ISO 10077-1:2017

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 10077-2 (frame and junction calculation details)
• ISO 12567-1 / ISO 12567-2 (whole-window testing)
• EN 673, EN 674, EN 675 (glazing U-value methods)
• ISO 6946, ISO 10211, ISO 8301 / ISO 8302 (opaque elements and heat transfer)
• EN 12412-2 (frame measurement)
• ISO/TR 52022-2 (technical report supporting EPB harmonization)

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.