4 Determination of Carbon Content in Wood and Wooden Products
4.1 Carbon content of wood
The carbon content of wood is 0.5.
4.2 Carbon content of wooden products
The carbon content (fC) of wooden products is calculated according to the formula (1).
Where:
Mwood,0 —— The absolute dry mass of wood contained in the wooden product (excluding the absolute dry mass of non-wood components such as adhesives), unit: kg;
M0 —— The absolute dry mass of the wooden product (including the absolute dry mass of non-wood components such as adhesives), unit: kg;
fC —— Carbon content of wooden products.
An example of calculation is given in Appendix B, Example 2.
5 Requirements for Determination of Absolute Dry Mass (M0) of Wood and Wooden Products
5.1 Measurement of Absolute Moisture Content (ω)
The measurement of absolute moisture content of wood shall be conducted according to GB/T 1927.4—2021, while the measurement of absolute moisture content of wooden products shall be carried out in accordance with GB/T 17657—2022, Section 4.3.
5.2 Measurement of Mass (Mω)
The mass (Mω) of wood or wooden products is directly measured by weighing.
According to GB/T 1927.5—2021, the density (ρω) and volume (Vω) of wood are determined; according to GB/T 17657—2022, Section 4.2, the density (ρω) and volume (Vω) of wooden products are measured.
The mass (Mω) of wood or wooden products at an absolute moisture content of ω is calculated using formula (2):
Where:
Mω —— The mass of wood or wooden product under an absolute moisture content of ω, unit: kg;
ρω —— The density of wood or wooden product under an absolute moisture content of ω, unit: kg/m3;
Vω —— The volume of wood or wooden product under an absolute moisture content of ω, unit: m3.
5.3 Calculation of Absolute Dry Mass of Wood and Wooden Products
5.3.1 Direct Calculation Method
The absolute dry mass (M0) of wood or wooden products is calculated using the absolute moisture content (ω) and mass (Mω), as follows:
Where:
M0 —— The absolute dry mass of wood or wooden product, unit: kg;
Mω —— The mass of wood or wooden product under an absolute moisture content of ω, unit: kg;
ω —— Absolute moisture content of the wood.
5.3.2 Indirect Calculation Method
If the moisture content and density of wood are unknown, reference values can be used for 12% moisture content conditions with the air-dry density of wood at 12% moisture content as a reference value according to formulas (2) and (3). The air-dry densities of major Chinese tree species under 12% moisture content can be found in Appendix A. Other possible methods may also be used to determine the absolute dry mass, such as calculating the product of green volume and basic density for live standing wood or freshly cut logs. Basic densities of major Chinese tree species are provided in Appendix A.
6 Calculation of Biomass Carbon Storage and Conversion to Biogenic CO2
6.1 Calculation of Biomass Carbon Storage
The biomass carbon storage of wood and wooden products is calculated according to formulas (4) and (5).
Where:
PC —— The biomass carbon storage of wood or wooden product, unit: kg;
fC —— Carbon content of the wooden product;
M0 —— Absolute dry mass of wood or wooden product, unit: kg.
6.2 Calculation of Biogenic CO2
The biogenic CO2 is calculated according to formula (6).
Where:
PCO2 —— The biomass CO2 of wood or wooden product, unit: kg;
PC —— Biomass carbon storage of wood or wooden product, unit: kg.
An example of the calculation of the biogenic CO2 from the biomass carbon storage of wood and wooden products is given in Appendix B.
7 Reporting
The report should include at least the following information:
a) Standard implemented;
b) Carbon content of wood or wooden products and method of determination;
c) Absolute dry mass of wood or wooden products and method of determination;
d) Biomass carbon storage of wood or wooden products;
e) Conversion of biomass carbon storage to biogenic CO2;
f) Date of the report;
g) Name of the testing institution.
T/CNFPIA 2003-2023 history
2023T/CNFPIA 2003-2023 Calculation of the carbon storage in wood and wood-based products