With summer almost over and the August utility bills paid, you may be feeling a little poorer.  You feel like your electric bills were a lot higher during the summer than the spring, but why? Doesn’t the sun stay up longer, reducing your need to turn on lights? Well yes, but then you remember, you and your roommates have been running fans and window AC units all summer! How much of an impact did this have on your electricity bill? And which is the bigger energy hog, the window fan or the window AC?? As an energy nerd and a roommate in an apartment with four window fans and one window AC, I have wondered about how much of an impact running these appliances during the summer has on our electric bills.  I decided to do a couple of calculations to measure energy usage, and was easily able to realize how much of an impact each appliance has on my apartment's utility bills.  I have to admit, I was a bit surprised by just how much each uses!  Learn how you can figure out just how much your cooling appliances are costing you with these 7 steps.

This step was really easy for me because I use WegoWise to track my apartment’s energy use, so I clicked into my account and downloaded my data.  However, if you keep track of your bills online through your utility company's website or keep paper copies, you can organize your usage in a spreadsheet, or, if you're really old school, just write them down!central air conditioning units size This isn’t scary, I promise! lg ac units pricesAll you have to do is pick out the three months where you have the lowest usage, and then average the usage.  ac unit and heaterThis average will serve as your baseline, and represents the amount of energy you use consistently each month.  For instance, it takes into account the energy you use to run your refrigerator, cooking appliances, TV, etc.

For more information on calculating your baseline energy use, check out this blog article. My three months with the lowest usage are March, April and May.  Averaging out the usage, my roommate’s and my baseline energy use is 138 kWh.  Not too horrible, huh? In some instances, the watts will be right there on the appliance. In other cases, you may have to do some simple math to calculate the watts. Don’t worry, you learned this equation in physics class!  Remember Watts = amps x volts? Either way, you'll be able to find the information you need somewhere on the appliance, either as a sticker on the side or back of the appliance, or on the plug. Sorry for the blurriness, but here's an example of where you might find the information you need.  In this case, I had the Amps (A) and the Volts (V) provided, so I was then able to calculate the Watts. My roommates and I have a combined four window fans and one window AC unit.  The wattage of the AC unit is 515, while the window fans are 48, 60, 66, and 70 watts.

If you can add 2+2, and then divide by 4, you can do this step! Just divide each of your appliances’ wattage by the total wattage of all your appliances.  515 +48+60+66+70 = 759 total watts for my apartment's cooling appliances Window AC unit: 515/759 = 67% of total energy! Window Fan #1: 48/759 = 6% of total energy Window Fan #2: 60/759 = 8% of total energy Window Fan #3: 66/759 = 9% of total energy Window Fan #4: 70/759 = 9% of total energy After talking with my roommates, I realized we all used our fans and AC unit pretty much the same amount – we only had it on at night, and we only used them during the hottest days of summer, which were in July and August.  In July, we used 244 kWh, and in August, we used 225 kWh. Now that you know the monthly usage, you can use that usage and your baseline to determine the excess usage from your cooling appliances.  To do this, add the usage from the months, multiply your baseline by the number of months you used your cooling appliances, and subtract this value from the total usage. 

244 kWh + 225 kWh = 469 kWh used in July and August 469 kWh – (138 kWh x 2 months) = 193 kWh from cooling appliances If you’re like my roommates and I and have used each appliance about the same amount, this is probably the easiest step! Just multiply your excess usage by the proportion of total energy each appliance uses. If you've used your appliances at different frequencies, you'll also want to take into account the total time you ran each appliance. Here’s the breakdown for my apartment’s appliances: Window AC unit: 130 kWh Window Fan #1: 12 kWh Window Fan #2: 15 kWh Window Fan #3 & 4: 17 kWh As you can tell, the window AC unit uses a great deal more energy than all the window fans combined! In fact, it’s more than two times the energy hog than the window fans! So while AC can be refreshing on the blistering hot days, keep in mind the impact its energy use has on your electric bills, and on the environment.  Try to minimize use, and always turn it off when you aren’t in the room!

For Residents » Save Energy It takes just a little energy to save on energy costs. If you pay attention to the little things, the money you save will add up in a big way. The chart below gives you a good idea of energy costs per electrical appliance, kind of like nutrition fact labels on food. See also our Twelve Easy Ways to Save Energy. 1.5 kWh per hour Baseboard heater (six foot unit) (250 W/foot) Heat Pump heat strips 10 kWh per hour w/fan 10.5 kWh per hour w/fan Heat Pump w/o heat strips (1.8 COP)*** 2.93 kWh per hour 9.77 kWh per hour Window/wall (8kBtu) (120V-12 EER) 0.73 kWh per hour 1.8 kWh per hour Central (3 ton-12 SEER) 3.0 kWh per hour 0.2-0.4 kWh per hour $0.03 - $0.05 per hour 0.03 kWh per hour Less than $0.03 per hour 0.075 kWh per hour 380 - 500 kWh per month $41.00- $55.00 per month Instantaneous (110 v 29 amp) @1gpm 70'F $41.00 - $55.00 per month Instantaneous (240 v 50 amp) @2.5 gpm 83'F

12 kWh per hour 2.3 kWh per hour 1-1.5 kWh per hour $0.11 - $0.17 per hour 6 kWh per hour cleaning 0.12 kWh per 5 min $0.01 per 5 min 0.12 kWh per brew Coffee maker/brew, warmer on 0.4 kWh per hour Dishwasher: normal cycle (not including hot water) 1 - 2.17 kWh per load $0.11 - $0.24 per load Dishwasher: Energy saver cycle 0.5 kWh per load 0.04 kWh per use 0.75 kWh per hour Waffle iron, 4 servings 0.33 kWh per use Refrigerator (frost-free), 15 cu. Ft. (1996 unit) 150 kWh per month Freezer (manual defrost), 15 cu. Ft. 90 kWh per month Newer Units - Energy Star Refrigerators Energy Star Refrigerator, 14 cu. Ft. 34.5 kWh per month $ 3.80 per month Energy Star Refrigerator (frost-free), 17 cu. Ft. 35 kWh per month $ 3.85 per month Energy Star Refrigerator (frost-free), 19 cu. Ft. 46 kWh per month $ 5.06 per month Energy Star Refrigerator (Side by Side) 21 cu. Ft.

51 kWh per month $ 5.61 per month Energy Star Refrigerator (frost-free) 24 cu. Ft. 54 kWh per month $ 5.94 per month Energy Star Refrigerator (Side by Side) 25 cu. Ft. 60 kWh per month $ 6.60 per month 0.48 kWh per hour 40" - 49" Plasma 0.016 kWh per hour Less than $0.01 per hour 40" - 49" LCD 0.012 kWh per hour 0.24 kWh per hour 40" - 49" DLP 0.2 kWh per hour 30" - 36" Tube 0.12 kWh per hour 25" - 27" Tube 0.09 kWh per hour 28.8 kWh per month 0.02 kWh per hour 0.15 kWh per hour 0.21 kWh per hour 0.06 - 0.25 kWh per hour $0.01 - $0.03 per hour Desktop Computer on sleep/standby mode 0.001 - 0.006 kWh per hour 0.02 - 0.05 kWh per hour Monitor - 17" CRT 0.08 kWh per hour Monitor - 17" LCD 0.04 kWh per hour Speakers (25 Watts x 2) normal volume 0.05 kWh per hour Incandescent bulb (40 W) Incandescent bulb (60 W)

0.06 kWh per hour Incandescent bulb (75 W) Incandescent bulb (100 W) 0.1 kWh per hour Incandescent bulb (150 W) Compact fluorescent (8 W) equivalent to 25 W incandescent 0.008 kWh per hour Compact fluorescent (11 W) equivalent to 40 W incandescent 0.01 kWh per hour Compact fluorescent (15 W) equivalent to 60 W incandescent 0.015 kWh per hour Compact fluorescent (20 W) equivalent to 75 W incandescent Compact fluorescent (27 W) equivalent to 100 W incandescent 0.027 kWh per hour Compact fluorescent (38 W) equivalent to 150 W incandescent 0.038 kWh per hour 0.3 kWh per hour Clothes dryer (light load vs. heavy load) 2.5 - 4 kWh per load $0.28 - $0.44 per load Warm Wash, cold rinse 2.3 kWh per load Hot wash, warm rinse 6.3 kWh per load 1.08 kWh per hour 2 - 4 kWh per month $0.22 - $0.44 per month Night light (4w on 12-hours/day) 1.44 kWh per month 0.05 - 1.21kWh per hour