Is the ISO 8996:2021 heart rate method accurate for predicting metabolic rate? An experimental validation based on Chinese young adults
DOI number:
10.1016/j.buildenv.2025.113235
Abstract:
The ISO 8996:2021 standard proposes a heart rate (HR)-based method for estimating metabolic rate (MR), offering a cost-effective alternative to direct calorimetry. However, its validity across ethnicity and activity types remains underexplored. This study evaluates the accuracy of ISO 8996:2021 for Chinese young adults and proposes a refined prediction model. MR and HR data from 256 participants (141 males, 115 females; aged 20–30 years) were collected during office work, housework, walking, and exercise. Results show that ISO 8996:2021 improves prediction accuracy over the 2004 version for most activities, except walking and HR >120 bpm. However, larger errors persist for females during moderate-to-high-intensity activities (mean relative error, MRE: 32.4 % vs. 20.9 % for males). To address this, we calibrated ISO reference values using empirically measured resting metabolic rate (M0: 54 W/m² for females, 57 W/m² for males) and resting heart rate (HR0: 74–76 bpm), reducing prediction errors by 10–12 % across activity categories. Furthermore, a simplified HR-based MR prediction model was developed using three parameters: heart rate reserve (%HRR), HR0, and fat-free mass (FFM). This model achieved slightly higher accuracy than ISO 8996:2021 while requiring fewer inputs, making it suitable for large-scale field studies. The findings highlight the necessity of ethnic-specific calibration for ISO 8996 and provides practical insights for optimizing thermal comfort assessments in building environments. This work advances the applicability of HR-based MR prediction across diverse populations and supports energy-efficient, occupant-centric building design.
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