Because of its high density, black locust is rather hard to get ignited. The minimum radiation heat intensity necessary for ignition is 2.6 W/cm2. For designing structural fire resistance, the burning rate recommended for calculations is 1.0 mm/min for conifers, 1.3 mm/min for poplars, and a very favourable 0.5 mm/min for black locust.
According to our studies, the calorific value of oven-dry black locust in kJ/kg is :
- bark-free wood: 17 777
- bark 19 145
- bole (in bark) 18 047
- thick roots 17 223
Assuming a density of 700 kg/m3 (bark included), the volumetric calorific value is 12 633 MJ/m3, i.e., 2.5 tons (or 3.5 m3) of air-dry black locust wood would replace 1 ton heating oil. Due to its low initial moisture content, black locust needs to be stored as firewood for only one year, and it will not be damaged by fungi or insects if appropriately stored.