Lowering the environmental impact of dishwashing and laundry in Europe: a LCA perspective

2.1.1 Geographical boundaries

The assessments span the following European countries: Austria (AT), Belgium (BE), Czech Republic (CZ), Germany (DE), Spain (ES), Finland (FI), France (FR), Great Britain (GB), Greece (GR), Hungary (HU), Italy (IT), The Netherlands (NL), Poland (PL), Portugal (PT) and Sweden (SE). Turkey (TR) and Israel (IL) were also included in the ADW study (Table 1). The selected countries represent those where Procter & Gamble (P&G) operates and thus, where primary data is available. LCAs were developed for each country individually. Aggregated results are based on a weighted average by sales volume and % share and are referred to as “EMEA-14,” “EU-10,” and “EU27 + GB” for ADW, HDW, and laundry, respectively.

2.1.2 Functional unit and reference flow

A functional unit is defined as the quantified performance of a product system for use as a reference unit. ^{9 , 10} This facilitates the determination of reference flows for the system being studied. The definitions of both for each product category are provided in Table 2.

2.1.3 System boundaries

All LCAs reported in this study were conducted as cradle-to-grave assessments, thus life stages include: formula ingredients production, packaging materials production and processing, transport of materials from suppliers to P&G plants, manufacturing at the plant, transport from P&G plants to consumer homes, the use phase, end-of-life of detergent formula, and end-of-life of packaging. Figure 1 presents a representative diagram of the product categories studied. Detailed system boundaries for each product category are defined in the Supplementary Material (Figures 1–3 and Table 1).

Figure 1:

System boundaries for the studied product categories. PD denotes primary data, while SD indicates secondary data, representing averaged data from third-party life cycle inventory (LCI) databases.

2.2.1 Data sourcing

Whenever possible, primary (i.e., company-specific) data was used. Primary data for ADW and HDW products is from 2021. Primary data for laundry studies is from 2020. In cases where primary data was unavailable, secondary data (SD) was obtained and averaged from third-party life cycle inventory (LCI) databases. Figure 1 provides a representative overview of the systems modelled. Secondary data was mainly sourced from Ecoinvent v3.8 ¹⁴ and Industry Data 2.0. ¹⁵ A complete overview of data sources is provided in the Supplementary Material (Table 1).

2.2.2 Scenario modelling for ADW

We compared the environmental impact of an improved product formula optimized for performance in short cycles under conditions representative of an average short cycle with that of the base product formula assessed under average conditions for auto/normal cycles (Table 3) in each of the countries in scope of assessment (Table 1) and for the aggregated weighted average. Data for the in-use phase were defined by a habits and practices (H&P) study of auto dishwasher cycle usage and brand penetration. Austria, Czech Republic, and Hungary were not included. The wash cycle parameters of temperature, energy, water, and duration for these missing countries in the EMEA14 model is the mean of those parameters per cycle type across the 10 of the 11 countries in the H&P study (excluding Russia). The average water and energy consumption per type of dishwashing cycle come from the assessment of 133 dishwasher manuals across 27 brands. Manuals consulted were for new machines to those 10 years old, with most of them being 5 years old. The average is weighted based on the machine penetration in each country.

Similar average conditions were also found by Tewes et al. in 2023 ¹⁶ by comparing the consumption data reported of 164 dishwashers in 11 countries, short cycles have been lauded as an economical and convenient alternative to the more time-consuming ‘eco’ programmes, ¹⁶ which is a significant barrier to consumer adoption. ¹⁷ This advantage is particularly pronounced when short cycles are paired with high-performing detergents. ¹⁸ Recent research indicates that a high-performance commercially available detergent can achieve cleaning results nearly as effective as those obtained in ‘eco’ cycles; ¹⁹ it was this insight that provided the impetus for developing the improved product formula tested in this study.

2.2.3 Scenario modelling for HDW

We examined the environmental impacts of various washing methods, product formulas, dosages, and temperatures across the EU-10 countries. The washing techniques analysed included: (1) direct application open tap (product applied on the sponge with the tap opened constantly during washing and rinsing); (2) direct application closed tap (product applied on the sponge with the tap only opened for rinsing) and (3) full sink (product applied on a sink filled with water used for washing and tap opened again for rinsing). These reflect the most recent H&P data, derived from recent consumer tests and surveys that were considered valid and fair to measure the consumption of water, product and energy throughout the in-use phase. Product formulas reflected the most recent and innovative product available in each market in 2022. Product dosage was assessed at both regular and double amounts. Washing temperature was modelled based on the current temperatures used in each country, which range from 33 °C to 45 °C, as well as a target temperature of 23 °C. This target was chosen based on the results of a survey of 88 consumers, which identified 23 °C (mean ± standard deviation: 23 °C ± 4.75) as the minimum comfortable water temperature for immersing hands in the sink or under the tap.

2.2.4 Scenario modelling for laundry

We investigated the environmental impact of washing laundry at two temperatures: 40 °C and 30 °C using the product formulation that had the highest sales in each country in 2022 (i.e., the % of volume of SUDs sold with respect to the P&G portfolio). These temperatures were chosen to reflect the current average wash temperature in Europe (42.6 °C according to A.I.S.E., i.e., International Association for Soaps, Detergents and Maintenance Products) and a target temperature promoted by several campaigns, including P&G’s ‘Turn to 30°’ and A.I.S.E.’s ‘I Prefer 30’ campaigns. The environmental impact of washing at these two temperatures was compared across three different years: 2020, 2025, and 2030. This comparison aims to evaluate how the increasing share of renewable energy in the electricity grid will impact the environmental footprint of laundry washing.

2.4.1 Modelling choices and tools

The Circular Footprint Formula (CFF) from the Product Environmental Footprint (PEF) method ²¹ was used for modelling recycled content and packaging end-of-life. The CFF models packaging waste treatment (including recycling, incineration with energy recovery, and landfill disposal) and instances when recycled content is used in packaging. The formula allocates the benefits and burdens of recycling and virgin material production between the life cycle that sends the material for waste treatment and the life cycle that uses the recycled material. Please see the “Modelling approaches” section in the Supplementary Material for a detailed description. For modelling the end-of-life of the product down the drain, the Wastewater Treatment Life Cycle Inventory (WWT LCI) tool ²⁶ was used. The WWT LCI tool specifically assesses the impacts of chemical substances going down the drain to sewers, wastewater treatment, and eventually the aquatic environment. This tool includes physical and chemical attributes specific to those substances, affecting their behaviour at typical municipal wastewater treatment plants in a country. Country-specific operations and infrastructure are also included in the model. All life cycle modelling was conducted using SimaPro software version 9.3.

2.4.2 Energy grid mix considerations

The energy grid mix of each country plays a significant role in determining the environmental impacts associated with the life cycle phases of the products, and thus merits consideration when interpreting the results. As such, country-specific overviews of the energy grid mix for electricity generation and residential water heating are provided in Supplementary Material (Tables 2–5).

3.1.1 Automatic dishwashing (ADW) detergents

The in-use phase is the largest contributor to the carbon footprint of ADW detergents in all countries (Figure 2A). This impact mainly arises from the energy needed to heat the washing water. For most countries, the in-use phase accounts for 78–92 % of global warming, but in France and Sweden, it accounts for significantly less (50 %). The in-use phase has a particularly high impact in markets that rely more on fossil fuels for electricity generation (Supplementary Material, Table 3) and residential water heating (Supplementary Material, Table 4). In France and Sweden, where the energy grid is cleaner, the relative impact of the use phase is lower, but it remains the most significant life cycle stage. This highlights the importance of nuclear and renewable energy in reducing the global warming impact of ADW detergents. The weighted average across EMEA-14 indicates that the in-use phase contributes the most to all other environmental indicators: fine particulate matter, fossil resource scarcity, water scarcity, and cumulative energy demand (Figure 2D). This pattern applies for all countries except those with a lower-impact energy grid mix i.e., France and Sweden, where the product formulation stage has the highest contribution. This reinforces the significant role that a country’s electricity mix plays in determining the environmental impact of ADW detergents.

3.1.2 Hand dishwashing (HDW) detergents

The in-use phase is the largest contributor to the carbon footprint of HDW detergents across all countries (Figure 2B), accounting for 83–95 % of the carbon footprint when considering country-specific wash temperatures and habits. The primary factor driving this impact is the energy consumed to heat the water. Energy mix also influences the product’s carbon footprint. The relative and absolute impact of the use stage is lowest in Sweden (Figure 2B), which has the highest share of renewable energy sources in its electricity mix (Supplementary Material, Table 2). The results for fine particulate matter, fossil resource scarcity, water use and cumulative energy demand mirror those observed for the carbon footprint i.e., the in-use phase has the highest relative contribution across EU-10 (Figure 2E). The contribution is most pronounced for fossil re-source scarcity and cumulative energy demand in those countries with a higher-impact energy mix. The results for water use were uncertain and hence no conclusions can be drawn for this impact category.

3.1.3 Laundry detergents

The in-use phase is the largest contributor to the carbon footprint of laundry at current wash temperatures of 40 °C, followed by formula ingredient production and formula end of life (Figure 2C). The in-use phase accounts for 40–72 % depending on the country. The impact of the in-use phase is highest in countries which are dominated by a high-carbon electricity grid mix. Germany, which has a high share of coal in its portfolio, exhibits the highest impact, followed by Italy, which has a high share of natural gas (Supplementary Material, Table 3). Like the results for carbon footprint, the in-use phase is the most significant life cycle stage for fine particulate matter, fossil resource scarcity, water scarcity, and cumulative energy demand when washing at 40 °C (Figure 2F).

3.2.1 Switching consumers from auto/normal to short cycles

For all environmental indicators studied, the improved product formula in short cycles has a lower impact than that of the base product formula in auto/normal cycles (Figure 3A). The average carbon footprint reduction for this scenario across EMEA-14 is 33 % (Figure 3A). This reduction is mainly due to short cycles using ∼42 % less energy per load than auto/normal cycles – 0.7 kWh versus 1.2 kWh. The carbon footprint of 1 kWh of electricity varies by country, making short cycles more beneficial in countries with a higher carbon-intensive grid mix. For instance, reductions equal 37 % in Poland and the Czech Republic, while France and Sweden see smaller reductions of 18 % and 22 %, respectively (Supplementary Material, Table 6). A sensitivity analysis confirmed the robustness of our results: the improved product formula in short cycles has a lower impact than the base product formula in auto/normal cycles in all cases as long as the short cycle consumes less electricity than the auto/normal cycle. The average reduction in fine particulate matter across EMEA-14 is 38 % (Figure 3A). While for fossil resource scarcity, the average reduction is 33 % (Figure 3A), with potential improvements ranging from 27 % in Belgium to 37 % in the Netherlands and Poland. The average reduction in water scarcity across EMEA-14 is 29 %, with reductions ranging from 5.5 % in the UK to 35.6 % in Italy. This is due to short cycles consuming less water on average (9.9–10.6 L per cycle) than auto/normal cycles (13.1 and 14.3 L per cycle). Finally, the average reduction for cumulative energy demand across EMEA-14 is 35 %, with potential improvements ranging from 33 % in Belgium to 38 % in the Czech Republic. These lower impacts are attributed to reduced extraction and less electricity generation needed for washing processes with lower energy demands.

3.2.2 Changing washing habits and using cooler water when hand dishwashing

The environmental impact of HDW is influenced by both washing habits and water temperature. The direct application open tap method has a carbon footprint that is more than double that of other techniques, such as direct application closed tap and full sink. While reducing washing temperatures from current levels (33 °C–45 °C) to 23 °C could lead to a 60 % reduction in the carbon footprint of HDW products across EU-10 countries (Figure 3B), primarily due to decreased energy demand for heating water. The carbon footprint associated with 1 kWh of energy varies by country, making the reduction from lower temperature washing more significant in countries with a higher carbon-intensive energy mix, such as the Netherlands, which rely heavily on natural gas for residential water heating (Supplementary Material, Tables 3 and 4). Sensitivity analyses were conducted by varying parameters such as product dosage, target washing temperature, and water volume. Even when the product dosage for washing at 23 °C is doubled, a significant carbon footprint reduction is still observed: 64 % with the recommended dosage and 60 % with the doubled dosage. Reductions are also seen when washing at temperatures above 23 °C but below current levels; for example, in the UK, washing at 23 °C results in a 64 % reduction, while washing at 27 °C yields a 49 % reduction. Furthermore, even in a hypothetical scenario where consumers use more water at lower temperatures, a reduced carbon footprint would still be achieved compared to washing at current temperatures. Reducing wash temperatures also yields significant environmental benefits, including a 55 % reduction in fine particulate organic matter, a 62 % reduction in fossil resource scarcity, a 10 % reduction in water scarcity and a 61 % reduction in cumulative energy demand (Figure 3B). Collectively, these findings indicate that using HDW products at a lower washing temperature of 23 °C, combined with the direct application closed tap method, can substantially reduce environmental impacts by decreasing energy and water consumption.

3.2.3 Reducing wash temperature in laundry and the impact of the greening of the electricity grid

Washing at cooler temperatures has on average, a positive impact on all environmental indicators (Figure 3C). Considering the weighted average of the countries in scope shows that washing clothes at 30 °C rather than 40 °C reduces the carbon footprint of laundry detergents by 16 %, fine particulate matter by 12 %, fossil resource scarcity by 17 %, water scarcity by 2 %, and cumulative energy demand by 21 % (Figure 3C). Interestingly, the relative contribution of the in-use phase remains stable, despite the projected greening of the electricity grid between 2020 and 2030 (Figure 3D). Washing at 30 °C remains better than washing at 40 °C as is evidenced by the offset between the two lines over time (Figure 3D).