The traditional way to quote equipment performance via steady state fuel efficiency (or COP for heat pump) is giving way to system or seasonal efficiency as appropriate test procedures are developed and established. From a consumer's point of view, and for comparative purposes, performance obtained for each invested operating cost dollar may be of more interest. For that purpose we defined Operating Cost Efficiency earlier. However, this did not involve initial and maintenance cost of the equipment.

This paper introduces the concept of Life Cycle Cost Efficiency, which includes all operating, maintenance and capital costs of the HVAC equipment, and shows how this and the ratio of electric efficiency is influenced by equipment cost, type of equipment and the ratio of electric to fossil fuel cost. Additional factors of influence are climate, heating load and the wide range in performance within each equipment category as learned from field tests.