In contrast to efficiencyRatio of machine output and input. The efficiency is related..., which compares the energyAbility to do work or diffuse heat. The unit of energy is th... input with the useful energyThe portion of final energy which is actually available afte... over a short periodreactor period of time, both are related for a long periodreactor period of time for the utilization ratio. Thus, an oil-fired heating system may have an efficiencyRatio of machine output and input. The efficiency is related... of 90% reached at nominal load. If only partly utilized in the transitional periodreactor period (e.g. summer) higher standstill losses occur so that a utilization ratio of only 65% annually results.