Overview
EN ISO 14683:2017 - "Thermal bridges in building construction - Linear thermal transmittance - Simplified methods and default values" is the 2017 CEN/ISO standard for assessing heat flows caused by linear thermal bridges at junctions of building elements. It provides simplified calculation approaches, requirements for thermal-bridge catalogues and manual methods, and includes default linear thermal transmittance (psi) values in the annexes for use where detailed data are not available. The standard is part of the EPB (energy performance of buildings) set used to support energy performance assessments and regulatory compliance across Europe.
Key Topics and Requirements
- Scope and intent
- Simplified methods to determine heat flows through linear thermal bridges (junctions between walls, floors, roofs, windows, etc.).
- Guidance to ensure consistency and transparency in energy performance calculations.
- Methods described
- Numerical calculations for detailed modelling.
- Thermal-bridge catalogues: standardized formats and requirements for reusable component data.
- Manual calculation methods for common junction types when numerical simulation is not available.
- Output and parameters
- Focus on linear thermal transmittance (ψ‑values) and their influence on overall heat transfer and transmission heat transfer coefficients.
- Documentation and templates
- Includes an input and method selection data sheet (Annex A) and informative default choices (Annex B). Default psi-values are provided in an annex (see Annex C in the ISO text).
- Accuracy and applicability
- Specifies available methods and discusses expected accuracy ranges and input data needs, allowing national or regional choices where required.
Applications
- Energy performance assessments and compliance with building energy regulations (EPBD-related methodologies).
- Early-stage design decisions for architects and building engineers to minimize thermal bridging and improve thermal insulation performance.
- Creation and use of thermal bridge catalogues by manufacturers, designers and certifiers.
- Manual or simplified calculations for retrofit projects, product selection, and certification where full 2D/3D numerical analysis is impractical.
- Input for building energy simulation tools where standardized psi-values or catalogue entries are needed.
Who Should Use This Standard
- Architects, structural and building services engineers
- Energy assessors and building certifiers
- Product manufacturers and façade/assembly designers
- Regulators and authorities adopting EPB standards or setting national parameters
Related Standards
- Part of the EPB (energy performance of buildings) series and developed in collaboration with CEN/TC 89 and ISO/TC 163. It supersedes previous editions (ISO 14683:2007) and supports harmonized energy performance calculation across member states.
Keywords: EN ISO 14683:2017, thermal bridges, linear thermal transmittance, psi-values, thermal bridge catalogues, simplified methods, energy performance of buildings, EPBD, CEN, ISO.
