Two days ago, both light bulbs went out at the same time in my study. What are the chances?! Anyway, up until June, this room had been occupied by a roommate for nearly 2 years.
Last night, I asked the Mr. to replace my bulbs, and to my great horror, he uncovered two regular, non-high efficiency bulbs! When we first got the house, we had replaced all the regular (i.e. energy-devouring) bulbs with high-efficiency (but pricier) ones. I inspected the dead bulbs a little closer – these were definitely not bulbs that had come with the house.
“I bet you he switched out the bulbs and took the good LED ones!” I ranted. “He’s the reason why our bills have been so high!” Granted, my accusations didn’t make much sense – after all, he had moved into his brother’s rented condo, where he wouldn’t really benefit from HE bulbs.
Still peeved, this morning I was set on determining how much this ex-roomie had cost us. I looked up our electricity provider’s rates and found the below:
I had no idea what any of that actually meant, but I quickly learned from Mr. Electricity’s site that 1000 watts used for 1 hour was equivalent to 1 kilowatt-hour, written as 1 kWh. So if I used 1 kWh during an off-peak period, I would be paying 8¢ for it, but using the exact same amount would more than double to 16.1¢ if used during an on-peak period instead.
The coolest thing about Mr. Electricity’s site is that it has a little electricity calculator, which I of course employed to find out just how much ex-roomie had cost me.
How I calculated how much these light bulbs cost
Because days and times are charged differently, I decided to try and average out the periods.
Saturday & Sunday = 48
7 pm – 7 am, M-F = 60
7 am – 11 am, M-F = 20
5 pm – 7 pm, M-F = 10
11 am – 5 pm, M-F = 30
I divided each period by 7 to calculate the average daily rate, which came up to approximately
Off-peak hours: 15
Mid-peak hours: 5
On-peak hours: 4
Under lights, I then selected 60-watt light bulb, selected 15 hours a day, set the Cost of Electricity to 8¢/kWh and left it as 31 Days used per month, then repeated it for the mid- and on- peak periods, rounding the prices down to 12¢ and 16¢, respectively.
Had the lights been left on 24 hours a day (which they weren’t), those two bulbs would have cost me $10.32 every month.
In contrast, the 60W equivalent bulbs would come up to only $2.72 per month, a savings of 73.6%! Over a year, those bulbs would have cost me $91.20 more than the HE bulbs.
Given that his rent was $600/month, I guess I really can’t be freaking out over $10.32 in electricity costs, especially since that estimate was based on the lights being left on 24 hours/day (I’m sure it was on for less than half of that).
Then it got me thinking. How many light bulbs are in use at my house? I did a rough estimate based on how many light fixtures I could think of off the top of my head and came up with a total of 62.
Since we’re out of the house for work around 10 hours/day including commute time and asleep for maybe 7 hours/day (on average), I’d guess we’re home and awake 7 hours/day on weekdays and maybe 12 hours/day on weekends, which averages out to 8.4 hours a day.
It’s hard to estimate how many bulbs would be on at any given moment but I’m going with 20.
Over a 12-month period, we’d be spending nearly $200 more on having normal lights vs. HE ones. Although we had made the upfront investment in LED bulbs when we first bought the, I’m sure there are still a couple outstanding that we might have let slip through the cracks.
So thank you, ex-roomie. Since our light bulb discovery in your old room, we’ll be combing all the light fixtures to make sure they’re all HE ones and that we’re not flushing more money down the toilet!