Jeff Kaufman  ::  Blog Posts  ::  RSS Feed  ::  Contact

Rough Utility Costs

Our utilities are measured in weird units like HCF (water) or therms (gas) that make them hard to think about. Here's an attempt to put them into a form that's more natural and figure out the marginal costs of some things we can easily vary.

First, the inputs (yours are probably different):

  • Water cost: $17.31/HCF ($0.023/gal)

  • Gas cost: $1.32/therm

  • Electricity cost: $7 + $0.21/kWh

Since I'm interested in marginal costs here I'll ignore the $7/month base charge for electricity.

What does hot water cost? Our water is heated by our furnace, which is a high-efficiency gas burner, rated at 96% efficient. A therm is 100k BTU, and heating a pound of water by 1F takes 1 BTU, there are 8.34 pounds per gallon of water, our water enters the house at about 60F, and we heat the water to about 130F. So, to turn a gallon of cold water into a gallon of hot water we need to heat it 70F, which requires 584 BTU. That's 0.0058 therms, but the boiler has 4% losses, so 0.0061. Then figure we lose 10% for water sitting in pipes, but during heating season that doesn't matter, and heating season is half the year, so 5% loss, which brings us to 0.0064 therms. At $1.32/therm that's $0.008/gal.

This means that hot water is 35% more expensive than cold water:

  • Cold water: $0.023/gal

  • Hot water: $0.031/gal

What would a shower be? Let's say you shower for ten minutes, and the shower head is an efficient 2.0gal/min. Then we have:

  • Cold shower: $0.46

  • Warm shower: $0.54

  • Full hot shower: $0.62

What about lights and fans? A modern 60-watt equivalent LED or CFL is about 10W, while a fan is more like 75W. Running one for a full 24hr is then:

  • Light: $0.05/day

  • Fan: $0.38/day

While we don't have AC [1], they run about 1W per 10BTU. A house our size might need 60k BTU, so 6kW at peak output:

  • Whole house AC on full: $30/day

  • Whole house AC on 1/3: $10/day

  • Single window AC on full: $3/day

I'd love to include something here for the cost of heating, per degree, so we can make a reasonable decision about (say) 66F vs 68F. Unfortunately this is pretty hard to figure without either good estimates of how our building works or some sort of test. You can get a very rough estimate, though, by looking at how much gas was burned and how far the average temperature was from the target house temperature. Here's a graph from our gas company:

Gas covers hot water and heating only, no cooking, and since summer months show ~0.5 therms/day that's probably hot water. For heating, assuming we were averaging 62F inside the house, I get:

month temp deficiency therms/day heating therms/day therms/F
Oct 58F 4F 1.4 0.9 0.64
Nov 45F 17F 4.5 4.0 0.89
Dec 35F 27F 6.7 6.2 0.93
Jan 33F 29F 7.4 6.9 0.93
Feb 32F 30F 7.0 6.5 0.93
Mar 35F 27F 6.2 5.7 0.92
Apr 49F 13F 3.3 2.8 0.85
May 54F 8F 2.2 1.7 0.77

It looks like figuring 0.93 therms/day/F for the core winter months is pretty close. At $1.34/therm that's $1.23/day/F.

I don't think any of these numbers are large enough to substantially change what we do, but it's nice to have a better sense of how much things cost.

[1] With this heat wave we may change our minds, though.

full post...

Appeals to Consequences

Jessica Taylor recently wrote a post objecting to what she describes as appeals to consequences. In general an appeal to consequences is saying that "X would have bad consequences" means that "X is false", but Jessica is using it in a broader way, to include the idea that "saying X would have bad consequences" means you should avoid saying X. Her motivating example is:
Carter: "So, this local charity, People Against Drowning Puppies (PADP), is nominally opposed to drowning puppies."

Quinn: "Of course."

Carter: "And they said they'd saved 2170 puppies last year, whereas their total spending was $1.2 million, so they estimate they save one puppy per $553."

Quinn: "Sounds about right."

Carter: "So, I actually checked with some of their former employees, and if what they say and my corresponding calculations are right, they actually only saved 138 puppies."

Quinn: "Hold it right there. Regardless of whether that's true, it's bad to say that."

Unfortunately, this is not a good example to build a post around, because Carter's statement actually has good consequences. Yes, it might lead to people donating less to this specific charity, and the charity still does some good with its money, but building a culture of caring about the actual effectiveness of organizations and truly trying to find/make the best ones is far more important than how much money any specific organization raises today. Plus if, say, ACE trusted this higher number of puppies saved and it had lead them to recommend PADP as one of their top charities, that that would mean displacing funds that could have gone to more effective animal charities. The whole Effective Altruism project is about trying to figure out how to get the biggest positive impact, and you clearly can't do this if discussing negative information about organizations is off limits.
How We Cool Our House

Kitchen thermostat when I came home from work today:

It's showing:

  • 90F: 24hr max outdoor temp
  • 87F: current outdoor temp
  • 80F: 24hr max indoor temp
  • 78F: current indoor temp
  • 70F: 24hr min indoor temp
  • 67F: 24hr min outdoor temp

This is mid-July in Boston, without air conditioning, just fans. The idea is you cool the house off at night, and then keep it from warming up too much during the day. It's cutting about 10F off the day's high.

Standardize Bottles

Products come in a wide range of containers varying in material, shape, color, texture, etc. This makes recycling very inefficient: instead of washing and reusing the containers we need break them down into raw materials and build back up from there. Standardization would help a lot here: figure out what range of shapes and sizes you need to cover most of the market, and design some sturdy reusable containers for them. Probably clear glass, which companies can then glue paper labels to. This makes it worth it to collect the containers whole and reuse them.
Sliding Scale

One thing I like about BIDA's $5-$15 sliding scale is that there are a wide range of reasons someone might not be able to afford our break-even rate: students, but also retirees, unemployed people, people with low paying jobs, people covering expenses for a lot of dependents, etc. While many organizations pick specific categories for discounts, a sliding scale means the organizers aren't in the business of judging people's financial situations.

This is enough of a reason to have a sliding scale that I think it's the right choice for Beantown Stomp and other capacity-constrained events. But most contra dance evenings don't sell out, and there I see another strong reason for a sliding scale: I'd rather have people come than stay home. Some people will always be on the fence about whether to come, and there are people who can afford $15 but at $15 would rather stay home. If they come and pay $5 then everyone is better off than if they had stayed home or went to a movie.

Carcassone Pirates

When playing with the river expansion the first few turns are often not that interesting. Half of the river tiles have nothing to do but farm, and farming that early isn't attractive since you don't know how the bridges will break up the area. So we play with pirates:

More Posts

Jeff Kaufman  ::  Blog Posts  ::  RSS Feed  ::  Contact