A fuel budget adds up what a household burns each year for cooking, heating, hot water and workshop use, which the parent article puts at 5-10 tonnes of air-dried wood, and divides it by the yield of an acre or hectare of coppice to find how much land is needed. Build the budget before planting, because a coppice takes years to give its first cut.
Part of Coppicing & Fuel Management
Working out how much fuel a household or group needs and how much coppice that takes, in three steps.
Three Steps
- Demand: how much fuel the household uses (Household Energy Needs).
- Supply per unit of land: the yield of the species you plan (Yield Calculations).
- Land: demand ÷ yield (Acreage Requirements), then top up from other fuels (Combining with Other Fuels).
Worked Example: One Household
Inputs from the parent’s table (air-dried wood a year): cooking 1-2 t, space heating 3-6 t, hot water 0.5-1 t, charcoal for the workshop 0.5-1 t.
- Low total = 1 + 3 + 0.5 + 0.5 = 5.0 t.
- High total = 2 + 6 + 1 + 1 = 10 t.
- At the parent’s yields of 3-5 t/ha/yr for hazel or oak: 5 ÷ 5 = 1 ha to 10 ÷ 3 = 3.3 ha.
That agrees with the parent’s 1-3 ha per family. The result is only as good as the yield: see the next articles for how much that varies.
What You Need
- A list of uses with a realistic estimate for each
- A set of yields you trust, ideally measured on your own land
- A calendar, because a new coppice gives nothing for years and the household must be bridged with other fuel
Common Mistakes
- Ignoring the start-up gap. Hazel’s first harvest is 7-9 years out, oak’s 15-20 (Coppicing & Fuel Management); budget other fuel meanwhile.
- Budgeting for a mild year. Plan for a hard winter.
- Forgetting that the land has other uses. Land in coppice is not growing food, and the budget should say what is given up.
Safety
Underbudgeted fuel means unsafe burning
A household that runs short may burn unseasoned or unsuitable material, which makes carbon monoxide and chimney tar, or may close the stove down to stretch the wood. Keep a reserve of seasoned wood, and do not burn painted, treated or unknown wood (Carbon Monoxide Risks).
What’s Next
- Learn next: Household Energy Needs — the demand side
- Combine with: Acreage Requirements — the land side