{
  "type": "gap",
  "id": "no-load-headroom-layer",
  "title": "Massachusetts publishes no load-headroom layer",
  "what_is_missing": "A public layer showing how much NEW LOAD each distribution circuit can accept. Eversource publishes DG hosting capacity — how much GENERATION may interconnect — and nothing that answers the load question. The two are not the same measure and are not convertible into one another.",
  "why_it_matters": "It is the decisive number for every question the atlas asks about the present. Whether a neighbourhood can electrify its heating, whether a street can take curbside charging, whether a data centre can connect and what its connection will cost everyone else — all of them turn on how much headroom the circuit has. Without it, the whole planning conversation is being conducted about a quantity that is not published. It is also why this atlas will not publish a constrained-versus-spare map: it does not have the data to make one, and neither does anybody outside the utility.",
  "what_was_tried": [
    "The ORNL Open Energy Data Portal mirror named in the project brief: dghosting_adminvw_dg_hosting_ced_ema_st returns records_count: 0, and both export endpoints return nothing. It is an empty datacard.",
    "Eversource's live ArcGIS service was found instead and pulled in full — 1,026 circuits in the study area. Every capacity field in it is a GENERATION field.",
    "Eversource's EV and load-headroom mapping, which does exist, was checked: it is Connecticut-only.",
    "Eversource's published hosting-capacity methodology (TSRG Meeting 21 attachment, 7 slides) was read. It describes generation hosting capacity and confirms that the 95% scaling applies to substation flow rather than feeder flow — a correction to the project's own earlier note.",
    "MassGIS and the Massachusetts DOER data holdings were searched for any equivalent statewide layer. None exists.",
    "The interconnection tariffs were read to see whether the number is disclosed procedurally instead of cartographically. M.D.P.U. No. 55G publishes a system-modification cost rule for generation; there is no equivalent instrument for load."
  ],
  "state": "not-published",
  "severity": "blocks-a-claim",
  "closes_if": "Eversource publishes a load-capacity or load-headroom layer for eastern Massachusetts at circuit resolution, as it already does in Connecticut — or the DPU requires it. A per-circuit figure with a stated method would be enough; a statewide average would not.",
  "who_could_close_it": "Eversource Energy, or the Massachusetts Department of Public Utilities by order",
  "workaround": "None that measures the right thing. The atlas shows DG hosting capacity and says in every place it appears that it measures generation. Where the reading needs to talk about constraint it uses tariff and queue evidence instead, which is qualitative. Substituting hosting capacity for load headroom would be the single worst error this project could make, and it is the reason this entry exists.",
  "eras": [
    "distributed-energy",
    "heat-pump",
    "compute"
  ],
  "grain_wanted": "feeder",
  "grain_available": "feeder",
  "first_recorded": "2026-09-15",
  "last_checked": "2026-09-15",
  "sources": [
    {
      "id": "ornl-dghosting",
      "title": "Eversource DG Hosting Capacity datacard, ORNL Open Energy Data Portal",
      "publisher": "Oak Ridge National Laboratory",
      "date": "2024",
      "url": "https://openenergyhub.ornl.gov/explore/dataset/dghosting_adminvw_dg_hosting_ced_ema_st/",
      "locator": "records_count: 0",
      "tier": "verified",
      "accessed": "2026-09-15"
    },
    {
      "id": "eversource-hc-method",
      "title": "Hosting Capacity Maps — Eversource (TSRG Meeting 21 attachment)",
      "publisher": "Eversource Energy / Massachusetts DOER",
      "date": "2021",
      "url": "https://www.mass.gov/doc/tsrg-meeting-21-attachment-hosting-capacity-maps-eversource/download",
      "locator": "7 slides; published methodology",
      "tier": "verified",
      "accessed": "2026-09-15"
    }
  ],
  "related": [
    "dataset:eversource-distribution-circuits",
    "decision:interconnection-dg-and-load",
    "decision:service-upgrade-cost-causation",
    "dataset:ev-charging-candidate-sites"
  ],
  "status": "published"
}