Editing Washing machine (section)

==Efficiency and standards==
Capacity and cost are both considerations when purchasing a washing machine. All else being equal, a machine of higher capacity will cost more to buy, but will be more convenient if large amounts of laundry must be cleaned. Fewer runs of a machine of larger capacity may have lower running costs and better energy and [[water efficiency]] than frequent use of a smaller machine, particularly for large families. However, running a large machine with small loads is typically inefficient and wasteful, unless the machine has been designed to handle such situations.

For many years energy and water efficiency were not regulated, and little attention was paid to them. From the last part of the 20th century, increasing attention was paid to efficiency, with regulations enforcing some standards. Efficiency became a selling point, both to save on running costs and to reduce [[carbon dioxide]] emissions associated with energy generation, and waste of water.

As energy and water efficiency became regulated, they became a selling point for buyers; however, the effectiveness of rinsing was not specified, and it did not directly attract the attention of buyers. Therefore, manufacturers tended to reduce the degree of rinsing after washing, saving water and electrical energy. This had the side-effect of leaving more detergent residue in clothes, which can affect people with allergies or sensitivity.<ref name="whitegoodshelp1"/> In response to complaints, some manufacturers have now designed their machines with a user-selectable option for additional rinsing.

===Europe===
[[File:EU washing machines label.jpg|thumb|upright|The EU requires that washing machines carry an efficiency label.]]
Washing machines display an [[EU Energy Label]] with grades for energy efficiency, washing performance, and spin efficiency. Grades for energy efficiency run from A+++ to D (best to worst), providing a simple method for judging running costs. Washing performance and spin efficiency are graded in the range A to G. However, all machines for sale must have washing performance A, so that manufacturers cannot compromise washing performance in order to improve the energy efficiency. This labeling has had the desired effect of driving customers toward more efficient washing machines and away from less efficient ones.

According to regulations, each washing machine is equipped with a wastewater filter. This ensures that no hazardous chemical substances are disposed of improperly through the sewage system; on the other hand, it also ensures that if there is [[backflow]] in the plumbing system, sewage cannot enter the washing machine.<ref name="Tilley">{{cite book|isbn = 978-3-906484-57-0|url = http://www.eawag.ch/forschung/sandec/publikationen/compendium_e/index_EN|title = Compendium of Sanitation Systems and Technologies |edition=2nd |author= Tilley, E. |author2=Ulrich, L. |author3=Lüthi, C. |author4=Reymond, Ph. |author5=Zurbrügg, C.|publisher = Swiss Federal Institute of Aquatic Science and Technology (Eawag) |location=Duebendorf, Switzerland|page = 147|year = 2014}}</ref>

===United States===
Top-loading and front-loading clothes washers are covered by a single national standard regulating energy consumption.<ref>{{Cite web |date=2024-03-15 |title=Energy Conservation Program: Energy Conservation Standards for Residential Clothes Washers |url=https://www.federalregister.gov/documents/2024/03/15/2024-04737/energy-conservation-program-energy-conservation-standards-for-residential-clothes-washers |access-date=2025-01-27 |website=Federal Register |language=en}}</ref> The old federal standards applicable before January 2011 did not restrict water consumption; there was no limit on how much unheated rinse water could be used.<ref>{{cite web|url=http://www.energystar.gov/index.cfm?c=clotheswash.pr_crit_clothes_washers |title=Clothes Washers Key Product Criteria |publisher=Energystar.gov |access-date=2012-06-01}}</ref> Energy consumption for clothes washers is quantified using the [[energy factor]].

After new mandatory federal standards were introduced, many US washers were manufactured to be more energy- and water-efficient than required by the federal standard, or even than required by the more-stringent Energy Star standard.<ref>{{cite web|url=http://www.energystar.gov/index.cfm?c=clotheswash.search_clotheswashers |title=ENERGY STAR Qualified Clothes Washers |publisher=Energystar.gov |date=2011-01-01 |access-date=2012-06-01}}</ref> Manufacturers were further motivated to exceed mandatory standards by a program of direct-to-manufacturer tax credits.<ref>{{cite web |url=http://energytaxincentives.org/builders/appliances.php |title=Tax Incentives Assistance Project |publisher=Energytaxincentives.org |access-date=2012-06-01 |archive-date=2011-05-20 |archive-url=https://web.archive.org/web/20110520151331/http://energytaxincentives.org/builders/appliances.php |url-status=dead }}</ref>

In North America, the Energy Star program compares and lists energy-efficient clothes washers. Certified Energy Star units can be compared by their Modified Energy Factor (MEF) and Water Factor (WF) coefficients.
 
The MEF [[figure of merit]] states how many [[cubic feet]] (about 28.3 liters) of clothes are washed per kWh (kilowatt hour). The coefficient is influenced by factors including the configuration of the washer (top-loading, front-loading), its spin speed, and the temperatures and the amount of water used in the rinse and wash cycles.

Energy Star residential clothes washers must have an MEF of at least 2.0 (the higher the better); the best machines may reach 3.5. Energy Star washers must also have a WF of less than 6.0 (the lower the better).<ref>{{cite web |url=http://www.energystar.gov/index.cfm?c=clotheswash.pr_crit_clothes_washers |title=Clothes Washers Key Product Criteria |url-status=live |archive-url=https://web.archive.org/web/20151109211645/http://www.energystar.gov/index.cfm?c=clotheswash.pr_crit_clothes_washers |archive-date=November 9, 2015 |publisher=Energy Star}}</ref>