Rough Marginal Costs |
April 6th, 2014 |
money |
I thought it would be useful to compile some rough costs of these pay-later activities:
Gas Oven | one hour | $0.16 [1] |
Gas Dryer | one load | $0.35 [2] |
Front Loading Washer, Warm | one load | $0.39 [3] |
Cold Shower | ten minutes | $0.57 [4] |
Hot Shower | ten minutes | $0.76 [5] |
Dishwasher | one load | $0.31 [6] |
Microwave | two minutes | $0.01 [7] |
Box Fan | overnight | $0.17 [8] |
This is based on a marginal cost of electricity of $0.21/kWh, natural gas of $1.40/therm, and water of $0.017/gallon which includes the sewer charge. [9] These come from our current bills in Medford MA; it's probably cheaper in lower cost of living states.
While these are approximately in line with what I'd thought, I do see two changes I should make:
- Be willing to use the dryer when line drying is inconvenient. (Previously I never used the dryer, for cost reasons.)
- A long cold shower (in summer) is actually more expensive than a short hot one.
[1] Gas Oven, 0.112
therms per hour.
[2] Gas Dryer, 0.21kWh to spin the drum and 0.22 therms to heat the clothes.
[3] Front Loader, 0.26kWH to run the machine, 0.064 therms for the water heater to heat the incoming water, 14.7 gallons of water.
[4] Cold Shower, 3 gallons per minute, 30 gallons total, $0.57 for the water.
[5] Hot Shower, 0.00014 therms per gallon per degree F. Ground water at around 55F, shower water at around 100F, so a 45F rise. Shower flow of about 3 gallons per minute. So over ten minutes that's thirty gallons each heated 45F. So $0.57 for the water [4] and $0.19 to heat it.
[6] Dishwasher, 4 gallons of hot water and 1kWh to run the machine. That's $0.10 for the water and heating [5] and $0.21 for the electricity.
[7] Microwave, 0.024 kWh per minute.
[8] Box Fan,100W.
[9] This is much higher than I'd thought, 10x the cost of desalination.
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