Saving the World, One Microwave at a Time

In today’s Dear Splitwise, we consider the troubles of a super-intense treehugger who lives off-campus with his roommates (and their girlfriends).

Dear Splitwise,Unplug that Microwave!

I live in an student-style apartment with 3 roommates, and we all have separate leases. The only thing not separate is the electricity, and there are a couple issues splitting it based on usage and our guests. Also, I’m an environmentalist, and every month, they hand me a $180 electric bill and asking me to pay for a third of it. To me, this is like saying, “Hey I need you to give me some of your money for something I need that you will not be using that will cause your friends to die, can I get that on the 20th?”

But first, there is this issue with my roommate’s girlfriend. She is quite a pain to everyone, and she stayed at our place for almost 3 weeks. Even after moving into her own place she still spent most of her time here. She is also always doing laundry, at least 2 or 3 times a week she washes 2 or 3 large loads and I suspect some of it belongs to her family members or that she just has a seemingly endless supply of dirty clothes from her old apartment.

When I first came to this place I was a guest of another tenant. When we calculated the utilities we split it by total cost per day and then figured who owed what by determining how many people were there for how many days, cost per person for 4 people a day and cost per person for 3 people a day, etc. I thought that the same rules would apply to my room mates girlfriend but when I asked him about it, he said no.

I am an environmentalist and a minimalist. I have school 11 hours a day, 4 days a week. I have one day a week where I mostly stay at the apartment. The only electronics I own are a laptop and a cell phone. I unplug the microwave (although I don’t use it) and other appliances when I’m not using them, and often my roommates leave them plugged in. I use the refrigerator and the washer for a medium load once a week, but I hang my clothes to dry. Also it is summer and we’re in Tucson I only like to use the air if it’s over 100. I may turn it on once a week but only for a few hours when I’m hot and overworked and then I turn it back off, but then they’ll turn it back on, sometimes for two days straight.  I go through a lot of effort in my personal life to lower my carbon footprint and costs at the same time. To me if you are responsible for the destruction of an ecosystem and people’s homes, livelihoods and very lives themselves then you should be responsible for the amount of the poison (coal) you use to kill those people and destroy those ecosystems. 

I know your site warns against the “guy at the restaurant with a calculator” role, but would this be an exception? I can look at the bill to see the billing dates and calculate everything if I have too, I can see how much everything costs per kilowatt hour and then configure my kilowatt hour usage compared to theirs. What is the right thing to do in a situation like this? If I’m technically paying for the electricity they are using, can I dictate how it’s to be used, when it’s to be used and use my authority to refuse anyone turning on the air, etc? Should I ask for my money back from when I was paying electricity as a guest if the girlfriend doesn’t pay?

Unplugged the Treehugger

Dear Unplugged,

First off, let’s talk about the girlfriend staying over constantly. You’re correct, she should be helping out with something around the house. That can include part of the bills, feeding everyone or random presents (who doesn’t like presents?!) Asking for the back pay of your electric bill from your couch surfing days isn’t reasonable, because you made a verbal agreement about paying before moving in, and it sounds like she didn’t. I’d have everyone in the house get together and iron the situation out. Show them this neat and trusty guest calculator to show them what her contribution should be.

Second, let’s talk about this electricity issue you’re having. I want to start out by saying I lived in Mesa, AZ when I was in my 20’s. There is a reason there is a law in that state that every building needs to have AC – dude, you’re living in a desert! You’re making a bunch of fancy moral arguments and thinking you might have a right to dictate how it’s used, but then in the next paragraph say you want the AC on when YOU’RE hot and overworked. You’re being hypocritical. Get over it.

In regards to breaking electric usage down by day you asked, “I know your site warns against the “guy at the restaurant with a calculator” role, but would this be an exception?” NO, this is not an exception, nor is this fair or enjoyable to anyone living with you. Household bills should be split evenly for each roommate. If you’re there for the month, then pay your share. If you were gone 3 weeks of the month on business, then that may be a leg to stand on when it comes to breaking it down any other way than an even split, but when you come home at night is not your roommate’s problem.

Personally, I’m having a hard time believing that your frustration has to do with your environmentalism – you’re using it as a crutch to pay less of the bills. The most environmentally conscious decision would be to move out of Tuscon in the first place.

If you feel this strongly about the way the electricity is used, then you should think about getting your own place or finding roommates who also “environmentalists and minimalists.” That way, you’ll be able to completely control the amount of resources that are being used in your living space and you’ll never feel ripped off again.


If you have a fairness or money sharing etiquette question you’d like Splitwise to address anonymously for you, email Dear Splitwise at

8 thoughts on “Saving the World, One Microwave at a Time”

  1. I sympathize with the treehugger. While breaking down electrical usage by day is a bit too extreme, I don’t see any harm in asking the roommates who use an in-window AC unit frequently to pay a a bit more, especially if the difference in usage is as clear as what the treehugger states. It’s easy for one to just estimate how many hours per day they use it. Sure, it won’t work out to be exactly right, but I’d contend you can get a lot closer to “exactly” right with minimal effort that nowhere nears “guy at a restaurant with a calculator”.

    On a more philosophical note, this seems a bit like the tragedy of the commons. You have one guy who is practicing “sustainable grazing” to try to prevent the usage rate of the commons from exceeding the replenishment rate. While he/she alone obviously cannot ensure that the commons is being used sustainably, he is doing his part. On the other hand, because of the very fact that they alone cannot have a significant impact on the commons, there are many others who do not practice “sustainable grazing.” It may be ugly to move towards an itemized bill payment, but is it not uglier to have the commons unavailable for the future? I suppose then you start asking whether we present-day people have the right to decide for other present-day people that they should care about future-day people, e.g. it’s their right to not care about the future-day people. I don’t have an answer.


    1. Hey Treehugger,

      Thanks for your comment. I think a general adjustment (more like the rent calculator, not a daily tracker) like you suggest could be ok in many cases between consenting adults who agree about their differing usage… but I also agree with Nellie that this is by no means normal, and I wouldn’t encourage it.

      Unless the roommate in question has such a tight budget that it’s necessary to preserve the relationship (for instance, rent is more than 40% of their monthly salary), I think something like that would have to be worked out in advance, not claimed when the bill comes due, since the usual assumption is that things are split equally. If the roommates won’t agree to it, I think it’s pretty annoying to track. The real problem is that it starts a cascade of value-oriented thinking about gas and water and cable that I think nearly everyone is happier not to spend the energy into diving into.

      To put it into perspective, let’s consider it solely from a roommate fairness point of view. We’re talking about some, but not a ton, of money (one 10,000 BTU Air conditioner * 12 hours * $0.05 / KWh = $1.75 per day). If you spent more than 15 minutes stressing about this today, you were probably better off doing a minimum wage job ($7.65 is the minimum wage in Arizona).

      From an environmental standpoint, there is probably a good argument to be made that electricity is under-priced (resource exploration credits, various tax subsidies, the cost of wars to preserve oil resources), so morally you should try and conserve electricity when you don’t need it. Nellie’s point is that that doesn’t give you a right to yell at your roommate, since we allow people to judge for themselves how much electricity they need at the given price. Perhaps they turn on the window AC on a bit more often because they know it will be split equally, but in Arizona, Nellie’s testimony is – they are going to turn it on no matter what.

      I agree with your philosophical point – there is definitely some hard-core tragedy of the commons going on with utility consumption in general (such as in dorms, where the price is fixed ahead of time and no one tracks it). And I stand equally confused about how to philosophically value future generations. But the environmental impact of these roommates in Arizona will probably be the same no matter how the bill is split. Unplugged was pissed about paying the bill (since it appears he is unable to convince them to adopt his lifestyle), so the tragedy of the commons in this case is pretty much limited to Unplugged’s wallet.

      1. Jon,

        I absolutely agree with you here. I think it’s worth having one frank conversation where you tell your roommates, “Look, I am really trying to minimize my use of resources here, so if you guys are going to run the AC all the time, I don’t want to pay for it. That’s $1.75 per day I don’t want to pay any of. $1.75/day * 30 days / 3 roommates = $17.50 per month. And then I’ll get off my high horse.”

        If they say no, then you should try to move on with your life, or do as Splitwise suggests, just move.

      2. By the way, as a dutiful treehugger, I’ve looked into the whole air conditioner thing. And to my disappointment, it’s even cheaper than you think (not disappointment in terms of efficiency, but in terms of economical hit). A 10,000 BTU air conditioner is rated to remove 10,000 BTUs from a room in one hour. It however doesn’t require 10,000 BTUs to do this. Air conditioners typically have an EER rating which is the ratio of BTU/hrs of capability and Watts this takes. This number is typically around 10. So, for every watt, the AC has the ability to remove 10 BTUs in one hour. That means, your 10,000 BTU air conditioner is actually only using 500 Watts, or half a kWh in an hour. So if electricity is indeed $0.05/kWh in Arizona, 12 hours of usage is only 30 cents a day. Indeed, electricity is under-priced.

        And just to add my opinion to the subjective question of what to do, if the estimate really did come out to 17.50 a month per AC, I would also just say “I’m trying to save electricity. I don’t want to dictate what you do, but by a rough estimate, I think each of yours AC usage is adding about 15 dollars to our bill every month. Would you each mind just chipping in an extra 10 dollars?” and if they are not amenable, just drop it or move.


  2. Awesome, thanks for the correction about the way air conditioners are labeled! I assumed the BTU/hr rating was power consumption, but I don’t know why – as you point out, it’s the wattage (the actual power consumption) that matters not the amount of heat moved per hour under some specific circumstances. I’m embarrassed as an ex-Physics person.

    All air conditioners / refrigerators / heat pumps have a coefficient of performance, which is how much heat they can move for how much energy. This is the thermodynamic quantity (and is typically around 3), but presumably depends on the ambient temperatures. The ~10 number is the ERR, which as you point out is a bit more relevant in this case since it gives you the wattage from the BTU/hr rating.

    The prices I found are historical, and based on usage – the maximum I saw was $0.09 per kWh in Tuscon, AZ. Definitely seems underpriced.

    Thanks for the insightful comments Treehugger!

  3. Why are you living in a desert if you’re so conscious of the environment? Dude, move your butt out of that place that nature never intended you to live in and stop contributing to its destruction.

    Maybe you’re share housing because you can’t afford to live alone? That’s cool, sharing reduces the strain on the environment anyway. But a shared housing arrangement is basically an agreement to mutually help each other to have a better standard of living. I can’t afford decent accommodation by myself, but I can get a pretty nice place if I share. This means my roomies are subsidising my living standard, but that’s cool because I’m doing the same for them.

    What if I want to subsidise theirs less than they’re subsidising mine? Not cool, not fair. Here’s a comparison scenario: I move into a place with internet access and a phone line, but I don’t have a computer and I always use my smartphone to make calls. We don’t specifically discuss this when I apply to move in; nobody says anything special about bills, which means it’s implied that they’re split equally. Supposing I decide that I don’t want to pay for internet access or the phone line, neither of which I’m using? In a four person house, this now means my roomies have to split those bills 3 ways instead of 4. Not cool, not fair. My roomies aren’t responsible for my technology choices, so unless otherwise stated, the internet and phone bills would be part of the expense I pay for the privilege of living in this house, and part of the condition for having my living standard subsidised by other people. In short, I should suck it up and pay. Likewise, your roomies aren’t responsible for your belief system. That’s your choice and your business.

    I think there is an argument for unequally splitting an electricity bill if one person has an appliance that others actually can’t use – e.g a heater or an aircon unit in their bedroom, where there’s no heating or cooling in the common areas. That’s the only situation that unequal splitting would be fair, in my opinion.

    1. I forgot to add this – splitting 3 ways with 3 people is more expensive than splitting 4 ways with 4 people. Apart from the whole girlfriend thing (I’m totally on your side about that one) it seems like your roomies signed on to live with 4 people splitting 4 ways, and to me it seems fair that they should expect this to happen.

  4. If you live with room mates, you have to split the costs equally all the time, otherwise you just get annoyed and confused with numbers and it will break down to “well you use your computer more, and she does laundry more, but he has a fan plugged in all the time,…” and then you end up writing advice letters asking people how you need to do math in your life. all the time.

    how lame is that?

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