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