: Help me out with my natural gas consumption
2009-02-18, 12:13 AM
I built a new house and spent a fair bit of money to make it as efficient as I could afford and the gas consumption seems high to me. I e-mailed the ATCO EnergySense group about it and they asked if I was an ATCO customer. After I said I wasn't they quit responding. Seems strange considering I am willing to shell out for an energy audit and even thermal imaging if it looks like there is a problem. So here I am looking for input as to whether my consumption seems high to anyone else.
Here are the details:
Myself, my wife and my 4.5 year old daughter
20 minutes SE of Edmonton, AB
1620 sq ft bungalow completed in April, 2008
R40 attic insulation-raised heel trusses so insulation is full depth all the way across
R20 wall insulation in 2x6 studs
1" R5 polystyrene insulation covering entire exterior (except roof)
unfinished basement with steel studs, R12 fiberglass and poly on all walls
Armstrong 95%, variable blower furnace. 56/80,000 btu input, 76,000 max output
Bradford White 48 gallon hot water tank: http://www.bradfordwhite.com/products2.asp?id=1&product_id=107
Programmable t-stat goes down to 17 celsius for most of the week and up to 21.5 when we are home in the mornings, evenings and weekends.
Hot water tank is set to 49 celsius.
We wash ALL of our laundry in cold water (Samsung front loader). Our dishwasher is a pretty efficient Bosch model with it's own water heater.
Here is the usage:
October 7- December 5 - 22.3 GJ in 59 days, .377 GJ/day
December 6- Feb. 5 - 38.4 GJ in 62 days, .62 GJ/day
So if we take the daily average from December to February we are saying that gas consumption in the coldest 30 days of the year will equal 18.6 GJ.
Does that seem high to anyone given the data I've provided? Maybe my expectations were too high? Appreciate any opinions out there, expert or not.
When I lived in Calgary, I used a range of 0.10 Mcf/day (which went to heating water) to about 1.5 Mcf/day on the coldest days. I believe an Mcf is roughly equivalent to a GJ. My yearly average was about 0.50 Mcf/day.
I had a 2200 sq. ft. 2 story house, two 80% efficient furnaces, R12 Walls, R30 ceiling, 6 mil vapour barrier and a setback thermostat not quite as agressive as you (home built in 1981). So, your numbers look fine...
I'm now living in Toronto - 1500 sq. ft. 2 story, R20 Walls, R40 ceiling, 96% efficient furnace, almost no setback since I'm usually home with electrical hot water heat, using an average of 0.15 Mcf/day, less than 1/2 of Calgary, after accounting for hot water.
When I started getting billed in Calgary, it was Mcf, that changed to GJ part way through my Calgary life. Billing in Toronto is cubic meters (adjusted for thermal content), but my tables for comparison are all Mcf because that's where I started in 1981, although I have my Toronto usage in cubic meters too.
Mcf = 1000 cubic feet = 1 MMBTU = 1 GJ (Roughly)
2009-02-18, 09:51 AM
Unfortunately I don't have my numbers handy... but yours sound reasonable given your setup and the fact that you had a particularly extra cold winter out your way this year (at least from what we got on the news in ON.) That would certainly explain part of the reason why your bills would be higher.
If you want to try and save some more money, there are other things you can do, some are lifestyle changes and some will require you to spend a little more money to change up some things (which I admit is not a pleasant thought given the current economy.)
I run my house at 70F (down from the default on the thermostat of 72F) which I find is still pretty comfortable, but did take a little getting used to. I know you have a young child, so the lower temp may not be an option, but try 21 instead of 21.5 and see if you can adapt... that will help a little. I run it at 62F when no one is home and at night (which is around 16.5C) and throw an extra blanket on the bed. Those two half a degree cuts should save about 2 to 4%, if what I have read is correct.
In ON the building code requires a mixing valve to prevent water from reaching the taps at more that 110F, you're currently set for 120F. I don't know if you have a similar law out there (if you did, then having the tank higher than 110F seems wasteful)... but you might want to consider lowering the set point of the hot water heater as well... Remember you are heating that water day and night, and only using it a small percentage of that time. In my house I installed a tankless system (heat on demand) so I don't heat water when I'm not using it. (Mine is rebranded Rinnai, http://www.rinnai.us/tankless-water-heaters/homeowners/ )
Your hot water bill is mostly going to be showers and baths plus the energy to keep that tank at the set point. Wrap the tank with insulation could help with keeping the heat in. And if you take mostly showers... you can save with a drain water heat recovery system, such as this one (PowerPipe) sold at Home Depot: http://www.homedepot.ca/webapp/wcs/stores/servlet/CatalogSearchResultView?storeId=10051&catalogId=10051&langId=-15&N=0&Ntk=level1&Ntt=power%20pipe&Nty=1&D=power%20pipe&Ntx=mode+matchallpartial&Dx=mode+matchallpartial&s=true
Can you get the efficiency of the furnace checked. I know we have one member here who said they carry a diagnostic tool in their service truck to do just that. He also suggested you check your furnace filter.
2009-02-18, 10:13 AM
fyi, you cannot insulate a gas water heater. if its not a part made specifically for your model u cannot use it.
2009-02-18, 10:16 AM
jake, we can do combustion analasy but t only accounts for part of the eff rating and on gas furaces the combustion mixture is fixed.
combustion eff checks are mostly done on oil burners
2009-02-18, 01:34 PM
That's a pretty good tank-based water heater - 2" insulation, so it's unlikely you'd get a big benefit by adding another layer of external insulation. I have a similar (but larger) model since I have some radiant heating in the basement.
Your place seems to be insulated well and your HVAC equipment is new, so barring HVAC installation issues it should be operating at or near peak efficiency. I'd be more inclined to suspect other gas appliances (do you have any fireplaces?) or cold air infiltration from badly sealed windows, doors, fan vents, etc. An energy audit will cost you a couple hundred dollars but they'll do a blower-door test and should be able to pinpoint any drafts.
I've been tracking my energy consumption since we built the house in 2000; first in terms of heating oil usage and now natural gas. With the old heating oil HVAC I was burning very close to 1 litre per degree day. You need to normalize your usage against the weather otherwise a very warm or very cold winter will trick you into thinking things are better or worse than they really are. I don't have enough natural gas data to get an accurate number, but it looks like it's in the vicinity of 0.6-0.8 m³ per degree day. Given that the BTU content of a m³ of NG is close to that of 1 litre of heating oil, the credit for the 20-40% improvement goes to the fact that the new NG furnace is just that much more efficient than the old oil one.
In absolute numbers, I averaged about 18 m³/day over the 31 days of our Ottawa January. Using a conversion of 0.03706605 GJ per m³ (I found that in a table - I hope that's the right conversion), that's 20.72 GJ for 31 days, or 0.67 GJ per day in January. Our house has close to 6000 sq ft of living space, so unless your Dec-Feb weather was exceptionally cold compared to Ottawa, I'd say your consumption for 1620 sq ft of living space seems high.
Is it possible that a lot of heat is getting dumped into the unfinished basement and then leaking out via drafts?
As an FYI, I have that number and have been using about 0.5 m3/HDD for the past 18 years (about 0.02 GJ/HDD). The HDD numbers are exact because I have a weather station at my home. (remember, no gas for hot water since that should be a "base load" which doesn't change much with conditions or time of year.) My gas bill for the past 8 years has been around $1000/year. Before that gas spike around 2000, it was more like $500/year...
2009-02-18, 02:58 PM
Tougher for me to split out domestic hot water load since my heater does double-duty in the winter for 2 radiant zones. I used to be able to get a decent baseline of about 2 litres of heating oil per day for hot water based on summer oil consumption, but now with all of my oil *and* propane appliances converted to NG, that's almost impossible. I'd have to factor out usage from the Jenn Air, BBQ, and stand-by generator as well.
I asked the HVAC contractor about installing some sort of sub-meters so that I could tell how many m³ each of the appliances were using. None of the HVAC guys I talked to were familiar with any that could be installed indoors, and it wasn't practical to split the gas feed N ways outdoors just for the sake of having sub-meters. www.excelamerica.com sells small gas meters that look like they would do the job nicely, but if nobody is willing to install them for me I really don't have much choice.
Yeah, I've got a gas BBQ and gas Fireplace too. The BBQ uses very little - I've tracked it separately during the summer for example (all other gas turned completely off). My fireplace is about 70% efficient, so that heat goes into the house, although at a lower efficiency, but it only does one room, so again not a major player...
2009-02-18, 10:34 PM
Wow. Thanks for the quick responses.
For the water heater temp I honestly didn't know what the temp was set at, the t-stat reads: "Very hot, D, C, B, A, Hot" and then just goes to little dots. I set it at hot when we moved in and decided I better look up what temp that actually is when I made the post. Doing some quick research suggests that 49 is optimal.
I listed all my gas appliances, no fireplace or gas stove.
There are no noticeable drafts around windows or doors but we do have quite a lot of windows so I guess that is a factor as well. Windows are all double pane low e. Here is the plan (mine has a bigger garage and the floorplan is reversed) to show how many windows: http://www.montoriohomes.com/Portals/0/PDF/OurHomes/RivaIII.pdf
I have the vents turned off in the basement so there is not a lot of heat going down there although it does stay quite warm. Come to think of it I think I have one exterior vent down there that may not be sealed off (extra vent put in by builder for venting future basement bathroom.... I am going to check right now.
I guess for peace of mind I am just going to have to do the energy audit.
2009-02-18, 10:45 PM
Unfortunately I don't have my numbers handy... but yours sound reasonable given your setup and the [B]fact that you had a particularly extra cold winter out your way this year
Is that correct? I heard Edmonton had hottest winter in 100 years. Also, I moved here for just about 5 months ago.
2009-02-18, 11:08 PM
Our last gas bill from Mid Dec - Mid Jan was $288. Sorry I do not have consumption
data, I just remember the amount as it seemed high to me. Although, that was a very
cold 30 days.
Out house is 1,800 sq ft, plus the basement. We typically leave the t-stat at 22 as
if often feels cold in some rooms. House is 10 years old, fireplace was on for a little,
and we have a gas dryer - and I do bbq, only on weekends. The kid gets a bath
every night, dishwasher is run every 2 days.
Hope this helps,
2009-02-19, 12:35 AM
That is a pricey bill! Makes sense considering you have more gas appliances, older house and higher temperature setting. We only bath our kid every 2nd or 3rd night in the winter or her skin gets too dry. But the wife takes the longest showers humanly possible. I BBQ in the winter too but I am running propane until I convert to NG in the spring.
tablo: November was very warm. December and January were very cold. December was 4.5 degrees colder than normal on average. Although I was in Jamaica from Dec. 3-17 so I got more relief than most. :cool: Did you not find it cold?
2009-02-19, 09:03 PM
Oh. I didn't know that. December was quite cold.
2009-02-21, 12:52 AM
December was BIT cold is more right... :)
2009-02-21, 04:35 AM
I would say you are doing fine. I am in "milder" BC have similar insulation and 1500 up and 1900 down walkout (some under garage , hills do this for you), fully finished lower level and our consumption is similar(about .4 and then .7) with 2 people in the home and a dog that wants out all the time(in out in out:)) The 21.5 temp is about 1.5 higher than we set and we set back at night but are home all day.
2009-02-23, 11:02 PM
Well, my latest bill just arrived, and I dug out the one before. I am in the general Toronto area (Greater GTA) and I have a year old full brick house with natural gas heat on a fairly efficient furnace (I forget the numbers but low 90% if I recall.) Have a gas cooktop (electric oven) and a gas fireplace in the family room that is only used very occasionally. The numbers in the summer are maybe extra low because we BBQ (separate tank not supplied by nat gas supply) a lot.
This is two adults, with 1 shower each per day. We have a nat gas hot water on demand system, so not paying to heat standing water.
The temps are for 70F when home/awake (about 6 hours per day on weekdays and 14 hours per day on weekends) and 62F the rest of the time. The house is about 1700 square feet with an unfinished basement that we keep a few vents open in.
Anyway, my numbers over the last year, in average daily cubic metres:
I'm not sure why this latest bill is seemingly a lot higher... but I guess we did have a few extra cold days in there... and also last year we may have had a few more weekends away when the temps would have been set lower.
2009-02-24, 12:44 PM
Placeholder, I have been charting our usage over the last couploe of years to compare with this years to see how our new upgrades are going to improve. Anyhow, I punched your last years in to my comparison chart and you're doing better than I am. I can send you a copy if you want to see the chart. I've got a couple of teenagers who like showers but other than that we're about the same in size and temps.