Stacked → solid m³

A stacked m³ includes air gaps; solid m³ is pure wood. Solidness factor: split 0.68–0.7, round 0.62, loose-poured 0.4–0.5. Sellers often sell a 'loose cubic meter' as a cube — it's really 0.4–0.5 m³ of wood. Heat value: oak/hornbeam ~2100 kWh/m³, pine ~1700, alder/aspen ~1400. Dry wood (20% moisture) gives twice the heat of green.