Overview
ISO 10456:2007 - Building materials and products - Hygrothermal properties - Tabulated design values and procedures for determining declared and design thermal values - defines how to obtain, convert and tabulate thermal and moisture-related (hygrothermal) design values for thermally homogeneous building materials and products. It provides procedures to convert measured or declared properties between conditions, tabulated design data for common construction materials, and rules for rounding and statistical reporting. Conversion procedures are valid for design ambient temperatures between −30 °C and +60 °C, with temperature and moisture conversion coefficients valid for mean temperatures 0 °C to 30 °C.
Key topics and requirements
- Scope: Applies to thermally homogeneous materials and products used in building construction; supplies tabulated design hygrothermal values for heat and moisture transfer calculations.
- Declared vs. design values:
- Declared thermal value - expected value based on measured data at reference temperature/humidity, given for a stated fraction and confidence level and service life.
- Design thermal value - value used in building design under specific internal/external conditions.
- Test methods and conditions:
- Thermal tests: guarded hot plate (ISO 8302), heat flow meter (ISO 8301) or calibrated and guarded hot box (ISO 8990).
- Moisture tests: water vapour transmission per ISO 12572.
- Required test reporting: thickness, density, mean test temperature, moisture content, ageing/conditioning.
- Conversion procedures:
- Provides conversion coefficients for temperature and moisture, plus guidance on age effects and natural convection in insulation.
- Conversion equations allow recalculation of thermal conductivity and resistance from one set of conditions to another.
- Rounding and statistics:
- Rules for rounding declared and design values (detailed thresholds for thermal conductivity rounding).
- Annex C offers statistical guidance and references for deriving single-value estimates.
- Tabulated data and annexes:
- Clause 8 supplies tabulated design thermal and moisture values (based on reviewed sources such as EN 12524).
- Annex A contains conversion data for extruded polystyrene (XPS) and polyurethane (PU).
- Annex B includes calculation examples.
Applications and users
ISO 10456:2007 is used by:
- Building physicists, thermal engineers and energy modelers for heat and moisture transfer and energy-performance simulations.
- Product manufacturers and test laboratories for declaring thermal values and creating product data sheets.
- Architects, specifiers and contractors selecting materials for thermal insulation and hygrothermal performance.
- Regulators and product standards committees for harmonized reporting and compliance.
Practical uses include converting measured properties to design conditions, sourcing tabulated material values when measurements are unavailable, and ensuring consistent rounding/statistical practice.
Related standards
Keywords: ISO 10456, hygrothermal properties, declared thermal value, design thermal values, conversion coefficients, thermal conductivity, thermal resistance, building materials, heat and moisture transfer.
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