Heating & cooling degree days
Heating degree days (HDD) and cooling degree days (CDD) measure how cold or warm the last twelve months were against a fixed base temperature. When a supplier quote assumes a normal weather year, this tells you whether your site has run colder or warmer than baseline so you can adjust the volume estimate before you sign.
Why this matters for procurement
Suppliers price fixed contracts on an estimated annual quantity. That estimate is usually the previous year’s consumption, normalised to a notional ‘average’ UK winter. If the year you used as the baseline was unusually mild or cold, the volume on your contract can be wrong by 5–15 per cent — which feeds straight into take-or-pay clauses and unit-rate trueing.
Degree days give you a transparent reference. Compare the last twelve months at your site against a long-run regional average and you can see how much of your bill movement was weather and how much was operational change. It is also the cleanest way to evidence the impact of an efficiency upgrade — lighting, controls, building fabric — after the fact.
Enter any UK postcode. We resolve coordinates through postcodes.io and pull the daily mean temperature series from the Open-Meteo archive. No personal data is stored.
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