Chapter 3

SENSITIVITY ANALYSIS OF LAUNDERING OPERATIONS

OVERVIEW
The consumer use aspect of this analysis proved to be one of the largest impacts from a life cycle perspective. Consumer use accounted for 82 percent of the total energy requirements and 66 percent of the solid waste volume created. The two operations included in the consumer use category are laundering (washer, dryer, and water heater) and detergent manufacture. Of the two operations, the laundering process dwarfs the detergent manufacturing in terms of both energy consumption and environmental releases.

This chapter focuses on both defining the impacts from the baseline laundering operations as well as investigates several variations to the laundering assumptions. The first section discusses the baseline laundering operation, while energy comparisons for the various sensitivity analyses are discussed later in the chapter.

BASELINE LAUNDERING DATA
Table 3-1 describes the energy requirements and environmental emissions associated with the home laundering process. The data in this table indicate impacts per one wash load. The data are described in terms of source: washer, dryer, and water heater. Assumptions associated with these operations include a warm wash cycle and all products being machine dried for 15 minutes.

As Table 3-1 indicates, electricity usage occurs at all three operations with most of the electricity being consumed by drying and water heating operations. The only process-related laundering waste is from waste-water being discharged from the washing operation (producing both solid and waterborne process wastes). As indicated in Table 3-2, fuel-related emissions from the generation of power are associated with each operation.

LAUNDERING SENSITIVITY ANALYSES
In addition to the baseline laundering analysis performed for this study, several sensitivity analyses including various laundering operations were also performed. The changes in energy consumption for each of these variations is described in Table 3-2.

Wash Temperature
The baseline wash temperature assumption used in this study was a warm wash cycle (approximately 94*F) and a cold rinse cycle. Two variations of this assumption were analyzed. The first variation substituted a cold wash cycle for the warm wash cycle. The second variation reflected changing the wash temperature 10 degrees. As Table 3-2 indicates, the only operation that these changes affected was the water heater. The use of a cold wash cycle eliminated the need for heating of water and resulted in an overall reduction in laundering energy consumption by over 60 percent. Changing the wash water temperature by 10 degrees resulted in approximately a 14 percent change in overall laundering energy needs. Similar changes in fuel-related air, water, and solid waste emissions would also be expected.

Table 3-1
DATA FOR ONE LAUNDRY LOAD
      Washer     Dryer     Water Heater 
 ENERGY            
   Electricity (kwh)   0.35     1.42    1.84 
   Natural Gas (cu. ft.)   -     0.46     10.26 
               
               
 SOLID WASTE (cu. ft.)            
   Process     0.0030    -     -  
   Fuel-Related   0.0013    0.0052     0.0071 
               
 AIR EMISSIONS (pounds)            
 (fuel-related)            
   Particulates   0.0018    0.0072    0.0094 
   Nitrogen Oxides   0.0025    0.010    0.018 
   Hydrocarbons   4.3E-04    0.0022    0.013 
   Sulfur Oxides   0.0046    0.019    0.024 
   Carbon Monoxide   5AE-04    0.0023    0.0043 
   Aldehydes   3.6E-07    1.5E-06    1.9E-06 
   Methane   3.2E-06    1.5E-05    4.8E-05 
   Other Organics   4.5E-07    1.SE-06    2AE-06 
   Kerosene   1.6E-07    6.5E-07    8AE-07 
   Anunonia   3.6E-07    1.5E-06     1.9E-06 
   Lead   2.7E-09    LIE-08    1AE-08 
               
 WATERBORNE EMISSIONS (pounds)            
 (process)            
   Dissolved Solids   0.13    -     -  
   Suspended Solids   0.0021   -     -  
   BOD   0.013    -     -  
   COD   0.020    -     -  
   Phosphates   0.0023    -     -  
 (fuel-related)            
   Acid   3.9E-04    0.0016    0.0020 
   Metal Ion   9.7E-05    3.9E-04   5.1E-0-4 
   Dissolved Solids   1AE-04    6.8E-04    0.0028 
   Suspended Solids   5.5E-07    2.2E-06    2.9E-06 
   BOD   3.6E-07    1.5E-06    1.9E-06 
   COD   I.0E-06    4JE-06    5.3E-06 
   Phenol   9.1E-08    3.7E-07    4.8E-07 
   Sulfide   9.1E-08    3.7E-07    4.8E-07 
   Oil   1.8E-07    7AE-07    9.6E-07 
   Sulfuric Acid   3AE-06    1AE-05    1.8E-05 
   Iron   2.9E-04    0.0012    0.0015 
Source: Franklin Associates, Ltd. 3-2

Table 3-2
ENERGY REQUIREMENTS FOR VARIOUS SENSITIVITY ANALYSES
                         
    Baseline Case   Changes in Wash   Changes In
    One Load Per 1MM Wearings Water Temperature   Machine Dryer Use  
      (25,000 loads)                
                         
Assumptions                        
  Wash Temp.   Warm (94° )   Warm (94°)   Cold   +/- 10°   n/c   n/c
  Dryer Time   15 min.   15 min.   n/c   n/c   0 min.   +/- 10 min.
                    (e.g. line dry)    
                         
         

  Note: Values below indicate percent change from baseline data
Energy Consumption (mil btu)                    
   Washer    0.004   107.1   n/c   n/c   n/c   n/c
   Dryer   0.016   387.9   n/c   n/c   -100.0%   66.7%
   Water Heater   0.032   778.0   -100.0%   22.3%   n/c   n/c
       Total   0.051   1,273.0   -61.9%   13.8%   -30.8%   20.5%
Note: n/c indicates that no change occured from baseline values.
Source: Franklin Associates, Ltd.

Machine Dryer Use
The baseline assumption for this analysis was that all laundered blouses would be dried in mechanical dryers for a period of 15 minutes. Two variations of this assumption are examined in Table 3-2. The first variation assumes that all blouses are dried outside on a line. The second variation changes the required drying time by 10 minutes. As indicated in Table 3-2, the elimination of mechanical drying reduces the overall laundering energy consumption by approximately 31 percent. A 10 minute variation in drying time accounts for nearly a 21 percent change in the overall laundering energy consumption. Because both of these variations involved changes in fuel consumption, similar changes in fuel-related emissions can also be expected.

 

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