Overview
EN ISO 13789:2017 (ISO 13789:2017) defines a steady‑state calculation method and conventions for determining the transmission and ventilation heat transfer coefficients of whole buildings and parts of buildings. The standard is applicable to both heat loss (internal temperature higher than external) and heat gain (internal lower than external) situations and assumes the conditioned space is at a uniform temperature. Annex C provides a method to calculate temperatures in unconditioned spaces adjacent to conditioned zones. EN ISO 13789:2017 supersedes the 2007 edition and is part of the EPB (energy performance of buildings) standards referenced in ISO 52000‑1.
Key Topics
- Steady‑state calculation method for heat transfer coefficients (transmission and ventilation).
- Scope and conventions for whole‑building and component‑level assessments.
- Transmission heat transfer coefficient: methods for mean thermal transmittance, direct transmission, ground transmission, and transfer through unconditioned spaces.
- Ventilation heat transfer coefficient: conventions for air change rates and associated heat transfer.
- Input data and measurement rules: required inputs, dimensions measurement, boundaries of conditioned space, and calculation time intervals.
- Reporting requirements: standardized output, templates and data sheets (Annex A: template; Annex B: default choices).
- Annex C (normative): steady‑state method to compute temperature in unconditioned adjacent spaces.
- Symbols, definitions and conventions: standardized terminology and subscripts to ensure consistency.
Applications
EN ISO 13789:2017 is used by professionals involved in building energy performance and thermal assessment, including:
- Energy assessors and certifiers for building energy performance certification.
- Architects and building designers to estimate whole‑building heat transfer for compliance and design decisions.
- HVAC engineers and consultants for ventilation-related heat impact and sizing support.
- Retrofit planners and building owners assessing heat loss/gain and cost‑effective envelope upgrades.
- Simulation tool developers and researchers implementing standardized steady‑state methods and default conventions.
Practical uses include calculating whole‑building U‑equivalents, estimating heating/cooling loads under steady conditions, defining boundary conditions for more detailed dynamic simulations, and supporting compliance with regional EPBD requirements.
Related Standards
- ISO 52000‑1 (context and modular structure for EPB standards)
- Other EPB calculation standards and national implementations referenced within the EN ISO 13789:2017 documentation.
Keywords: EN ISO 13789:2017, ISO 13789:2017, transmission heat transfer coefficient, ventilation heat transfer coefficient, steady‑state calculation method, thermal performance of buildings, EPB standards, heat loss, heat gain.
