Rated value of thermal conductivity (Source: ONORM B 8110-7)

1. Determination of measurement values

1.1 Insulation in accordance with harmonised European product standards
The measurement value for heat conductivity is to be determined in accordance with ÖNORM B 6015-5. It is determined from the fractile value for heat conductivity (90% fractile) by multiplying by the conversion factor for the moisture content Fm for the moisture state of equilibrium at 23°C and 80% relative humidity.
The conversion factor for the moisture content Fm is generally calculated from the moisture-conversion coefficients fu or fy and the moisture content u or ?, which originate from ÖNORM EN ISO 10456:2010, table 4.
The moisture conversion coefficients and the moisture contents must be specially determined for a specific insulation product, including from an accredited test centre in accordance with the respective harmonized European product standards.
The rounding must be in accordance with ÖNORM EN ISO 10456.

1.2 Insulating materials in accordance with a European Technical Approval
The determination of the measurement value for heat conductivity is done by multiplying the fractile value for heat conductivity (90% fractile) or limit value for heat conductivity with the conversion factor for moisture content Fm for the moisture state of equilibrium at 23°C and 80% relative humidity.
If, in a European Technical Approval, only the nominal value for heat conductivity based on the fractile value or limit value for heat conductivity is specified, the nominal value is divided by the conversion factor for the moisture content Fm based on the moisture state of equilibrium at 23°C and 50% relative humidity and subsequently multiplied with the conversion factor for the moisture content Fm based on the moisture state of equilibrium at 23°C and 80% relative humidity.

1.3 Insulating materials in accordance with an Austrian Technical Approval
The measurement value for heat conductivity is specified in the approval. The measurement value for heat conductivity in approvals, which were issued before November 2009, must be extensively checked, to verify whether due to the changed rules on determination, particularly the changed rounding rules, the value to date should be increased.

1.4 Insulating materials in accordance with national standards
The determination of the measurement value for heat conductivity is done by multiplying the fractile value for heat conductivity (90% fractile) with the conversion factor for the moisture content Fm for the moisture state of equilibrium at 23°C and 80% relative humidity.
The moisture conversion coefficients are to be taken from ÖNORM B 6015-2 or determined in accordance with ÖNORM B 6015-5.

1.5 Masonry
The designation and determination of measurement values must be conducted in accordance with ÖNORM EN 1745, ÖNORM B 3200 and ÖNORM EN ISO 10456. The measurement value for heat conductivity of the masonry (including material, brick geometry and joint section) is designated with ?design,mas, and determined with 50% fractile values.

1.6 Masonry and plaster
The measurement values for heat conductivity for masonry and plaster are designated in accordance with ÖNORM EN 1745 with ?design,mor. The fractile values for masonry and plaster are designated with ?10,dry,mor and can be taken from the tables of ÖNORM EN 1745:2012 or determined by the methods specified there.

1.7 Concretes
The measurement value for heat conductivity of concretes (particularly of concretes with lightweight aggregates and woodchip concrete) is designated with ?r and determined with the 50% fractile values.

1.8 Wood and engineered wood
The measurement value for heat conductivity is determined from the fractile value (50% fractile) of the measured heat conductivities (?10tr) multiplied by the conversion factor for the moisture content Fm based on the moisture state of equilibrium at 23°C and 80% relative humidity corresponding to ÖNORM
B 6015-2:2009, table 2.

1.9 Special construction materials
The heat conductivities for base materials were taken from ÖNORM EN 13370.
2 Statistics framework conditions
If no note for the fractile value for heat conductivity in the respective product standard for the trust tolerance interval to be used is specified, the following regulation applies:
For ?r = 0.08 W/(m × K) the 90% fractile applies; the calculated value is to be rounded to the nearest 0.001 W/m × K.
For ?r > 0.08 W/(m × K) the 50% fractile applies; the calculated value is to be rounded to the nearest 0.005 W/m × K.
During the calculations, no value must be rounded to lower than three decimal places

Source: ONORM B 8110-7 S. 5f

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