
Photochemical ozone formation kg NMVOC eq
Abiotic depletion kg Sb eq
Fossil resource depletion MJ
Particulate matter disease incidence

Environmental indicators according to NF EN 15804 +A2

Focus on the Climate Change Indicator

The Climate Change indicator evaluates the contribution of a product to greenhouse gas accumulation in the atmosphere.

Emissions are expressed in kg CO\(_2\) eq, combining all GHGs.

Tip

1 kg of CH\(_4\) has a much higher warming potential than 1 kg of CO\(_2\).

Main reasons for its widespread use:

  • High visibility and urgency,
  • Simplicity and accessibility,
  • Data availability,
  • Alignment with regulations,
  • Integration into calculation tools.

Calculation of Environmental Impacts

Impacts are calculated by multiplying activity data by emission factors (EF).

Only a partial life cycle is considered in geotechnical works:

  • A1–A3 (production),
  • A4 (transport),
  • A5 (installation).

Technical Choices

The tool simplifies inputs to match design-stage data availability and provides result ranges (low, medium, high).

Main emission sources:

  • Primary:
  • Materials,
  • Transport,
  • Energy,
  • Secondary:
  • Personnel,
  • Equipment,
  • Waste.

Only primary sources are considered in Ecow.

Interface Overview

Tool Philosophy

A project is divided into techniques.

  • Home: technique selection,
  • Technique tabs: input data,
  • Summary tab: variant comparison.

Variants combine multiple techniques.

Available Techniques

  • Land take
  • Earthworks
  • Shallow foundations
  • Bored piles
  • Displacement piles
  • Micropiles
  • Diaphragm wall
  • Pile wall
  • Sheet piles
  • Anchors
  • Soil nailing
  • Soil mixing
  • Free calculation

Emission Categories

  • Materials
  • Transport
  • Energy

Summary Tab

Comparison tools:

  • Tables,
  • GHG charts,
  • Radar (multi-criteria) charts.

Bibliography

  • CEREMA (2020) – GHG emissions for road projects
  • Keller (2022) – Sustainability brochure
  • EFFC DPI – Carbon calculator guide
  • NF EN 15804+A2 – Environmental product declarations
  • TERCO2 (2023) – Earthworks carbon footprint