22 May 2008

A NEW TEST AND EVALUATION METHOD OF ANNUAL ENERGY EFFICIENCY OF MULTIPLE AIR-CONDITIONERS FOR BUILDINGS


We made the partial load performance tests of multiple air-conditioners for
buildings powered by electric motors, the rating cooling performance of which was 56 kW, by
using the air-enthalpy method testing apparatus. The coefficient of performance (COP) and
annual energy consumption measured by those tests were closely compared with those
predicted by the current calculating method provided by Japanese Industrial Standards (JIS
B 8616:2006). The performance of the air-conditioner changed depending on the outdoor air
temperature and the indoor thermal load. The current calculating method could not
reproduce the deteriorations of COPs that appeared under the low thermal load operating
conditions in both the cooling and heating seasons. As a result it seriously underestimated
the annual energy (electricity) consumption; the error amounted to about 20 % of the
measured value of the annual electric energy consumption. Based on these results, we
proposed new testing conditions for the performance evaluation and a calculation method of
the annual electricity consumption that could improve noticeably the accuracy of the
estimation of the annual electricity consumption.