Impact of load capacity on washing machine energy efficiency labeling and the intrinsic relationships among key parameters

The performance test results reported on washing machine energy labels are averaged from tests conducted under half-load and full-load conditions, which may differ substantially from the half-load conditions more commonly encountered in actual use. In addition, correlations among different performance parameters may undermine the scientific basis for applying a uniform energy-efficiency threshold as an evaluation criterion. In this work, the effects of load capacity on cleaning performance, water extraction performance, rinsing performance, and energy and water consumption results were investigated. The results show that load capacity affects different performance metrics of the two washing machine types to varying degrees. For the conventional top-loading washing machines, load capacity had the greatest impact on rinsing performance. For the front-loading washing machine, water consumption and cleaning score were the indicators most significantly affected by load capacity. In addition, the intrinsic relationships among the five performance parameters were analyzed. For conventional top-loading and front-loading washing machines, the two pairs of performance metrics exhibiting the strongest correlations were energy consumption and residual moisture content, and energy consumption and water consumption, with correlation coefficients of − 0.69 and 0.90, respectively. However, when mini washing machines were included, the correlations among the performance parameters changed significantly, with water consumption and cleaning score becoming the pair of performance metrics showing the strongest correlation. This study can provide a reference for adjusting the weighting of half-load conditions in future standard revisions, establishing differentiated reference thresholds for energy-efficiency grades according to washing machine types, and guiding manufacturers in improving washing performance.