---
title: "Temperature demand proxy - heating/cooling degree-days (Sugra derived)"
method: GET
path: "/api/v2/energy/demand"
tags: ["Energy"]
---

# Temperature demand proxy - heating/cooling degree-days (Sugra derived)

`GET /api/v2/energy/demand`

Heating (HDD) and cooling (CDD) degree-days at any coordinate worldwide, computed by Sugra from sovereign 2 m temperature - the same Sugra Earth forecast spine that powers /api/v2/weather. A grid-derived free-rider (no new external fetch). A temperature-driven demand PROXY, not metered load; degree-days from averaged analysis snapshots underestimate the true daily integral.

## Query parameters

- `lat` number, required — Latitude, decimal degrees.
- `lon` number, required — Longitude, decimal degrees.
- `base_c` number — Degree-day base temperature, Celsius (default 18 C ~ 65 F).
- `cycles` integer — Recent analysis cycles to average into Tmean (window = cycles x the model run cadence; 4 x 6 h ~ a day).

## Response `200`

Successful Response

- EnvelopeDemandFeed
  - `data` DemandFeed, required
    - `location` DemandLocation, required
      - `requested` object, required — The requested {lat, lon}.
      - `tile` string, required — Spine tile id serving this coordinate.
    - `base_c` number, required — Degree-day base temperature, Celsius.
    - `t_mean_c` number, required — Mean 2 m temperature over the averaged snapshots, Celsius.
    - `n_snapshots` integer, required — Number of analysis snapshots averaged into Tmean.
    - `hdd` number, required — Heating degree-days: max(0, base_c - Tmean).
    - `cdd` number, required — Cooling degree-days: max(0, Tmean - base_c).
    - `samples_c` number[] — The per-snapshot 2 m temperatures (Celsius) averaged.
    - `provenance` DemandProvenance, required
      - `institution` string, nullable
      - `model` string, nullable
      - `grid` string, nullable
      - `cycles` string[] — Model cycle stamps averaged into Tmean (YYYYMMDDHH).
      - `valid_time` string, nullable — Valid time of the newest contributing snapshot (ISO 8601 UTC).
    - `attribution` DemandAttribution, required
      - `attribution` DemandAttributionEntry[] — The Sugra-derived entry first (no sovereign shield), then each contributing base model.
        - `registry_key` string, required
        - `source_name` string, required
        - `licence` string, nullable
        - `citation` string, nullable
        - `disclaimer` string, required
      - `effective_reexport` string, required
    - `methodology` string, required
    - `disclaimer` string, required
  - `meta` SugraMeta, required — Metadata attached to every /api/v1/* response envelope.
    - `endpoint` string, required — Requested endpoint path.
    - `data_time` string, required — ISO 8601 UTC timestamp of the source data, not of the request.
    - `response_time` string, required — ISO 8601 UTC timestamp when this response was produced.
    - `provider` string, required — API name and version.
    - `source` string, nullable — Identifier of the primary upstream source used for this response.
    - `attribution` string, nullable — Human-readable attribution mandated by an upstream source (e.g. a securities regulator or self-regulatory organization). Present only on responses whose source requires the owner and source to be clearly identified. Do not remove or alter it when using the response.
    - `fallback_used` boolean, nullable — True when the primary source failed and a fallback produced the data.
    - `fallback_chain` string[], nullable — Ordered list of sources attempted, in the order they were tried.
    - `cached` boolean, nullable — True when this response was served from the internal cache.
    - `stale` boolean, nullable — True when the cached response was returned after the upstream rate-limited or errored. Clients can use this to detect degraded data.

## Other responses

- `401` — Missing or invalid `x-api-key` header. JSON body with a stable `code` distinguishing `missing_api_key` (no header sent) from `invalid_api_key` (header sent, key not accepted); any other 401 source carries the generic `unauthorized` with its detail as `reason`. Plus `hint`. `plan` is always null on 401 - an unauthenticated request has no plan; quota exhaustion is 429, not 401.
- `422` — Validation Error
- `429` — Daily rate limit exceeded. Check `X-RateLimit-Reset` for the next window.
- `503` — Upstream source is temporarily unavailable. Retry after a short delay.

---

[API](https://skmtc.net/sugra/apis/sugra-api.md) · [All operations](https://skmtc.net/sugra/apis/sugra-api/llms.txt) · [OpenAPI document](https://skmtc-service-staging.skmtc.workers.dev/v1/apis/sugra/sugra-api/versions/4c4530760ba1/schema)