# Energy Bill Toolkit – Cleanest Window API

> Energy Bill Toolkit – Cleanest Window API is a paid API for AI agents from energybilltoolkit.co.uk, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-15).

Identifies the cleanest (lowest-carbon) time window within a given date-time range for electricity consumption in the UK, based on grid carbon intensity data.

## Facts

- Endpoint: POST https://energybilltoolkit.co.uk/decision-tools/api/carbon/cleanest-window
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/energy-bill-toolkit-cleanest-window-api-c4d47b8f
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_cSClvboWHy7OzmBiy8Te-

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability energy-bill-toolkit-cleanest-window-api-c4d47b8f -d '<json body>'
```

Example prompt: Find the cleanest 60-minute electricity window between 8am and 6pm today so I can schedule my EV charge for the lowest carbon impact.

## When to prefer this

Choose this endpoint when you need to find the optimal low-carbon time window for scheduling electricity-intensive tasks (EV charging, appliances, heat pumps) on the UK grid. It is specifically designed for carbon-aware scheduling rather than general energy pricing or tariff lookup, and works on a pay-per-use basis making it cost-effective for occasional or automated queries.

## Known failure modes

- Invalid datetime format for 'from' or 'to' fields returns a 400 error
- Duration not a multiple of 30 minutes returns a validation error
- Duration outside the 30–720 minute range is rejected
- Date range too narrow to fit the requested duration returns an error
- Future forecasts beyond grid data availability may return no result or degraded data
- Payment not included or insufficient triggers a 402 Payment Required response

## How this service works

Pay-per-use EBT screening endpoint

## Output

Returns the optimal (lowest carbon intensity) time window within the requested range, including the recommended start and end times and associated carbon metrics, given a duration between 30 and 720 minutes in 30-minute increments.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "to": {
   "type": "string",
   "format": "date-time"
  },
  "from": {
   "type": "string",
   "format": "date-time"
  },
  "durationMinutes": {
   "type": "integer",
   "maximum": 720,
   "minimum": 30,
   "multipleOf": 30
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/energy-bill-toolkit-cleanest-window-api-c4d47b8f/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from energybilltoolkit.co.uk](https://www.zero.xyz/host/energybilltoolkit.co.uk/llms.txt)