The Sustainable Wash: Washing Machine Wash Performance Explained
Paper 1 of 3 in Sustainable Laundry by Design
Determinants of washing machine wash performance
Wash performance is the measure of how well a laundry system removes soil from fabric. Standard procedures for evaluating soil removal differ across markets and may be a standalone index reported on a product label (in China), or may be a threshold which energy consumption is measured against, as in the European Union.[1,2]
The lack of a single global label format creates opportunities for product differentiation across markets, while the underlying science of soil removal remains consistent. Broadly, four controllable variables influence wash performance: temperature, chemistry, mechanical action and time.[3]
Temperature – Water temperature within the drum can improve soil removal through a positive effect on detergent chemistry and by increasing the solubility of soil particles, particularly fats, proteins and oils. It is often one of the most effective levers for improving wash performance, but it carries a significant energy cost because water heating is a major contributor to washing-machine electricity use.[4,5]
Chemical – This is the washing solution comprised of water and detergent. Detergent dose, detergent chemistry, water pH and hardness can all affect the soil removal effectiveness of the solution. Detergent dose is readily adjustable; however, its relationship to cleaning efficacy is not linear and excessive chemistry can increase cost, create unwanted residue and environmental burden.[3]
Mechanical – This is the scrubbing action generated by tumbling, driving water and detergent through clothes, and generating friction with the drum and between fabrics to physically remove soil. Mechanical action supports soil removal, but abrasion and repeated laundering can contribute to fibre release into the environment and fabric wear.[3,6,7]
Time – More specifically, cycle time. Soil removal is not instantaneous: detergent requires contact time to suspend soil particles and repeated mechanical agitation cycles are required to remove and rinse away those particles. Time can therefore compensate for reductions across other variables, but longer cycles can increase energy use, water exposure and fabric stress depending on program design.[3,5]
Increasing cycle time comes at the expense of user convenience and satisfaction. From the above it is evident that no single variable can be maximised without cost elsewhere, but it also forms a foundation of understanding from which it is possible to calibrate each to a level of wash performance which is sustainable. This emphasizes the importance of application knowledge and system level design across critical aspects of the laundry appliance such as electro-mechanical componentry.
Wash performance is best understood not as the product of any single variable but as the outcome of a balanced system in which temperature, chemistry, mechanical action and time are interdependent where each lever carries its own trade-off. Optimising one variable in isolation, therefore risks shifting the burden to another, whereas calibrating all four together allows manufacturers to achieve a desired level of wash performance with lower energy use, reduced detergent, and improved fabric care. The drive system is central to striking this balance, it directly governs the mechanical action and achievable cycle profile, it indirectly influences how effectively heat and chemistry are put to work.
Selecting a drive system partner with deep application knowledge of wash performance, rather than one focused on motor specifications alone is critical. Such a partner can tailor specification and control strategies to the wider system; this enables manufacturers to meet regulatory thresholds and differentiate across markets. The result is a sustainable, high-performing appliance.
Papers 2 and 3 in this series are coming soon.
References
1. European Commission. Washing machines: energy labelling and ecodesign requirements. Brussels: European Commission; 2026.
2. Standardization Administration of China. GB 12021.4—Energy efficiency and water efficiency grades for electric washing machines. Beijing: Standardization Administration of China (2026).
3. Kärcher. The Sinner’s Circle: the basics of cleaning. Winnenden: Alfred Kärcher SE & Co. KG.
4. Boyano Larriba A, Cordella M, Espinosa Martinez M, Villanueva Krzyzaniak A, Graulich K, Rüdenauer I, et al. Ecodesign and Energy Label for household washing machines and washer dryers. Luxembourg: Publications Office of the European Union; 2017. doi:10.2760/029939.
5. GINETEX. Laundry: how washing machine programs affect electricity consumption. Paris: the International Textile Care Labelling Group; 2022.
6. Lant NJ, Hayward AS, Peththawadu MMD, Sheridan KJ, Dean JR. Microfiber release from real soiled consumer laundry and the impact of fabric care products and washing conditions. PLoS One. 2020;15(6):e0233332. doi:10.1371/journal.pone.0233332.
7. Vassilenko E, Watkins M, Chastain S, Mertens J, Posacka AM, Patankar S, et al. Domestic laundry and microfiber pollution: Exploring fiber shedding from consumer apparel textiles. PLoS One. 2021;16(7):e0250346. doi:10.1371/journal.pone.0250346.
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