Overview - ISO 10077-1:2017 (Thermal performance of windows, doors and shutters)
ISO 10077-1:2017 defines the general method for calculating the thermal transmittance (U-value) of windows, pedestrian doors and shutters. Part 1 sets out scope, definitions, input data, calculation procedures, reporting requirements and templates used across the ISO/CEN EPB (energy performance of buildings) set of standards. The standard applies to assemblies composed of glazed and/or opaque panels fitted in frames, with or without shutters, and supports consistent evaluation of window thermal performance for design, certification and regulatory compliance.
Key topics and technical requirements
- Scope and output: Specifies the calculation output (overall U-value and related data) and applicable time intervals for dynamic calculations.
- Input data: Requires geometric and thermal characteristics for glazing, opaque panels, frames and junctions (e.g., dimensions, material conductivities, air space properties).
- Component approach: Thermal transmittance is evaluated from component parts:
- glazing thermal transmittance (EN 673; measurement EN 674/675),
- opaque panel transmittance (ISO 6946, ISO 10211; measurement ISO 8301/8302),
- frame transmittance (ISO 10077-2 or EN 12412-2; Annex F),
- linear thermal transmittance of frame–glazing junctions (Ψ, ISO 10077-2 or Annex G).
- Annexes and templates: Includes normative templates (Annex A) and default choices (Annex B) to ensure unambiguous application and national/regional adaptation. Normative annexes cover surface resistances, air space resistances, frame data and tabulated values for junctions.
- Reporting: Defines required contents of a test/calculation report and drawing conventions for reproducible results.
Practical applications and who uses it
ISO 10077-1 is used to:
- Evaluate and compare thermal performance (U-value) of window, door and shutter products.
- Support product development and optimization for thermal efficiency.
- Provide inputs for building energy simulations and compliance with energy codes.
- Produce standardized calculation reports for certification, tendering and regulatory approval.
Primary users:
- Window and door manufacturers and R&D teams
- Façade and building-envelope engineers
- Energy assessors and consultants
- Regulatory bodies and certification schemes
- Test laboratories performing or validating thermal calculations and measurements
Related standards (selection)
ISO 10077-1:2017 is essential for anyone needing consistent, traceable calculation of window and door thermal transmittance for energy-efficient design, product certification and regulatory compliance.
Open preview (PDF)Thermal performance of windows, doors and shutters — Calculation of thermal transmittance — Part 1: General