Local Utility Rates
- Electricity: If water and power are combined in your bill, subtract those items that give
reference to water before you divide total cost of the bill by kilowatt hours used. Do not
be concerned with "number of days," "energy costs," and separately listed taxes and
- Natural gas: Divide total cost at bottom of the bill by the number of therms used. Do not
be concerned with "billing factor," "adjusted therms," "scheduled billing rates," or any
separately listed taxes.
- Water: Divide the total charges by the number of "100 cubic feet." If the water is part of
your electric bill, water charges are the total of "water used" and "sewer service charge."
Laundry Room Utility Costs
Apartment house and condominium owners need to have a clear understanding of their
laundry room utility costs. The California Route Operators' Association has prepared a
guideline upon which this worksheet is based so that you can easily compute the amounts
of energy used in washers and dryers. Utility rates change almost monthly. This formula
will enable you to take those changes into consideration when computing costs. In order
to do so, certain assumptions will be combined with factual information gathered for this
worksheet. Utility companies and the appliance manufacturers have been most helpful in
providing the following data:
- There are 748 gallons of water per 100 cubic feet.
- One thermal unit (therm) = 100,000 btu.
- One wash load = one dry load.
- Washer water consumption per total cycle is 34 gallons. Since water rates are quoted
at so much per 100 cubic feet, 34 gallons = .045 of 100 cubic feet. That means there are
22 washer cycles for every 100 cubic feet of water.
- To compute what part of the water is hot water, we are assuming that for every four
coin-operated loads washed, two will use hot water wash at 18 gallons per cycle,
one will use warm water at 8 gallons per cycle, and one will use only
cold water for a total of 44 gallons and an average of 11 gallons of hot water per cycle.
This is most important since approximately 90% of the energy used in a washing machine
goes to making water hot. It takes 11,000 btu's of gas or 0.11 therms to heat 11 gallons
- It takes 3.3 therms per month to keep 11 gallons of water hot in a water heater.
- Washing machines use .30 kilowatts of electricity per cycle.
- Dryer energy is quoted at maximum (we assume the heater is running for the complete
- Gas dryers use an average of 17,000 btu per complete cycle, or 0.17 therm. By
national average for every four loads dried, two will be at high heat, one will be at
medium heat, and one at low heat. Average maximum btu consumption at high heat is
25,000 per hour and medium and low are both 20,000, so 2 times 25,000 plus 2 times
20,000 equals 90,000 per hour, divided by 3/4 (45 minute cycle), and divided again by four
loads equals 17,000 btu per complete cycle or 0.17 therms. Electric usage in a gas dryer
will average 0.5 kilowatt hours per load.
- An all-electric dryer will use 3.3 kilowatt hours in a 45-minute cycle.
- Industry averages show 72 cycles per month on both washers and dryers (this equals
2.2 cycles per day).
- Your cycles per month can be computed by dividing the gross amount collected by the
total of one washer vend and the amount of money necessary to run the dryer for 45
minutes - for example, a $0.50 wash and a $0.50 dry for 45 minutes would equal $1.00
Summary of Usage Per Complete Cycle
|1. Water uses:
||0.045 of 100 cubic feet of water,
0.300 kwh of electricity,
and 0.110 therms of gas
|2. Gas dryer uses:
||0.170 therms of gas, and 0.500 kwh of electricity
|3. Electric dryer uses:
||3.30 kwh of electricity