Fuel Wood Use Maths

Hi all.
I have a problem this heating system year.
Just half of the dry seasoned fuel wood I will need.
I was just too time, and sweating busy, finishing up our location moving last summer to do any significant wood harvesting and stacking to drying.

I need an average of 60 pounds daily of 20% moisture dried down fuel wood for 7 months.
Easy math. 7 X 30 = 210 days. 210 X 60 = 12,600 pounds.
By stacked volume be 5.25 Cords of our dry in one summer Fir/Spruce woods.
We only have half of what we will need.

Decades of exprences to be able to do these real-use simplified Maths.

The nearly 2X change in true weights from growth saps wet woods to good dried down seasoned fuel wood is why you only buy/sell by the volume.
Cords measures. Cubic meters. Even cubic feet.
128 cubic feet in a Cord measure of good true air dried fuel wood will last us ~40 days.

Sigh. So a choice for us.
Have morning and evening fires and run out of wood along about halfway through into February?
Or just evening warming; sitting/watching, enjoying fires all thru the evening darkness to bedtime? And be able to do that though to the end April, into a wet cool May.
I am listening right now to the mini-split heat pump wailing away this morning. 22F this morning. It keep having to stop. Electric heat-off the outside unit when frosting up.

So . . .how do you calculate your true fuel wood needs.

Steve Unruh


Hello Steve, I don’t count anything, I prepare firewood for two houses, ours has insulation, but I don’t need to take that into account, because the wife opens some windows that are open during the day, well, she burns her stove all day. The boiler for central heating also works almost every day, so that the total consumption exceeds 20 cubic meters per year. The second house, where the father-in-law lives, also uses about the same amount of firewood. Now another user has appeared, my Fergie, who has done 250 working hours in one year and burned approx. 10 volumetric meters of wood chips. In total, this is approximately 50 volume meters of wood. The current supply of wood is for about 4-5 years with such consumption. :grin::grinning:


:smiley::smiley:we have kind of the same problem, not enough supply this year. But all our needs will be fulfilled, if not we needed to much. We used 3000 m3 gas a year before we started heating on pellets. Pellets were 6000 kg, wood is the same, also 6 ton. Pellets are for emergency and we still got our gas for cooking (expensive cooking this way, €5/m3). One IBC/ m3 weights around 250 kg, that means 24 IBC yearly. Haha, burned up two already. On the land are around 4-5 filled and dry. And some more waiting to get cut. Dry and ready to burn. There are a few IBC with palletwood. But in total we will be short around 10 m3 :smiley::confused:. Image my CHP plans, 6 ton will rise to 12 ton, mmm….


I never calculated how much fuel wood I use but the last couple winters I have gone around the house insulating and sealing up leaks. Used to need to fire the furnace constantly and never get it really warm. Burnt a lot of wood and coal along with electric and propane heaters for the really cold times.

The insulation, caulking, and spray foam has made a big difference in the amount of fuel needed. Covering windows with plastic or even blankets or heavy curtins can help depending on how good your windows are and how good they are sealed up. I’ve lived places where you could feel the air blowing or just the cold coming right through the glass or especially around them.

Blocking off spaces can make a big difference in the ability to heat but, of course, you need to consider where any pipes and drains are so they don’t freeze.

As far as the heat pump (mini split), maybe building an enclosure (solar heated if possible) around the outside unit would make it more efficient in the heating season.

I haven’t done it (other than at a workshop) but one of the diesel heaters rigged up like a window air conditioner to exhaust outside might be an option.

Short of buying more firewood or other fuel, dressing warm and lots of blankets and heat tape on the pipes?

I have used kerosene heaters before and loved the steady heat (and often the ability to cook or heat water to add humidity) but the fumes can get really bad. Aladdin lamps throw a lot of light as well as heat. They can use a good bit of kerosene (lamp oil) compared to normal kerosene lamps but they seem to burn clean and have WHITE light using a mantle. The heat could be a nice byproduct if you can safely use it. Besides the fire risk, the mantle is fragile and the glass itself can be broken.

Somewhere around here I have a book called “Movable Insulation” by William K. Langdon. That one has a lot of ideas.

Good luck this winter. I’m sure you will figure it out and be more prepared next year.


My last post got me curious so I dug out my copy of Movable Insulation.

This is just one of the simpler ideas from that book. It’s just 4 layers of cardboard with aluminum foil and duct tape. The foil is partially to protect the cardboard from rapid flame spread in case of a fire and also for a bit of wear resistance.

It could easily be taken out during the day to let light in and put back in at night to block the heat loss.

That book has more advanced insulating methods but this one looked cheap and something that could be made and used by anyone even in a rented house.

I don’t have any numbers but I know the insulating I did so far made the house warmer and uses a lot less fuel. It could still use more work and will probably never be finished but every little bit helps. At least with an older house.

This isn’t pretty but made a big difference. The wall with the exposed fiberglass is only a 2x4 and I can feel cold near it. It needs drywall put on it but probably should get some caulking first since there must be some air leaking in.


Yes, all heat you dont loose you dont have to burn wood for. We dont use the biggest room during winter and go back to smaller compartments.


MY old 1975 house trailer is sort of drafty-not the best insulated,metal and roof-I heat the center section-kitchen-bath room and my 10 by 27 foot bed room- I use about 5 or 6 bondles of 60$ each.The boundles are about 3.5 feet round by 10 or 12 feet long mostly hard wood at that price-i could get soft wood slabs about 30 bucks a bundle- then i might use 8 bundles. here in michigan–probbley milder winters than washington state though. I am thinking about using wood truck gasifier next to center of my trailer to pipe hot air in close range. Well my wood burner in barn smokes more than i hoped for-i could get a better clean burn with like a 12 or 14" burn tube. and put cooling rail indoors with no rubber hose conections for hear recovery, and pipe the gas into a heat exchanger to burn the clean gas for heat just outside in a insulated shed,with smoke detector to power exaust fan. PROBBLEY put some vents in the gasifier shed so no gas is building up from any leaks.?


God provides, in this case his name is Remco :grinning:. Nine more to find


I don’t. Every year when the heating season is over with in April, I find myself with at least another winter’s worth of firewood still left. No need for calculations. The downside is logistics. Takes some extra work stack outdoors what doesn’t fit in the shed. But it doesn’t bother me, since it’s a lot of fun. Being late or in a hurry tends to make any task less fun.


So right about the last. And what about bugs and inside the house? Dont you worry about that?


What bugs? :smile:
Well, inside the bark of spruce and pine they thrive and, but other than that it’s not a problem. Same with dimentional lumber. Any live edge I debark when sawing lumber - or that part of a board will end up a Swiss cheese over time.


I find it interesting that you have such large areas outdoors with paving bricks instead of concrete or asphalt like you see here in the US. Do you know the reason for that? Something to do with water drainage I’m guessing?


Well I am glad the talk has stayed focused on wood-for-fuel.
It is futile to go to maths energy comparisons to liquid, gaseous and electric heating.
The nature of how each makes; and distributes heating, makes them in my strong opinion, not comparable.
Speaking as one who has long cool/cold winters sometime in my lifetime used them all. Including black-rock fossil coal.

Using wood for heating each one of us by locations; true needs; and preferences will vary Best-Practices a lot. A tremendous lot.
Here for me in the PNW wet-side rain forest, it is never-ever stack wood against habitated buildings.
Never store wood stack to piles under plastic tarps longer than 3-6 months over the rainy season.
Never-ever store wood even in sheds longer than 2-3 years.
Never leave felled trees down for a whole year. Uncut up. Un-split and un-stacked able to be exposed to the air and sun.
First the wood eating bugs will move into to every crack and crevice. They and their larva eating their ways throughout.
Then the bugs eating spiders will occupy, habitat; lay eggs and generational occupy your wood stacks.

No fun at all to get spider bite every year from taken in wood chunks. Inside the house warmed, brought out of hibernation, and then hopping mad. Someone getting bit every 3rd year or so, and losing that teaspoon of flesh is just the nature of using wood here for your heating.

This house we are in now although old as first built in 1987 from four families of owning and renovating is actually now super-insulated. Super-sealed up. From caulking. From added second interiors ovelayed sheet rock. From interior layers of repainting. From a second added outside walls board and batten sheathing. From a now over 24 inches of additional added ceilings insulation. Under the floors too. From even the metal roof slapped down over the previous asphalt shingles.
Now on out third wintering over; this house from the low mini-split electric bills, and low wood consumption is half the use-needs of our previous houses. Houses that were smaller by half.
We are realizing at 68 and 71 we’ve neither of us ever lived in a truly sealed up, well insulated house.

Sealed up in our wet, wet humid climate can have very bad downsides. Interiors molds building up. Stale air stinks. I keep the main bathroom ventilating fan on a 20 minutes per hour timer that the previous owner had set up.
Small interior volumns are the undiscussed downsides to the tiny house concepts. Those who have lived year around in RV’s out here PNW suffer a lot from literally rotting from the inside out. Many, many electrical issues from humidity moistures corroding in their interior electrical systems. I learned to pass on the impossibility of keeping their electrical systems functioning.

Go tiny, simplistic, you are better off in a wall tent; a teepee; a yurt out here.

Don I was given for free haul away pickup bed loads of apartment houses, used precast concrete steps. It was easy to just lay down some sand or pea-gravel and turn muddy between the houses pathways into “paved” walk ways.
No forms to have been made up, then removed. No heavy expensive concrete delivery truck to order. No multiples wheel barrows of concrete to hand mix up.

Steve Unruh


Mmm, I think more with history and practice. Bricks you can take out and put back. It is a little difficult to do that nice and smooth with asphalt or concrete. And there is a lot of asphalt of course, some think to much :grinning:
History is bricks, houses roads , everything. No wood . Clay we can find everywhere here, so all the bricks are baked and left to see in a building, no plaster. Belgium does it the same, more concrete there but they also have their Arden Blue. Beautifull in the details.


Sorry Mr Steve, I was typing as you wrote yours.


Not a problem JoepK.
Your answers to DonM. were more specific to his question.


Nice looking wood blessings for gentile-Maybe the time of the gentiles in the bible are nearly fulfilled. That truely is a large brick pavers fine detail of a yard there.


Supposed to snow and if it stays it will put a dent in getting more wood for the pile, This time last year we already had 30 inches and it stayed until March. I have 3 full cords in a storage area accessible from inside the house, a face cord stacked by the front door that I keep replenished and this pile I’ve been building. Most of this came from the hills around my property. I have at least another 3 cords of dead staying timber I can cut even if the snow stays. No idea how much is in that pile. It’s twenty five foot long and about 7 foot high. I can split and stack this as the winter progresses. It’s all dead and dry.


I have kept track of how much I use and also the dates I bring firewood in for eight years now so I know about how much I need to make, with extra of course, every year.
I use a simple system of a clipboard and a fairly exact box measurement bringing it inside. It depends a little on how the wood is thrown in there, I stack the front and just chuck wood behind it.

Every even number on the clipboard is a full box which is calculated to be (if stacked) 1,7m3 or 0,47 true cords of wood, this makes it easy to know evn with changes in weather, cold year or warm winter and so on.
Sometimes I made a note of bringing in small crap from the bottom of the pile as a cleanup, that is why there is half ones or so on the paper.

Easy system and not much work to keep track.


Having lived in New England for many years heating with wood, the one thing I trained myself to do was to get wood in early. In Chile, the weather is much milder, but still cold and damp. I am anal about getting the wood shed full before November so it can dry properly through the summer. My wife tells me before December or January is good enough, but I just can’t help myself. :smile:

Happiness is a full woodshed in mid spring:

I started a spreadsheet to track usage through the heating season. The solid blue line is usage based upon degree-days if a full shed is consumed. The bottom line are the data points of actual usage.

My sickness is getting so bad that I have the following year’s wood cut already. Now I have to build another woodshed, or maybe turn it all into charcoal? :thinking: