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ISO 25745-3:2015 – Energy Performance of Lifts — Measurement and Verification
Measurement and verification methods for lift energy performance assessment
1. Overview and Scope
ISO 25745-3:2015 specifies methods for the measurement and verification of energy performance of lifts (elevators), escalators, and moving walks. It establishes a standardized framework for assessing actual energy consumption against design specifications or baseline measurements. The standard covers both new installations and existing systems undergoing retrofit or performance improvement measures.
Energy performance verification is critical for green building certification schemes such as LEED and BREEAM. Lift systems can account for 2-10% of a building’s total energy consumption.
The verification process defined in this standard involves three key phases: pre-measurement planning, on-site data collection, and post-processing analysis. Measurements must account for variables including travel distance, load conditions, standby power, and regenerative energy recovery. The standard provides specific guidance on instrumentation accuracy requirements and measurement uncertainty evaluation.
| Parameter | Measurement Method | Accuracy Requirement |
|---|---|---|
| Running energy consumption | Power analyzer at main supply | ±2% of reading |
| Standby power | True RMS wattmeter | ±0.5 W |
| Travel distance | Encoded position sensor | ±1 mm |
| Load mass | Calibrated test weights | ±1% of rated load |
| Round-trip time | Digital timer / PLC log | ±0.1 s |
2. Measurement Procedures and Data Analysis
The standard defines a tiered approach to measurement. A basic assessment uses a minimum of 10 round trips at nominal load, while a comprehensive assessment requires measurements across multiple load conditions (0%, 25%, 50%, 75%, 100% rated load). For each load condition, a minimum of five round-trip measurements are required to establish statistical significance.
Statistical analysis reveals that a 5% reduction in standby power through optimized controller settings can yield annual savings of 500-1200 kWh per lift unit in typical commercial buildings.
Data analysis must include calculation of specific energy consumption (kWh/kg-km), standby power classification according to ISO 25745-1, and comparison with reference values. The standard recommends presenting results using energy performance indicators normalized by travel distance, rated load, and number of stops. Measurement reports must document all environmental conditions, instrumentation calibration status, and uncertainty budgets.
3. Engineering Design Insights
From an engineering design perspective, ISO 25745-3 highlights several critical considerations. First, measurement point selection significantly impacts results — upstream measurements at the main distribution board capture all auxiliary loads (controller, door operator, ventilation) while downstream measurements at the drive input isolate traction performance. Second, regenerative drive systems require bi-directional power measurement capability. Third, traffic pattern analysis (peak vs. off-peak) must be incorporated into the verification protocol.
Common pitfalls include failing to account for auxiliary loads (cabin lighting, ventilation fans, signaling systems) which can contribute 15-30% of total energy consumption. Always verify that measurement periods include representative standby intervals.
4. Frequently Asked Questions
Q: How long should the measurement period be?
A: Minimum 24 hours for comprehensive verification, capturing both peak and off-peak operation. Basic verification requires at least 10 round trips.
A: Minimum 24 hours for comprehensive verification, capturing both peak and off-peak operation. Basic verification requires at least 10 round trips.
Q: Can simulation replace on-site measurement?
A: No — simulation can complement but not replace actual measurement. ISO 25745-3 requires empirical verification data.
A: No — simulation can complement but not replace actual measurement. ISO 25745-3 requires empirical verification data.
Q: What is the acceptable measurement uncertainty?
A: Total combined uncertainty should be less than 5% at 95% confidence level (k=2).
A: Total combined uncertainty should be less than 5% at 95% confidence level (k=2).
Q: How often should verification be repeated?
A: Annually is recommended, or after any major component replacement or control system modification.
A: Annually is recommended, or after any major component replacement or control system modification.
