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

[
  {
    "siteId": "<string>",
    "intensity": 123,
    "period": "<string>",
    "benchmark": 123,
    "rating": "<string>"
  }
]