curl --request GET \
  --url https://api.voltview.co.uk/v1/sites/emissions \
  --header 'x-api-key: <api-key>'

[
  {
    "siteId": "<string>",
    "period": "<string>",
    "emissions": 123,
    "emissionsIntensity": 123,
    "emissionsBySource": {
      "electricity": 123,
      "gas": 123,
      "other": 123
    },
    "historicalData": [
      {
        "period": "<string>",
        "emissions": 123
      }
    ],
    "carbonSavings": 123,
    "targetReduction": 123
  }
]