Saturday, January 26, 2019

half way there

Just finished burning half of the firewood I split for this winter. Since it is toward the end of January, I think we'll make it to spring.
(This does not include my contingency cord of wood in the old shed) A cord of wood is a volume four feet by four feet by eight feet. ( 3.6 cubic meters)

So I wondered, on a long term sustainable basis, how many acres of woods does one need to heat their home in our climate?

We are at roughly N43 latitude, with pretty cold winters. ( It got down to -18F (-27C) yesterday, and they are forecasting -26F (-31C) for Tuesday night, but these are about as cold as it gets)

Tending outside chores was not too comfortable.

I did some googling at forestry and wood heating forums, and a rough average is 1/2 cord of wood per acre that can be harvested in perpetuity. There is obviously a wide range, depending on soil, rainfall and climate. Since we have been burning around three cords each winter, I need six acres (2.4 hectares) to heat our home.

In the rural areas of America, and here in Wisconsin, there are no natural gas pipelines, so most people heat with trucked in propane, though some regions heat with diesel fuel. And what about the cities, where by far the most people live? Natural gas is relatively cheap right now, but it will not last. There is a lot more to sustainable living than this but just the one example of home heating shows how precarious things could get.

I've been fortunate enough to afford buying land which has around  15 acres (6 hectares) of woods, so this home will be ok if fossil fuels fade, especially after I get more good quality trees planted. But what about everyone else? Even if they could afford the land, there is not enough for everyone.

This is an old photo from last fall. It is about 1.5 cords, or half of our annual firewood use. We currently have around eight inches of snow on the ground.


  1. Hi, Steve!

    I really appreciate your figures on how much firewood is needed through a winter. Boy, do you have colder winters than we do, so I am figuring that maybe we don't need as much. That said, fairly often we burn 2 - 2 /2 cords per winter. We have 5 acres, almost completely wooded, just a clearing for the garden and barn and a work area around the barn (used to be a small paddock).
    So far we have had no shortage of wood, but my son does bring in a lot whenever a neighbor or acquaintance wants fallen trees cleared off of their properties. One hopes these connections last as then we have to harvest less of our own trees that way.


    1. Hi Pam;
      Thanks for stopping by.

      The amount of firewood that an acre can produce each year is a rough average of the comments I saw on line, but how much each home needs has another wide range. Our home is a bit larger than we really need, but is fairly well constructed, and we try to keep the main living area at 65F.

      So some things help reduce the wood needed, some things increase it. I know of some folks heating with wood in drafty old farmhouses, that use much more than we do, and others who have small, tight homes that use less. And of course, the further south you go, the less heating degree days you have.

      Efficiency of your wood stove also enters into it. We have a Russian furnace, which is essentially a kind of masonry stove. The large mass of brick or stone absorbs more of the heat from the fire before exiting the flue, and radiates it for hours afterward. Some of the homemade stoves I've seen are cheap, but pretty inefficient.

      Stay warm!

  2. Hi Steve,

    Thanks for this information. I've been bringing in the firewood for next winter over the past few weeks and the job is mostly done - which is a relief. Do you use trucked in propane for part of your heating? Delivered here it is about $5.10 per gallon. Needless to say I heat entirely with firewood - including hot water (except for the summer when that is done by the solar panels) and I'm not entirely sure as it varies from year to year, but that takes about 3.9 cords for the entire season. A few years back I thought it was more, but we keep double the supply ready to hand - just in case. I have tens of thousands of hardwood trees and they grow very fast here, so over the years I've barely made a dent in the forest - and it needs thinning badly. I have no idea how people in cities may intend to heat their houses if energy costs continue to rise.


    1. Hi Chris;
      We try to heat was much was possible with wood, but aren't 100% yet. Our water is heated with electricity (!!) from the grid, and my project to install solar water heating has drug on, but maybe this next summer. We have backup propane heat, with circulating water tubing in the concrete floor, and a high efficiency boiler, but I try to keep it from ever coming on. It seldom does, except for this week. -25F predicted for tonight!

      Once we get the water heating off the grid, we might consider going off grid, but even if we don't, a huge improvement in our carbon footprint and less cost.

      It would be interesting to know how much mass your trees put on each year. You have a longer growing season than here, but maybe less water? And some species just grow faster. Anyway, sounds like you have plenty.

  3. Hi Steve,

    Yeah, the solar hot water tubes bursting in the sort of weather that you are experiencing is no joke at all, and I'd look around the area to see what systems actually work in your weather before committing. If the power went (to circulate water through the tubes in the solar hot water heater) out during a hard freeze, then that could be a problem. My system is a drain back system, but even so not all of the water escapes and when it gets below zero'C the system wastes hot water by sending it through the solar hot water panels. My solution to this was to get a larger wood boiler 25kW that sits inside the house. Bizarrely it uses less wood than the previous heater - which had an oven (which I miss). After the loss of the oven I had to beef up the solar electric to cope with the electric oven during winter. Mate this game is like whack a mole!!!

    The trees grow at least 1m (3.3ft) per year, and this year due to the good rain up until New Years Day, they have just sky rocketed. Even the well established fruit trees have exceeded 1m growth this season. My main water usage is the vegetables and berries.