Conserving Energy in the Laundry Room

The University of Wisconsin Eau Claire is devoted to a standard of excellence that encompasses a multitude of goals related to attaining a well-rounded liberal arts education. Certain values and goals have been identified and sought by the University of Wisconsin Eau Claire for decades now, such as providing students access to top-notch faculty, a variety of opportunities to enhance their learning, advice and support in finding a path to the adult world, and many more well-intentioned objectives. As the University of Wisconsin Eau Claire grows and changes with the times, the focus also changes to reflect the current students and faculty. The most recent such change in priority regards sustainability and reducing our negative impact on the environment. The University of Wisconsin Eau Claire has already taken inventory of emission levels on campus, and finding significant room for improvement, has made a commitment to reducing UWEC's carbon footprint. Current efforts to achieve that goal include remodeling campus facilities to be more environmentally friendly, and reducing the usage of trays in the cafeterias. There is no doubt in my mind that these initiatives will have a positive impact, but it seems that many people limit their efforts to these few project s, and fail to recognize the impact of seemingly insignificant and yet extremely wasteful everyday activities and behaviors. In the end, the little, wasteful things we do add up to cause a significant amount of hazard to the environment.

I have observed one such behavior, the significance of which is completely disregarded by both students and staff: clogging the lint traps in the University of Wisconsin Eau Claire clothes dryers. Congested lint traps decrease the efficiency of the machine, which results in longer periods of time required in order to dry a load. In this experiment, I hope to discover the amount of energy that would be saved if students residing in the residence halls cleaned out the lint trap every time they dried their clothes. Additionally, I will determine the overall cost of the inefficiency caused by extra lint left in the lint trap.

To begin, I decided to collect and calculate data surrounding the amount of energy used in a dryer with a dirty lint trap versus a dryer with an empty lint trap. This was accomplished by timing standard sized loads in "clean lint trap" machines versus the same sized laundry loads drying in "dirty lint trap" machines. Then, based off of the calculated time, I needed to determine the amount of energy that could be saved if students cleaned out the lint traps after each use over the course of one academic year. From there, I planned to calculate the cost difference resulting from clogged lint screens by using the previously calculated energy consumption and an estimated of the cost of energy on campus.

Given restraints on time and resources, some of the information needed was impossible to calculate, so instead I conducted outside research and extracted necessary, information that would have been extremely difficult to obtain on my own, such as how large of laundry loads students have and how often they use the machines. This research consisted of obtaining statistics such as the average number of loads Americans wash and dry every week. This information was necessary for calculations, but to obtain it first-hand would have meant beginning an entirely different investigation (although this does provide another idea for future research-identifying frequency of student laundry use and load size their impact). I decided to use reliable research so that I could focus on my chosen topic. Unfortunately, this decision may have led to inaccuracies in the investigation, due to the fact that the activities of UWEC students don't necessarily fit what national studies deem as average. The complexity of this experiment and the numerous factors that could have an effect on results led to other assumptions such as the assumption that all campus dryers exhibit the same amperage and voltage as those in Katherine Thomas, and that the dryer vents were clean and well-maintained, negating their effect on dryer efficiency. Of course, I hope that the vents are clean, since clogged dryer vents decrease inefficiency at levels much higher than clogged lint traps, not to mention, they are a terrible fire hazard! This is another potential topic to pursue further research on in the future: are the dryer vents at UWEC clean, and how do the clogged vents impact energy use on campus? Another action I took that may have impacted results was only calculating the energy and money used on drying for one academic year, and not during the summer or winterim, because the varied number of students staying on campus during breaks make it impossible to accurately calculate dryer usage.

Identifying the countless variables that could impact the the experiment, and then deciding how to deal with these factors was by far the most difficult and frustrating aspect of the experiment, and it all occurred before I even began! Once this was taken care of, I began the actual experimental procedures.

1. I identified the voltage on the back of the dryer as 240 volts

2. The amperage listed as 30 amps on the back of the machine, and this was confirmed when I calculated the current with an AC Anmeter.

3. Next, I used the amperage and voltage to determine the power of the dryer.

Power in watts= volts X amps

So, dryer wattage=240 volts X 30 amps=7200 watts

4. Powerkilowatts = (Powerwatts ) (1 kilowatt/ 1000 watts)=7.2 kilowatts

5. This is where calculations became more complex. I decided to run a load of laundry with a dry mass of 3 kg (this is the average laundry mass found in an experiment conducted by the Danish Energy Agency¹) through the washing machine and then dry this load in a dryer with an empty lint trap three times and repeat the procedure for a dryer with a dirty lint trap. I had no idea how to calculate when some idea of clothing was officially "dry" and as such, my lack of quantitative standards in this area may lead to some inaccuracy. I decided dry meant that no moisture could be seen or felt in clothing, and that the clothing felt warm (often clothes will feel dry, but if they come out of the dryer cold they really aren't-I have learned this through experience). Another inaccuracy could stem from the fact that I did not calculate seconds (lack of precision may affect results) and I kept stopping the dryer to check if the clothes were dry, but on occasion I may have waited too long and they may have been in the dryer longer than necessary.

6. I averaged the three times for a clean lint trap and the three times for a dirty lint trap.

Clean Lint Trap:

Test 1=42 minutes Test 2=45 minutes Test 3=44 minutes

Average=43.66 minutes

Dirty Lint Trap:

Test 1=51 minutes Test 2=49 minutes Test 3=51 minutes

Average=50 minutes

Difference in average time=50-43.66=6.333 minutes per load

7. To calculate energy, I had to convert the time to hours:

Clean: 44 minutes/60 minutes per hour= 0.733 hours

Dirty: 50 minutes/60 minutes per hour= 0.833 hours

Electrical Energy kilowatt-hrs = (Power kilowatts) ( time hrs)

Energy (Clean)=7.2 kilowatts X 0.733 hrs= 5.27 kilowatt-hrs.

Energy (Dirty)=7.2 kilowatts X 0.833 hrs = 6.0 kilowatt-hrs

Average Charge Rate in Wisconsin (DOE ²)= 11 cents per kilowatt-hour=0.11 $ per kw-hr

$ Money = (Electrical EnergykW-hr) (Power Company Rate cents/kW-hr)

Cost (clean)=5.27 kw-hr X .11= $ 0.58 per load

Cost (dirty)=6.0 kw-hrs X.11= $ 0.66 per load

So, for one hour of laundry use, it costs an extra 8 cents to run a machine with a dirty lint trap.

8. According to a study conducted by the Multi-housing Laundry Associaton, the average person dries 1.5 laundry loads per week.

So the average student living on campus for 30 academic weeks dries 45 loads of laundry.

According to the Residence Life Staff at UWEC, an average of 3900 students reside in the residence halls each year, so 3900X45 loads=175500 loads of laundry per week.

5.27 kw-hrs per clean lint trap loadX 175500 loads= 924885 kw-hrs. annually

Cost=924885 X .11 $ per kw-hr= $101737.35 per year if the lint trap is always clean

9. To determine how often the lint trap was dirty, I checked 10 dryers a day for 5 days.
Day 1: 4/10 lint traps were dirty

Day2: 7/10 traps were dirty

Day 3: 5/10 traps were dirty

Day 4: 4/10 traps were dirty

Total=20/50 traps dirty= 40 % of loads are dried with a dirty lint trap

175500 laods X 0.4= 70,200 loads per year with dirty lint trap

70,200 loads X 6.0 kw-hrs= kw-hrs. per year

221974 X0.11 $ per kw-hr=$421200 per year on loads with dirty trap

This leaves 60% of laundry completed with clean traps, so 60% of the annual clean lint trap laundry calculation above= .6 ($101737.35)=$61042.41

Total cost=laundry in clean lint trap machines+ laundry in dirty lint trap machines

Total cost=$61042.41 + $421200 =$482242.41 spent on laundry use annually

482242.41 -101737.35=$380,505 wasted annually due to dirty laundry lint traps!

This doesn't even factor in the cost of maintenance and replacements due to overly inefficient dryers (which are made much more inefficient by not maintaining clean lint traps and vents)

Energy Wasted?

5.27 kw-hrs per clean lint trap loadX 175500 loads= 924885 kw-hrs. annually for clean lint traps

70,200 loads X 0.4= 369954 loads per year with dirty lint trap

70,200 loads X 6.0 kw-hrs= 421,200 kw-hrs. per year for loads in machines with dirty lint traps(which constitute 40% of loads)

The remaining 60% energy use= 924885 kw-hrs. X0.6= 554931 kw-hrs

Total Energy=554931 + 421200 kw-hrs.=976131 kw-hrs per year used

Difference in energy for one academic year= 976131 kw-hrs (clean) -924885 kw-hrs. (60% clean, 40% dirty)=51246 kw-hrs. wasted in a year

The results of this experiment make it clear that the significance of cleaning out the lint trap is greater than most people think. In any given academic year, on-campus laundry uses 976131 kw-hrs if students fail to clean out the lint traps after use. This means that 51246 kw-hrs are wasted over the course of an academic year. This is significant in terms of cost, because this energy consumption leads to $ 482242.41 being spent annually on laundry costs, versus the ideal $101737.35. This means that on campus, we are losing $380,505 a year to the simple bad habit of forgetting to clean the lint trap.

It is important that in our effort to create a "green" campus at the University of Wisconsin Eau Claire, we do not overlook the impact of student habits outside the UWEC classrooms. One area of mass energy expenditure often forgotten is the laundry room. Through this experiment, I have shown that a seemingly insignificant habit like cleaning out a lint trap can add up and have a huge impact, both in terms of energy used, and the cost of using that energy. I hope that students at the University of Wisconsin Eau Claire can learn to improve their habits in a way that will benefit both the environment, and student checkbooks.

Sources Cited:

Danish Energy Agency, http://www.ens.dk/sw11492.asp

Multi-Housing Laundry Association, http://www.mla-online.com/

UWEC Housing and Residence Life, http://www.uwec.edu/housing/

Wisconsin Department of Energy, http://www.energy.gov/wisconsin.htm