Laundry energy consumption in multistory buildings: Technology versus laundering practices

ABSTRACT Laundry remains a major contributor to energy consumption in multistory buildings. Better understanding of the contribution of habits and routines versus technology can contribute to efficiency improvements. This study expands bottom-up water and energy models by linking washing and drying within one framework, by integrating user habits and routines, by incorporating a primary energy framework and by validating them with paired laboratory/field and literature data. Water, hot water and electricity consumption in front-loading washers (FLW) and dryers were measured in the laboratory varying user-controlled settings and monitored in selected apartments (N = 10) equipped with the same appliances. Water and electricity consumption in the apartments were 10 – 33 L/(cap · d) water, 0.19 – 3.8 L/(cap · d) hot water, 0.02 – 0.17 kWh/(cap · d) washer electricity and 0.27 – 1.0 kWh/(cap · d) dryer electricity. Based on a scenario analysis, primary energy consumption decreased as follows: conventional top-loading washer (TLW) > small loads in FLW > efficient TLW > lower final spin speed in FLW > base case FLW > cold water in FLW > newer high spin speed FLW > lower dryness level in dryer > heat pump clothes dryer > 50 % clothesline dried. Technical features reducing drying energy are key to energy conservation such as installing heat pump dryers and replacing TLWs. However, FLWs perform similar to TLWs, if the loads are small or the spin speed is lowered. Some are creating spaces in buildings for air drying, an old even more efficient drying method.