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Post in 'The Green Room' started by velvetfoot, Nov 20, 2012.
Base 65 HDD = 8288
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Annual electricity 10400kwh = 35.5 MBTU
Average Propane: 591 gal = 54 MBTU
Wood, varies widely: 1 cord = 22MBTU
Total Energy useage 111.5 MBTU
2400 sqft, 5000 HDD
Comes to 7BTU/sqft/HDD for heating, considering the inefficiency of wood heat and a 30 year old house, not too bad.
Interesting thread here - Looks like we're way ahead on the electric usage, but overall energy consumption is above average for our area. I'm calculating a total of about 127Mbtu - the average based on that link was about 110 for my area. My breakdown is:
Electric 5,880 Kw/yr 20 Mbtu
Oil 220 Gallons/yr 30.8 Mbtu
Wood 3.5 Cords/yr 75.6 Mbut
Total - 127 Mbtu
I guess we just like to burn our wood Our oil use is for our hot water almost exclusively - interesting that it is about 25% of our total home energy use which seems to be pretty much in line with averages I've read although I can't cite one off hand.
Have not used propane since 2006
Electric about 6000 kwh/yr = 20.5 MBTU
Wood about 2 cord/yr = 44 MBTU
Total = 64.5 MBTU/yr
This is with just me here and my daughter sometimes. Back when I had a wife and her kids here a year ago, electricity use was nearly triple. Am waiting for the electric company to think there is something wrong with my meter . I don't consider myself a miser with electric use. All my satellite equipment stays on standby. Porch light stays on 24/7 and a couple other lights stay on all night. Computer stays on 24/7 but I shut the CRT monitor off. I play music and run stereos and amps. Often I will run a space heater at my feet when sitting at the computer, or keep one going if I'm gonna be gone for a really cold weekend so the pipes don't freeze. Which is all included in the electric use. And I might go through less wood this winter with nobody feeding the fire all day.
Wow...this is quite a bit of data.
We use around
200 Gal oil
4 cords wood
I think that as soon as we add wood to the BTU consumption, it is going to disproportionately skew the overall number, firstly because of the inefficiency of the average wood stove, and secondly because stoves usually result in room temperatures far higher than anybody would pay to get using oil or gas. Imagine the bill to keep several rooms at 80F using fossil fuels or electric?
Thats the thing... Its hard to keep the usage down when you are the only person in the household who has any interest in conservation.
If I lived alone I'd be using only a fraction of what I do. But I cant complain.
Is that the 1050 ft2 chalet?
Could a wood boiler contribute to lower overall household energy use then? More like a conventional central heating system? The accepted theory is that area heating allow lower overall energy use.
Yes that use is for me.
I'm not totally sure what her electric bill is though from what she said it used to be similar to mine + about $100 which accounted for running an Edenpure 24/7. She said she used "some" propane, which I know to be 1 fill a year but that's all. Besides the pellet stove has only been in place a couple months.
Geez, you guys are all making me feel very bloated.
Just converted my consumptions from page 1 to MBTU. I just converted by factoring from other peoples conversion recipes.
750 l. oil = 33 MBTU
8000 KWH = 27 MBTU
7.5 Cords Wood = 162 MBTU.
Total 222 MBTU. Zoinks.
I made some big changes here this fall - got rid of the oil all together (it did our backup heat & non-heating season DHW) by yanking the oil/wood boiler, and put in an 80 gal. electric hot water heater, gassifying wood boiler & electric boiler for backup heat (backup heat rarely gets used). So kind of curious to see what my numbers wll be at the end of next year. Oil will go to zero, wood will be reduced hopefully considerably, electric up hopefully minimally. The big one, wood, is pretty darned fuzzy - my wood is a hodgepodge of old rotten trash & decent hardwoods. But it's a FREE (neglecting equipment capital costs & my time) renewable resource from my back yard - I think its quite a skew to the numbers.
We're all electric and located in central NY (about 7200 annual HDD). Last 12 mo's electric use total was
12627 kwh or 43.1 MBtu. We heat the whole house (1400 sq. ft, 170 year old house) and set the tstat to 67 without any setbacks, and air condition to 72 as needed. We cheat, though...GSHP. To the OP, when I used to heat primarily with a wood stove located in my cellar, the btu #s were skewed higher using wood (over our existing oil furnace at the time). I figured this was due to the inefficiencies of the stove and having the wood stove in the cellar, more than anything.
You would expect the higher users by state to be the states with the highest heating dominated climates. But what's up with New Jersey. I mean, really.
NJ is one of the wealthier states == more square footage.
Revisiting this thread. One thing I noticed before, is that the low #s from my house and Woodgeek's had heat pump technology in common. I re-ran the #s for my house from the time before we had the geo system installed. In the years we heated with wood it ran around 179 MBtu (averaged 6.5 cords wood and 20-50 gal oil) and in oil only years (no wood heat) around 135 MBtu.
The higher #s for wood show the inefficiencies of heating with wood, especially with a stove located in the cellar. More importantly, though, it shows just how much energy use is reduced, on site, by switching to heat pump technology, at least in the northeast, where we do a lot of heating. Now I know there's the argument about taking the inefficiencies of the electrical grid into consideration. In my case, I pay a little more for wind energy for all my electricity, so I can at least feel good about supporting the wind industry. There's also the economics to consider when determining whether it's a good idea to switch over to a heat pump system, and what combination of insulation and tons of heating system make the most sense for a particular house. But in the future, whether it's new construction or retrofitting old housing stock, using heat pumps, whether ground source, or the newer air source units, seems like a no-brainer to me for decreasing residential energy use.
As much a fan as I am of HP technology (I can go on and on about it) I still think 'primary energy' is a better measure than site energy. Just switching from an oil boiler to a ASHP looks to reduce your site energy massively, but does little to reduce your carbon footprint (depending on where you live). Not unlike the coal powered EV story.
Of course, if you are getting your kWh from a non-fossil source, then the primary energy can be the same as the site energy. So, like EVs, HPs are only really green if you source your energy appropriately.
But lest you think I am some sort of green snob, I put in an ASHP for the old fashioned reason that it was cheaper than than any other option over the 10 yr timeframe, even when a wind power surcharge is added. The rest is green gravy.
Yea, same here. In my case, even a ground source system was way less expensive than staying with oil as we figured a simple payback of less than 7 years over oil (with the federal incentives in the mix).
Not cheaper than cutting wood off my property for sure, but an injury forced me out of that game. I can say that I couldn't buy firewood for less than the geo system costs to me tor run.
10/25/10 - 10/24/2011
hot water consumption 2650 kwh 9.01 mbtu
general power 8750 kwh 29.75 mbtu
wood 2.3 cords 50.6 mbtu
oil 30 gal 4.23 mbtu
total 93.59 mbtu
10/24/11 - 10/23/2012
hot water consumption 2379 kwh 8.0886 mbtu
general power 8748 kwh 29.7432 mbtu
wood 2.2 cords 48.4 mbtu
oil 5 gal 0.705 mbtu
total 86.9368 mbtu
Alright, lots of data here. Here is mine for the last 2 year s(based on the dates listed).
The house is 1800ft^2 split level of 1950's construction, and certainly not great insulation.
It is electric hot water, cooking, and a space heater in my daughtes room. She is a year and a half old, so its kept pretty warm.
The house is heated with wood, and a heat pump, with oil fired backup. Oil use is estimated based on the fuel gages, thats rough. Same for wood use, guessing the use. Heat pump use is very hard to estimate BTU delivered to the house, all I can do is cite the power consumption (here).
So I am doing ok, could be better. As everyone else seems to say, its hard being efficient when others in the house arent working very hard at it. Of course I am the guy who likes turning on the 600watt christmas tree that I have!
10,429 KWH Oct 2011
12,400 KWH Oct 2012 after adding inground pool with heat pump $2285.64 42.31 MBtu??
Electric oven, stove, dryer and central a/c
850-950 gallons oil $3300-3600 ouch....before installation of wood stove
Guesstimating 5 cords wood? Hoping for less but our stove seems to be eating wood.
Did I miss how to figure out MBtu? I did find one calculator for KW.
I am doing a test tonight of using the electric radiator backups for the first time to see if they can hold the place around 68 to 70. Watching the whole house power monitor is painful. 35 outside and kicking an average of 3 kwh per hour since noon. Probably gonna be a fire in one of the wood stoves tomorrow.
Oil is 139,000 BTU/gal, so 900 gals is = 125 MBTU
Hardwood is ~23 MBTU/cord, so that is 115 MBTU
You total would now appear to be ~155 MBTU.
It seems unlikely that you dropped your MBTU when you switched fuels. Either your 5 cord estimate is short, or you reduced your heating load when you you switched. Or your oil boiler is from the stone age.
This is my first heating season with wood. People have told me I would use 3-5 cords of wood per year. The season barely started and I probably used 1/2 cord already! I guess I will go over the 5 cord estimate. I dont think I have more than 5 cords seasoned.
OK MBtu is not an efficiency thing, it is how many BTU's of energy my home requires? I was thinking the lower number the better?
Thanks for the calculations woodgeek.
That does sound bad - is that just maintaining or trying to raise the temp? I too have a whole house monitor (TED5002) and sometimes I think it is a mixed blessing - too much knowledge drives the rest of the family crazy.
MBTU is shorthand for Million BTU.
That sounds pretty darn good to me. Ive read the average HHI for US houses is around 10,code minimum new construction gets you to 7 and super tight houses hit 5ish.
When I calculate mine I get 9.7 on a net energy basis, and about 12 on a gross input basis.(I never remember which is the proper way to estimate?) Not great but I think not bad for the age of the house and a lot better than the 12/15 values I calculated from before I started insulating and sealing. I'd love to get it down to 10 gross but that will be difficult with this place.
What size house are you heating? Your year-round electric is comparable to mine, but your oil cost is so much higher than my propane. When you say 1/2 cord used, do you mean a "real" cord (4x4x8) or a face cord?
BTU is simply a measure of energy, 125MBTU oil, at 90% furnace efficiency is 112.5 MBTU. To get 112.5 MBTU from wood at 70% efficiency you'd need 160MBTU, which is 7 cords. That's what some 24/7 burners in very cold places use in a season. Your existing furnace might only be 70% efficient, in which case you'd only need just over 5 cords. Maybe if you have an inefficient furnace, and inefficient distribution system, you'd need less wood.
An crude way to compare heating efficiency is BTU/HDD/SQFT, but people have such varied heat use, it can only give you a rough guide. For single family homes, under 5 is great, 5-10 is okay, over 10 has lots of room for improvement. Use only the BTU for heating.