ISO 14683:2017

Overview - ISO 14683:2017 (Thermal bridges, linear thermal transmittance)

ISO 14683:2017 provides simplified methods and default values for assessing the effect of linear thermal bridges at junctions of building elements. It is part of the EPB (Energy Performance of Buildings) standards suite and is intended to support consistent, transparent evaluation of how thermal bridges influence heat flows and energy performance without always requiring full numerical modelling.

Key outputs of the standard include a recommended approach to determine the linear thermal transmittance (psi‑value) for common junctions, requirements for thermal‑bridge catalogues, and template data sheets (Annex A/B) plus a set of informative default values (Annex C).

Key topics and requirements

• Scope and purpose: Simplified determination of heat flows through linear thermal bridges occurring at element junctions.
• Methods covered: Guidance on available approaches - from manual calculation methods and catalogues to when numerical calculations are appropriate.
• Input and output data: Specification of required input data, output (linear thermal transmittance), and calculation time intervals.
• Thermal bridge catalogues: Requirements for cataloguing typical details and using tabulated psi‑values for recurring junctions.
• Default values: Annex C provides default psi‑values to be used where detailed calculation is not required or practical.
• Template for choices: Annex A (normative) and Annex B (informative default choices) help harmonize application and national/regional adaptation.
• Accuracy and applicability: The standard describes expected accuracy for each method and guidance on method selection.

Practical applications

• Performing building energy performance assessments (EPB) where thermal bridges affect transmission heat loss.
• Producing or using thermal‑bridge catalogues for common construction details to speed up modelling and compliance checks.
• Providing default psi‑values for designers, energy assessors and regulators when full 2D/3D thermal bridge modelling (ISO 10211) is not feasible.
• Supporting regulatory compliance, energy certification and early‑stage design decisions to reduce heat loss and avoid condensation risks.

Who should use it

• Architects and building designers for detail selection and early thermal performance estimates.
• Thermal performance engineers and energy assessors for energy calculations and certification.
• Regulators and standards bodies when specifying default national or regional choices for energy compliance.

Related standards (for reference)

• ISO 10211 - Detailed numerical calculations for thermal bridges
• ISO 52000‑1 - EPB assessment framework
• ISO 7345, ISO 13370, ISO 13789 - Related thermal and heat‑transfer definitions and methods
• ISO 6946 - Treatment of repeating thermal bridges in element U‑value calculations

Keywords: ISO 14683:2017, thermal bridges, linear thermal transmittance, psi‑value, simplified methods, default values, thermal bridge catalogues, building energy performance.