Is this a high electric bill?

July 24, 2012 8:11 PM

I moved into a new loft. About 1,100 sqft with 12 ft ceilings. It is new, with thick walls of concrete on all sides. The a/c doesn't keep it very cool, about 77 degrees in the current heat wave. I was surprised to see a bill for 2251 kWh! That's about $300. Does this seem right?

All my lights are high energy efficiency. I have electric appliances but only ran the dish washer once, and do several loads of laundry about once every two weeks. Otherwise, I have no other electric loads except my computer.

This seems pretty extreme or not? Should I contact my electric company?

posted by geoff. to Home & Garden (30 answers total)

Make sure it is just for the time youve lived there. I once started utilities at a new apartment and the first bill included some unpaid amount from the previous tenant. It was easy enough to get it sorted out though.
posted by ian1977 at 8:15 PM on July 24, 2012

Response by poster: About 4-5 years old.
posted by geoff. at 8:16 PM on July 24, 2012

You say the A/C doesn't keep things very cool. Is this because it's set to 77F in order to conserve energy, or because it is unable to cool the apartment below 77F despite having the compressor running constantly? If the latter, then that's your problem right there.
posted by Scientist at 8:16 PM on July 24, 2012 [3 favorites]

How hot is your heat wave? What are your sun exposures (western facing?)?
posted by katemonster at 8:16 PM on July 24, 2012

How much space is your AC rated for?
posted by ocherdraco at 8:18 PM on July 24, 2012

Response by poster: It has been over 100 degrees for the last several weeks. I have no western facing walls. In fact, most my walls are over 100 degrees. The A/C has been running constantly as it can't keep the temperatures below 77-78 degrees.
posted by geoff. at 8:19 PM on July 24, 2012

Response by poster: I should say, "In fact, most my walls are not exposed to direct sunlight due to taller buldings around me."
posted by geoff. at 8:20 PM on July 24, 2012

Are we talking about a small window unit here? A large window unit? A central air system with an outdoor compressor? I know if I made my central air run all day and night for a month I could easily rack up a $300 energy bill, no problem. Not sure for smaller units.
posted by Scientist at 8:25 PM on July 24, 2012

That does actually seem feasible to me, as cooling a 1500sft house with a high-ceilinged living room and a brutal west-facing wall with windows that radiated heat (Texas, 100+ degrees) would cost us $400-500 in July and August with okay but not fancy central air. If you're not getting your air terribly cool, the air that's being pulled in through the registers takes longer to cool, your A/C runs longer for each cycle, and woomp goes your electric bill.

All of which you've probably figured out. Short answer is yes the bill is high in the sense that $300 sucks, but as a recovering Texan I'd say no, that seems about right. You may or may not be able to accomplish anything from having it serviced, though you should if it hasn't been in the past couple of years, but if your heat waves are rare this may be just a thing you have to live with occasionally. In a loft, you're probably going to have a hard time doing the sort of things that might help, and there's only so much you can do anyway.
posted by Lyn Never at 8:27 PM on July 24, 2012

How many btus does your ad put out. An 1100 sq ft space should use a 10,000 btu a/c, as I recall.
posted by dfriedman at 8:28 PM on July 24, 2012

Response by poster: Central air system with outdoor compressor. Crap, I wonder why I can't get this place cool. I've lived in larger houses without these issues. I can't physically get to the unit so I don't know what it is rated for. Would a larger unit be more energy efficient?
posted by geoff. at 8:28 PM on July 24, 2012

A 5000 BTU air conditioner (which is barely sufficient for a 500-600 sqft place none the less a 1200 sqft place) has to consume at least 1.5 KW even at 100% efficiency.

If it is really on 24 hours/day, that is 1080 KWh just by itself.

If you have a central air system, it is quite likely you have 10,000 BTU - 15,000 BTU, which would be a multiple of this number.
posted by saeculorum at 8:29 PM on July 24, 2012

If it's been that hot that long I'm not really surprised at an electric bill of $300. I think that's about what I paid one month during an over-100 heat wave in an apartment about the same size, well shaded, and with little else running. And that was 12 years ago, and electricity was cheap at the time.
The fact that it can't get below 77 is unsurprising. Very few home air conditioning units can cool more than about 30 degrees. Larger won't help (and going too large can be bad for reasons I can't remember right now).
posted by katemonster at 8:30 PM on July 24, 2012 [2 favorites]

I'm trying to figure out what your loft looks like, how many external walls, etc. Concrete has quite a good thermal mass I think, so if it is hot outside (doesn't need direct sunlight) then the outside temps will slowly migrate through the walls and turn them into radiators at some point in the evening/night. If the external walls were in direct sunlight they would get even hotter.

Alos if the ceilings are high, maybe warm air collects up there.

Do you have ceiling fans? Some AC effect, plus a down draft, might feel cooler.
posted by carter at 8:41 PM on July 24, 2012

Also, where's the thermostat? If it's in constant 90 degrees plus temps, then it would be running non-stop probably.
posted by carter at 8:42 PM on July 24, 2012

Is the air coming out of your vents actually cold? Like, not just below ambient temperature, but actually cold like AC should be? If you have a freon leak, the AC unit can run all day long, using electricity the whole time, and not actually cool the place successfully. That said, in Atlanta in the summer in our terribly-insulated house a $300 bill would be high but not so crazy that I would call it unthinkable.
posted by wondercow at 8:44 PM on July 24, 2012 [3 favorites]

Also, since you're in a loft, have you asked your neighbors what their electricity bills are? Presumably they have similar-sized units and the same model of AC on the roof, so they can probably give you the best estimate of what utilities run this time of year. We can give you anecdotes all day but we're in different cities, sized homes, have different models of AC, etc. Al Gore allegedly used 22,000 kWh in one month, so to him your energy usage is pretty low. I bet his house is bigger than yours though.
posted by wondercow at 8:54 PM on July 24, 2012

What I would do is I would put the blinds down for the duration of the heat wave, and turn the A/C up to 81F except maybe at night if you can't stand it. When I was out of the house I would let it run up to 85F or so. I would run ceiling fans in any rooms that I was using, otherwise I would turn them off. I would also be diligent about putting my computer to sleep when I wasn't using it and about not leaving lights on (even CFLs) in areas of the house that were not in use.

That is basically what I do in a similarly-sized apartment (10 ft ceilings but a bit more square footage) here in New Orleans where it is pretty much highs in the mid-90's from June through September. I don't have a washer/dryer (I go to a laundromat) but otherwise my usage is similar. My bills are in the neighborhood of $120/month.
posted by Scientist at 9:21 PM on July 24, 2012 [1 favorite]

I've had a bill that was $150 in a 500 square foot apartment with no direct sunlight during last summer's heat wave. And that was with a pretty efficient and new central a/c in a well insulated building. So unfortunately that seems totally plausible to me in a much larger place with tall ceilings.
posted by whoaali at 9:35 PM on July 24, 2012

Dude geoff, it's been the month of new record high temps in Kansas. It hit 115 in parts of western Kansas. Average monthly temperature is so central to electricity usage that they print it on your bill. Heat rises, but this is a mixed blessing: the high ceilings should help buffer temperatures slightly, but your downstairs neighbor may be contributing to your problem.

Still, it's certainly worth a few diagnostics. What you can do is find the freon line that leads to your central air fan unit. If this line isn't cold to the touch, then the air coming through it won't be really cooling off either. If you can locate your compressor (the outdoor unit) you can try improving airflow and heat transfer. The compression coils should be free of dust, dirt, leaves, grass, spiderwebs, etc.
posted by pwnguin at 12:52 AM on July 25, 2012

We have been facing a similar problem in our home. Vaulted ceilings, outside compressor not strong enough to push air throughout the vaulted-ceiling area, hot air just seems to stay trapped in that upper 4-5 feet of space at the apex of the roof, etc.

One solution: a ceiling fan, if at all possible.
posted by kuanes at 4:18 AM on July 25, 2012 [1 favorite]

I just recently went through a similar detective exercise, also with central air/outdoor compressor that is about 6 years old. In my case the best it could do was 82 degrees. The culprit turned out to be a $20 capacitor that took the guy under five minutes to switch out. He told me that they commonly fail after about five years.

Also, change your filters.
posted by carmicha at 5:44 AM on July 25, 2012 [1 favorite]

A few thoughts:

• Concrete is a very bad insulator. It's high mass can mean overall cool temperatures in climates like the high dessert where 100+F days are followed by 50-60F nights (this is why adobe is a good building material int he dessert) but if your night time temperatures are not dropping below your set point temperature then the exterior heat is pretty well going to come straight through.
• You haven't really given enough information for an informed opinion of your heat load. Do you have any insulation at all? What percentage of each facing (N/S/E/W) is window? Assuming your roof isn't concrete how is it constructed and how well insulated is it?

If your 2251 kWh hours was solely the result of your A/C use that would be 2251/30/24=3.1kW per hour. 3100W/240V (most central A/Cs run 240v with the exception of the negliable draw of the interior fan motor) = 12.9A of draw. With a EER of 10 that's about 20,000 btu or in the ball park of being right right for your square footage. So if your A/C was indeed running 100% of the time 2251kWh is not out of line.

However a Central A/C unit shouldn't have to run 100% of the time to only cool the interior 30F below exterior ambient. So either the unit is too small or it is defective in some way. If this is some sort of apartment building then consulting with your neighbours is a good idea to see what the installed equipment is capable of and if they aren't having these problems I'd call a technician out to have them inspect the unit and do a cooling requirements assessment.

saeculorum writes "A 5000 BTU air conditioner (which is barely sufficient for a 500-600 sqft place none the less a 1200 sqft place) has to consume at least 1.5 KW even at 100% efficiency."

A modern 5000 BTU A/C with an average EER of 10 is only going to consume ~500W.
posted by Mitheral at 7:32 AM on July 25, 2012 [1 favorite]

I recently had the same problem with my central ac with an outdoor compressor unit. Check your feedback vents to make sure they are open and MAKE SURE the filter is clean. If I hadn't changed the filter, the thing would have turned into one giant ice block.
posted by floweredfish at 8:12 AM on July 25, 2012

It's the Kansas heat wave we're dealing with right now. My bill for a small Townhome went up from $85 in May to $140 the next month and currently rising. Could you contact the power company and ask about a level payment plan? I did that the other day for electricity and next month I'll only pay $100 (it's for 12 months, so when we don't need the air your bill will still be $100).
posted by Sweetmag at 8:19 AM on July 25, 2012

BTW - given your high ceilings, you might want to consider installing ceiling fans which can substitute nicely for A/C on less hot days and compliment it on hotter ones. They aren't too expensive too install and save money and energy. In my opinion, they look cool too.
posted by beisny at 10:36 AM on July 25, 2012

You may also want to check out the outside unit to see if the fins are dirty. Hose them down from the sides to get dirt off of them. Also inspect the unit to see if any of the fins are bent. The dirtier and more deformed the fins are the less efficient the AC will be.

Our utility bills went down when we started using a programmable thermostat. Get one that has different settings for the weekends. They are easy to install and set up.

When the temperature outside is as hot as it is for you, you may have to bump the temperature up a bit. 77 is a huge drop from 100+. Try setting it at 79-81. Also consider switching the mode to "Fan On" instead of "Auto". Then, if the AC ever does cycle off, the fan will keep circulating the air around. You draw more power when the fan starts up, so it should cost less to keep the fan running. When the outside temp is not so high, this tip doesn't really apply, but it does for really hot days.
posted by achmorrison at 10:48 AM on July 25, 2012

One thing you can do is contact your electric company and see if they do energy audits. Mine subsidized a whole magilla including a door blower test. I found out some facinating things (we have no insulation in our attic!) The contractor also gave us some great advice about opening the vents in the basement in the winter to warm it, and to close them in the summer to drive the cool air upstairs.

We got an programmable thermostadt and that's helped a lot too.

When we had 90 days over 95 degrees (this is Atlanta, it's hot, but it ain't supposed to be THAT hot) our bills were outrageous.

We put cellular blinds on the windows, that helps some.

Call your electric company and see what you can get.
posted by Ruthless Bunny at 10:58 AM on July 25, 2012

If you have big windows that get a lot of sun, get window shades/curtains with a 'blackout' layer, and keep them closed during the day. (If you already have window coverings you love, you can get curtains made of just the blackout fabric and hang them behind your current curtains.) It will make a huge difference.
posted by Kololo at 12:11 PM on July 25, 2012

When you start electrical service, you'll sometimes get a bill that is longer than the full typical billing cycle; for instance, I received one that was a little under three months' worth instead of the standard two. This made the resulting bill even higher than it should have been, as my area has multi-tier pricing and the partial third month pushed me into a higher tier. So check that.
posted by davejay at 2:23 PM on July 25, 2012