Overview
ISO/TR 52120-2:2021 is a technical report that explains and justifies the normative requirements of ISO 52120‑1. It consolidates informative content to help users correctly understand, apply and nationally adapt the ISO 52120 series on the energy performance of buildings and the contribution of building automation, controls and building management (BAC / TBM / BACS). The report is an explanatory companion to the Part 1 framework and provides background, rationale, worked examples and an accompanying spreadsheet to support implementation.
Key topics and technical content
- Scope and purpose: Clarifies how BAC and TBM influence building energy performance and supports correct adoption of ISO 52120‑1.
- Method descriptions: Two calculation approaches are described:
- Method 1 - detailed impact assessment (time-step based, assumptions and calculation inputs).
- Method 2 - BACS factor method (simplified factor-based approach).
- BAC function descriptions: Informative detail on control functions across systems:
- Heating, domestic hot water (DHW), cooling
- Ventilation and air-conditioning
- Lighting and blind/shade control
- Control characteristics:
- Control accuracy: role of sensor/actuator precision and setpoint deviation; links to standards for CA definitions.
- Control function and strategy: functions such as interlock (prevent simultaneous heating/cooling), operation modes (comfort, pre-comfort, economy, frost protection) and intermittence strategies.
- Data and calculation guidance: Time steps, input data, simplified inputs, assumptions, and calculation information needed to quantify BAC/TBM impact.
- Method selection and worked examples: Guidance to choose the appropriate method and sample calculations to illustrate use.
- Supporting material: Information about the accompanying spreadsheet and references to related normative documents.
Practical applications and users
ISO/TR 52120-2 is useful for:
- Energy assessors and modelers quantifying BAC/BMS effects on building energy performance
- HVAC and BMS engineers specifying control functions and evaluating control accuracy
- Facility managers and building owners optimizing operations and commissioning BACS/TBM
- Regulators and standards bodies adapting ISO 52120‑1 for national EPB (Energy Performance of Buildings) regulations
- Consultants preparing compliance reports or lifecycle energy analyses
Practical uses include estimating energy savings from control upgrades, selecting appropriate calculation methods (detailed vs factor), and documenting justification for BACS-related energy performance credits.
Related standards
- ISO 52120-1 - Part 1: General framework and procedures (normative companion)
- ISO 52000-1 - Overarching EPB assessment framework
- ISO 7345 - Thermal performance terminology and definitions
- References to EN standards (e.g., EN 15500‑1) are used for control accuracy and operation mode definitions.
Keywords: ISO/TR 52120-2, ISO 52120‑1, building automation, building controls, building management, BACS, TBM, energy performance of buildings, control accuracy, BACS factor method.
Open preview (PDF)Energy performance of buildings — Contribution of building automation, controls and building management — Part 2: Explanation and justification of ISO 52120-1