Abstract
To address climate change and other are sustainability imperatives, the private sector has launched various initiatives that are aimed to evaluate and reduce the impact throughout the life cycle of consumer products. Recently, multi-national retailers and manufacturers have initiated a unified approach in creating sustainable indexing programs for the products they make and sell. Often overlooked in addressing pressing sustainability imperatives such as climate change are the consumptive patterns and impact of consumer goods during the consumer use phase. This article presents an empirical study of the consumer use phase of laundry care with a specific focus on electricity consumption and carbon dioxide emissions. By understanding the climate change impact associated with the consumer use phase, innovations in the manufacturing phase as well as life cycle benefits of different technologies and consumer actions can be explored. Incentives offered to consumers on appropriate technologies used in this phase can be examined to identify the effectiveness of change-agents. Our results indicate that a carbon dioxide reduction of 105 MMT and electricity savings of 142 thousand GWh can be obtained by optimizing and modifying technological and consumer behavior strategies. This is roughly equivalent to removing 12.1% of the 135.4 M passenger cars in the United States per year or taking 23 coal power plants off the grid. In addition, more than 60% of water consumption (512 billion gallons) while laundering can be reduced through these strategies.
Introduction
The United States is the second leading global emitter of carbon dioxide emissions at 22% (PBL 2008). The residential sector in the United States contributed 21% of the national carbon dioxide emissions in 2005. Residential laundry, which traditionally includes washing (0.9%), drying (5.8%), and water heating (1.59%), contributed 8.29% of the total residential sector emissions (EIA Citation2004). Electricity generation related carbon dioxide emissions contributed 33.3% of the total greenhouse gas (GHG) emissions and 41% of the energy-related CO2 emissions in 2007 (EIA Citation2009a). Major initiatives to reduce carbon dioxide emissions in the United States have historically been cantered in the electricity generation sector. In 2003, the Edison Electric Institute formed the Electric Power Industry Climate Initiative along with all the power sector groups that represent 100% of U.S. electricity generation. This initiative was formed to reduce the carbon intensity of the electricity generation sector (DOS 2003). Regional climate initiatives that focus on electricity generation sector include Regional Greenhouse Gas Initiative (RGGI), Midwest GHG Reduction Accord (MGGRA), and Western Climate Initiative (PCGCC Citation2009). Recently, major global retailers and manufacturers have undertaken an initiative with university researchers, non-governmental organizations (NGO) and governmental agencies to address sustainability imperatives including climate change (Rosenbloom Citation2009). This has taken the form of creating an industry standard indexing of the sustainability of consumer products throughout the life cycle, including the consumer use phase.
This article focuses on energy-carbon conservation in a particular segment of the residential sector – laundry, and thereby intends to provide a distributed effort to contribute to climate change mitigation efforts in the United States. Saouter and van Hoof (Citation2001) have documented that approximately 80% of the energy consumption across a laundry detergent's life cycle occurs during consumer use. Rudenauer et al. (Citation2005) have indicated that the dominant phase in the life cycle assessment of a clothes washer is the use phase. They concluded that the use phase attributed to 80% of the cumulative energy demand, 76% of the global warming potential, and 65% of the cumulative environmental burden. Sabaliunas et al. (Citation2006) modeled potential energy conservation and cost savings through reduced laundering temperatures. Petkewich (Citation2005) and McCoy (Citation2006) limit their evaluations to economic and not to environmental impact of lower laundering temperatures (Cameron Citation2007). Richter (Citation2005) approached energy conservation from a systemic viewpoint of appliance modification and laundry chemistry, together. Lin and Iyer (Citation2007) related the local cultural practices to the choice of clothes washer types and its associated energy/water consumption. Jacobsen (Citation1999) discussed the federal efficiency standards, the increasing market-penetration of high efficiency (HE) washers and its impact on detergent formulations. While each of these prior works provides a suitable platform for specific intervention strategies, there does not exist a more holistic systems perspective to address energy and climate sustainability imperatives.
The authors performed a system analysis of the consumer use phase through the development of an energy use and conservation model. This model incorporated the current household and used characteristics of laundry appliances, along with that of water heaters to calculate the related carbon dioxide emissions. One of the important segments of residential laundry – energy associated with the water-use cycle that has been excluded in prior studies and reports has been included in this study. Different scenarios were extrapolated to determine the amount of carbon dioxide savings that can be obtained. By increasing our understanding of the consumer use phase, we can more effectively support sustainable indexing efforts of industry as well as governmental policies and incentives geared towards appropriate technologies.
Washing phase
In 2005, 83% of all U.S. households owned clothes washers, of which 24% were Energy Star® rated (EIA Citation2008a). Three predominant types of washing machines exist in the world ( ). Their adoption has varied based on cultural and behavioral preferences.
Table 1. Common washing conditions present worldwide.
Design trends in laundry appliances and detergents vary largely based on regional preferences (Simpson Citation2007). In Europe, front-loading machines (horizontal axis (h-axis) units) with lower energy and water consumption are most widely used, while Japan uses top-loading machines with impellors. In the United States, which is the focus of this research, the top-loading agitator-type machine (vertical axis (v-axis) units) with high energy and water consumption (Smulders Citation2002) is the most common, with 92% market penetration (EIA Citation2008a). H-axis washers attributed to the remaining 8% of the market in the United States. HE v-axis washers do exist in the United States but since the market share is clearly below 1%, we excluded it from the scope of this study. H-axis washers were first introduced in the United States in 1940s but it never gained significance for multiple reasons (Jacobsen Citation1999). In 1998, the popularity of h-axis washers increased after they were re-engineered (AHAM Citation2009). The reengineering was based on the consumer behavior of Americans, which included the need for bigger tub for larger loads, widened door, and increased machine height by 13 inches (Nelson Citation2002). Simpson (Citation2007) states that North Americans prefer large capacity appliances because of larger room sizes whereas consumers in Europe and Japan prefer smaller and quieter appliances due to smaller living spaces. According to Nelson (Citation2002), the predominant number of top loaders in the United States is attributed to the non-preference of Americans to bend over and access the door of the front loader. The Bern's study indicates that in 1998, only 2% of the clothes washers market comprised of h-axis washers (Tomlinson and Rizy Citation1998). In 2005, after 7 years, the market share had increased to 8% (EIA 2008). There is one critical difference between the h-axis washers of the United States and the h-axis washers of Europe: both have internal heaters but their intended purpose is different. The internal heaters present in h-axis washers in Europe are used to heat water from ambient temperature, whereas the internal water heaters in the United States are used to maintain the temperature of the hot/warm water (in the washers) supplied by an external heater. This construction design change can be attributed to the fact that 99% of the households in the United States already have external water heaters (EIA Citation2008c).
The federal standards for clothes washers in the United States are expressed as modified energy factor (MEF) in cycles per kWh per cubic foot of tub volume. In 2007, clothes washers available in the United States had minimum MEFs of 1.26, while the voluntary Energy Star (Government Performance Initiative) level reached 1.72, with a water factor of 8.0 gal (30.28 l) per cubic foot (Energy Star Citation2009a).
The main characteristics that define the consumer washing phase are: average load size, composition of the load, consumer pre-treating, machine temperature selection, type of cloth being washed, bleach usage, washes per week, and the use of fabric softener. The scope of this study does not include the performance characteristics of the consumer use phase and therefore consumer pretreating, bleach usage, and the use of fabric softener have not been considered in our analysis. Tomlinson and Rizy (Citation1998) undertook a field campaign in Bern, Kansas for the U.S. Department of Energy (DOE) to study laundry behavior, evaluate energy and water savings of HE washers, and also collect information for the DOE Energy Star market transformation program. The study surveyed over 20,000 laundry loads in 103 households. During the first phase of experiments, they collected data from common domestic top-loading machines (v-axis) and then switched the households with a higher efficiency front-loading washer (h-axis) for the second phase. The summary of their findings is presented in .
Table 2. Household laundry survey in Bern, Kansas.
The number of wash loads per year varies from study to study: 315 (Home Energy Citation1996; Nelson Citation2002), 350.4 (Lutz Citation2005), 384 (Pedersen et al. Citation1988), 392 (Sabaliunas et al. Citation2006), 400 (CEC Citation2009); 442 (Tomlinson and Rizy Citation1998). Using the weighted average of different number of wash loads of different populations from the 2005 Residential Energy Consumption Survey (RECS) (EIA Citation2008b), it can be determined that the average wash loads per household per year is 315 (6.06/week).
To quantify the volume of water used in residential washing, an OMEGA Turbine flow rate sensor coupled with an OMEGA Ratemeter/Totalizer was utilized to accurately measure water flow during multiple washings. Two flow rate sensors were used – one for hot water measurement and the other for cold water measurement. Our field trials measured an average water consumption of 30.84 gal (116.74 l)/load for a v-axis machines and 11.57 gal (43.80 l)/load for h-axis machines. The water consumption percentages over different washing phases of a washing cycle are presented in .
Table 3. The percentages of water consumed in different phases of the washing machine cycle.
In 2005, 99% of all households in the United States owned a water heater, of which 39% was electric, 53.4% was natural gas, and 7.2% was equally shared by fuel oil and propane/liquid petroleum gas (EIA Citation2008c). Residential water heaters come in several types: electric storage, electric instantaneous, electric heat pump, gas-fired storage, gas-fired instantaneous, oil-fired storage, and solar. Kempton (Citation1988) identifies hot water consumption to be behavior driven and therefore foresees large potential for energy savings. Koomey et al. (Citation1995) notes that the use behavior w.r.t. water heaters varies based on water-inlet temperatures, water-using equipment, hot water temperature-set points, water-use temperatures, water distribution system, water heater insulation, ownership of other associated appliances and their characteristics (Lutz Citation2005; Sabaliunas et al. Citation2006).
In our study, the heating energy of water used for clothes washing was based on Equations (1) and (2) due to the non-availability of water heaters for experimentation. Warm water of 88°F (31.11°C) was used in all our experiments. This water temperature was obtained from a mix of 23% hot water and 77% cold water for v-axis washers, and 18% hot water and 82% cold water for h-axis washers – as per machine pre-determined settings for water consumption. The v-axis washers consumed almost three times as much as water as the h-axis washers and also heated an additional 5 gal of water as compared to h-axis washers. The end-use consumption of hot water for laundry in a household varies from 16% (Koomey et al. Citation1994) to 19% (Ladd and Harrison Citation1985; Lutz et al. Citation1996). This study uses the average (17.5%) of these two values in calculating residential end-use energy consumption and carbon dioxide emissions that are attributed to hot water use in washing. The average temperatures of water that were used for washing was measured to be 61°F (16.11°C) for cold water and 121°F (49.44°C) for hot water. Based on the need to heat 7.06 gal (23%) of cold water for v-axis washers and 2.04 gal (18%) of cold water for h-axis by 60°F to achieve the average hot water temperature (121°F) using a 100% efficient electric water heater, the kWh required to heat the water was calculated as: 
In addition to direct heating energy, we take a more systems approach to include the infrastructural electricity required for water delivery and treatment. Public water in the United States originates from two sources: surface water (80%) and ground water (20%) (Barber Citation2009). Ground water requires 30% more electricity for the purpose of pumping than do surface water (Goldstein et al. Citation2002). A typical water-use cycle starts when the water is collected and conveyed from the source. It is then treated and distributed to the user, after which, the waste water is collected, treated and then discharged to the source (Klein et al. Citation2005; Stillwell et al. Citation2009). Energy driven pumps are used to move water against the force of gravity based on geography and other structural considerations. This includes extracting water from the ground, as well as, moving water through pipes and canals. In the United States, 75% of the wastewater enters the treatment facilities and 25% enters a home treatment/septic tank system (Sedlak Citation1995). Although the energy intensity of the water cycle varies spatially, water needs are intrinsically woven with its energy needs. In the United States, 55,000 water systems process about 34 billion gallons of water a day and distribute it over a network of pipelines that is about 600,000 miles (AWWA Citation2005).
On average, 74 gal (280 l) of water per person per day is consumed in a typical residence in the United States with clothes washing accounting for 21% of all residential indoor water usage (AWWA Citation2005). According to Goldstein et al. (Citation2002), Klein et al. (Citation2005), and Stillwell et al. (Citation2009), there is no typical urban water system. Different technologies are employed to treat raw water and wastewater. Additionally, the age and size of the infrastructure introduce more variations in the energy intensities. Klein et al. (Citation2005) put together a range (low and high) of energy intensities for the different segments of a water-use cycle from several different data sources. Since there does not exist a national average data for the energy intensity of the water-use cycle, we use the mean values of the energy intensity ranges provided by Klein et al. (Citation2005) to be representative of the national average. Accordingly, the water-use cycle requires a total of 19,050 kWh/Mgal, which includes: (1) Water supply and conveyance at 7000 kWh/Mgal, (2) Water treatment at 8050 kWh/Mgal, (3) Water distribution at 950 kWh/Mgal, (4) Waste water collection and distribution at 2,850 kWh/Mgal, and (5) 200 kWh/Mgal for wastewater discharge. Recycled water treatment and distribution have been intentionally excluded, as it does not fall into the primary water-use cycle for residential laundry in the United States. The water-use cycle values of northern urban California (3950 kWh/Mgal), southern urban California (12,700 kWh/Mgal), (Klein et al. 2005) and Phoenix (10,404 kWh/Mgal) (City of Phoenix 2006) give an idea of the electricity consumption related to water in the south-western United States.
The total electricity consumed by the water-use cycle for personal laundry care is: 0.58 kWh/load for a v-axis machine and 0.22 kWh/load for an h-axis machine.
These values were calculated based on the total water consumption per load of the two washer types in association with the mean energy consumption of the water-use cycle in the United States. The energy consumption for water heating, supply and distribution is given in .
Table 4. Comparison of findings for the electricity consumed in each step of the residential laundry process (per load).
Combined washing–drying phase
In 2005, 79% of all U.S. households were equipped with clothing dryers, of which 77% were electric (DOE 2008a). The federal minimum energy factor (EF) for a standard capacity electric dryer is 3.01 (lbs. of clothing/kWh). Dryers are not Energy Star rated because there is little difference in energy consumption between different models (Energy Star Citation2009b).
To effectively quantify drying energy variation in relation to different washer technologies, we measured washing and drying electricity consumption for loads that have been laundered in v-axis and h-axis washing machines using an energy logger. The standard test load sizes adopted in this study used DOE survey results (Tomlinson and Rizy Citation1998) of 6.65 lbs (3.02 kg)/load for v-axis machines and 6.98 lbs (3.17 kg)/load for h-axis machines.
The dryers utilized for the experiments were Whirlpool dryers with drum size 7 cu. ft. The Whirlpool brand dryer was chosen due to the fact that, after the 2006 takeover of Maytag Corp., Whirlpool had the largest market share of dryers of 74% (29th Annual Portrait of the U.S. Appliance Industry Citation2006). A consumer representative from Whirlpool confirmed that the mechanical system of the dryers of both brands – Whirlpool and Maytag – consumed very similar amounts of energy, under standard conditions of medium heat. Based on an analysis of 197 electric dryers available from all dryer brands websites' in the United States, it was determined that the mode in the dataset representing the most commonly available drum size was 7 cu. ft. This explains the choice of a 7 cu. ft drum size. Whirlpool dryers seemed appropriate to represent the most common dryers present in the US market because of the above two reasons.
The washing machine utilized for the experiments were Whirlpool v-axis washers with drum size 3.2 cu. ft. and Kenmore Elite h-axis washers with drum size 3.8 cubic ft. The Kenmore brand appliances are manufactured by Whirlpool as a private brand for the appliance retailer ‘Sears’. Both the washer brands (Kenmore and Whirlpool) were chosen because they represent the majority of the market share (70%) of washers by the Whirlpool brand. As in the case of dryers, a consumer representative confirmed that the mechanical systems of the two chosen washers consumed very similar amounts of energy to washers in their categories, under standard conditions of normal wash and regular spin cycle. The drum sizes were chosen based on the most common drum sizes (mode of the data set) in an analysis of 201 washers in the US market that were available from all brands that sell washers in the United States.
The warm wash and cold rinse cycle was identified to be the most commonly adopted wash cycle in the United States (EIA Citation2008b). This was because that 88.3% of the hot and warm wash users utilized warm water in the wash cycle and 78.4% of all rinses utilized cold water in the rinse cycle (EIA Citation2008b). Additionally, 72% of 1200 respondents in a study conducted by the University of Kentucky examining the consumer use of laundry products said that, they usually use warm water for laundry as compared to 9% who said that they would use hot water (Consumers Studied 1985).
Three experimental runs in total were conducted, with each run consisting of two wash and two dry cycles in identical but different machines. According to Sabaliunas et al. (Citation2006), 43% of the households in the United States prefer large load sizes (7 lbs) to extra large (10 + lbs) and medium loads (5.5 lbs). The test conditions for a large size load included warm wash, cold rinse, and a normal spin in a regular wash cycle.
The full cycle time for a v-axis and h-axis, which was determined by the machine pre-set conditions were 38 min and 45 min, respectively. Two sets of experiments were conducted to keep align with the objective and to identify any bottlenecks in the laundry process. The test load comprised of white colored pillow-cases (60% cotton, 40% polyester) with the edges hemmed, that closely resembled the test cloth description in the Federal Register's Test Procedure for Washers (Federal Register Citation2003).
According to Rudenauer et al. (Citation2005) and Richter (Citation2005), any remaining moisture in the clothing is passed on to the dryer, where the resulting energy consumption to remove that moisture is much higher. The first experiment quantified the retained moisture in clothing after washing, also known as residual moisture content (RMC). The testing procedure in this study involved five steps: (1) measuring the dry bone weight of the test load, (2) washing the test load based on the test conditions (normal wash, no detergent, regular spin, and medium load), and (3) weighing the test load after the final spin. The experimental results indicate that the weight of the test load for a v-axis washer increased by roughly 60% whereas the test load weight of the h-axis washer increased by 21%. The RMC of the wash load is the primary factor that determines the duration of drying time and the associated dryer energy consumption. In this case, since the v-axis wash load had three times higher moisture content (as identified from its weight) than the h-axis wash load, it is understood that the drying time of the v-axis wash load is going to be much higher than that of the h-axis wash load. Rudenauer et al. (Citation2005) and Richter (Citation2005) reported that the spin speed in the washer is inversely proportional to the RMC. Although, increased spin speeds can reduce the life span of the washer (Rudenauer et al. Citation2005).
The second experiment quantified electricity used per cycle for both v-axis and h-axis washing machines and electric drying. Based on our experimentation, the direct electricity consumption for a v-axis washer was calculated to be 0.21 kWh per load while the h-axis washer consumed 0.10 kWh. The total electricity consumed in the laundry use phase includes the electricity associated with water use ( Figure 1), thus resulting in higher electricity consumption than prior works ( ).
Published online:
05 March 2010Figure 1. Percentage electricity use in the laundry cycle using a v-axis washing unit.
Figure 1. Percentage electricity use in the laundry cycle using a v-axis washing unit.
Environmental sustainability implications
Based on the energy consumption data for a single laundry cycle (Table 4), we examined the annual electricity, water and carbon dioxide emissions per the average US household of 2.59 persons (Census Bureau Citation2001) and on a national basis.
In 2005, the United States had 111.1 million households of which 83% owned washers and 79% owned dryers (EIA Citation2008a) which represents a 13% increase of clothes washers and 43% in clothes dryers as compared to 2001 RECS data (EIA Citation2001). Using these figures, we calculated that the residential clothes washing and drying contributed approximately 142 MMT combined and consumed 191,000 GWh. It was assumed that all households that owned a dryer used it to dry the clothes while the rest used non-mechanical drying (hang/line drying). In the United States, using the 2005 fuel mix of 50% coal, 18% natural gas, 20% nuclear, and 3% petroleum (EIA Citation2007) to generate electricity, it was determined that 0.78 kg of CO2 is emitted per kilowatt hour of electricity produced (eGRID2007 2008). Wilson et al. (Citation2003) claim that 1.55 lbs (0.70 kg) of CO2 was emitted during the production and use of 1 kWh of electricity, based on a study sponsored by the American Council for Energy-Efficient Economy (Sabaliunas et al. Citation2006). The average of both the values (0.78 kg/kWh and 0.70 kg/kWh) results in 0.74 kg of CO2 per kWh, which is used as a conversion factor in this study to estimate CO2 reductions from various energy conservation initiatives. The conversion factor is an estimated value that takes into consideration the variability that is present in different data sources. Based on a market penetration of 92% for v-axis washers and 8% for h-axis washers, the annual consumption of water for residential laundry (91.8 million households) equals 847 billion gallons. The quantifications made in take into consideration all the major processes identified in as the entire laundry process.
Table 5. Electricity, CO2, and water consumption for the complete laundry process.
The US residential sector recorded 1253.8 MMT carbon dioxide emissions for 2005, which represented 21% of U.S. energy-related carbon dioxide emissions (EIA Citation2007). The emissions from residential laundry care (water supply, treatment and distribution, water heating, clothes washing, clothes drying, waste water treatment and discharge) represents approximately 18% of that of the entire residential sector emissions and roughly 3% of the national carbon dioxide emissions in 2005. Within the residential sector, the pro-rated share of electric power sector carbon dioxide emissions, 890 MMT, accounted for more than two-thirds of all emissions.
Strategies for the consumer use phase
Three primary actions (technological and behavioral) during the consumer use phase have been identified, that could reduce environmental and economic sustainability burdens associated with residential laundry. They are: (1) washing machine selection, (2) the temperature of water used for washing, and (3) laundry drying method. These actions were modeled individually to analyze savings in carbon dioxide emissions.
Figure 2 presents the variation in energy consumption and carbon dioxide emissions based on the varying market penetration of h-axis and v-axis clothes washers in the United States. Calculations are based on 92% v-axis washers and 8% h-axis washer market penetrations for the year 2005. It is assumed that consumer behavior remains constant over the period, and only if this condition is satisfied, the results of these models will remain valid. Our modeling indicates ( Figure 2), that nationally, the United States can obtain an average 5% reduction in electricity consumption and carbon dioxide emissions with every 25% increase in market penetration of h-axis washing units to replace existing v-axis units. Tomlinson and Rizy (Citation1998) indicate water savings of 38% from the switch to h-axis washers from a single load. The washing machines used in our study uses 25% (v-axis) and 55% (h-axis) less water than their predecessors from the Tomlinson and Rizy (Citation1998) study. In our experiments, the switch to h-axis washers resulted in 62% water savings from a single load. Thus, we can correlate that the increased market penetration of h-axis washers increases the water savings in a much larger way. The savings in water consumption reflect on the savings of energy required for the water-use cycle.
Published online:
05 March 2010Figure 2. Reduction in energy consumption and CO2 emissions (5%) obtained with every 25% increase in market penetration of h-axis washers in the United States.
Figure 2. Reduction in energy consumption and CO2 emissions (5%) obtained with every 25% increase in market penetration of h-axis washers in the United States.
Similarly, an average of 3% decrease in electricity consumption and carbon emissions can be achieved with a 25% increase on consumers transitioning from warm water washing to cold water washing ( Figure 3). Although the energy required for water heating ( ) is much higher than that of the energy consumption of an h-axis washer, the percentage decrease in electricity consumption in this strategy is lower than the prior strategy. This can be attributed to a high market penetration (37.7%) of cold washes as compared to a low market penetration of h-axis washers.
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05 March 2010Figure 3. Reduction in energy consumption and CO2 emissions (3%) with every 25% increase in consumer use of only cold-water washing in the United States.
Figure 3. Reduction in energy consumption and CO2 emissions (3%) with every 25% increase in consumer use of only cold-water washing in the United States.
As presented in this article, clothes drying is the most energy intensive process in the consumer use phase of laundry care. In the process of line drying of clothes, besides energy from the sun and the wind, there is no other energy used (Rudenauer et al. Citation2005). Nationally, if a 25% reduction in dependence of mechanical/electric drying could be achieved by hang-drying of clothes, an average of 29% decrease in electricity consumption and carbon dioxide emissions for residential laundry in the United States would be realized ( Figure 4).
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05 March 2010Figure 4. Reduction in energy consumption and CO2 emissions (29%) through every 25% increase of US consumers eliminating mechanical drying.
Figure 4. Reduction in energy consumption and CO2 emissions (29%) through every 25% increase of US consumers eliminating mechanical drying.
Systems approach
Rather than evaluating each mitigation strategy separately, we sought to achieve a systems optimization of these strategies. Specifically, we have created four scenarios with different combinations of strategies (A–D). Scenario A is based on 100% h-axis washing units, 95% of the households using mechanical drying (current market penetration of dryers in households that already own washers), and 62% of the market using 100% warm water (consumer behavior on temperature settings of hot and warm wash cycles in households that own washers). Scenario B is based on 100% h-axis, 95% mechanical drying, and 50% cold water use, where the 50% cold water use is a transformation from 62% warm water use. Scenario C is based on 100% h-axis, 50% non-mechanical drying, where the 50% non-mechanical drying is a transformation from 95% mechanical drying. Scenario D is a combination of all the three strategies. It is based on 100% h-axis ownership, 100% cold washing and 50% non-mechanical drying. Figure 5 provides a summary of our modeling results for electricity consumption savings and Figure 6 presents modeled savings in carbon dioxide emissions.
Published online:
05 March 2010Figure 5. Reduction in actual electricity consumption (left axis) in thousand GWh and the corresponding percentage reduction (right axis) in electricity consumption for personal laundry care resulting from four separate reduction strategies.
Figure 5. Reduction in actual electricity consumption (left axis) in thousand GWh and the corresponding percentage reduction (right axis) in electricity consumption for personal laundry care resulting from four separate reduction strategies.
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05 March 2010Figure 6. Reduction in actual CO2 emissions (left axis) in MMT and the corresponding percentage reduction (right axis) in CO2 emissions for personal laundry care resulting from four separate reduction strategies.
Figure 6. Reduction in actual CO2 emissions (left axis) in MMT and the corresponding percentage reduction (right axis) in CO2 emissions for personal laundry care resulting from four separate reduction strategies.
The percentage savings in Figures 5 and 6 are the same because carbon dioxide emissions are calculated as a multiple of electricity consumption and the CO2 conversion factor. Scenario A of 100% h-axis penetration provides 20% savings in energy consumption. Considering that Scenario B is 100% h-axis and 50% cold washing, we can deduce that 50% cold wash penetration from the current level provides only 4% energy savings – much smaller than the savings from h-axis penetration. In comparison, there is roughly 33–35% difference between scenarios A–B and scenario C. This is due to the fact that electricity consumption for drying comprises 71% of the total laundry electricity consumption in a single load cycle ( Figure 1). Scenario D provides a roughly 4% increase in savings from Scenario C, and about 189% increase in savings to Scenario A. At the residential level, the annual savings in laundry costs from Scenario D equals $140.47 per household based on a national average kWh cost of $0.1099 (EIA Citation2009b). The annual reduction in per household kWh consumption for Scenario D is 1278.13 kWh (142,000 GWh/111 M/households).
Additionally, efforts such as those presented can provide support to policy makers who seek to develop and address domestic and global sustainability imperatives such as climate change. As an example, records from the US Environmental Protection Agency (Citation2009b) indicate that the average CO2 emissions per vehicle in the United States is 12,100 pounds (5.59 metric tons). Thus, Scenario D of our proposed consumer use phase intervention strategy is the equivalent of removing 18.78 M cars off the road per year or roughly 14.3% of the 135.4 M passenger cars in the United States (RITA Citation2008).
On May 19, 2009, the White House announced a national fuel efficiency policy that adopts uniform federal standards to regulate both fuel economy and greenhouse gas emissions while preserving the legal authorities of DOT, EPA and State of California. This program proposes to raise fuel efficiency standards on vehicle models released between 2012 and 2016 and thereby save roughly 950 MMT of CO2 equivalent, i.e. 16.2 MMT of carbon dioxide emissions (DOE Citation2009; White House Citation2009). This is equivalent to removing 2.9 million cars of the road per year. Comparative calculations indicate that Scenario D saves 6.6 times the amount of carbon dioxide emissions that the newly proposed fuel efficiency standard intends to save. Given that an average coal power plant in the United States emits 4.6 MMT of CO2 emissions per year (EPA Citation2009b), the proposed fuel efficiency standards can take 3.5 coal power plants off the grid while Scenario D can take 23 coal power plants off the grid.
Discussion
The result from scenario modeling provides some effective systemic strategies on the GHG mitigation, while keeping other factors such as energy efficiency of the appliances, energy/water leaks in the distribution system, laundry chemistry, and appliance build constant. In reality, all these factors will be constantly changing and hence a dynamic model might suit this effort better. At the same time, the electricity data associated with water-use cycle is surrounded with uncertainty that we were not able to quantify. More geographically focused research in the area of quantifying energy associated with the water-use cycle is necessary to improve qualitative models of climate change mitigation.
Although, there continues to be improvement in HE washer technology to reduce RMC (Richter Citation2005), the energy conservation opportunities are much larger when v-axis washers are replaced by h-axis washers – as seen in Scenario A. Roughly 65.7% of the washers in the US market are less than 9 years old (EIA Citation2008a). Washers have an average lifetime of 11 years (29th Annual Portrait of the U.S. Appliance Industry Citation2006) based on mechanical problems, lifestyle changes, and the purchase of a new house. In 2006 and 2007, 29th Annual Portrait of the U.S. Appliance Industry (Citation2006) estimated that an average of 7 million units of washers will be replaced. The earliest h-axis washers that were (re) introduced in 1998 would have just reached their average life expectancy this year. Therefore, any expected replacement units of washers in 2006 and 2007 would most probably be v-axis washers. If washer replacements continue at the trend of 7 million/year, then it would take roughly 12 years to transform the entire US clothes washer market into h-axis washers. A survey of 201 clothes washers from all manufacturer websites, indicate that 68% of the Energy Star rated washers were front loaders.
Various local utilities and city governments throughout the United States provide incentives up to $150 for the purchase of HE washers. Examples include Denver Water, City of Austin (Texas) through the WashWise program, City of Allen (Texas), City of Gallup (New Mexico), San Francisco Public Utilities Commission, Pacific Gas and Electric Company, and Metropolitan Water District of Southern California through the SoCal Water Smart program. If incentives such as the above were to continue or improve, the market penetration of h-axis washers will be much faster than 12 years.
When choosing to line dry clothes, consumers forego the maintenance, equipment, and operational cost of a dryer (Pedersen et al. Citation1988). Dryers have an average lifetime of 12 years and it was estimated by 29th Annual Portrait of the U.S. Appliance Industry (Citation2006) that roughly 4 million electric dryers would be replaced each year in 2006 and 2007. It takes approximately 7 min and 15 s to hang one load of laundry thereby expending 12 Kcal as opposed to machine drying for 50 min and expending 3 kWh (equivalent to 2631.58 Kcal). Therefore, Pedersen et al. (Citation1988) report that the only major trade off that exists between machine and line drying is the cost savings of energy. They suggest that any efforts to motivate consumers to switch to line drying must primarily focus on cost savings and secondarily on the opportunity to increase exercise activity. While line-drying might reduce energy consumption, provide cost savings to the consumer, and reduce GHG emissions, Morris et al. (Citation1984) report that consumers were less acceptable of the line-dried clothes because they appeared more wrinkled than machine-dried clothes. They also noted that brief tumbling of line-dried clothes improved appearance and acceptability. In this case, consumers may still have to own a dryer for its minimal use to obtain acceptable quality of dried clothes. Although, consumers would not be able to take advantage of the cost savings from not owning a dryer, they would still be able to obtain savings from partial dryer operation. At the same time, the partial dryer use could lead to increased life span of the dryer.
Many housing community associations and Home Owners Associations (HOA) restrict residents from visibly displaying their clotheslines, as it can be aesthetically unattractive. This creates obstacles for people who live in properties with HOA (Chaker Citation2007). Currently, more than 20% of the US households belong to 300,000 association-governed communities, which include homeowners associations, condominiums, cooperatives, and other planned communities (CAI Citation2006; Urbina Citation2009). HOA and community associations find the need to have the responsibility of protecting the purity of the place that they live in. According to Urbina (Citation2009), lawmakers in Colorado, Hawaii, Maine, and Vermont passed laws in the last year to protect the right to line dry clothes, thereby overriding local rules. Considering that similar laws already existed in Florida and Utah, other states such as Maryland, North Carolina, Oregon, and Virginia are considering similar laws. The major drive behind this initiative seems to be the concern for the environment and cost savings.
At the same time, there have been several innovations in dryer technology. Most notably, microwave clothes drying technology has shown to have increased efficiency as compared to traditional dryers but more work is required in terms of hazard detection and mitigation (Gerling Citation2003). Richter (Citation2005) found that chemistry additives could quicken the moisture evaporation rate in the dryer, but the concentration and delivery method of the additives did not pass consumer behavioral needs. These additives improved RMC reduction by over 20%.
Any strategy that includes line drying saves energy, costs, and carbon dioxide emissions. Considering that reduced RMC in a washer comes at a monetary cost or reduced appliance life span, a convenient way to dry clothes is line drying. With growing interest in line drying, concern for the environment, motive to save money, and increasing legislations that override local rules, it can be projected that the market penetration of line drying will increase rapidly in the future.
Cold-water use seems to be the transformation that people can make with the least effort – lack of any major hurdles. With increasing number of cold-water detergents that perform better in cold water than traditional concentrated detergents in warm water, the ability to switch is easier than ever. At the same time, any energy conservation that is an outcome of this process will be minimal as seen in Figure 3. Although, it can be argued that some savings is better than no savings – it is a better option. Cold-water detergents have more enzymes and surfactants to compensate for the lack of warm water – the impact of the production of enzymes and surfactants on the environment must be weighed against the GHG savings from cold-water use.
Kempton (Citation1988) states that programs that focus on technical fixes such as new equipment or retrofits are less controversial than conservation programs that focus on behavioral changes and he notes that consumer underestimation of hot water cost is an area where conservation efforts can focus. Thus, the consumers could use water heaters that are more energy efficient, including Energy Star water heaters are a conveniently better choice. According to the American Council for an Energy Efficient Economy (ACEEE), the electric heat pump water heater has the highest EF of 2.2 and the lowest lifetime cost of $4,125 (based on installation cost, yearly operating cost and appliance lifespan) (ACEEE Citation2007). Therefore, an electric heat pump water heater could serve as a better alternative than other water heater types. At the same time, the distribution pipes need to be better insulated to prevent heat leaks.
Schmidt et al. (Citation2008) suggest a sector-based approach for GHG emission reduction for developing countries -post 2012. They insist that the sector-based approach is more effective than the economy wide approach due to a multitude of factors such as: ease of administration, data availability, greater equity, increased technology transfer, target emission reductions, cost effectiveness, limited extent, and leakage. The advantages of the sector-based approach are relevant to the U.S. in every way as it is relevant to the developing countries. This case of systems analysis of the residential laundry sector can be used as an example to analyze and identify opportunities for climate change mitigation in other sub-sectors and/or sectors in the economy.
Scenario D provides better energy savings and lends itself to climate change mitigation in a much larger way that the newly proposed fuel efficiency standards by the White House. Thus, a careful assessment of different climate change mitigation initiatives is required to convert strategies with larger impact into effective policies.
Given the significant variables in the presented strategies, it is only critical that we try to assess perspectives from multiple social groups in order to recognize plural ways of framing and understanding so that we can solve these problems effectively.
Conclusion
This article has analyzed different strategies for climate change mitigation with relevance to some prior research. The results can be used to support policies at the local and state level aimed at climate change mitigation. The optimization of technological strategies and the modification of consumer behavior strategies have been explored in detail to increase our understanding of the consumer use phase of residential laundry in the United States. Thus so, it is our intention that this research can support sustainable indexing efforts and be a guide in framing policies and incentives geared towards climate change mitigation in the sub-sector level.
| United States | Europe | Japan | |
|---|---|---|---|
| Machine type | v-axis top loader (agitator) | h-axis front loader (drum) | v-axis top loader (pulsator) |
| Water heating | External water heater | Electric internal heating by washer | Predominantly cold fill |
| Washing time (min)a | 8–18 | 20–60 | 5–15 |
| Amount of water (l) | 60a,b,c,d–157c,d,e | 8a–15a | 30a–60a |
| Temperature (°C)a | 10–40 | 30f–95f | 5–25 |
| Water hardnessa | Low/medium | Medium/high | Very low |
| Detergent dosage (g/l)a | 1–2 | 5–10 | 0.5 |
| Average load size (kg)c | 3d | 2.8 | 2.5 |
| Washes per weeka,b,c,g | 6–11 | 5 | 10 |
| aSmulders (Citation2002). | |||
| bNelson (Citation2002). | |||
| cWilson et al. (Citation2003). | |||
| dTomlinson and Rizy (Citation1998). | |||
| eEPA (Citation2009a). | |||
| fRudenauer et al. (Citation2005). | |||
| gSabaliunas et al. (Citation2006). | |||
| Average clothes washer use characteristics | v-axis | h-axis | ||
|---|---|---|---|---|
| Customary units | SI units | Customary units | SI units | |
| Load weight | 6.65 lbs/load | 3.02 kg/load | 6.98 lbs/load | 3.17 kg/load |
| Washer energy use | 0.23 kWh/load | 0.11 kWh/load | ||
| Cold water use | 29.89 gal/load | 113.15 l/load | 20.96 gal/load | 79.34 l/load |
| Hot water use | 11.57 gal/load | 43.80 l/load | 4.83 gal/load | 18.28 l/load |
| Total water use | 41.46 gal/load | 156.94 l/load | 25.79 gal/load | 97.63 l/load |
| Loads/day | 1.21 | 1.21 | ||
| Source: Tomlinson and Rizy (Citation1998). | ||||
| Phases | Temperature (°F) | v-axis | h-axis |
|---|---|---|---|
| Washing | 88 | 47.56% | 41.05% |
| Rinsing | 61 | 52.44% | 58.95% |
| Total consumption (gal/load) | 30.84 | 11.57 |
| Literature | Type of washer | Water supply, conveyance, treatment and distribution (kWh) | Water heating (kWh) | Clothes washing (kWh) | Waste water treatment and discharge (kWh) | Clothes drying (kWh) | Total (kWh) |
|---|---|---|---|---|---|---|---|
| Experimental results from this study | v-axis | 0.49 | 1.03 | 0.21 | 0.09 | 4.49 | 6.32 |
| h-axis | 0.19 | 0.30 | 0.10 | 0.04 | 4.17 | 4.80 | |
| DOE, 1998 (Bern's Study) | v-axis | – | 2.03 | 0.22 | – | – | 2.25 |
| h-axis | – | 0.85 | 0.1 | – | – | 0.95 | |
| Sabaliunas et al., Citation2006 | v-axis | – | 1.24 | 0.26 | – | – | 1.50 |
| h-axis | – | 0.46 | 0.2 | – | – | 0.66 | |
| EIA, Citation2001 (RECS) | v-axis | – | – | 0.33 | – | 4.1 | 4.43 |
| Rudenauer et al., Citation2005 | h-axis | 0.003a | 0.10 | 0.19 | – | 3 | 3.29 |
| aindicates that energy consumption for water distribution was excluded. | |||||||
| Washer type | Market penetration (%) | Per loada,b,c | Per household/yeara,b | US National/yeara,b,c,d | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Water requirement | Energy requirement (kWh) | CO2 Emissions (metric tons) | Water requirement (gal) | Energy requirement (kWh) | CO2 Emissions (metric tons) | Water requirement (million gal) | Energy requirement (Thousand GWh) | CO2 emissions (million metric tons) | ||
| v-axis | 92 | 30.84 | 6.32 | 0.00 | 9,718 | 1,991 | 1 | 820,769 | 226 | 167 |
| h-axis | 8 | 11.57 | 4.80 | 0.00 | 3,646 | 1,512 | 1 | 26,776 | 15 | 11 |
| Total | 847,545 | 241 | 179 | |||||||
| aAverage six laundry loads per week. | ||||||||||
| bNormal load, warm wash, cold rinse cycle and sensory dry. | ||||||||||
| cWater and energy are emperical data while CO2 emissions are based on an estimated average of 0.74 kg/kWh from eGRID2007 and Wilson et al. (Citation2003). d91.8 M households with washers (57.2 M warm washing) and 87.5 million households with dryers. | ||||||||||
Acknowledgments
This work was partially supported by the Dial Corporation, A Henkel Company ( www.henkelna.com) and the National Center of Excellence on SMART Innovations ( www.asuSMART.org) at Arizona State University.
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