How to Read an EPD: A Practical Guide for Construction Professionals

How to Read an EPD Results Table

EPD results are typically presented in a table with impact categories in rows and life cycle modules in columns. Here’s how to interpret it effectively:

Step 1: Identify the declared unit

Look at the top of the table. Understanding what quantity the numbers represent is essential before interpreting values.

Step 2: Check which modules are included

Scan the column headers. Are A1–A3 the only modules reported, or does the EPD include construction, use, and end-of-life? This tells you the assessment’s completeness.

Step 3: Look at the production stage first (A1–A3)

These modules are always included and form the baseline for understanding manufacturing footprint.

Step 4: Examine use-stage impacts (B1–B7)

If included, these can dominate for products requiring energy, maintenance, or replacement. A window with good thermal performance may have higher production impacts but lower overall impacts when operational energy savings are considered.

Step 5: Consider end-of-life and Module D

End-of-life impacts depend on assumed scenarios. Module D benefits are potential, not guaranteed, and depend on actual end-of-life practices.

What this number actually means: A GWP value of 250 kg CO₂e per declared unit means producing that quantity of product generates emissions equivalent to 250 kg of carbon dioxide. Whether this is high or low depends on the product category and functional performance.

A common misunderstanding: Higher numbers don’t automatically make a product “worse.” A thicker insulation might show higher production emissions but deliver greater lifetime energy savings. Context and functional performance are essential.

This does not mean the product is better or worse: EPDs provide data, not judgments. A product with lower GWP might have higher water use, shorter lifespan, or inferior performance. Environmental data must be weighed against all project requirements.

Common Mistakes When Reading or Using EPDs

Comparing EPDs with different declared units: Comparing “per kg” with “per m²” without conversion leads to meaningless conclusions.

Ignoring system boundaries: A cradle-to-gate EPD excludes significant life cycle impacts. Comparing it with a cradle-to-grave EPD creates false impressions.

Using EPD data outside its intended scope: EPDs are product- and facility-specific. Data may not represent products made in different regions.

Assuming lower GWP always means a better product: Climate impact is one of many considerations. Product performance and durability must guide decisions.

Ignoring data quality: Third-party verified EPDs following international standards are more reliable than self-declared claims.

Overlooking temporal validity: EPDs expire, typically after five years. Outdated EPDs may not reflect current practices.