What am I doing wrong?

kitchendesignFebruary 14, 2007

We recently built a home and tried to take extra measures with regard to energy efficiency. We put Geothermalheating and cooling; we put windows with high u values and solar heat gain coefficient, upgraded both wall and attic insulation, put radiant barrierin attic, tile roof.... We have been living in the house few months and our average usage is a whapping 4500 KW/ month -more than twice the average energystar calculated for a house our size in the area.

We live in Texas. 3900sq ft air conditioned space; well water pump, pool pump operating 8 hrs/day, sewer pump, electric clothes washer, dishwasher, new energy eff. refrigeratoe,two computers and miscellaneous kitchen appliances - What am I missing? Where is it all going?

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Find out what your biggest uses are . . . I'll bet the pool pump / heater is a big one. Sewer pump . . does this pump up in batches, or do you mean an aerobic septic system? Some of these run 24 / 7 and aren't energy misers by any definition. Also, do you use electric hot water heater; or do you derive this from your geothermal system ? What is your climate . . . if you're doing a lot of heating, heat pumps don't do well below certain temps . .. and the auxiliary ( electric heating elements ) kick in. Can be big consumers of electric. Do you KNOW that your geothermal system is properly sized / installed / operating condition ? Electric stove / oven ? Do you use them a lot ? . . . Anything that uses electricity to produce heat are killers if they're used for any meaningful period . . . . hot tub ?

I've never used more than 2600 kWh in a year . . you've got a LOT of juice going somewhere . . .


    Bookmark   February 14, 2007 at 9:06PM
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The septic is an aearater system. I believe it runs 24/7.
The pool is not heated. Water heater, stove and clothes dryer are propane.

Other electrical gadgets: There is a water softner/reverse osmosis system with an aerator to oxidize the high amount of sulphur dissolved in the well water.

A water sprinkler system 12 zones; turns on at midnight for 15 minutes.

We have an electric oven that we use infrequently.

We have two computers, a printer, a coffee maker, a dishwasher.

Our geothermal system I believe is well sized and was done by reputable folks.

I will look at the links and definitely make all the effort to identify our biggest energy sinks.

Assuming it is the outside appliances (well, pool, septic pump, water purifier, sprinkler..pumps) is there a way to install solar for that portion of our energy use and leave the rest on the grid?

For household lights, we had ut energy efficient bulbs (in all except recessed lighting). How big an energy drain is it compared to the other stuff we have going? Thank you

I will look at the l

    Bookmark   February 14, 2007 at 9:45PM
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Check out Onset Computers. I drove by their place on Tuesday they were advertising a new logger kit on their marquis for energy savings. My golly 4500kw would cost me $967.50 at our new rates. Luckily I use about 270 kwh due to the ceiling fans to circulate air from the wood stove. The aerator is a pig, not to mention the well and Geo system, obviuosly non of these pumps are efficient like some of the new Goulds and Taco pumps. Jeez that's a lot of power. 200 amp box?

    Bookmark   February 15, 2007 at 3:34AM
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The time to build-in energy efficiency is BEFORE you build; not after.

You've got some energy hogs built in. Consider your aerator. Assume it's 1/2 hp and 100% efficient. That will use just under 9 kWh / day => 270 kWh / month. That's 6 % of your total usage. It's built in; and you likely cannot change that now. I'm sure there were alternatives to that type of system . . but your choice is now made. I rarely use as much as 10 kWh / day to run my entire place . . .

"well sized and put in by reputable folks" . . you think that; but do you KNOW that? Even reputable places can make mistakes etc. Seems to me that with your bills it would be a wise thing to have someone CHECK it. Again; if your geothermal can't keep up ( very cold weather, something not right etc ) then electric resistance element make up the difference and they can chew up LOTS of power. You would not necessarily know that it's happening as the temp in the house will be nice either way.

Not sure what type of light bulbs you're using; but CFL's ( Compact Fluorescent Lights ) give the same amount of light for ~ 25% of the electricity. May not be a choice for some fixtures; but you should have lots of them in place of conventional bulbs. Halogen bulbs are not quite as bad as standard bulbs. CFL's are MUCH better. Look around and you can find LOTS of different shapes / color spectrums etc. Not only do you save in lighting costs; but also in cooling costs => standard bulbs are heaters that happen to give off light => CFL's can reduce the load on your A/C.

Your reverse osmosis system can draw LOTS of power too . . I looked at such a system once and was amazed at what they draw with high pressure pumps, UV sterilizers etc. While they are great at removing virtually everything ( including GOOD taste ) it may not have been your ONLY choice to treat whatever is in your water. Did you get a good water analysis BEFORE choosing a treatment system ? Sulphur can be treated other ways, so can iron. Reverse osmosis systems also waste at least some water. While you may collect / use it for garden or such; you're still paying to pump it out of the ground with your well pump. That's extra run time / extra power for doing it. While the total amount of ON time of your pump may not be huge; they do pull a good bit of juice . . and your reverse osmosis system adds to that by requiring pumping extra water that eventually gets tossed out somehow.

As far as solar panels to help out; sure. But it's NOT gonna make a dent in your energy usage unless you put in a huge array costing far more than you'll be willing to pay. Every dollar spent reducing your usage, SAVES about $20 in cost of an alternative energy source.

I'm sure you can find some things and reduce your usage somewhat; but you've also got some built-in killers. Your home itself may indeed be quite energy efficient . . in terms of how it was built / insulated etc . . . . but you've got, or have added; energy killers as well . . .

Good luck . . .


    Bookmark   February 15, 2007 at 6:32AM
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I would agree with Bob that the geothermal heat pump should be checked carefully -- maybe by someone other than the people who put it in.

Does the aearater system really need to run 24/7? Could it be put on a timer to run (say) 15 minutes an hour?

Another way to get some idea where the power is going is to use your electric meter. For example, you could turn the geothermal heat pump off for a day, and see how much difference it makes on the meter. The meter will measure quite small quantities, but its hard to separate out all the different power consumers. But,I have found that you can get a pretty good feel for what the larger loads are pulling by using the meter to get readings during times when other loads are pretty constant. Turn the load you are interested in off for while, then back on for a while with corresponding meter readings. Its not perfect, but you can get an idea.
Here is a how to read the meter:
and another,


    Bookmark   February 15, 2007 at 5:50PM
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Bob and Gary covered it very well with their excellent posts. The only other thing I would mention, which may be obvious to you anyway, is to replace your GSHPs filter regularly as a plugged up filter will restrict air flow and thus trigger the back-up to activate more often than otherwise necessary. I know this wont solve your problems, but in the interest of energy efficiency, itÂs something that shouldnÂt be overlooked.


    Bookmark   February 16, 2007 at 9:10PM
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We built last year to the R-2000 standards. The whole house was pre-designed with efficiency in mind. Our heat source is an air-source heat pump, which is like geothermal, only it gets its heat from the air, not the ground. The air-source heat pump can capture heat from teh air as far down as -20 Celcius. After that, it has to draw its kW from teh power company. We know when that happens becasue a red light comes on the thermostat. Typically it hovers around -18 to - 22 Celcius when that happens. The house is almost 3000 sq ft which includes a full basement. Heating system also doubles as an air conditioner.

Certification test showed the house was 91% efficient for air-tightness. Apparently that's quite high. Great! First 6 months (spring and summer) were ok, monthly average 1000 kW during the spring, 700 kW during the summer.

The next billing cycle (fall, mild weather) the kW useage doubled and we could not figure out why. We eventually figured out we had the heat pump on the wrong setting. When had it running on "E HEAT" which we thought was "efficiency heat" when it acutally means "Emergency Heat". So in essense we were drawing all our heating kW's from the power company rather than using the heat pump. A hard lesson learned.

Nothing else in our habit had changed, so that one thing made a HUGE difference. So my advice to you is to make sure you are using your thermostat properly. We consulted a lot with our heating company who did the install (Halifax Heating), they were a great and helped us through figuring out the problem.

What I now do is each morning I go read the power meter and record on a spreadsheet the useage for the previous day. If it spikes, I review the previous day to see what was done. I factor in weather conditions as well.


Jim Barry

    Bookmark   February 18, 2007 at 9:33AM
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Also consider a programmable thermostat. Most contractor grade stats call for electric back up when you temp drops 2 degrees below the set point. I disconnected the electric core on our geothermal until I got the new stat.

I would be surprised that any air source based heat can extract any heat below zero or -5C.

    Bookmark   February 20, 2007 at 5:19PM
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