Although I’m not a big fan of my power company, they do provide me with some good information about my swamp cooler, and energy use in general. NV Energy has an online feature that allows you to get your actual energy costs in 15 minute increments. The information is very telling.
The picture above is my personal usage on hot, humid day in late July last year.
I picked a day that was humid enough where I would not be able to use a swamp cooler and would have to use traditional air conditioning. This would allow me to see the actual costs of running the A/C.
To get my swamp cooler power costs, I used a Kill-a-watt meter and ran the cooler for several days. Some of the days were run on “low” and at other times on “high”. The “low” setting used .35 kWh (at $0.13 per kWh costs me $0.045 cents per hour to run), and at the “high” speed used .62 kWh to run (at $0.13 per kWh cost me $0.08 cents per hour to run). So depending on the speed, if I ran the swamp cooler 24 hours per day, my cost would be between $1.08-1.92 per day in electricity.
Shifting to air conditioning, if you look at the graph above, you can see spikes in the usage. These are times when the air conditioner turns on. The tall spikes between Noon and 8 pm indicate times when both air conditioners are running simultaneously.
On this day, it looks like my baseline electricity usage is about .75 kWh every 15 minutes (way too high).
When the air conditioners turn on, the kWh usage rises by approximately 2 kWh every 15 minutes (or about 8 kWh per hour!). At it’s peak usage, that would cost $1.04 PER HOUR for air conditioning only! According to the graph, that would be the maximum. I arrived at this my deducting the baseline amount from the peak usage.