An experimental investigation of energy saving potentials for room type variable-speed air conditioners in public offices: A case study from Istanbul

This study includes the comparison of constant speed air conditioners (non-inverter AC) and variable speed air conditioners (inverter AC) in two identical public office rooms in terms of the energy consumption by reflecting user comfort conditions as a field test. The period of this field test was totally 64 days from 31st of July to 2nd October 2012 and ACs were operated for 43 days intermittently. After collecting real data, total and operational energy consumptions, weighted average power and energy consumptions of the selected typical days were conducted. As can be derived from the conducted analyses, the energy saving ratio of inverter AC to non-inverter AC varies between 11% and 38%. The second important observation is that the lower cooling loads than minimum rated power results in shifting inverter AC to on/off mode. The last but not the least, usually energy efficiency ratio (EER) is used as an indicator for evaluating cooling efficiencies of ACs and in this field test although both inverter and non-inverter ACs have the similar EER values, their energy consumptions differ from each other. This results in the requirement of a new indicator for better comparison of energy efficiencies of ACs.