Pilio uses data from 77 MET office weather stations around the UK.
The main data we use is the hourly temperature, as this allows Pilio to calculate the Heating Degree Days for the week.

Heating Degree Days is a measure of how cold it has been, and so how much you need to heat your building to keep it at a comfortable temperature. The colder the weather is in a particular week, the higher the Heating Degree Day value.

Pilio uses the Heating Degree Day value for each week to estimate your building's heating costs based on the details that you have entered – floor area, insulation types etc.