Engine Coefficients
GRADE aggregates engine scores using published coefficients. The coefficients reflect the relative contribution of each dimension to overall AI compute infrastructure efficiency. Coefficients are versioned — changes are documented with rationale.
Current coefficients (v2.0)
Section titled “Current coefficients (v2.0)”| Engine | Weight | Rationale |
|---|---|---|
| ACE | 0.35 | GPU utilization is the primary measure of compute efficiency |
| PACE | 0.25 | Scheduler policy determines whether utilization is achievable |
| COOL | 0.20 | Cooling overhead is the largest non-compute energy consumer |
| CORE | 0.12 | Hardware fit affects efficiency ceiling; embodied carbon is a lifecycle factor |
| FLUX | 0.08 | Carbon accounting methodology matters; weight reflects current data availability |
Coefficients sum to 1.00. When an engine is excluded from an assessment, remaining engine scores are normalized proportionally before aggregation.
Normalization for partial assessments
Section titled “Normalization for partial assessments”If COOL and FLUX are excluded (a common pattern for first assessments), the remaining engines — ACE, PACE, CORE — are re-weighted proportionally:
- ACE: 0.35 / 0.72 = 0.486
- PACE: 0.25 / 0.72 = 0.347
- CORE: 0.12 / 0.72 = 0.167
The composite is computed against the normalized weights. The certification report discloses which engines were included and the normalized weights applied.
Why ACE is weighted highest
Section titled “Why ACE is weighted highest”GPU utilization directly measures whether allocated compute is doing useful work. A cluster where 89% of jobs run below the 40% utilization threshold is wasting the majority of its purchased GPU capacity, regardless of how well-cooled or carbon-accounted it is. ACE is weighted highest because it is the most direct measure of the fundamental problem PTL is designed to address.
Why FLUX is weighted lowest
Section titled “Why FLUX is weighted lowest”Carbon accounting methodology is important. It is also the dimension where organizational control is most constrained by geography, utility availability, and regulatory environment. An organization in a region with no viable PPA market cannot easily move from 0.50 to 1.00 on FLUX in one assessment cycle. The coefficient reflects this constraint — FLUX is measured and reported, but not allowed to dominate the composite.
Coefficient versioning
Section titled “Coefficient versioning”Current coefficients: v2.0, published 2026-01-15. Changes from v1.0: CORE weight increased from 0.08 to 0.12 (Blackwell embodied carbon significance); FLUX weight decreased from 0.12 to 0.08 (geographic constraint acknowledgment). Previous version coefficients are archived in the ptl-methodology repository.