The programme exists so that every machine is measured the same way. It is usually the most energy-efficient cotton programme, and often one of the longest, because lower temperatures held for longer use less energy than heating water quickly. The specification's programme duration is the eco 40-60 time at full load.
The actual water temperature may be lower than 40 °C or 60 °C; the regulation requires the cleaning result, not a particular temperature.
Where this comes from
Frequently asked questions
What does eco 40-60 programme mean on a washing machine?
Eco 40-60 is the standard programme that energy label figures are measured on. It washes normally soiled cotton laundry labelled for 40 °C or 60 °C together, at whatever temperature achieves the declared performance most efficiently.