Rough Marginal Costs

April 6th, 2014
money
We pay for most things directly as we use them: to park at a meter you put in quarters; to rent an apartment you send a check each month. For some things, however, our usage is metered and we pay after the fact: electricity, gas, water. In these cases we're often not well calibrated for marginal cost, which means we're not in a good position to make tradeoffs. Can I leave the fan on all night? Should I worry about letting this frozen food thaw in the fridge before I put it in the oven? How much should I be trying to take shorter showers? Colder ones?

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.

Comment via: google plus, facebook

Recent posts on blogs I like:

Animal Welfare and Capabilitarianism

All ethics is a special case of animal welfare science

via Thing of Things December 18, 2024

Developing the middle ground on polarized topics

Avoiding false dichotomies The post Developing the middle ground on polarized topics appeared first on Otherwise.

via Otherwise November 25, 2024

How to eat vegan on Icon of the Seas

Royal Caribbean has a new giant cruise ship, Icon of the Seas, which has a large selection of food options.

via Home November 21, 2024

more     (via openring)