Heating your home with firewood should be economical as well as cosy. With changing fuel prices across the UK, wood-burner owners are looking closely at value for money. Silver birch has long dominated retail shelves as the premium fast-lighting wood. Yet kiln-dried alder has quietly emerged as an efficient, budget-friendly contender.

As explored in our main comparison, Alder or Birch? The Ultimate Duel Between Fast-Burning Logs, both species light effortlessly. But when you break down heat output against purchase price, which log actually gives you more kilowatt-hours (kWh) per pound spent?

Understanding Calorific Value by Weight

A common misconception in firewood shopping is that heavier logs contain more energy by weight. In pure physics, all dry wood species deliver roughly the same heat output per kilogram. Completely dry wood cellulose yields approximately 5.2 to 5.3 kilowatt-hours of potential energy per kilogram.

When firewood is kiln-dried to under 20% moisture content, both alder and silver birch deliver around 4.1 to 4.3 kWh per kilogram of usable thermal energy. The difference lies in wood density:

• Silver Birch: Roughly 650 kg per solid cubic metre (air-dry density).
• Common Alder: Roughly 490 to 510 kg per solid cubic metre.

Birch packs more weight into the same physical volume. However, firewood retailers usually sell logs by volume (cubic-metre crates or bulk bags) or by pallet weight. That distinction changes the true cost equation.

The Brand Premium on Silver Birch

Silver birch enjoys massive brand recognition in Britain. People know the white bark. They know it lights easily. Because demand is high, timber suppliers charge a premium for birch crates. In contrast, alder is widely harvested across sustainable European river basins and woodlands, facing less retail competition.

A 1.2 cubic-metre crate of kiln-dried silver birch often sells for 10% to 18% more than an identical volume crate of kiln-dried alder. While the birch crate contains slightly more total mass, you are often paying disproportionately more for the familiar name and the decorative white rind. To learn about the differences in how their barks behave in the fire, read Bark, Sparks and Heat: Real Differences Between Alder and Silver Birch.

Calculating Real-World Heat Costs

Let us look at standard stove performance. Suppose you pay £210 for a standard crate of kiln-dried alder containing roughly 440 kg of wood. At 4.2 kWh per kg, that crate holds 1,848 kWh of energy. The raw cost sits around 11.3 pence per kWh of thermal energy.

A comparable birch crate might cost £245 for 510 kg of wood. At the same calorific output, it holds 2,142 kWh of energy. The cost works out to roughly 11.4 to 11.8 pence per kWh. On paper, the unit price looks close. In daily practice, however, birch tends to burn off its volatile oils much faster. If you want to know how quickly that energy warms your room, see Which Log Warms a Chilly Living Room Faster? Alder vs Birch.

Efficiency in Everyday Heating Cycles

The true cost of firewood is decided by how you burn it. Most UK households do not heat their homes twenty-four hours a day with wood. Instead, they light a fire between 6:00 pm and 10:30 pm on weekday evenings.

In a four-hour evening window, burning heavy, expensive logs can waste heat after you go to bed. Birch creates a fiery peak that may force you to choke stove air vents down. Choking vents drops stove combustion efficiency below 65%, wasting fuel up the chimney as smoke. Alder, with its moderate density, burns steadily at normal vent openings, keeping stove efficiency at 78% or higher. You extract more actual heat per log into your living space.

The Bottom Line

When evaluated strictly on heat delivered to your room per pound spent, alder frequently wins. It avoids the retail markup attached to silver birch while offering identical lighting ease and clean combustion. For practical, cost-conscious homeowners, alder represents outstanding value across the heating season.