by Lauren Breckenridge, LEED AP
Sustainability Associate at Green Badger
For years, embodied carbon lived comfortably in the design phase. It appeared in early studies, sustainability narratives, and long-term climate goals. Then construction started, schedules tightened, procurement kicked off, and embodied carbon quietly fell out of focus.
That approach no longer works.
In LEED v5, embodied carbon is no longer implied or optional. It is explicitly quantified, assessed, and reduced, and construction decisions now directly influence certification outcomes. At the center of this shift is one metric contractors are increasingly seeing: Global Warming Potential (GWP).
What Global Warming Potential (GWP) Actually Tells Contractors
Global Warming Potential, or GWP, measures the greenhouse gas emissions associated with a product or material, expressed as kilograms of carbon dioxide equivalent (kg CO₂e). For contractors, GWP answers a practical question: What level of climate impact is locked in when this product is installed?
GWP values are reported in Environmental Product Declarations (EPDs) and serve as the primary embodied carbon metric in LEED v5. Two products can meet the same structural or performance criteria while having significantly different GWP values. Concrete mixes with varying cement content, steel from different mills, or insulation with different blowing agents can all perform identically while carrying very different carbon impacts.
Once installed, that carbon impact is fixed.
Where GWP Is Locked In During Construction
GWP is determined through everyday construction decisions, including:
- Concrete mix design approvals
- Steel mill and fabrication sourcing
- Insulation selection
- Product substitutions during value engineering
- Schedule-driven procurement decisions
Because these decisions occur during submittals and purchasing, contractors are central to embodied carbon outcomes.
Industry Trends: How LEED v5 Is Changing Contractor Responsibilities
General contractors are already seeing measurable shifts as LEED v5 requirements gain traction.
1. Earlier Carbon Conversations During Preconstruction
With MRp2: Quantify and Assess Embodied Carbon now a prerequisite, projects must quantify embodied carbon impacts. That requirement pushes carbon discussions into preconstruction rather than closeout.
GCs are increasingly:
- Requesting EPDs during bid leveling
- Reviewing the concrete mix GWP before approval
- Engaging suppliers earlier for transparent data
Carbon is becoming part of procurement strategy, not post-construction documentation.
2. Material Transparency Is Becoming Standard Practice
Under MRc: Building Product Selection and Procurement, product documentation and environmental disclosures are formalized. This trend aligns with growing owner expectations beyond LEED alone.
Contractors are adapting by:
- Building EPD tracking into submittal workflows
- Coordinating closely with suppliers on documentation
- Reducing last-minute substitutions that lack environmental data
Material transparency is shifting from a sustainability initiative to a baseline compliance expectation.
3. Carbon Data Is Feeding Whole-Project Assessments
The prerequisite IPp3: Carbon Assessment integrates operational carbon, refrigerants, and embodied carbon into a unified carbon projection.
This reflects a broader industry shift: embodied carbon is no longer siloed within Materials and Resources. It is part of the project’s total carbon profile.
For contractors, this means:
- GWP values collected under MRp2 influence the larger carbon narrative
- Incomplete documentation creates ripple effects beyond a single credit
- Embodied carbon is now tied to broader decarbonization goals
4. Demonstrated Reductions Are Becoming Competitive Differentiators
The credit MRc: Reduce Embodied Carbon moves projects beyond reporting and toward measurable reductions.
Across the industry, GCs are:
- Comparing GWP between similar products
- Working with suppliers to identify lower-carbon alternatives
- Incorporating embodied carbon discussions into value engineering
Projects that demonstrate lower embodied carbon are gaining reputational and competitive advantages in public and institutional markets.
One Set of GWP Data, Multiple LEED v5 Impacts
One of the most important takeaways for contractors is that GWP data is not collected for a single purpose.
The same product-specific GWP values:
- Satisfy MRp2: Quantify and Assess Embodied Carbon
- Support performance under MRc: Reduce Embodied Carbon
- Feed into IPp3: Carbon Assessment
- Strengthen compliance under MRc: Building Product Selection and Procurement
This means early coordination reduces redundancy and simplifies documentation later.
The Risk of Treating GWP as a Closeout Task
When embodied carbon tracking is delayed until late in construction, teams often encounter:
- Scrambling to locate EPDs after installation
- High-GWP products discovered too late to influence
- Additional LEED review comments
- Increased coordination time at project closeout
Tracking GWP throughout procurement and submittal reviews leads to smoother project closeouts, reduces the risk of last-minute complications, and helps teams achieve LEED goals efficiently. Treating GWP as an early, core task is key.
GWP Is Becoming a Core Construction Metric
A decade ago, LEED construction credits felt optional or experimental. Today, they are standard practice on many projects. GWP is following the same trajectory.
Owners are asking earlier questions. Architects are formalizing commitments. LEED v5 embeds embodied carbon into prerequisites and credits across categories. Contractors who understand GWP gain clarity, control, and alignment with evolving expectations.
Conclusion
Embodied carbon is no longer theoretical. In LEED v5, it is quantified under MRp2: Quantify and Assess Embodied Carbon, evaluated through MRc: Reduce Embodied Carbon, integrated into IPp3: Carbon Assessment, and supported by MRc: Building Product Selection and Procurement.
Global Warming Potential is the metric that ties those requirements together.
The key takeaway: for contractors, embodied carbon is a daily construction decision, not a future consideration. Each product installation impacts project outcomes and LEED success.
