ISO 50046:2019

Overview

ISO 50046:2019 - "General methods for predicting energy savings" - provides standardized, measure-based (bottom-up) methods for calculating predicted energy savings (PrES) before implementation of energy performance improvement actions (EPIAs). The standard focuses on transparent, reproducible workflows for estimating savings at the action (unit) level and for aggregating those results into action plans, programmes or policies. It applies across all sectors, energy end‑uses and levels of aggregation and can express savings in primary or final/delivered energy.

Key technical topics and requirements

• Scope and method selection
  • Emphasizes measure-based (EPIA-based / bottom-up) approaches; excludes indicator-based and total-consumption-based methods (see ISO 17742 and ISO 50047).
  • Guides selection of an appropriate calculation method based on context, required accuracy and available resources.
• Three approved calculation approaches
  • Empirical estimation, statistical modelling, and engineering modelling - each suited to different data availability and accuracy needs.
• Baseline and prediction
  • Procedures for determining the energy baseline (EnB), selecting baseline periods, and calculating predicted energy consumption for the post‑implementation scenario.
• Aggregation and causality
  • Rules for aggregating PrES across multiple EPIAs and for assessing causal links between programmes/policies and individual measures.
• Quality, uncertainty, documentation and validation
  • Requirements and guidance for ensuring quality, estimating uncertainty, and documenting and validating assumptions, calculations and results.
• Stakeholder considerations
  • Addresses needs of diverse stakeholders-auditors, ESCOs, policy makers, equipment suppliers, and investors-and includes templates and case examples.

Practical applications and who uses it

ISO 50046 is practical for:

• Energy auditors and consultants preparing pre‑implementation savings estimates for retrofit projects.
• Energy service companies (ESCOs) and project developers for investment proposals and performance contracting.
• Facility managers and organizations selecting and prioritizing EPIAs based on predicted returns.
• Policy makers and programme designers forecasting savings from efficiency programmes and verifying aggregated claims.
• ** financiers and auditors** requiring documented, validated PrES for funding, accounting or crediting mechanisms (e.g., savings certificates).

Common uses include selecting measures, supporting investment decisions, designing energy efficiency portfolios, and producing credible, auditable estimates for regulatory compliance.

Related standards

• ISO 17742 - classification of measure‑based and indicator‑based methods
• ISO 50047 - total‑consumption/top‑down methods for organizations
• ISO 17743 / ISO 17741 - methodological framework and measurement/verification guidance
• ISO/IEC 13273-1 - energy terms and definitions

ISO 50046 is essential for anyone needing robust, transparent, and validated predicted energy savings estimates (PrES) that support investment, policy and procurement decisions in energy efficiency projects.