Methodology · THI
Transmission Headroom Index
Estimated available transfer capability (MW) at the sub-region level, net of queued projects and committed upgrades — the practical 'how much can land here?' answer.
Inputs
Source feeds and weights.
| Feed | Class | Weight |
|---|---|---|
| FERC Form 715 planning models | MODELED INTELLIGENCE | 35% |
| ISO OASIS ATC postings | LIVE PUBLIC DATA | 25% |
| Active queue MW (deliverability claim) | LIVE PUBLIC DATA | 25% |
| Approved network upgrade in-service dates | MODELED INTELLIGENCE | 15% |
Model
Formula and plain English.
Formula
THI = ATC_posted − Σ queuedDeliverability + Σ approvedUpgradesByYear
In plain English
Start with posted available transfer capability, subtract deliverability already claimed by queue projects, add in committed upgrades by their in-service year.
Operations
Cadence and confidence.
Refresh cadence
Daily refresh on OASIS; weekly on planning model.
Confidence interval
Sub-region resolution; site-level reads carry ±20% band absent diligence overlay.
Limitations
What this index does not do.
- L/01Does not model surplus interconnection or shared-infrastructure plays.
- L/02Behind-the-meter co-location is reported separately.
Change log
Recent calibration history.
2026-Q2
Added committed-upgrade vintage to time-shift headroom curves.